WO2005088888A1 - データ受信装置及びデータ受信方法 - Google Patents
データ受信装置及びデータ受信方法 Download PDFInfo
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- WO2005088888A1 WO2005088888A1 PCT/JP2005/001459 JP2005001459W WO2005088888A1 WO 2005088888 A1 WO2005088888 A1 WO 2005088888A1 JP 2005001459 W JP2005001459 W JP 2005001459W WO 2005088888 A1 WO2005088888 A1 WO 2005088888A1
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Classifications
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- H04N21/40—Client devices specifically adapted for the reception of or interaction with content, e.g. set-top-box [STB]; Operations thereof
- H04N21/43—Processing of content or additional data, e.g. demultiplexing additional data from a digital video stream; Elementary client operations, e.g. monitoring of home network or synchronising decoder's clock; Client middleware
- H04N21/434—Disassembling of a multiplex stream, e.g. demultiplexing audio and video streams, extraction of additional data from a video stream; Remultiplexing of multiplex streams; Extraction or processing of SI; Disassembling of packetised elementary stream
- H04N21/4344—Remultiplexing of multiplex streams, e.g. by modifying time stamps or remapping the packet identifiers
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- H04J3/062—Synchronisation of signals having the same nominal but fluctuating bit rates, e.g. using buffers
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- H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
- H04N21/23—Processing of content or additional data; Elementary server operations; Server middleware
- H04N21/236—Assembling of a multiplex stream, e.g. transport stream, by combining a video stream with other content or additional data, e.g. inserting a URL [Uniform Resource Locator] into a video stream, multiplexing software data into a video stream; Remultiplexing of multiplex streams; Insertion of stuffing bits into the multiplex stream, e.g. to obtain a constant bit-rate; Assembling of a packetised elementary stream
- H04N21/23608—Remultiplexing multiplex streams, e.g. involving modifying time stamps or remapping the packet identifiers
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- H04N21/44—Processing of video elementary streams, e.g. splicing a video clip retrieved from local storage with an incoming video stream or rendering scenes according to encoded video stream scene graphs
Definitions
- the present invention relates to a data receiving device and a data receiving method for receiving video / audio data such as a transport stream (TS) in a Motion Picture Experts Group (MPEG) 2 system, for example.
- TS transport stream
- MPEG Motion Picture Experts Group
- a data transmission system that wirelessly transmits a stream such as a TS.
- a TS output from a coding device in a data recording / reproducing device is transmitted to a digital tuner built-in television (TV) via a wireless network (including a wireless transmitting device and a wireless receiving device).
- TV digital tuner built-in television
- the wireless transmission device performs packet transmission on the TS transmitted via a wired network (for example, a network conforming to the IEEE 1394 standard), and the encoding device in the data recording / reproducing device. It transmits to the wireless receiver via the wireless network.
- the wireless receiver restores the received TS packet and sends it to the TV with a built-in digital tuner via a wired network (for example, a network conforming to the IEEE1394 standard).
- the decoding device in the TV with a built-in digital tuner decodes the received TS.
- a PCR Program clock reference
- STC System Time Clock
- TS packets including PCR must be transmitted at least once every 100 ms. For this reason, for a TS including a PCR, its jitter needs to be suppressed to several tens / z s (for example, 50 ⁇ s) or less.
- FIGS. 33A to 33C are diagrams for explaining a conventional data transmission method.
- FIG. 33 (a) illustrates the timing at which TS-0 to TS-17 packets are input to the wireless transmission device, and also includes TSs including PCRs (ie, TS-0, TS-5, and TS-13). Are indicated by arrows.
- FIG. 33 (b) shows the timing at which a TS knocket (from TS-0 packet to TS-10 packet is shown) is transmitted from the wireless transmission device to the wireless reception device.
- FIG. 33 (c) shows the timing at which the reception TS (TS-0 to TS-7 are shown) is output from the wireless reception device. As shown in FIGS.
- the wireless receiving device outputs the TS from the wireless transmitting device with a delay of a certain data delay amount.
- the jitter amount of the delayed received TS needs to be within a predetermined range. Therefore, for example, an ATM (Asyncronous Transfer Mode) is used (for example, see Patent Document 11). 4).
- Patent Documents 1 to 4 describe a communication method based on an SRTS (Synchronous Residual Time Stamp) method and a communication method based on an adaptive clock method.
- the SRTS method is a method used when a common clock on the transmitting side and the receiving side for communication can be referred to.
- the transmitting side measures the common clock at the interval of the fixed data transfer rate information for every N bits, and inserts only the part of the measured value whose value changes due to the transmission clock frequency fluctuation as synchronous timestamp residual information into the packet. To send.
- the receiving side reproduces the interval of N-bit fixed speed information from the transmitted synchronous time stamp residual information and the common clock, and reproduces the clock based on this interval.
- the adaptive clock method uses
- the fixed speed information stored in the received packet is stored in a buffer, and the read clock information of the buffer is controlled so that the stored information amount holds a reference value.
- Patent Document 1 Japanese Patent Application Laid-Open No. Hei 9 214477
- Patent Document 2 JP-A-7-46257
- Patent Document 3 JP-A-9-36846
- Patent Document 4 JP-A-5-210914
- Patent Document 5 JP-A-11 317768 (FIGS. 1 and 2)
- the clock recovery method disclosed in the above-mentioned Patent Documents 1 to 4 has a fixed bit rate. It is assumed that data is transmitted and received at a constant bit rate (CBR). When data is transmitted and received at a variable bit rate (VBR), an appropriate clock can be reproduced. There is a problem.
- CBR constant bit rate
- VBR variable bit rate
- the data transmission method disclosed in Patent Document 5 can cope with VBR data transmission, but since it is a method in which additional information is added to a valid packet for transmission, it is not applicable to wireless transmission. There is a problem that the throughput is reduced. It should be noted that the network bandwidth is similarly squeezed by wire. Further, in the data transmission method disclosed in Patent Document 5, it is necessary for the receiving device to store the valid packet and the invalid packet added based on the additional information in the buffer, which increases the circuit scale of the receiving device, There is a problem that control of the receiving device becomes complicated.
- Patent Documents 115 it is basically assumed that the receiving device is connected one-to-one with the transmitting device (peer-to-peer connection).
- the wireless receiver 111 needs to receive the TS output from the plurality of wireless transmitters 110. is there.
- N-to-1 or N-to-M connection is assumed (N and M are integers of 2 or more, respectively).
- N and M are integers of 2 or more, respectively.
- Patent Document 2 adopts a configuration in which the system clock is PLL-applied according to the remaining memory to perform clock recovery on the receiver side, and Patent Document 4 applies a gate to the clock signal to reproduce the clock. Therefore, there is a problem that it is not possible to perform clock recovery for each TS transmitted from a plurality of transmitters. Also, in Patent Document 5, there is a problem that the transmission throughput of the TS is deteriorated in order to flow new additional information on the network in order to support VBR.
- the present invention has been made to solve the above-described problems of the related art, and an object of the present invention is to suppress the decrease in throughput and the complexity of a reception circuit while suppressing the reception side memory.
- An object of the present invention is to provide a data receiving apparatus and a data receiving method capable of continuously outputting data without causing an underflow. Means for solving the problem
- a data receiving device of the present invention is a data receiving device that receives packet data via a transmission path and outputs the packet data based on time information previously added to the packet data, Storage means for storing the received packet data; control means for separating the time information added to the received packet data, and for reading the packet data from the storage means based on the separated time information; When the reading timing is generated by the control means, based on the integration result of the amount of received packet data temporarily stored in the storage means and the measurement result of the integration period of the integration, Calculate the deviation of the clock frequency between the data transmitting device and the data receiving device, and add the offset amount based on the deviation to the read timing of the received packet data. And it generates a read timing of the serial received packet data.
- the data receiving method of the present invention is a data receiving method for receiving packet data via a transmission path and outputting the packet data based on time information previously added to the received packet data. Temporarily storing the received packet data in storage means; separating the time information added to the received packet data; and storing the time information added to the received packet data based on the separated time information. Reading out the packet data in the step of reading out the packet data, when the readout timing is generated, the integration result of the amount of the received packet data temporarily stored in the storage means and the integration period of the integration Based on the measurement result, the deviation of the clock frequency between the data transmitting device and the data receiving device is calculated, and The offset timing based on the above deviation is added to the read timing to generate the read timing of the received packet data.
- the data receiving device or the data receiving method of the present invention when generating the readout timing, the integration result of the amount of the received packet data temporarily stored in the storage means and the measurement result of the integration period of this integration Based on the (measurement time and number of received packets processed), calculate the deviation of the clock frequency between the data transmitting device and the data receiving device, and calculate the offset amount based on the calculated deviation at the timing of reading the received packet data. Adding Since the read timing of the received packet data is generated by this, the effect that the jitter of the TS can be suppressed to a predetermined value or less can be obtained.
- FIG. 1 is a diagram schematically showing a configuration of a data transmission system that implements a data receiving method according to Embodiments 17 of the present invention.
- FIG. 2 is a block diagram schematically showing a configuration of a radio transmitting apparatus according to Embodiments 17 to 17.
- FIG. 3 is a block diagram schematically showing a configuration of a transmission side memory control circuit in the wireless transmission device shown in FIG. 2.
- FIG. 4 is an explanatory diagram of a TS to which a time stamp is added.
- FIG. 5 is a block diagram schematically showing a configuration of a wireless reception device (data reception device) according to Embodiments 17 to 17.
- FIG. 6 is a block diagram schematically showing a configuration of a reception side memory control circuit in the wireless reception device shown in FIG. 5.
- FIG. 7 is a diagram for explaining a storage area of a memory in the wireless reception device shown in FIG.
- FIG. 8 is a block diagram schematically showing a configuration of a TS data read timing generation circuit in the reception side memory control circuit shown in FIG. 6.
- FIG. 9 is a block diagram schematically showing a configuration of a TS memory read control circuit in the reception side memory control circuit shown in FIG. 6.
- FIG. 10 is a flowchart showing an operation of the receiving-side memory control circuit shown in FIG. 6.
- FIG. 11 is a flowchart showing a clock jitter detection operation of the wireless reception device according to the first embodiment.
- FIG. 12 is a flowchart showing an operation of calculating and setting a target value in the flow shown in FIG. 11.
- FIG. 13 is a diagram showing a change in the amount of data stored in a memory in the radio reception device when a TS of the radio reception device VBR according to the seventeenth embodiment is received.
- FIG. 14 shows a case where the data transmission system according to the embodiment 17 has clock jitter.
- FIG. 7 is a diagram showing a change in a data amount stored in a memory in the wireless receiving device.
- FIG. 15 is a diagram illustrating a conversion table held by the wireless reception device in the first embodiment to calculate a clock jitter correction value.
- FIG. 16 is a flowchart showing a clock jitter detection operation of the wireless reception device according to the second embodiment.
- FIG. 17 is a diagram showing a table used for selecting a conversion table by the wireless reception device according to the second embodiment.
- FIG. 18 is a diagram illustrating a conversion table used by the wireless reception device in the second embodiment to calculate a clock jitter correction value.
- FIG. 19 is a flowchart showing a clock jitter detection operation of the wireless reception device according to the third embodiment.
- FIG. 20 is a flowchart showing an operation of calculating and setting an initial value in the flow of FIG. 19.
- FIG. 21 is a flowchart for explaining the operation of clock jitter correction (clock jitter value calculation) of the flow shown in the flow of FIG. 19.
- FIG. 22 is a flowchart illustrating an operation of calculating a clock jitter correction value in the flow shown in the flow of FIG. 21.
- FIG. 23 is a flowchart for explaining a convergence determination operation of a clock jitter correction value when calculating a clock jitter value of the flow shown in the flow of FIG. 21.
- FIG. 24 is a diagram showing an example of a measurement time used in each correction value calculation stage of Embodiment 3, a threshold table used for convergence determination, and the like.
- FIG. 25 is a diagram illustrating an example of a conversion table used by the wireless reception device in the third embodiment to calculate a clock jitter correction value.
- FIG. 26 is a flowchart illustrating an operation of a clock jitter correction value according to the fourth embodiment of the flow shown in the flow of FIG. 21.
- FIG. 27 is a flowchart illustrating a convergence determination operation of a clock jitter correction value in calculating a clock jitter value according to the fourth embodiment of the flow shown in the flow of FIG. 21.
- FIG. 28 is a diagram showing an example of a measurement time used in each correction value calculation stage of Embodiment 4, a threshold table used for convergence determination, and the like.
- FIG. 29 is a flowchart illustrating an operation of a clock jitter correction value according to the fifth embodiment of the flow shown in the flow of FIG. 21.
- FIG. 30 is a flowchart illustrating an operation of clock jitter correction (clock jitter value calculation) according to the sixth embodiment of the flow shown in the flow of FIG. 19.
- FIG. 31 is a flowchart for explaining the operation of clock jitter correction (clock jitter value calculation) according to the seventh embodiment of the flow shown in the flow of FIG. 19.
- FIG. 32 is a flowchart illustrating an operation of clock jitter correction (clock jitter value calculation) according to a modification of the seventh embodiment of the flow shown in the flow of FIG. 19.
- FIG. 33 (a) One (c) is a diagram for explaining a conventional data transmission method, (a) is a diagram showing a timing at which a TS including a PCR is input to a radio transmission apparatus, (b) is a diagram showing a timing at which a TS packet is transmitted to the wireless receiving device, and (c) is a diagram showing a timing at which the received TS is output to the wireless receiving device.
- FIG. 34 is a diagram for explaining a configuration of a conventional TS wireless transmission system.
- FIG. 1 is a diagram schematically showing a configuration of a data transmission system that performs a data receiving method according to Embodiment 1 of the present invention.
- the data transmission system shown in FIG. 1 has a first wired network 10, a second wired network 20, and a third wired network 30.
- the first, second, and third wired networks 10, 20, and 30 also constitute a wireless network compliant with the IEEE802.11a standard (wireless LAN) that can perform wireless communication with each other, and the entire configuration shown in FIG. Constitutes a home network.
- the first wired network 10 includes a wireless transmission / reception device (A) 11, a liquid crystal television (liquid crystal TV) 12, and a DVD (digital versatile disc) recorder (DVD recording / reproducing device) 13, for example, according to the IEEE1394 standard. It is configured by wired connection in a system conforming to the standard.
- the second wired network 20 includes a wireless transmission / reception device (B) 21, an AV-HDD recording / playback device (audio-visual 'node disk drive recording / playback device) 22, and a D-VHS (data / video home system).
- the recording / reproducing device 23 is configured to be connected to the recording / reproducing device 23 in a wired manner, for example, in accordance with the IEEE1394 standard.
- the third wired network 30 is configured by connecting the wireless transmitting / receiving device (C) 31, the television (TV) 32, and the set-top box (STB) 33 by, for example, a wired connection according to the IEEE1394 standard. It is configured.
- FIG. 1 shows an example of a system configuration to which the data receiving method and the data receiving device of the present invention can be applied.
- the data receiving method and the data receiving device of the present invention Also applicable to
- Each of the wired networks 10, 20, and 30 conforming to the IEEE1394 standard is a jitter-free network.
- a wireless network conforming to the IEEE 802.11a standard is a network having jitter.
- three wired networks 10, 20, and 30 conforming to the IEEE 1394 standard shown in FIG. 1 are configured to be capable of wireless communication by a system conforming to the IEEE 802.11a standard.
- the liquid crystal TV 12 in the first wired network 10 is connected to the wireless transceiver 31 and the wireless transceiver 11 (ie, from the STB 33 in the third wired network 30). , Wireless network) And the DVD recorder 13 in the first wired network 10 transmits the content recorded on the AV-HDD recording / reproducing device 22 in the second wired network 20 to the wireless transmission / reception device.
- the case of receiving and recording via the wireless transmission / reception device 21 and the wireless transmission / reception device 11 that is, a wireless network
- the wireless transceiver 11 on the receiving side is synchronized with the second wired network 20 to which the wireless transceiver 21 on the transmitting side belongs and the third wired network 30 to which the wireless transceiver 31 on the transmitting side belongs. Need to be regenerated (ie, clock synchronized).
- VBR variable code rate
- each of the radio transmission / reception device 11, the radio transmission / reception device 21, and the radio transmission / reception device 31 has a function as a radio transmission device 40 shown in FIG. 2 described later and a function shown in FIG. 5 described later. It has both functions as the wireless transmission device 50.
- FIG. 2 is a block diagram schematically showing a configuration of radio transmitting apparatus 40 according to the first embodiment.
- the wireless transmitting device 40 is a wireless transmitting circuit provided in each of the wireless transmitting and receiving devices 11, 21, and 31 shown in FIG.
- the wireless transmission device 40 includes an input terminal 41 for receiving a TS transmitted by a wired network power conforming to the IEEE 1394 standard, and an input terminal for receiving a TS control signal indicating a head of the TS, a signal area, and the like.
- a terminal 42 a CPU (Central Processing Unit) 43 for controlling the entire wireless transmission device 40, a transmission side memory control circuit 44, a memory 45, a wireless LAN (Local Area Network) module 46, and a CPU bus 47.
- the transmission-side memory control circuit 44 attaches a time stamp to the TS input via the input terminal 41 and stores the time-stamped TS (hereinafter also referred to as “TS with time stamp”) in the memory 45. Write to. Further, the transmission-side memory control circuit 44 reads the TS with time stamp stored in the memory 45 based on the control signal input from the CPU 43.
- the wireless LAN module 46 has a memory 45 The time-stamped TS with the read power is transmitted wirelessly.
- FIG. 3 is a block diagram schematically showing a configuration of the transmission side memory control circuit 44 in the wireless transmission device 40 shown in FIG.
- the transmission-side memory control circuit 44 includes a timestamp generation circuit 441, a timestamp-added circuit 442, a TS memory write control circuit 443, and a bus arbiter circuit 444.
- the time stamp generation circuit 441 generates a time stamp (time information) to be added to the TS input from the input terminal 41 using the reference clock of the wireless transmission device 40.
- the time stamp generating circuit 442 adds the time stamp generated by the time stamp generating circuit 441 to the TS.
- the TS memory write control circuit 443 based on the TS control signal input from the input terminal 42, writes a time-stamped TS output from the time-stamped TS 442 to the memory 45, etc. Generates a control signal.
- the bus arbiter circuit 444 includes a TS write control signal (TS write request) to the memory 45 output from the TS memory write control circuit 443 and a TS read control signal (TS read request) from the memory 45 output from the CPU 43.
- FIG. 4 is an explanatory diagram showing an example of a signal format of a time-stamped TS transmitted wirelessly in the data transmission system of the first embodiment.
- a TS packet is composed of 188 bytes, and each TS is prefixed with a 4-byte time stamp! /.
- the TS input to the input terminal 41 is added with a time stamp by the transmission side memory control circuit 44 and stored in the memory 45.
- the time-stamped TS stored in the memory 45 is read from the memory 45 based on the memory read control signal output from the CPU 43, and is input to the wireless LAN module 46.
- the wireless LAN module 46 adds a header for wireless transmission to the input TS with a time stamp, performs packet filtering, and wirelessly transmits the TS to another wireless transmitting / receiving apparatus (a wireless receiving apparatus 50 described later).
- a predetermined number of time-stamped TSs are collected to form a packet in order to minimize the overhead in a wireless section.
- the TS control signal T input to the transmission side memory control circuit 44 via the input terminal 42 is a
- the time stamp-added circuit 442 detects the head of TS-T input via the input terminal 41 based on the input TS control signal T. Thailand
- the time stamping circuit 442 When detecting the beginning of TS, the time stamping circuit 442 outputs a time stamp request signal T to the time stamp generation circuit 441.
- the reference time in the wireless transmission device 40 is generated when the time stamp request signal T is input from the time stamping circuit 442.
- a time stamp is added to the head of the TS input from the input terminal 41, and the TST with the time stamp is output to the bus arbiter circuit 444 as shown in FIG.
- a 4-byte time stamp is added to the head of the 188-byte TS-T input via the input terminal 41, and a predetermined number of these timestamps are collected and wirelessly transmitted. Construct and transmit packets.
- a wireless packet is composed of data for 7 TSs.
- the TS memory write control circuit 443 outputs the output from the time stamped clock circuit 442 based on the TS control signal T input via the input terminal 42.
- a data read request signal T is generated to the CPU 43 (FIG. 2) via the CPU bus 47.
- the CPU 43 shown in FIG. 2 receives the data read request signal T from the bus arbiter circuit 444, it activates DMA (Direct Memory Access) and stores 7 TS data including the time stamp into the memory 45. And writes it to the wireless LAN module 46 via the CPU bus 47.
- the CPU 43 when a predetermined number of input TSs are collected, the CPU 43 outputs a read control signal (read address or the like) to the memory 45.
- the bus arbiter circuit 444 outputs a signal that also outputs the power of the CPU 43 (FIG. 2).
- the control signal T 7 arbitrates the TS data writes on the control signal T output from the TS memory write control circuit 443.
- the bus arbiter circuit 444 receives data from the CPU 43.
- the wireless LAN module 46 shown in FIG. 2 forms a wireless packet by adding a wireless header to the head of the input data for 7TS when the data for 7TS is input.
- the wireless header includes data type information for identifying whether the data is for TS data device control, wireless packet length information, and a MAC address (Media Access Control Address: Control device address), information such as device identification information unique to the wireless transmission device 40 (for example, an IP (Internet Protocol) address), and device identification information unique to the wireless transmission device 50 (for example, an IP address) ) Is added.
- the wireless LAN module 46 shown in FIG. 2 wirelessly transmits the packetized data to which the wireless header is added.
- FIG. 5 is a block diagram schematically showing a configuration of radio receiving apparatus 50 according to the first embodiment.
- the wireless receiving device 50 is a wireless receiving circuit provided in each of the wireless transmitting and receiving devices 11, 21, and 31 shown in FIG.
- radio receiving apparatus 50 has a function of receiving up to two TSs at the same time.
- the wireless receiving device 50 includes a wireless LAN module 51 that receives wireless packets transmitted from the wireless transmitting device 40, a receiving-side memory control circuit 52, a memory 53, and a wireless receiving device 50.
- the receiving-side memory control circuit 52 writes the TS received by the wireless LAN module 51 to the memory 53 based on a write control signal (such as a write address signal) output from the CPU 54, and writes the TS to the memory 53.
- the TS (temporarily stored as a result) is read and output at a timing based on the time stamp.
- the control signal R is output to a device connected according to the IEEE1394 standard via the output terminal 57.
- FIG. 6 is a block diagram schematically showing a configuration of the receiving-side memory control circuit 52 in the wireless receiving device 50 shown in FIG.
- the receiving-side memory control circuit 52 includes a TS data read timing generation circuit 521, a TS memory read control circuit 522, and a bus arbiter circuit 523.
- the TS data read timing generation circuit 521 shown in FIG. 6 is a TS memory 53 (FIG. 5) that is received by the wireless LAN module 51 (FIG. 5) and temporarily stored in the memory 53 (FIG. 5).
- the memory read control circuit 522 generates a TS read control signal R based on the TS read timing signal R output from the TS data read timing generation circuit 521.
- the TS data read timing generation circuit 521 shown in FIG. 6 has a time correction value for correcting the TS read timing generated by the TS data read timing generation circuit 521 via the CPU bus 55. (In the first embodiment, this is also referred to as a clock jitter correction value.) R is input.
- FIG. 5 The power is also output and the data write request to the memory 53 (FIG. 5) input via the CPU bus 55 and the data read request output from the TS memory read control circuit 522 are arbitrated.
- FIG. 7 is an explanatory diagram schematically showing a configuration of a storage area of the memory 53 in the wireless receiving device 50 shown in FIG.
- the memory 53 since the wireless receiving device 50 simultaneously handles a maximum of two TSs, the memory 53 (FIG. 5) includes a first TS storage area 531 for storing the first TS, and a second TS storage area 531 for storing the first TS. And a second TS storage area 532 for storing TS.
- the number of TSs simultaneously handled by the wireless receiving device 50 may be three or more. In this case, it is necessary to increase the number of storage areas according to the number of TSs simultaneously handled.
- the TS data read timing generation circuit 521 and the TS memory read control circuit 522 in the reception side memory control circuit 52 Only independently. (The TS data read timing generation circuit 521 and the TS memory read control circuit 522 are arranged independently in each storage area.)
- FIG. 8 is a timing chart of reading the TS data in the reception-side memory control circuit 52 shown in FIG. FIG. 4 is a block diagram schematically showing a configuration of a generation circuit 521.
- the TS data read timing generation circuit 521 includes an input terminal 5211 to which the time stamp signal R sent from the TS memory read control circuit 522 (FIG. 6) is input, and a TS read timing
- a time control circuit 5214, a time correction value storage register 5215, and a time comparison circuit 5216 measures the output timing of the received TS.
- the time correction value storage register 5215 shown in FIG. 8 stores the time correction value R which is also output from the CPU 54 (FIG. 5) and input via the CPU node 55.
- the time measurement counter control circuit 5214 controls the count value of the time measurement counter 5213 based on the time correction value stored in the time correction value storage register 5215.
- the time comparison circuit 5216 shown in FIG. 8 includes a time stamp signal value (time stamp value) R input through the input terminal 5211 and a time measurement clock output from the time measurement counter 5213.
- FIG. 9 is a block diagram schematically showing a configuration of the TS memory read control circuit 522 in the reception side memory control circuit 52 shown in FIG.
- the TS memory read control circuit 522 includes a FIFO (First-In First-Out) memory 5225, a FIFO memory control circuit 5226 that controls the FIFO memory 5225, and a TS read address generation circuit 5227.
- a TS write address storage circuit 5228 a memory storage data amount integration circuit 5229, an integration result storage register 5230, a TS output number measurement counter 5231 for measuring the number of TS outputs, and a count of the TS output number measurement counter 5231.
- It has a TS output number storage register 5232 for storing the result, a measurement time measurement counter 5233, and a measurement time storage register 5234 for storing the count result of the measurement time measurement counter 5233.
- the TS read address generation circuit 5227 shown in FIG. 9 is configured based on the TS read timing signal R input via the terminal 5212 of the TS data read timing generation circuit 521 (FIG. 6). (Fig. 5) Generates a read control signal R for TS
- the TS write address storage circuit 5228 receives the address information input via the CPU 52 (FIG. 5) via the terminal 5224, that is, the wireless LAN module 51 (FIG. 5). Was the TS stores the address information R 7 when writing to the memory 53 (FIG. 5).
- the memory storage data amount integration circuit 5229 shown in FIG. 9 includes a TS read address information from the memory 53 (FIG. 5) output from the TS read address generation circuit 5227, and a TS write address storage circuit 5228.
- the amount of data written (temporarily stored) to the memory 53 (FIG. 5) is integrated based on the write address information output from the CPU, and the integration result (corresponding to the area of the shaded area in FIG. 13 described later) is obtained. Output.
- the integration result storage register 5230 shown in FIG. 9 stores the integration result output from the memory storage data amount integration circuit 5229. In the first embodiment, when the integration result storage register 5230 is accessed by the CPU 54 (FIG. 5), the integrated value measured by the memory storage data amount integration circuit 5229 and the value of the integration result storage register 5230 are stored. The initial value is set to '0'.
- the TS output number measurement counter 5231 shown in FIG. 9 measures the number of TS outputs, and the TS output number storage register 5232 stores the count result of the TS output number measurement counter 5231.
- the measurement time measurement counter 5233 shown in FIG. 9 measures the measurement time measured by the memory storage data amount integration circuit 5229 and the TS output number measurement counter 5231.
- the measurement time storage register 5234 shown in FIG. 9 stores the measurement result output from the measurement time measurement counter 5233.
- FIG. 10 is a flowchart showing the operation of the receiving-side memory control circuit 52 in the wireless receiving device 50 when receiving a TS.
- FIG. 11 is a flowchart showing the clock jitter detecting operation by the CPU 54 in the wireless receiving device 50 according to the first embodiment.
- FIG. 12 shows the calculation and setting of the target value in the flow shown in FIG. 12 is a flowchart showing the operation of step S16) in FIG.
- FIG. 13 is a diagram schematically showing a change in the amount of data (the number of TS lines) stored in the memory 53 in the wireless reception device 50.
- FIG. 14 shows that the data transmission system in the first embodiment has a clock jitter.
- FIG. 9 is a diagram schematically showing a change in the amount of data (the number of TS lines) to be stored when the data is stored.
- FIG. 15 shows each correction value calculation stage (also referred to as each correction value calculation stage) in which radio receiving apparatus 50 according to Embodiment 1 calculates a time correction value (hereinafter also referred to as “clock jitter correction value”).
- FIG. 5 is a diagram showing an example of an amplitude conversion table when calculating a clock jitter correction value in FIG.
- the wireless reception device 50 that has received a wireless packet including a TS transmitted from the wireless transmission device 40 will be described with reference to FIGS. 5 to 15.
- the wireless LAN module 51 (FIG. 5) in the wireless receiving device 50 transmits the wireless header added to the head of the wireless packet. It analyzes and detects from which wireless transmission device (transmission source) the received packet is transmitted, and to which wireless reception device (transmission destination) it is transmitted. As a result of this detection, if the wireless packet is not sent to its own wireless receiving device 50, the wireless LAN module 51 (FIG. 5) in the wireless receiving device 50 discards the wireless packet.
- the wireless LAN module 51 (FIG. 5) in the wireless receiving device 50 performs identification of the type of the wireless packet and the like. The result is output to the CPU 54 (FIG. 5) in the wireless receiving device 50.
- Wireless LAN module 51 (Fig. 5) The CPU 54 (Fig. 5) that receives the power detection result, if the received data is a TS with a time stamp, stores the TS with a time stamp in the memory 53 (Fig. Start DMA to transfer to 5). If the data received by the wireless LAN module 51 (FIG. 5) is device control data, the CPU 54 (FIG. 5) performs predetermined processing on the device control data, and then performs device control data.
- the IEEE1394 interface multiplexes the video stream (TS signal and DV signal) and AVZC command (device control signal) on the same signal line and transmits them in a time-division manner.
- the IEEE 1394 interface and the input / output terminals of the device control signal (AVZC command) are omitted in the figure to describe in detail the transmission and reception of the TS stream.
- the reception side memory control circuit 52 (FIG. 5) in the wireless reception device 50 performs wireless communication based on the TS write control signal transmitted from the CPU 54 (FIG. 5) via the CPU bus 55.
- the TS received by the LAN module 51 (Fig. 5) is written to the memory 53 (Fig. 5) and temporarily stored in the memory 53.
- the received TS is written in the first TS recording area 531 (FIG. 7) in the memory 53 (FIG. 5).
- the TS read timing signal R is generated by the TS data read timing generation circuit 521 (FIG. 6) according to the flow shown in FIG. It should be noted that the reception of the TS from the wireless transmission device 40
- the CPU 54 (FIG. 5) checks whether there is any free space in the memory 53 (FIG. 5) for storing the TS, and the two storage regions 531 and 532 shown in FIG. If it has already been used, it notifies wireless transmission device 40 via wireless LAN module 51 (FIG. 5) that it cannot receive the TS.
- the CPU 54 (FIG. 5) in the wireless reception device 50 stores the received TS in a memory 53 (FIG. 5).
- the storage area in 5) is determined, and the determined storage area is notified to the TS memory read control circuit 522 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5).
- the TS memory read control circuit 522 (FIG. 6) determines a storage area in the memory 53 (FIG. 5) from which the TS is read based on the determined storage area in the memory 53 (FIG. 5).
- the TS memory read control circuit 522 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5) writes the received first TS to the memory 53 (FIG. 5). Confirm that it has been completed (Step Sl in Fig. 10).
- the first TS written at the beginning of the first TS storage area 531 (FIG. 7) in the memory 53 (FIG. 5) after the start of reception is referred to as a “top TS”.
- the TS memory read control circuit 522 (FIG. 6) in the receiving side memory control circuit 52 (FIG. 5) is output from the TS write address storage circuit 5228 (FIG. 9) in the TS memory read control circuit 522 (FIG.
- the first TS storage area 53 1 in the memory 53 (FIG. 5) is detected. It can be confirmed that the writing of the first TS to (FIG. 7) has been completed.
- the TS memory read control circuit 522 (FIG. 6) in the reception-side memory control circuit 52 (FIG. 5) sets the memory 53 (FIG. 5).
- the time stamp added to the first TS stored in 5) is read (step S2 in FIG. 10).
- step S2 in FIG. 10 When the reading of the time stamp is completed in step S2 in FIG.
- the TS memory read control circuit 522 (FIG. 6) in the control circuit 52 (FIG. 5) waits until the amount of data stored in the memory 53 (FIG. 5) exceeds a predetermined value (step S3 in FIG. 10). This standby is performed in order to perform clock recovery on the VBR TS using the clock frequency of the wireless reception device 50.
- FIG. 13 shows an example in which the clock signals between the wireless transmission device 40 and the wireless reception device 50 are synchronized.
- the vertical axis represents the amount of data stored in the TS stored in the memory 53 (FIG. 5), and the horizontal axis represents time.
- FIG. 13 shows TSs output from the AV-HDD recording / reproducing device 22 (FIG. 1) and the like, which corresponds to a case where, for example, control is performed such that video data compressed by the MPEG2 system is read out frame by frame. I do.
- Embodiment 1 a case where a 20 Mbps HD (High Definition) video stream is transmitted in the TS format in an MPEG2 system will be described.
- a GOP Group of Pictures
- the data amount of an intra frame in one GOP is 20% of the total data amount of one GOP. I do.
- the first TS storage area 531 (FIG. 7) in the memory 53 (FIG. 5) has a storage capacity capable of storing one GOP worth of data.
- a PCR Program Clock Reference
- the throughput in the wireless transmission section between the wireless transmitting device 40 and the wireless receiving device 50 is about 20 Mbps, and the amount of TS received via wireless is input to the wireless receiving device 50 at a substantially constant rate.
- the reading of the data in the memory 53 (FIG. 5) in the wireless receiving device 50 is performed based on the time stamp added to the TS based on the clock frequency of the transmitting side at the time of transmission.
- Memory 53 (Fig.
- the change in the amount of stored data in TS is represented by a straight line (line segment D D, line segment
- the radio receiver 50 stores a predetermined amount of data in the memory 53 (FIG. 5) at the start of reception to prevent the TS stored in the memory 53 (FIG. 5) from overflowing or underflowing. Reading of data from the memory 53 (FIG. 5) is not started until the TS is stored.
- the memory 53 (FIG. 5) stores a TS of half the data amount of one GOP (F in FIG. 13),
- step S3 of FIG. 10 when the amount of data stored in the memory 53 (FIG. 5) exceeds a predetermined value, the time measurement counter control circuit 5214 (FIG. 6) in the TS data read timing generation circuit 521 (FIG. 6) 8) sets the time stamp value added to the received first TS to the time control counter 5213 (FIG. 8) as the initial value, and sets the time measurement counter 5213 (FIG. 8) to the time measurement.
- the control signal is output to start the count-up operation for (step S4 in FIG. 10).
- step S4 in FIG. 10 the count-up operation of the time measurement counter 5213 (FIG. 8) in the TS data read timing generation circuit 521 (FIG. 6) is started, and thereafter, the time comparison circuit 5216 (FIG. 8) outputs the TS read timing signal R.
- the TS read address generation circuit 5227 (Fig. 9)
- the system Based on the signal R, the system reads data for the ITS stored in the memory 53 (Fig. 5).
- Control signal R is output from terminal 5223 (step S5 in Fig. 10).
- the TS read out from the memory 53 passes through the bus arbiter circuit 523 (FIG. 6) in the receiving-side memory control circuit 52 (FIG. 5), and the TS memory read control circuit 522 (FIG. Input to FIFO memory 5225 (Fig. 9) in 6).
- the FIFO memory 5225 uses a bus arbiter circuit 523 (FIG. 6) between the TS write control signal from the CPU 54 (FIG. 5) and the TS read control signal from the TS memory read control circuit 522 (FIG. 6). Absorbs the read data delay time that occurred during bus arbitration.
- the delay amount for a fixed time is determined based on the TS read timing signal R input from the TS data read timing generation circuit 521 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5).
- FIFO memory 5225 (FIG. 9)
- the FIFO memory control circuit 5226 (FIG. 9) outputs a read control signal to the FIFO memory 5225 (FIG. 9) so that the TS is also read.
- the write control to the FIFO memory 5225 (Fig. 9) in the TS memory read control circuit 522 (Fig. 6) in the reception side memory control circuit 52 (Fig. 5) is output from the TS read address generation circuit 5227 (Fig. 9).
- the data read completion signal (not shown in FIG. 9 and shown as signal R in FIG. 6), which also outputs the bus arbiter circuit 523 (FIG. 6), is output from the TS read address.
- step S6 of FIG. 10 when the reading of data for ITS from the memory 53 (FIG. 5) is completed, the TS read address generation circuit 5227 (09) in the TS memory read control circuit 522 (FIG. 6) Based on the write address information stored in the TS write address storage circuit 5228 (FIG. 9), it is checked whether the TS of the next line is stored in the memory 53 (FIG. 5) and stored. If so, a TS data read control signal R for reading the time stamp of the TS of the next line is generated (step S7 in FIG. 10). Note that memory 53 (Fig.
- step S7 of FIG. 10 when receiving the time stamp of the TS of the next line (also referred to as “next TS”), the time comparison circuit 5216 in the TS data read timing generation circuit 521 (FIG. 6) ( Figure 8) is output from the time stamp signal R and the time measurement counter 5213 ( Figure 8).
- the time measurement count value R is compared with the input time measurement count value R.
- the dress generation circuit 5227 (FIG. 9) outputs the TS data read control signal R (see FIG. 10).
- the reception side memory control circuit 52 repeats the operation of steps S5 to S8 of FIG. 10 (that is, step S9 surrounded by a broken line).
- the receiving-side reference clock at which the oscillator of the wireless receiving device 50 oscillates is faster than the transmitting-side reference clock at which the oscillator of the wireless transmitting device 40 oscillates (that is, the receiving-side clock frequency of the wireless receiving device 50 is wirelessly
- the reception reference time (reception clock frequency) and the time stamp signal obtained based on the power counter value of the time measurement counter 5213 (Fig. 8).
- the first embodiment is configured to control the receiving-side memory control circuit 52 (FIG. 6).
- the CPU 54 in the wireless receiving device 50 identifies the transmitter (corresponding to the wireless transmitting device 40) based on the header information added to the wireless packet. (Step S11 in FIG. 11).
- the transmitter is identified using, for example, one or both of the MAC address added to the header information of the wireless packet and the device identification information (eg, IP address) unique to the transmitter. If the MAC address or the IP address is used as the device identification information, the device identification information can be obtained without adding new information to the wireless packet, so that the processing load on the wireless transmitting device 40 and the wireless receiving device 50 can be reduced. In addition, transmission and reception can be performed without increasing the load on the communication band.
- the CPU 54 (FIG. 5), based on the device identification information of the transmitter, stores in the storage unit (for example, a part of the memory 53 or It is checked whether or not the time correction value (the previous time correction value) of the identified transmitter has already been stored in another memory (not shown) (step S12 in FIG. 11). If the time correction value (that is, the clock jitter correction value) of the identified transmitter is already stored in the wireless receiving device 50, the CPU 54 (FIG. 5) transmits the stored time correction value (clock jitter correction value). (Correction value) as the initial value. It is set in the time correction value storage register 5215 (FIG. 8) in the data read timing generation circuit 521 (FIG. 6) (step S13 in FIG.
- the CPU 54 sets an initial value '0' to the time correction value storage register 5215 (FIG. 8) ( Step S14 in Fig. 11).
- the stored previous time correction value is initialized.
- the reason for using as a value is as follows.
- the wireless receiving device 50 performs clock reproduction of the VBR TS.
- the average data transmission rate of VBR TS is about 20Mbps. In short time units, the average data transmission rate fluctuates greatly.
- the minimum measurement time is set as the period of one GOP.
- the measurement result (previous time correction value) measured when the previous TS reception was performed is stored in the wireless reception device 50.
- the time before the time correction value converges within the predetermined range by using the previously stored time correction value (in step S17 in FIG. 11 described later). The time required for the time correction value to converge) can be reduced.
- the CPU 54 sets the TS memory read control circuit 522
- the initial value “0” is set in the integration result storage register 5230 (FIG. 9), the TS output number storage register 5232 (FIG. 9), and the measurement time storage register 5234 (FIG. 9) in (FIG. 6).
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231 (FIG. 9), and the measurement time measurement counter 5233 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) are also provided.
- step S15 in FIG. 11 the CPU 54 (FIG. 5) measures and sets a target value (step S16 in FIG. 11).
- a method of measuring the target value will be described with reference to FIG.
- the CPU 54 When the reception of the TS is started, the measurement of the target value is started.
- the CPU 54 (FIG. 5) first determines whether the memory 53 (FIG. 5) has started reading the TS. (Step S31 in FIG. 12). When it is confirmed that the reading of the memory 53 (Fig. 5) is started, the CPU 54 (Fig. 5) sets the time for measuring the target value (target value measurement time) to the internal timer. (Step S32 in FIG. 12). For example, set the target value measurement time to 0.5 second, which is the time of 1 GOP. Note that the target value measurement time can be set to the time for multiple GOPs.
- the CPU 54 (FIG. 5) waits until the target value measurement time set in the timer elapses (step S33 in FIG. 12). After the elapse of the target value measurement time, the CPU 54 (FIG. 5) sets the integration result storage register 5230 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6), the TS output number storage register 5232 (FIG. 9), and The measurement result stored in the measurement time storage register 5234 (Fig. 9) is read (step S34 in Fig. 12), and then, the integration result storage register 5230 (Fig. 9), the TS output number storage register 5232 (Fig. 9), The initial value “0” is set in the measurement time storage register 5234 (FIG. 9) (step S35 in FIG.
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231 (FIG. 9), and the measurement time measurement counter 5233 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) are also included. Set to the initial value '0'.
- the CPU 54 calculates a target value using various register values. Specifically, the value A stored in the TS output number storage register 5232 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) is stored in the measurement time storage register 5234 (FIG. 9).
- the integration in the memory storage data amount integration circuit 5229 (FIG. 9) is performed by integrating the reference capacity F and the memory storage as shown in FIG.
- the area of the hatched part in FIG. 13 is the integration result D in the memory storage data amount integration circuit 5229 (FIG. 9).
- the integration in the memory storage data amount integration circuit 5229 (FIG. 9) is performed at the timing when the TS is read from the memory 53 (FIG. 5).
- the measurement and setting of the target value E are completed.
- the time correction value (clock)
- the CPU 54 (FIG. 5) waits until a predetermined measurement time has elapsed (step S18 in FIG. 11).
- the measurement time in step S18 in FIG. 11 is the time of one GOP, similarly to the target value measurement time used in setting the target value (step S32 in FIG. 12).
- the CPU 54 (FIG. 5) stores the integration result storage register 5230 (FIG. 9), the TS output number storage register 5232 (FIG. 9), as in the case of the target value measurement.
- the measurement result stored in the measurement time storage register 5234 (FIG. 9) is read (step S19 in FIG.
- the integration result storage register 5230 (FIG. 9) and the TS output number storage register 5232 (FIG. 9) ) And the measurement time storage register 5234 (FIG. 9) are set to the initial value '0' (step S20 in FIG. 11).
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231, and the measurement time measurement counter 5233 are also set to the initial value '0'.
- the CPU 54 uses the various register values to store in the TS output number storage register 5232 (FIG. 9) as in the case of the target value measurement (step S36 in FIG. 12).
- the value A 111 is divided by the value B stored in the measurement time storage register 5234 (Fig. 9).
- the value corresponding to the calculated deviation is set as a time correction value (clock jitter correction value).
- step 1 for the clock jitter correction value, two predetermined conversion tables as shown in FIG. 15, that is, two conversion tables in which the calculated deviation is associated with the clock jitter correction value are prepared. , And the clock jitter value is calculated.
- the number of prepared conversion tables may be one or three or more.
- FIG. 14 shows a case where the receiving side clock frequency of the wireless receiving device 50 is higher than the transmitting side clock frequency of the wireless transmitting device 40, and the reference clock of the wireless receiving device 50 is faster than the reference clock of the wireless transmitting device 40.
- the actual clock frequency deviation depends on the oscillation of the wireless transmission device 40.
- the maximum clock deviation is about ⁇ 100 ppm (parts per million) when a crystal oscillator is used, depending on the accuracy of the oscillator of the receiver and the radio receiver 50.
- the clock jitter value dSUM is emphasized for simplicity of description (ie, the gradient of the line segment DD with respect to the line segment DD is drawn steeper than actual).
- the receiving clock frequency of the wireless receiving device 50 is higher than the transmitting clock frequency of the wireless transmitting device 40, the count value of the time measurement counter 5213 (FIG. 8) in the wireless receiving device 50 advances rapidly. Then, the data amount of the TS stored in the memory 53 (FIG. 5) gradually decreases (as indicated by the line segment DD in FIG. 14). In this case, the receiving clock frequency and the transmitting clock
- the deviation between the clock frequency and the clock frequency is constant (ie, does not change due to a change in the input rate of the TS, etc.). Therefore, the hatched portion shown in FIG. 14 is the clock jitter value dSUM (a value corresponding to the difference between the measured value E and the target value E).
- the CPU 54 calculates a clock jitter correction value according to the clock jitter value. Then, the CPU 54 (FIG. 5) sets the calculated clock jitter correction value in the time correction value storage register 5215 (FIG. 8) (Step S21 in FIG. 11). Since the calculated clock jitter correction value is based on the control result already controlled by the time correction value storage register 5215 (FIG. 8), the clock jitter value calculated by the above algorithm is the difference between the two. It is. Therefore, when setting the clock jitter correction value in the time correction value storage register 5215 (FIG. 8), the calculated clock jitter correction value is added to the currently set clock jitter correction value.
- the average read rate C of the TS when calculating the target value E) and C (when calculating the measurement value E) are used. This is
- the TS read address generation circuit 5227 ( Figure 9)
- the TS is read out in synchronization with the timing at which the power of the memory 53 (FIG. 5) is also read out. Therefore, the clock jitter value (the integrated value in the shaded area in Fig. 14) between the case where a TS with an average data transfer rate of 20 Mbps is received and the case where a TS with an average data transfer rate of 5 Mbps is received is determined. Since the size of) is different, normalization is performed at an average read rate of the TS in order to normalize the difference.
- the time measurement counter control circuit 5214 (FIG. 8) in the TS data read timing generation circuit 521 (FIG. 6) corrects the time at predetermined time intervals (every 100 ms in the first embodiment).
- the output value of the time measurement counter 5213 (FIG. 8) is corrected by adding the clock jitter correction value stored in the value storage register 5215 (FIG. 8) to the count value of the time measurement counter 5213.
- the case shown in FIG. 14 is a case where the amount of data stored in the memory 53 (FIG. 5) in which the receiving clock frequency in the wireless receiving device 50 is higher than the transmitting clock frequency in the wireless transmitting device 40 is decreasing. Is shown.
- the time measurement counter 5213 returns the time by the clock jitter correction value once every 100 ms (forcibly delays the time). By returning, the reference time based on the clock frequency in the wireless receiving device 50 can be made closer to the reference time based on the clock frequency in the wireless transmitting device 40.
- time measurement counter 5213 in TS data read timing generation circuit 521 (FIG. 6).
- the counter value of (Fig. 8) is configured so that the time correction value (clock jitter correction value) stored in the time correction value storage register 5215 (Fig.
- appropriate clock regeneration can be realized without changing the system clock frequency in the wireless receiving device 50. Therefore, if the wireless receiving device 50 of the first embodiment is used (that is, if the data receiving method of the first embodiment is used), each of the TSs to which a plurality of wireless transmitting devices have also been transmitted is stored in the memory 53 (FIG. 5).
- the time measurement counter 5213 (FIG. 8) corresponding to each storage area enables the generation of the read timing of each TS sent from a plurality of wireless transmission devices. Then, the clock recovery of the received TSs can be performed in parallel.
- the CPU 54 determines whether or not the clock jitter correction value has converged. Specifically, when the calculated clock jitter correction value falls within the predetermined range, it is determined that the convergence has occurred (step S22 in FIG. 11). If it is determined that the convergence has not occurred, the clock jitter measurement is started again under the same measurement conditions. If it is determined that the convergence has occurred, the measurement time is changed (step S23 in FIG. 11), The clock jitter measurement is started again (from step S18 in FIG. 11). At this time, it is desirable to change the conversion table for calculating the clock jitter correction value from the solid line conversion table (straight line with a steep slope) shown in Fig.
- the clock jitter value depends on the deviation of the system clock frequency, it becomes almost constant once the device is specified. Therefore, when pulling the clock jitter correction value to within a certain convergence range (for example, immediately after the start of reception), the gain (the gradient of the straight line indicating the conversion table) for calculating the clock jitter correction value is increased. Save time. Then, after the clock jitter correction value is drawn within a certain convergence range, the gain is reduced and the system stability is emphasized.
- the reason for increasing the measurement time is to increase the measurement time to improve the accuracy of the measured value, and to operate the wireless receiver 50 stably after the convergence of the clock jitter correction value. This is to make it possible.
- PLL Phase-Locked Loop
- the wireless receiving device 50 according to the first embodiment when the data receiving method according to the first embodiment (the wireless receiving device 50 according to the first embodiment) is used, it is possible to receive the VBR TS transmitted through the wireless communication having the jitter. Even in this case, TS can be output continuously without causing underflow or overflow. For this reason, when decoding and playing back the TS of the MPEG2 system on the receiving device, it is possible to play back the MPEG2 data without interrupting the video.
- receiving-side memory 53 has a plurality of storage areas. Packet data output from a number of data transmitting devices can be received, and data can be continuously output without underflow or overflow for each received packet data. Also, the receiving memory 53 stores a plurality of storage areas. Therefore, a plurality of streams can be handled with a simple circuit configuration, and the circuit scale can be reduced, and power consumption and manufacturing cost can be reduced.
- FIG. 16 is a flowchart showing a clock jitter detection operation of the wireless reception device according to Embodiment 2 of the present invention.
- FIG. 17 is a diagram showing a table used for selecting a conversion table by the wireless reception device according to the second embodiment.
- FIG. 18 is a diagram showing a conversion table used by the radio receiving apparatus according to Embodiment 2 to calculate a clock jitter correction value.
- the data receiving method according to the second embodiment is the same as that of the first embodiment except for the integration method, the convergence determination method of the clock jitter correction value, and the clock jitter detection method in the memory storage data amount integration circuit 5229 (FIG. 9). Is the same as the data reception method in Specifically, the first embodiment and the second embodiment have the following differences.
- the timing at which the memory storage data amount integration circuit 5229 (FIG. 9) integrates the storage data amount of the TS stored in the memory 53 (FIG. 5) is determined in order to simplify the control.
- the TS read address generation circuit 5227 (FIG. 9) in the memory read control circuit 522 (FIG. 6) is configured so that the power of the memory 53 (FIG.
- the timing for integrating the data amount stored in the TS is configured to be a predetermined timing created based on the clock frequency of the receiving side in the wireless receiving device. .
- FIG. 1 to FIG. 10 and FIG. 12 used in the first embodiment are also referred to.
- steps that perform the same processing as the steps in FIG. 11 are denoted by the same reference numerals.
- a clock recovery flow in radio receiving apparatus 50 when receiving a radio packet including a TS transmitted from radio transmitting apparatus 40 according to Embodiment 2 will be described with reference to FIGS. 16 and 12. .
- the CPU 54 FIG. 5
- the radio receiving apparatus 50 transmits the TS (the radio transmitting apparatus) based on the header information added to the radio packet. (Equivalent to 40) is performed (step Sl l in Fig. 16).
- the transmitter is identified using, for example, one or both of the MAC address added to the header information of the wireless packet and the device identification information (eg, IP address) unique to the transmitter. And implement.
- the device identification information can be obtained without adding new information to the radio packet, so that the processing load on the wireless transmission device 40 and the wireless reception device 50 is reduced.
- the transmission and reception can be performed without imposing a load on the communication band, while reducing the load.
- the CPU 54 (FIG. 5) in the wireless receiving device 50 stores the storage unit (for example, the memory 53 in the wireless receiving device 50) based on the device identification information of the transmitter. It is confirmed whether or not a force has already been stored in a part or in another memory (not shown) of the transmitter in which the time correction value of the transmitter identified in the past (also referred to as “previous time correction value”) is already stored. (Step S12 in Fig. 16)
- step S12 of FIG. 16 if the previous time correction value (clock jitter correction value) has already been stored in the wireless receiving device 50, the CPU 54 (FIG. 5) The time correction value is set as an initial value in the time correction value storage register 5215 (FIG. 8) in the TS data read timing generation circuit 521 (FIG. 6) (step S13 in FIG. 16).
- the measurement time T (n) used for measuring the target value is set, and the conversion table for calculating the clock jitter correction value is set to Table (n) (step S41 in FIG. 16).
- n is i, and as shown in FIG. 17, in the second embodiment, i can take five values from 0 to 4. Further, by switching the value of i according to the convergence result at the time of calculating the clock jitter correction value, the measurement time T (n) and the conversion table for calculating the clock jitter correction value Table (n) can be switched. Make up! /
- T O
- step S42 in FIG. 16 the measurement time is set to T (O)
- the conversion table for calculating the clock jitter correction value is set to Table (0) (step S42 in FIG. 16).
- the clock In order to estimate the utter value with higher accuracy, it is necessary to lengthen the measurement time.
- the deviation of the clock frequency of the crystal oscillator between the radio transmitter 40 and the radio receiver 50 is 100 ppm (parts per million) with respect to the center frequency for the radio transmitter 40, and Is +1 OOppm with respect to the center frequency, and if the system clock is 27MHz, each system clock frequency is as follows.
- the radio receiver 50 since the maximum value of the jitter allowed for the TS is 50 Ps, the radio receiver 50 needs to converge the correction of the clock jitter as soon as possible.
- the minimum control unit is 1 GOP.
- clock jitter correction control is performed in units of 1 GOP. Therefore, the clock jitter value must be suppressed to a predetermined clock frequency deviation or less as soon as possible. Therefore, it is configured to have a plurality of measurement times and a plurality of jitter correction tables for estimating the clock jitter value. At the start of transmission / reception (and during the period immediately after the start of transmission / reception), the clock jitter value rapidly converges.
- the measurement result measured when the previous TS reception was performed with the wireless transmission device 40 is stored.
- the correction value that is, by using the time correction value that can keep the deviation of the clock frequency small
- the power at the start of reception can also stabilize the system operation.
- the CPU 54 sets the integration in the TS memory read control circuit 522 (FIG. 6).
- the TS memory read control The memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231, and the measurement time measurement counter 5233 in the path 522 (FIG. 6) are also set to the initial value '0' (step S15 in FIG. 16). ).
- the target value is measured and set (step S16 in FIG. 16).
- a method of measuring the target value in the second embodiment will be described with reference to FIG.
- radio reception apparatus 50 starts measuring a target value when TS reception is started.
- the operation in steps S31 to S33 in FIG. 12 is the same as in the first embodiment.
- the measurement time for measuring the target value (hereinafter, referred to as “target value measurement time”) is 2 seconds.
- the CPU 54 sets the integration result storage register 5230 (FIG. 6) in the TS memory read control circuit 522 (FIG. 6).
- Fig. 9 the TS output number storage register 5232 (Fig. 9), and the measurement result storage register 5234 (Fig.
- step S34 in Fig. 12 are read (step S34 in Fig. 12).
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231 (FIG. 9), and the measurement time measurement counter 523 3 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) Is also set to the initial value '0'.
- the CPU 54 calculates a target value using various register values. Specifically, the value A stored in the TS output number storage register 5232 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) is stored in the measurement time storage register 5234 (FIG. 9).
- the CPU 54 (FIG. 5) stores the value D stored in the integration result storage register 5230 (FIG. 9) in the measurement time storage register 5234 (FIG. 9).
- Step S36 In the second embodiment, as in the first embodiment, the difference A F between the reference capacity F and the amount of data stored in the memory is integrated as shown in FIG. Obedience
- the integration timing in the memory storage data amount integration circuit 5229 is based on the fact that the integration timing in the memory storage data amount integration circuit 5229 (FIG. 9) is created based on the reference clock in the wireless receiver 50. This is different from the case of Embodiment 1 in which the timing is matched with the TS read timing. Therefore, when setting the target value, as in the first embodiment, the integrated value of the memory storage data amount integration circuit 5229 (FIG. 9) is calculated by averaging the TS read from the memory 53 (FIG. 5). The target value is obtained by dividing the integrated value of the memory storage data amount integration circuit 5229 (Fig. 9) by the measurement time instead of dividing by the reading rate.
- the calculation power S of the clock jitter correction value is started.
- the CPU 54 (FIG. 5) waits until a predetermined measurement time T (n) has elapsed (step S18 in FIG. 16).
- the CPU 54 sets the integration result storage register 5230 (Fig. 9) in the TS memory read control circuit 522 (Fig. 6) and the number of TS outputs.
- the measurement results stored in the storage register 5232 (Fig. 9) and the measurement time storage register 5234 (Fig. 9) are read (step S19 in Fig. 16), the integration result storage register 5320 (Fig. 9), the number of TS outputs
- the storage register 5232 (FIG. 9) and the measurement time storage register 5234 (FIG. 9) are set to the initial value '0' (step S20 in FIG. 16).
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231 (FIG. 9), and the measurement time measurement counter 5233 (FIG. 9) are also set to the initial value “0”.
- the CPU 54 uses the various register values to calculate the measured value, as in the case of the target value measurement (Step S36 in FIG. 12). Specifically, the value A stored in the TS output number storage register 5232 (FIG. 9) is written in the measurement time storage register 5234 (FIG. 9).
- the received data rate of the TS has changed more than the specified value during the measurement period based on Check whether or not. If the average read rate C of TS changes more than the specified value,
- the target value setting routine is re-entered to change the target value.
- the clock jitter value is caused by a frequency deviation of the system clock between the wireless transmitting device 40 and the wireless receiving device 50. Therefore, even if the reception rate changes during reception, the clock jitter value does not change.
- read control is started. Therefore, when the average receiving rate of the TS changes in the wireless receiving apparatus 50, the wireless receiving apparatus 50 has a delay time corresponding to a predetermined number of TSs stored in the memory 53 (FIG. 5).
- the amount of TS written in the memory 53 (FIG. 5) is compared with the case where a 20 Mbps TS is received. As a result, the average storage data amount stored in the memory 53 (FIG. 5) is reduced by the TS reception rate difference (8 Mbps) corresponding to the delay time. On the other hand, when the average reception data rate increases from 8 Mbps to 20 Mbps, the average storage data amount stored in the memory 53 (FIG. 5) increases by the TS reception rate difference (12 Mbps) corresponding to the delay time. Therefore, in the second embodiment, it is determined whether or not to reset the target value using the calculation result of the average read rate of the TS.
- the value D stored in the integration result storage register 5230 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) is stored in the measurement time storage register.
- the measured value E (that is, obtained for the TS received after the head TS) is obtained.
- Measured value i.e., the measured value obtained for the first TS.
- the difference (that is, the difference) is calculated, and a value corresponding to the calculated deviation is set as a time correction value (clock jitter correction value).
- clock jitter correction value a plurality of conversion tables associating the predetermined calculation result (deviation) with the clock jitter correction value as shown in FIG.
- the clock jitter correction value is calculated by switching the clock jitter correction table according to the value of i.
- the calculation result is set as a clock jitter correction value in the time correction value storage register 5215 (FIG. 8) (step S21 in FIG. 16).
- the calculated clock jitter correction value is already Since it is based on the control result controlled by the value storage register 5215 (FIG. 8), the clock jitter value calculated by the above algorithm is the difference between them, as in the first embodiment. Therefore, when the clock jitter correction value is set in the time correction value storage register 5215 (FIG. 8) in the TS data read timing control circuit 521 (FIG. 6), the clock jitter correction value calculated above is set to the currently set clock jitter correction value. Set the value obtained by adding the clock jitter correction value.
- the time measurement counter control circuit 5214 (FIG. 8) in the TS data read timing generation circuit 521 (FIG. 6) operates at predetermined time intervals (Embodiment 2).
- the clock jitter correction value stored in the time correction value storage register 5215 (Fig. 8) is added to the time measurement counter value to output the time measurement counter 5213 (Fig. 8). Correct the value.
- the case shown in FIG. 14 is a case where the receiving clock frequency in the wireless receiving device 50 is higher than the transmitting clock frequency in the wireless transmitting device 40 and the amount of data stored in the memory 53 (FIG. 5) is decreasing. Is shown.
- the time measurement counter 5213 returns the time by the clock jitter correction value once every 100 ms (forcibly delays the time.) O In this way, the time is returned by the clock jitter correction value.
- the reference time based on the clock frequency in the wireless receiving device 50 can be made closer to the reference time based on the clock frequency in the wireless transmitting device 40.
- the conversion table for calculating the clock jitter correction value is also changed as shown in FIG.
- the reason for performing the above control is as follows, as in the case of the first embodiment. Since the clock jitter depends on the deviation of the system clock frequency, it becomes almost constant once the device is specified. Therefore, when pulling the clock jitter correction value to within a certain convergence range, the gain (gradient of the straight line in FIG. 18) in calculating the clock jitter correction value is increased to shorten the pull-in time.
- the gain at the time of calculating the clock jitter correction value is reduced to emphasize the stability of the system.
- convergence of the system can be accelerated, and the system can be operated more stably even in a stage before convergence.
- the reason for lengthening the measurement time is to lengthen the measurement time to improve the accuracy of the measured value and to stabilize the system at the time of convergence.
- the PLL control and the like are not used for the clock jitter even after the convergence, it is necessary to continuously update the clock jitter correction value at the time of data reception.
- the second embodiment is the same as the first embodiment.
- the data receiving method of the second embodiment if the data receiving method of the second embodiment is used, if the average receiving rate changes significantly, control is performed so as to reset the target value for calculating the deviation of the clock frequency. Clock recovery can be performed even if the average data reception rate changes. For this reason, when decoding and playing back the TS of the MPEG2 system on the receiving device, the MPEG2 data can be played back without interruption of the video.
- the data receiving method according to the third embodiment of the present invention is different from the data receiving method according to the first embodiment described above in that the CPU 54 in the wireless receiving device 50 performs a clock jitter detecting operation. Except for this point, the data receiving method according to the third embodiment is the same as the data receiving method according to the first embodiment. Therefore, in Embodiment 3, Reference is also made to FIGS. 1 to 10 and FIGS. 13 and 14 used in the first embodiment.
- FIG. 19 is a flowchart showing a clock jitter detecting operation by CPU 54 in radio receiving apparatus 50 according to Embodiment 3, and FIG. 20 shows initial value measurement and setting (FIG. 19) in the flow shown in FIG. 20 is a flowchart showing the operation of step S216) in FIG.
- FIG. 21 is a flowchart illustrating an operation of calculating a clock jitter value according to the third embodiment.
- FIG. 22 is a flowchart showing an operation of calculating a clock jitter correction value according to the third embodiment.
- FIG. 23 is a flowchart showing an operation of determining convergence of a clock jitter correction value when calculating a clock jitter value in the third embodiment. Further, FIG.
- FIG. 24 shows measurement time in each correction value calculation stage (each correction value calculation stage) used when the wireless reception device 50 in the third embodiment calculates a time correction value (clock jitter correction value).
- FIG. 6 is a diagram showing an example of a table for determining a convergence determination condition and a threshold used for convergence determination.
- FIG. 25 is a diagram illustrating an example of a conversion table (a gain table by which a measured value is multiplied) used by the wireless receiving apparatus according to Embodiment 3 to calculate a clock jitter correction value.
- the wireless LAN module 51 (FIG. 5) in the wireless receiving device 50 discards the wireless packet. If the wireless packet is sent to its own wireless receiving device 50, the wireless LAN module 51 (FIG. 5) in the wireless receiving device 50 identifies the type of the wireless packet and performs other operations. The result is output to the CPU 54 (FIG. 5) in the radio receiver 50. Upon receiving the detection result from the wireless LAN module 51 (FIG. 5), the CPU 54 (FIG. 5) converts the received data into a time-stamped TS. If there is, the DMA is started to transfer the TS with the time stamp to the memory 53 (FIG.
- the CPU 54 (FIG. 5) performs predetermined processing on the device control data, and then performs device control.
- the IEEE1394 interface multiplexes the video stream (TS signal, DV signal) and AVZC command (device control signal) on the same signal line in time division and transmits them.
- the IEEE 1394 interface and the input / output terminals of the device control signal (AV ZC command) are omitted in the figure to explain the transmission and reception of the TS stream in detail.
- the reception side memory control circuit 52 (Fig. 5) in the wireless reception device 50 performs wireless communication based on the TS write control signal transmitted from the CPU 54 (Fig. 5) via the CPU bus 55.
- the TS received by the LAN module 51 (FIG. 5) is written to the memory 53 (FIG. 5), and is temporarily stored in the memory 53.
- the received TS is written in the first TS recording area 531 (FIG. 7) in the memory 53 (FIG. 5).
- the TS read timing signal R is generated by the TS data read timing generation circuit 521 (FIG. 6) according to the flow shown in FIG. It should be noted that the reception of the TS from the wireless transmission device 40
- the CPU 54 (FIG. 5) checks whether there is any free space in the memory 53 (FIG. 5) for storing the TS, and the two storage regions 531 and 532 shown in FIG. If it has already been used, it notifies wireless transmission device 40 via wireless LAN module 51 (FIG. 5) that it cannot receive the TS.
- the CPU 54 (FIG. 5) in the wireless reception device 50 stores the received TS in a memory 53 (FIG. 5).
- the storage area in 5) is determined, and the determined storage area is notified to the TS memory read control circuit 522 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5).
- the TS memory read control circuit 522 (FIG. 6) determines a storage area in the memory 53 (FIG. 5) from which the TS is read based on the determined storage area in the memory 53 (FIG. 5).
- the TS memory read control circuit 522 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5) transmits the memory 5 of the received first TS. 3 Confirm that writing to (Fig. 5) is completed (step SI in Fig. 10).
- the first TS written at the head of the first TS storage area 531 (FIG. 7) in the memory 53 (FIG. 5) after the start of reception is referred to as a “head TS”.
- the TS memory read control circuit 522 (FIG. 6) in the receiving side memory control circuit 52 (FIG. 5) is output from the TS write address storage circuit 5228 (FIG.
- the first TS storage area 53 1 in the memory 53 (FIG. 5) is detected. It can be confirmed that the writing of the first TS to (FIG. 7) is completed.
- the TS memory read control circuit 522 (FIG. 6) in the reception-side memory control circuit 52 (FIG. 5) sets the memory 53 (FIG. 5).
- the time stamp added to the first TS stored in 5) is read (step S2 in FIG. 10).
- the TS memory read control circuit 522 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5) stores the data in the memory 53 (FIG. 5). It waits until the data amount becomes equal to or more than the predetermined value (step S3 in FIG. 10). This standby is performed in order to perform clock recovery on the VBR TS using the clock frequency of the wireless reception device 50.
- FIG. 13 shows an example in which the clock signals between the wireless transmission device 40 and the wireless reception device 50 are synchronized.
- the vertical axis represents the amount of data stored in the TS stored in the memory 53 (FIG. 5), and the horizontal axis represents time.
- FIG. 13 shows TSs output from the AV-HDD recording / reproducing device 22 (FIG. 1) and the like, which corresponds to a case where, for example, control is performed such that video data compressed by the MPEG2 system is read out frame by frame. I do.
- the third embodiment a case where a 20 Mbps HD (High Definition) video stream is transmitted in the TS format in an MPEG2 system will be described.
- a GOP is composed of 15 frames, and the data amount of an intra frame in one GOP is 20% of the total data amount of one GOP.
- the first TS storage area 531 (FIG. 7) in the memory 53 (FIG. 5) has a storage capacity capable of storing one GOP worth of data.
- the PCR is added to the first TS of each frame, and the description is continued assuming that the PCR is transmitted every 33 ms.
- the throughput in the wireless transmission section between the wireless transmitting device 40 and the wireless receiving device 50 is about 20 Mbps, and the amount of TS received via wireless is input to the wireless receiving device 50 at a substantially constant rate.
- the reading of the data in the memory 53 (FIG. 5) in the wireless receiving device 50 is performed based on the time stamp added to the TS based on the clock frequency of the transmitting side at the time of transmission.
- Memory 53 (Fig. 5) When reading the intra frame, the data of 20% of the data amount of 1 GOP is read in a very short time, so as shown in Fig. 13, the memory 53 (Fig. 5) The amount of data stored in the TS of the TS rapidly decreases (the period t segment D in Fig. 13).
- the amount of stored data gradually returns to the initial value F (line segment D D, line segment D D in FIG. 13).
- a straight line is drawn to facilitate understanding of the invention.
- a predetermined amount of TS is stored in the memory 53 (FIG. 5) so that the TS stored in the memory 53 (FIG. 5) does not overflow or underflow. Do not start reading data from memory 53 ( Figure 5) until In the third embodiment, the memory 53 (FIG. 5) stores half the data amount of one GOP (F in FIG. 13).
- step S3 of FIG. 10 when the amount of data stored in the memory 53 (FIG. 5) exceeds a predetermined value, the time measurement counter control circuit 5214 (FIG. 6) in the TS data read timing generation circuit 521 (FIG. 6) 8) sets the time stamp value added to the received first TS to the time measurement counter 5213 (FIG. 8) as an initial value, and sets the time measurement counter 5213 (FIG. 8) to time measurement.
- the control signal is output to start the count-up operation for (step S4 in FIG. 10). Then, in step S4 in FIG. 10, the count-up operation of the time measurement counter 5213 (FIG. 8) in the TS data read timing generation circuit 521 (FIG.
- the time comparison circuit 5216 (FIG. 8) outputs the TS read timing signal R.
- the TS read address generation circuit 5227 (Fig. 9) Based on the signal R, the system reads data for the ITS stored in the memory 53 (Fig. 5).
- Control signal R is output from terminal 5223 (step S5 in Fig. 10).
- the TS read out from the memory 53 passes through the bus arbiter circuit 523 (Fig. 6) in the receiving-side memory control circuit 52 (Fig. 5), and the TS memory read control circuit 522 (Fig. Input to FIFO memory 5225 (Fig. 9) in 6).
- the FIFO memory 5225 uses a bus arbiter circuit 523 (FIG. 6) between the TS write control signal from the CPU 54 (FIG. 5) and the TS read control signal from the TS memory read control circuit 522 (FIG. 6). Absorbs the read data delay time that occurred during bus arbitration.
- the delay amount for a fixed time is determined based on the TS read timing signal R input from the TS data read timing generation circuit 521 (FIG. 6) in the reception side memory control circuit 52 (FIG. 5).
- FIFO memory 5225 (
- the FIFO memory control circuit 5226 (FIG. 9) outputs a read control signal to the FIFO memory 5225 (FIG. 9) so that the TS is also read.
- the write control to the FIFO memory 5225 (Fig. 9) in the TS memory read control circuit 522 (Fig. 6) in the reception side memory control circuit 52 (Fig. 5) is output from the TS read address generation circuit 5227 (Fig. 9).
- the data read completion signal (not shown in FIG. 9 and shown as signal R in FIG. 6), which also outputs the bus arbiter circuit 523 (FIG. 6), is output from the TS read address.
- step S6 of FIG. 10 when the reading of data for ITS from the memory 53 (FIG. 5) is completed, the TS read address generation circuit 5227 (09) in the TS memory read control circuit 522 (FIG. 6) Based on the write address information stored in the TS write address storage circuit 5228 (FIG. 9), it is checked whether the TS of the next line is stored in the memory 53 (FIG. 5) and stored. If so, a TS data read control signal R for reading the time stamp of the TS of the next line is generated (step S7 in FIG. 10). Note that memory 53 (Fig.
- step S7 in FIG. 10 when receiving the time stamp of the TS (next TS) of the next line, the time comparison circuit 5216 (FIG. 8) in the TS data read timing generation circuit 521 (FIG. 6) Stamp signal R and time counter output from time measurement counter 5213 (Fig. 8)
- Step S8 in FIG. 10 the TS read timing signal R is output.
- FIG. 27 (FIG. 9) outputs the TS data read control signal R (step S5 in FIG. 10).
- the receiving-side memory control circuit 52 repeats the operation of steps S5 to S8 in Fig. 10 (that is, step S9 surrounded by a broken line).
- the receiving-side reference clock at which the oscillator of the wireless receiving device 50 oscillates is faster than the transmitting-side reference clock at which the oscillator of the wireless transmitting device 40 oscillates (that is, the receiving-side clock frequency of the wireless receiving device 50 is wirelessly
- the receiving-side clock frequency of the wireless receiving device 50 is wirelessly
- the reception reference time reception clock frequency
- the time stamp signal obtained based on the power counter value of the time measurement counter 5213 (Fig. 8).
- the third embodiment is configured to control the receiving-side memory control circuit 52 (FIG. 6).
- the CPU 54 in the wireless receiving device 50 identifies the transmitter (corresponding to the wireless transmitting device 40) based on the header information added to the wireless packet. (Step S211 in FIG. 19).
- the transmitter is identified using, for example, one or both of the MAC address added to the header information of the wireless packet and the device identification information (eg, IP address) unique to the transmitter. If MAC address or IP address is used as device identification information, new information is added to the wireless packet. Since the device identification information can be obtained without adding a character string, the processing load on the wireless transmission device 40 and the wireless reception device 50 can be reduced, and transmission and reception can be performed without increasing the load on the communication band.
- the CPU 54 (Fig. 5), based on the device identification information of the transmitter, stores in the storage unit (for example, a part of the memory 53 or a part of the memory 53, It is confirmed whether or not the time correction value (the previous time correction value) of the identified transmitter has already been stored in another memory (not shown) (step S212 in FIG. 19). If the time correction value of the identified transmitter (ie, the clock jitter correction value) is already stored in the wireless receiver 50, the CPU 54 (FIG. 5) stores the stored time correction value (clock jitter correction value). The correction value) is set as an initial value in the time correction value storage register 5215 (FIG. 8) in the TS data read timing generation circuit 521 (FIG.
- the wireless receiver 50 according to the third embodiment has a five-stage table from 0 to 4 (from tableO to table4) as shown in FIGS. 24 and 25, and stores the time correction value.
- the wireless reception device 50 when there is a time correction value stored in the wireless reception device 50 (for example, a previous time correction value obtained by receiving past data), the stored previous time is used.
- the reason for using the correction value as the initial value is as follows.
- the wireless reception device 50 performs clock recovery of the VBR TS.
- the average data transmission rate of VBR TS is about 20 Mbps. In short time units, the average data transmission rate fluctuates greatly. Therefore, if the evaluation is performed for a relatively long time, the average data transmission rate is almost constant, and the clock jitter value can be estimated. Therefore, in the third embodiment, the minimum measurement time is set to the period of one GOP (about 0.5 seconds).
- the radio receiving apparatus 50 receives the previous TS reception.
- the measurement result (previous time correction value) measured at the time of the execution of the clock recovery is stored.
- the time required for the correction value to converge within a predetermined range (the time required for the time correction value to converge in step S217 in FIG. 19 described later) can be reduced, and the time received by the MEPG2 decoding device can be reduced.
- the CPU 54 sets the TS memory read control circuit 522
- the initial value “0” is set in the integration result storage register 5230 (FIG. 9), the TS output number storage register 5232 (FIG. 9), and the measurement time storage register 5234 (FIG. 9) in (FIG. 6).
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231 (FIG. 9), and the measurement time measurement counter 5233 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) are also provided.
- step S215 in FIG. 19 the CPU 54 sets initial values to various parameters used when calculating a time correction value (hereinafter, referred to as a clock jitter correction value) (step S215 in FIG. 19).
- CONVF is a convergence determination flag.
- CONV—CNT is a counter that counts the number of times that the difference value dCORRECTTM of the clock jitter correction value, described later, enters the predetermined convergence area continuously in the stage of calculating each clock jitter correction value (stage).
- n indicates that when the TS rate used in another embodiment described later changes significantly, the calculation operation of the clock jitter correction value is stopped until the sudden change in the storage capacity of the TS in the memory 53 (FIG. 5) converges. In this case, it is the counter value of the counter that counts the suspension period.
- the CPU 54 (FIG. 5) measures and sets initial values (step S216 in FIG. 19).
- the method of measuring and setting the initial value will be described with reference to FIG.
- the CPU 54 When the reception of the TS is started, the measurement of the initial value is started.
- the CPU 54 When measuring the initial value, the CPU 54 (FIG. 5) first determines whether the memory 53 (FIG. 5) has started reading the TS. (Step S231 in FIG. 20). When it is confirmed that the reading of the memory 53 (FIG. 5) is started, the CPU 54 (FIG. 5) sets a time for measuring the initial value (initial value measuring time) in the internal timer ( Step S232 in Figure 20). For example, set the initial value measurement time to 0.5 second, which is the time of 1 GOP. Note that the initial value measurement time can be set to a time for a plurality of GOPs.
- the CPU 54 (FIG. 5) waits until the initial value measurement time set in the timer elapses (step S233 in FIG. 20). After the elapse of the initial value measurement time, the CPU 54 (FIG. 5) sets the integration result storage register 5230 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6), the TS output number storage register 5232 (FIG. 9), and performs measurement.
- the measurement result stored in the time storage register 5234 (Fig. 9) is read (step S234 in Fig. 20), and then, the integration result storage register 5230 (Fig. 9), the TS output number storage register 5232 (Fig. 9), and The initial value '0' is set in the measurement time storage register 5234 (Fig.
- step S235 in Fig. 20 the memory storage data amount integration circuit 5229 (FIG. 9), TS output number measurement counter 5231 (FIG. 9), and measurement time measurement counter 5233 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6). ) Is also set to the initial value '0'.
- the CPU 54 calculates an initial value using various register values. Specifically, the value D stored in the integration result storage register 5230 (FIG. 9) is stored in the measurement time.
- the integration in the memory storage data amount integration circuit 5229 calculates the difference between the reference capacity F and the memory storage data amount.
- the output is output as the integration result D in the area force memory storage data amount integration circuit 5229 (FIG. 9) indicated by the hatched portion in FIG. Also,
- the integration in the memory storage data amount integration circuit 5229 is performed by the integration value meter (not shown) provided in the memory storage capacity integration circuit 5229 (FIG. 9). Based on the control signal generated by the time measurement counter, the difference AF is measured and integrated at regular intervals. With the above processing, the measurement and setting of the initial value MEMSUM are completed.
- the memory storage capacity Based on a control signal generated by an integration value measurement time generation counter (not shown) provided in an integration circuit 5229 (FIG. 9), the difference AF is measured at regular intervals and integrated.
- the difference ⁇ F may be measured based on the TS read timing signal output from the TS data read timing generation circuit 521 (FIG. 6).
- the measurement and setting of the initial value MEMSUM are completed (step S238 in Fig. 20), and the measurement time (TIME [table]) for calculating the time correction value (clock jitter correction value) Is set (step S239 in FIG. 20).
- the time correction value measured in the past is stored in the radio receiver 50
- the time correction value is obtained by using the time correction value when the video stream transmission / reception starts. Stream transmission and reception becomes possible.
- the reference clocks in the radio transmitter 40 and the radio receiver 50 are crystal-accurate (for example, the maximum frequency deviation is about 100 ppm)
- this is not a problem, but if the reference clock has a frequency deviation of about 1%, Until the clock jitter correction value is within a certain range, the PLL in the MPEG2 decoding circuit is not inserted and the image may be distorted.
- the clock jitter correction value is brought to the convergence value immediately after the start of transmission / reception by using the previous correction result instead of measuring the clock jitter correction value from the beginning. Therefore, even in the case described above, there is an effect that images can be transmitted and received without being disturbed from the beginning.
- the measurement time is shortened in order to converge the clock jitter correction value quickly, and the gain of the system when calculating the clock jitter correction value g [table] (Fig. 25) The slope of the straight line). If the measurement time is shortened, the change in the input rate of the input TS becomes a disturbance, and the stability near the convergence value of the clock jitter correction value is low.
- the control reacts sensitively to the change in the rate of the input TS.
- the system gain g [table] in calculating the clock jitter correction is increased, the time until convergence is increased, but the stability around the convergence value of the clock jitter correction value is also low. Therefore, in the third embodiment, when calculating the clock jitter correction value, a plurality of stages are provided, and the measurement time, the threshold for determining convergence, and the system gain when calculating the clock jitter correction value are calculated at each stage. By switching, the measurement time is shortened and the system gain g [table] is increased so that convergence is fast at the start of transmission and reception of the TS stream between the wireless transmitter 40 and the wireless receiver 50.
- the clock jitter correction value converges substantially, the above measurement time is lengthened, disturbance due to a change in TS rate caused by VBR or the like is reduced, and the system gain g [table] is reduced, thereby stabilizing the system. It is configured so that it is possible to perform a game. As a result, the convergence time when calculating the clock jitter correction value can be shortened, and in the region where the clock jitter correction value has converged, the convergence time is not affected by changes in the TS rate caused by VBR and the like. This has the effect of allowing the system to operate stably.
- the measurement time (TIME [table]) for calculating the time correction value (clock jitter correction value) in step S239 in FIG. 20 is completed, the calculation of the time correction value starts.
- the CPU 54 (FIG. 5) waits until a predetermined measurement time has elapsed (step S51 in FIG. 21).
- the measurement time in step S51 of FIG. 21 is the time of one GOP, similarly to the initial value measurement time (step S232 in FIG. 20) used in setting the initial value.
- the measurement time elapses in step S51 in FIG. 21 first, the previously measured value MEMSUM and the average read rate TSRate are saved as the previous measured value PMEM SUM and the previous average read rate PTSRate (see FIG. 21). 21 steps S52).
- the CPU 54 (FIG. 5) 30 (Fig. 9), read the measurement results stored in the TS output number storage register 5232 (Fig. 9), and the measurement time storage register 5234 (Fig. 9) (step S53 in Fig. 21), and then store the integration result storage register 5230 (FIG. 9), TS output number storage register 5232 (FIG. 9), and measurement time storage register 5234 (FIG. 9) are set to the initial value '0' (step S54 in FIG. 21).
- the memory storage data amount integration circuit 5229 (FIG. 9), the TS output number measurement counter 5231, and the measurement time measurement counter 5233 are also set to the initial value “0”.
- the CPU 54 (FIG. 5) stores the integration result storage register 5230 (FIG. 9) using the above various register values in the same manner as in the case of the initial value measurement (Step S236 in FIG. 20). Store the value D in the measurement time storage register 5.
- a deviation that is, a difference between the measured value MEMSUM and the initial value PMEMSUM is calculated by the following equation to obtain a clock jitter value dSUM (step S57 in FIG. 21).
- step S58 a clock jitter correction value is calculated using the calculated clock jitter value dSUM.
- a difference value dCORRECTTM also referred to as “clock jitter correction difference value” or “dCORRECTTM value”
- dCORRECTTM value the clock jitter correction difference value
- the vertical axis shows the clock jitter correction difference value (dCORRECTTM value), and the horizontal axis shows the measured value (dSUMZTSRate).
- the slope of the straight line corresponds to the system gain g [table] of each table.
- the clock jitter value dSUM is divided by the average read rate TSRate of the TS. This is due to the following reason.
- the magnitude of the required clock jitter value (corresponding to the integrated value in the shaded area in FIG. 14) differs between when receiving a TS with a data transfer rate of 5 Mbps and! /. In order to normalize it, it was configured to normalize with the average read rate of TS.
- the clock jitter correction value calculated previously (CORRECTTM value) and the clock jitter correction difference value calculated this time (dCORRECTTM value) are added to calculate the clock jitter correction value (step S72 in FIG. 22).
- the calculated dCORRECTTM value is based on the control result already controlled by the time correction value storage register 5215 (FIG. 8), and the clock jitter correction difference value calculated by the above algorithm is the difference. is there. Therefore, when the clock jitter correction value is set in the time correction value storage register 5215 (FIG. 8), the calculated clock jitter correction difference value is added to the currently set clock jitter correction value.
- FIG. 14 shows a case where the receiving side clock frequency of the wireless receiving device 50 is higher than the transmitting side clock frequency of the wireless transmitting device 40, and the reference clock of the wireless receiving device 50 is faster than the reference clock of the wireless transmitting device 40.
- the actual clock frequency deviation depends on the accuracy of the oscillator of the wireless transmitter 40 and the oscillator of the wireless receiver 50.If a crystal oscillator is used, the maximum clock deviation is about ⁇ 100 ppm. .
- the clock jitter value dSUM is drawn in an emphasized manner to make the description easier to understand (that is, the line segment DD).
- the count value of the time measurement counter 5213 (FIG. 8) in the wireless receiving device 50 advances rapidly, and the memory 53 (FIG. 5)
- the amount of TS data stored in the Sea urchin) In this case, the deviation between the clock frequency on the receiving side and the clock frequency on the transmitting side is constant (that is, does not fluctuate due to a change in the input rate of the TS, etc.).
- the shaded portion is the clock jitter value dSUM (a value corresponding to the difference between the above measured value MEMSUM and the above initial value PMEMSUM).
- the clock jitter correction value CORRECTTM when calculating the clock jitter correction CORRECTTM, is set to be within a predetermined value range (denoted by ⁇ in FIG. 22). Is carried out.
- the maximum deviation (clock jitter correction value) of the clock frequency generated between the two devices is as follows. The value is within the maximum clock frequency deviation of the crystal that is the oscillator. Therefore, in the third embodiment, the clock jitter correction value is calculated according to the flowchart shown in FIG. 22, and when a correction value exceeding the range of the correction value determined by the crystal frequency accuracy is calculated, it is determined between the two devices.
- the third embodiment is configured to control the clock jitter correction value CORRECTTM to be within a predetermined value range.
- the clock jitter correction value CORRECTTM by controlling the clock jitter correction value CORRECTTM by limiting the amplitude within a predetermined range, it is possible to stabilize the system control (clock jitter correction control) of the wireless reception device 50. effective.
- step S73 it is checked whether the clock jitter correction value CORRECTTM is within a predetermined range (one ⁇ ⁇ COR RECTTM ⁇ ⁇ ). If it is within the predetermined range, the operation of calculating the clock jitter correction value ends.
- the clock jitter correction value CORRECTTM is obtained.
- extreme clock jitter correction is not performed and MPEG2 decoding is not performed.
- the entire system including the circuit can be operated stably.
- the clock synchronization does not deviate beyond a predetermined value, the jitter of the TS stream can be suppressed to a predetermined value or less, and the overflow and underflow of the memory 53 can be suppressed.
- the CPU 54 sets the calculated clock jitter correction value CORRECTTM in the time correction value storage register 5215 in the TS data read timing generation circuit 521 (FIG. 6). (Step S59 in FIG. 21).
- the CPU 54 determines whether the clock jitter correction value CORRECTTM has converged (step S60 in FIG. 21).
- the convergence determination flow of the clock jitter correction value CORRECTT M will be described with reference to FIG.
- FIG. 24 shows the convergence determination threshold (CONV [tabl e]) at each stage.
- CRCTML is a predetermined constant. As shown in Fig. 24, the threshold value at each stage decreases as the stage goes up (clock jitter correction value CORRECTTM moves toward convergence).
- the transmission and reception of the video stream will start for a while (wireless transmission (Until the deviation of the clock frequency between the device 40 and the wireless receiving device 50 is reduced to a predetermined range.) Since the TS jitter cannot be sufficiently absorbed, clock synchronization can be performed by the MEPG2 decoding circuit. It is not possible and the displayed image is disturbed. Therefore, in the third embodiment, the convergence determination stage is divided into five stages, and the convergence accuracy of the clock jitter value is gradually increased.
- the clock jitter value is quickly and quickly drawn to the vicinity of the convergence area, so that the period during which the clock is not synchronized by the MEPG2 decoding circuit and the displayed image is disturbed is minimized.
- the clock jitter correction value converges, there is an effect that clock synchronization can be compensated by a stable operation with respect to disturbance caused by a change in TS rate or the like.
- the power described when the convergence determination stages are controlled in five stages is controlled.
- the present invention is not limited to this. For example, two stages, three stages, ten stages, etc. The same effect can be obtained by setting other than five levels.
- the parameters of each stage are configured to be different from each other.
- the present invention is not limited to this.
- the convergence determination condition is switched from table3 (tableO-table2 has the same value). The same effect can be obtained even if the configuration is adopted.
- step S81 If it is determined in step S81 that the clock jitter correction difference value dCORRECTTM does not fall within the predetermined range, the CPU 54 (FIG. 5) sets the variable CONV-CNT to 0 and ends the convergence determination operation (FIG. 23). Step S82). On the other hand, if the clock jitter correction difference value dCORRECTTM is within the predetermined range in step S81, the CPU 54 (FIG. 5) sets 1 to CONV-CNT (step S83 in FIG. 23) and converts the result to CONV-CNT. — Compare with NUM [tabl e] (Step S84 in Figure 23). If the result of this comparison is less than CONV-NUM [table], the convergence determination ends.
- the convergence determination flag (CONVF) is set to "1"
- CONV-CNT is set to "0". The determination operation ends.
- the clock jitter correction difference value dCORRECTTM is within a predetermined range continuously plural times, it is determined that the clock jitter correction value CORRECTTM has converged.
- the clock jitter correction difference value dCORRECTTM accidentally falls within the predetermined range due to a factor such as a TS rate change even though the clock jitter correction value CORRECTTM has not converged. it can.
- the convergence determination of the clock jitter correction value CORRECTTM can be reliably performed, and the system can be operated stably.
- the clock jitter correction difference value dCORRECTTM falls within a predetermined range continuously plural times. If the clock jitter correction value CORRECTTM is determined to have converged, the present invention is not limited to this.For example, if the clock jitter correction value CORRECTTM is calculated continuously within a predetermined threshold range, the convergence may occur. The same effect can be obtained even if it is determined that it has been performed.
- step S62 the table value is compared with a predetermined value
- 8 4 in the third embodiment) (step S62 in FIG. 21), and if it exceeds ⁇ , the table value is set to j8 (step S62). Step S63 in FIG. 21). In the third embodiment,
- the CPU 54 FIG.
- step S64 in FIG. 21 sets a measurement time (step S64 in FIG. 21).
- the CPU 54 (FIG. 5) detects whether or not the reception of the stream from the wireless transmission device 40 has been completed, and if not, calculates the next clock jitter correction value. Then, wait for the measurement time set in step S64 to elapse (step S51 in FIG. 21), and calculate the clock jitter correction value again.
- the convergence determination stage (table value) is equal to or greater than ⁇ (step S219 in FIG. 19). If the table value is less than ⁇ , the TS reception operation ends. On the other hand, if the table value is greater than or equal to ⁇ , the current table value and the clock jitter correction value CORRECTTM are stored (step S220 in FIG. 19), and the TS reception operation ends.
- the time measurement counter control circuit 5214 in the TS data read timing generation circuit 521 (FIG. 6), the time is measured at predetermined time intervals (every 100 ms in the third embodiment).
- the output value of the time measurement counter 5213 is corrected by adding the clock jitter correction value CORRECTTM stored in the correction value storage register 5215 (Fig. 8) to the count value of the time measurement counter 5213.
- the case shown in FIG. 14 is when the receiving clock frequency in the wireless receiving device 50 is higher than the transmitting clock frequency in the wireless transmitting device 40, and the amount of data stored in the memory 53 (FIG. 5) is decreasing.
- the time measurement counter 5213 closes once every 100 ms.
- the time is returned by the clock jitter correction value CORRECTTM (the time is forcibly delayed.) O
- the operation time based on the clock frequency in the wireless receiver 50 can be reduced.
- the operation time based on the clock frequency in the wireless transmission device 40 can be approached.
- time measurement counter 5213 in clock recovery (clock jitter correction) in radio receiving apparatus 50, time measurement counter 5213 (FIG. 8) in TS data read timing generation circuit 521 (FIG. 6) is used. ), The time correction value (clock jitter correction value) stored in the time correction value storage register 5215 (Fig. 8) can be adjusted at regular intervals as an offset. Appropriate clock regeneration can be realized without changing the system clock frequency in the device 50. Therefore, if the wireless receiving device 50 of the third embodiment is used (that is, if the data receiving method of the third embodiment is used), each of the TSs to which a plurality of wireless transmitting devices have also been transmitted is stored in the memory 53 (FIG. 5). And the time measurement counter 5213 (Fig. 8) corresponding to each storage area. With such a configuration, there is an effect that clock recovery of a plurality of received TSs can be performed independently.
- the wireless receiving device 50 when the data receiving method according to the third embodiment (the wireless receiving device 50 according to the third embodiment) is used, it is possible to receive a VBR TS transmitted via a wireless communication having jitter.
- the clock can be synchronized between the wireless transmission device 40 and the wireless reception device 50, and the memory 53 (FIG. 5) in the wireless reception device 50 can be controlled without underflow or overflow. It is possible to output TS continuously. Therefore, when the TS of the MPEG2 system is decoded and reproduced by the receiving device, there is an effect that the MPEG2 data can be reproduced without interrupting the video.
- receiving side memory 53 has a plurality of storage areas, so that one wireless receiving device 50 Packet data output from a number of data transmitting devices can be received, and the effect is that data can be output continuously without causing underflow or overflow for each received packet data. Also, if the receiving memory 53 Since the storage area is provided, a plurality of streams can be handled with a simple circuit configuration, and there is an effect that the circuit scale can be reduced, and power consumption and manufacturing cost can be reduced. Further, as described above, since the clock jitter value depends on the deviation of the system clock frequency, the value becomes almost constant when the device is specified.
- the gain (gradient of the straight line indicating the conversion table) for calculating the clock jitter correction value is increased. Save time. Then, after the clock jitter correction value is drawn within a certain convergence range, the gain is reduced and the system stability is emphasized. As a result, the time for drawing the clock jitter correction value to within the convergence range can be reduced, and the radio receiving apparatus 50 can be operated stably after the clock jitter correction value is within the convergence range.
- the reason for increasing the measurement time is to increase the measurement time to improve the accuracy of the measurement value, and to allow the wireless reception device 50 to operate stably after the convergence of the clock jitter correction value.
- the clock jitter value converges, since the PLL control or the like is not employed, it is necessary to continuously update the clock jitter correction value when receiving data.
- FIG. 26 is a flowchart showing an operation of the radio receiving apparatus according to Embodiment 4 of the present invention when calculating a clock jitter correction value.
- FIG. 27 is a flowchart illustrating a convergence determination operation when calculating a clock jitter correction value in the wireless reception device according to the fourth embodiment.
- FIG. 28 is a diagram illustrating an example of a measurement time used in each correction value calculation stage and a threshold value table used for convergence determination in Embodiment 4.
- FIG. 4 a flow for limiting the correction range of the clock jitter correction difference value dCORRECTTM (also referred to as “dC ORRECTTM value”) is newly added as compared with the third embodiment! .
- the data receiving method according to the fourth embodiment is the same as the data receiving method according to the third embodiment except for the operation flow when calculating the clock jitter correction value and the flow for determining whether the clock jitter correction value converges.
- the third embodiment and the fourth embodiment have the following two differences.
- the dCORRECTTM value calculated when calculating the clock jitter correction value Is limited. This is for the following reasons.
- the TS input in this system targets VBR instead of CBR (fixed bit rate). Therefore, for clock synchronization of a system targeting VBR, the dCORRECTTM value calculated when calculating the clock jitter correction value includes the clock jitter value due to the clock frequency deviation between the wireless transmitter 40 and the wireless receiver 50. In addition to this (see the shaded area in Fig. 14), this also includes fluctuations in the TS reception rate caused by VBR, the effects of wireless packet retransmission control in wireless sections, and the like.
- the amplitude of the dCORRECTTM value calculated when calculating the clock jitter correction value is limited. Provided. As a result, even if the reception rate of the TS fluctuates based on VBR and the dCORRECTTM value changes greatly, the value is clipped within a predetermined range, and therefore the clock jitter correction value deviates significantly from the original value. Clock jitter can be corrected without the need.
- the second difference is that an observer-one-bar OBS is introduced in the flow for determining the convergence of the clock jitter correction value.
- the clock jitter correction value itself is used as the convergence determination condition.
- the accuracy of the convergence determination is improved by introducing an observer. Specifically, a filter for extracting a low-frequency component of the clock jitter correction value is provided, and the convergence of the clock jitter correction value is determined using the filter output. As a result, it is possible to minimize the influence of disturbances such as fluctuations in the TS reception rate and retransmission control of wireless packets in a wireless section due to the above-described VBR, and to determine the convergence of the clock jitter correction value. .
- FIGS. 1 to 10, FIG. 13, FIG. 14, and FIGS. 18 to 25 used in the above third embodiment are also referred to.
- steps that perform the same processing as the steps in FIGS. 22 and 23 are denoted by the same reference numerals.
- the CPU 54 FIG. 5
- the radio reception device 50 transmits the TS (the radio transmission device) based on the header information added to the radio packet. (Equivalent to 40) (see step S in FIG. 19). 211).
- the transmitter is identified using, for example, one or both of the MAC address added to the header information of the wireless packet and the device identification information (eg, IP address) unique to the transmitter.
- the CPU 54 (FIG. 5) in the wireless receiving device 50 stores the storage unit (for example, a part of the memory 53, Alternatively, it is confirmed whether or not the time correction value of the transmitter identified in the past (also referred to as “previous time correction value”) is already stored in another memory (not shown) (FIG. 19).
- the CPU 54 (FIG. 5) stores the stored previous time correction value.
- the initial value is set in the time correction value storage register 5215 (FIG. 8) in the TS data read timing generation circuit 521 (FIG.
- the initial value '0' is set (step S215 in FIG. 19).
- the memory storage data amount integration circuit 5229 (FIG. 9), TS output number measurement counter 5231 (FIG. 9), and measurement time measurement counter 5233 (FIG. 9) in the TS memory read control circuit 522 (FIG. 6) ,
- the initial value '0' is set.
- the CPU 54 sets initial values to various parameters CONVF, CONV—CN ⁇ , n used when calculating the time correction value (step S215 in FIG. 19).
- CONVF is a convergence determination flag.
- the convergence determination flag CONVF is set to '1' and CONV-CNT is At the stage of calculating each clock jitter correction value, a count value of a counter that counts how many times a difference value dCORRECTTM of a clock jitter correction value described later continuously enters a predetermined convergence region, where n is If the TS rate changes significantly, the TS in the memory 53 (Fig. 5) When the calculation operation of the clock jitter correction value is stopped until the rapid change of the storage capacity converges, this is a counter value of a counter that counts the stop period.
- step S216 in FIG. 19 the initial value is measured and set based on the flow shown in FIG.
- the CPU 54 (FIG. 5) starts calculating the clock jitter correction value.
- the operation at the time of calculating the clock jitter correction value will be described with reference to FIG.
- the CPU 54 (FIG. 5) waits until a predetermined measurement time elapses (step in FIG. 21). S51).
- step S51 When the measurement time elapses in step S51, the previously measured value MEMSUM and average reading rate TSRate measured in step S52 are saved to PMEMSUM and PTSRate. Then, in step S53, the CPU 54 (FIG. 5) stores the integration result storage register 5230 (FIG. 9), the TS output number storage register 5232 (FIG. 9), and the measurement time storage register 5234 (FIG. 9). The measured result is read and the integration result storage register 5230 (Fig. 9), TS output number storage register 5232 (Fig. 9), and measurement time storage register 5234 (Fig. 9) are initialized to '0' in step S54. Set to. At this time, the memory storage data amount integration circuit 5229 (FIG.
- the CPU 54 calculates the measured value MEMSUM and the average read rate TSRate using the various register values in the manner described in Embodiment 3 (steps S55 and S55 in FIG. 21). And step S56).
- step S57 a deviation (ie, difference) between the measured value MEMSUM and the initial value PMEMSUM is calculated, and a clock jitter value dSUM is calculated.
- step S58 the clock jitter correction value CO RRECTTM is calculated using the calculated clock jitter value dSUM.
- the clock jitter correction value calculation flow according to the fourth embodiment will be described with reference to FIG.
- step S71 similarly to the third embodiment, the clock jitter correction difference value dCORRECTTM is calculated using the clock jitter value dSUM.
- step S91 compares the absolute value of the amplitude with a predetermined constant dCRCTLIM [table] in step S91. If the absolute value exceeds dCRCTLIM [table], the amplitude is limited. To do. Specifically, if the clock jitter correction difference value dCORRECTTM is positive in step S92,
- the correction range of the clock jitter correction value is limited, so that the clock jitter correction value is limited.
- Control can be performed so that the value does not greatly deviate from the predetermined range.
- the clock jitter correction value can be controlled within the range determined in each convergence determination stage, so that the system can be operated stably.
- the clock jitter value dSUM can be quickly converged immediately after the start of TS reception, and the clock jitter correction value may be significantly disturbed at the converged stage. There is an effect that even when is input, it can be kept within a predetermined range.
- the clock jitter correction value is calculated by adding the previously corrected clock jitter correction value and the currently calculated clock jitter correction difference value dCORRECTTM (step in FIG. 26). S72). This is because the calculated clock jitter correction difference value is already controlled by the time correction value storage register 5215 (FIG. 8) and is based on the control result. The jitter correction difference value is the difference. Therefore, the time correction value storage register 5 When setting the clock jitter correction value to 215 (Fig. 8), the calculated clock jitter correction difference value is added to the currently set clock jitter correction value.
- the clock jitter correction value CORRECTTM when calculating the clock jitter correction value, is in a predetermined value range (denoted by ⁇ in FIG. 26). Clipping is performed in step S73—step S76 so that Specifically, in step S73, it is checked that the CORRECTTM value is within a predetermined range (1 ⁇ ⁇ CORRECTTM ⁇ ⁇ ). If it is within the predetermined range, the operation of calculating the clock jitter correction value ends. On the other hand, if the CORRECTTM value is outside the predetermined range, it is checked in step S74 whether the CORRECTTM value is positive.
- the CPU 54 (FIG. 5) stores the calculated clock jitter correction value in the time correction value storage register 5215 in the TS data read timing generation circuit 521 (FIG. 6). Set (Step S59 in FIG. 21).
- the CPU 54 (FIG. 5) determines whether the clock jitter correction value has converged (step S60 in FIG. 21).
- the convergence determination flow of the clock jitter correction value according to the fourth embodiment will be described using FIG. 27 and FIG.
- the observer OBS is used to determine the convergence of the clock jitter correction value.
- the calculated clock jitter correction value is input to a low-pass filter having a relatively large time constant! ⁇ , and the low-frequency component is extracted. Then, the convergence of each convergence stage is determined using the extracted low-frequency component of the clock jitter correction value.
- the CPU 54 (FIG. 5) sets the clock jitter correction value in the time correction value storage register 5215 in the TS data read timing generation circuit 521 (FIG. 6).
- a convergence determination is performed.
- the observer OBS measured last time is retracted as POBS in step S101.
- the observer OBS is not calculated immediately after the start of TS reception. '0' is substituted for POBS.
- the convergence determination is performed by extracting the low-frequency component of the clock jitter correction value as described above. Therefore, in the fourth embodiment, only the extraction of the low-frequency component of the clock jitter correction value is performed for the predetermined number of times immediately after receiving the TS without performing the convergence determination of the clock jitter correction value (step in FIG. 27). S102).
- step S102 the convergence determination operation of the clock jitter correction value is binosed in step S102. If it is determined in step S102 that the execution of the clock jitter correction operation has not been completed for a predetermined number of times (for example, 10 times), the CPU 54 (FIG. 5) performs the first time after the initialization in step S104. Is determined. If this is the first process after initialization, the CORRECTTM value is assigned to the observer OBS as an initial value (step S105 in FIG. 27). If power is not applied immediately after initialization, the observer OBS is calculated according to the following equation to extract the low-frequency component of the clock jitter correction value (step S106 in FIG. 27).
- step S102 in FIG. 27 After the above process is repeated a predetermined number of times and the initial setting of the observer OBS is completed, next, the convergence determination of the clock jitter correction value is started (step S102 in FIG. 27).
- the CPU 54 calculates the observer-one OBS in step S103.
- the time constant at the time of calculating the observer OBS in step S106 and the time constant at the time of calculating the observer OBS in step S103 indicate the same force. The same effect can be obtained even if the time constant of step S106 is made smaller than the time constant of step S103.
- the time constant in step S103 is set to the same value in each convergence stage as shown in FIG. 27. The force is not limited to this. The same effect can be obtained even if the time constant for calculating the OBS is set large.
- the CPU 54 checks whether the OBS-POBS I is within a predetermined range (OBSCONV [table]) ( Step S107 in FIG. 27).
- FIG. 28 shows the convergence determination threshold (OBSCONV [table]) at each stage.
- OBSCRCTML is a predetermined constant.
- the threshold value at each stage decreases as the stage goes up (clock jitter correction value approaches convergence), as in the third embodiment.
- the parameters of each stage are not limited to the forces set as shown in FIG.
- step S107 If it is determined in step S107 that IOBS-POBS
- the convergence determination flag (CONVF) is set to 1, and CONV-CNT is set to 0 to terminate the convergence determination operation.
- the CPU 54 detects whether the reception of a stream of as many as 40 wireless transmission devices has been completed, and if not completed, calculates the next clock jitter correction value in step S64. Wait for the measurement time set in to elapse (step S51 in FIG. 21), and calculate the clock jitter correction value again.
- the stream reception has been completed, it is determined whether the convergence determination stage (table value) is equal to or greater than ⁇ (step S219 in FIG. 19). If it is less than ⁇ , the TS reception operation ends. On the other hand, if it is ⁇ or more, the current table value and clock jitter correction value are stored (see FIG. 19). Step S220), end the TS receiving operation.
- the clock reproduction method using the clock jitter correction value is the same as that of the third embodiment, and thus the description is omitted.
- the calculation of the clock jitter correction value and the determination of the convergence of the clock jitter correction value are performed as described above. Therefore, when calculating the dCORRECTTM value, even if a large external disturbance is input, Since the correction range of the clock jitter correction value is limited, the clock jitter correction value does not greatly deviate from the predetermined range. Therefore, the clock jitter correction value can be controlled within the range determined in each convergence determination stage, and the system can be operated stably. In addition, by introducing an observer as described above when determining the convergence of the clock jitter correction value, the convergence determination of the clock jitter correction value can be performed without erroneous determination even when a large external disturbance is input.
- the radio transmitting apparatus 40 Since the clock synchronization between the wireless receiving devices 50 can be stably achieved, the TS can be continuously output without causing underflow or overflow. Therefore, when the TS of the MPEG2 system is decoded and reproduced by the receiving device, there is an effect that the MPEG2 data can be reproduced without interrupting the video.
- FIG. 29 is a flowchart illustrating an operation of calculating a clock jitter correction value in radio receiving apparatus 50 according to Embodiment 5 of the present invention.
- the clock jitter correction value is forcibly offset according to the amount of TS stored in the memory 53 (FIG. 5).
- Embodiment 3 is different from Embodiment 3 in that a flow for controlling the value to be within a predetermined range is added. By adopting such a configuration, even after the clock jitter correction value has converged, the clock jitter correction can be performed more stably. Will be able to Hereinafter, the principle of the fifth embodiment will be briefly described with reference to FIG. FIG.
- the reference clock of the wireless receiving device 50 in which the receiving clock frequency of the wireless receiving device 50 is higher than the transmitting clock frequency of the wireless transmitting device 40 is faster than the reference clock of the wireless transmitting device 40.
- the clock jitter correction value when the clock jitter correction value is calculated, the average TS number temporarily stored in the memory 53 (FIG. 5) gradually decreases until the clock jitter correction value converges.
- the receiving clock frequency of the wireless receiving device 50 is lower than the transmitting clock frequency of the wireless transmitting device 40, the average number of TSs temporarily stored in the memory 53 (FIG. 5) gradually increases. To go.
- the clock jitter correction value converges at a position where the maximum value of the storage capacity of the TS temporarily stored in the memory 53 (FIG. 5) is lower than the position F in the figure. .
- the memory 53 (FIG. 5) underflows.
- the clock jitter correction difference value also referred to as “dCORRECTTM value”
- control is performed using only the deviation between PMEMSUM and MEMSUM. This occurs because the average memory in Fig. 5) is controlled at a skewed position, not at the center of the number of TSs.
- the offset is forcibly adjusted to the clock jitter correction value to become the center of the average storage TS memory in the memory 53 (FIG. 5). By performing such control, the calculation control of the clock jitter correction value is performed so as to be able to cope with the change in the average rate of the input TS.
- step S216 the CPU 54 (FIG. 5) starts the clock jitter correction operation.
- step S51 the measurement time has elapsed. After the measurement time has elapsed, the CPU 54 (FIG.
- a predetermined value the upper limit of the MEMSUM value
- step S113 if the measured value MEMSUM is larger than the predetermined value (upper limit of the MEMSUM value)! /, The operation of calculating the correction value of the clock jitter correction value using the numerical value (COMPTM) predetermined for the current CORRECTTM value is terminated ( Step S113 in FIG. 29).
- step S113 if the offset value is forcibly added to the CORRECTTM value through the present routine at the time of the previous calculation of the CORRECTTM value, the CORRECTTM value is output as it is without performing any processing. The flow is not shown.
- step S112 determines whether the measured value MEMSUM is smaller than the predetermined value (the upper limit of the MEMSUM value). If it is determined in step S112 that the measured value MEMSUM is smaller than the predetermined value (the upper limit of the MEMSUM value), then in step S114 the measured value MEMSUM is reduced to the predetermined value (the lower limit of the MEM SUM value). ) Is smaller! If the value is smaller than the predetermined value (the lower limit of the MEMSUM value), a predetermined numerical value (COMPTM) is subtracted from the current CORRECTTM value, and the correction value calculation operation ends (step S115).
- COMPTM predetermined numerical value
- the CORRECTTM value is output without any processing (note that the CORRECTTM value is output as it is). Row is not shown. If the measured value MEMSUM is larger than the predetermined value (the lower limit of the MEMSUM value) in step S114, the clock clock is calculated in step S116 according to the clock jitter correction value calculation flow shown in FIG. 22 described in the third embodiment. Calculate the jitter correction value.
- the offset is forcibly applied to the CTTM value in step S113 or step 3115 in the previous clock jitter correction value calculation in step S113 or step 3115. If it has been added, as shown in step 72 in FIG. 22, it is necessary to subtract the forcibly added offset value from the current CORRECTTM value instead of calculating the dCORRECTTM value to the current CORRECTTM value from the current CORRECTTM value. To be configured. In this way, in the first stage of returning to the normal clock jitter correction value calculation flow, the calculation of the clock jitter correction value is masked, and the forcibly added offset value is added to the current CORRE CTTM value. In the above control, the offset value added to the converged CORRECTTM value does not cause disturbance, which has the effect of stably controlling the system.
- Embodiment 5 when calculating the clock jitter correction value, according to the flow shown in FIG. 29, if the clock jitter correction value has converged, the offset of the clock jitter correction value is forcibly set. Since the control is performed so that the center of the number of TS stored in the memory 53 (Fig. 5) is maintained, the clock jitter correction value calculation control ( This is effective in performing control without memory underflow or overflow.
- FIG. 30 is a flowchart showing an operation of the radio receiving apparatus according to Embodiment 6 of the present invention when calculating a clock jitter correction value.
- the TS reception rate is newly monitored, and when the TS reception rate greatly changes, the flow for calculating the clock jitter correction value and masking the clock jitter correction value convergence determination is added. Difference from Embodiment 3 described above. As described above, for example, when the broadcast program is switched and the received stream is H When the D stream (20 Mbps) power also changes to the SD stream (6 Mbps), the measured value MEMSUM (also referred to as “MEMSUM value”) changes significantly in the third embodiment. This is due to changes in the average receive rate of the received stream, not due to clock jitter values.
- MEMSUM also referred to as “MEMSUM value”
- Embodiment 3 (FIG. 21)
- the clock jitter correction value deviates greatly. Therefore, the sixth embodiment focuses on the change in the measured TS average rate, and when the change is large, masks the clock jitter correction calculation operation, thereby stably operating the system.
- step S216 the CPU 54 (FIG. 5) starts the clock jitter correction operation.
- step S51 the measurement time has elapsed. After the measurement time elapses, the CPU 54 (FIG.
- the CPU 54 (FIG. 5) calculates the measured value MEMSUM, the average read rate TSRate, and the clock jitter value dSUM, and calculates the correction value (steps S52 to S57 in FIG. 30).
- step S121 the CPU 54 (FIG. 5) determines the force at which the TS rate has significantly changed in step S121 (FIG. 30). If it is determined that the TS average rate has changed significantly, '0' is input to n in step S123. On the other hand, if it is determined that there has not been a large change, the value of n is incremented by one (step S122 in FIG. 30). And Then, it is determined in step SI24 whether n exceeds a predetermined value (N). If n exceeds the predetermined value N, a clock jitter correction value calculation flow from step S58 is performed. On the other hand, if n is equal to or smaller than the predetermined value N, the flow of calculating the clock jitter correction value is skipped, and the flow of calculating the clock jitter correction value is terminated.
- N a predetermined value
- the sixth embodiment controls the clock jitter correction value calculation flow as described above, even when the TS reception rate greatly changes, the clock jitter correction value calculation and the clock jitter correction value convergence determination are masked. For example, when the broadcast program is switched and the receiving stream changes from HD stream (20 Mbps) to SD stream (6 Mbps)! However, there is an effect that the system can be operated stably without the clock jitter correction value being largely deviated.
- the correction of the clock jitter value is masked a predetermined number of times after the TS rate greatly changes. This is for the following reason. As described above, the received TS is read from the memory 53 (FIG. 5) based on the time stamp information added to the head of the TS.
- the change in the received TS rate is not limited to the force calculated based on the change in the number of TSs read from the TS output number storage register 5232. Even if a counter for measuring the number of TS input to the memory 53 is prepared and the receiving TS rate is determined based on the counter value of the counter for measuring the number of TS input, the receiving TS rate can be determined. Since a change can be detected, a large change in the received TS rate can be detected, and the calculation of the clock jitter correction value is masked until the control point in the memory 53 is stabilized, thereby stabilizing the system. There is an effect that can be operated. Further, the change in the reception TS rate is not limited to the above.
- the reception TS rate greatly changes even when the normal reproduction power is switched to the high-speed reproduction in D-VHS. Even in such a case, there is an effect that the system can be operated stably by controlling as described above. [0148] Embodiment 7.
- FIG. 31 is a flowchart showing an operation of the radio receiving apparatus according to Embodiment 7 of the present invention when calculating a clock jitter correction value.
- the remaining memory integration difference value clock jitter value dSUM
- the clock jitter value dSUM changes significantly
- a point where a flow for masking the clock jitter correction value calculation and the clock jitter correction value convergence judgment is added is different from the third embodiment (FIG. 21).
- MEMSUM also referred to as “M EMSUM value” greatly changes.
- Embodiment 7 is configured to detect a change in the average TS rate of the received stream using the clock jitter value dSUM. (In Embodiment 6, the determination is made based on the received TS rate.)
- step S216 the CPU 54 (FIG. 5) starts the clock jitter correction operation.
- step S51 the measurement time has elapsed. After the measurement time has elapsed, the CPU 54 (FIG.
- step S133 it is determined whether the clock jitter value dSUM has changed significantly. If it is determined that the clock jitter value dSUM has changed significantly, '0' is input to n in step S133. On the other hand, if the force is not significantly changed, the value of n is incremented by one (step S1 in FIG. 31).
- step S134 it is determined in step S134 that n exceeds the predetermined value N. If n exceeds the predetermined value N, a clock jitter correction value calculation flow from step 58 is performed. On the other hand, if n is equal to or smaller than the predetermined value N, the flow of calculating the clock jitter correction value is skipped, and the operation of calculating the clock jitter correction value ends.
- the clock jitter correction value calculation flow is controlled as described above. Therefore, even when the clock jitter value dSUM (TS reception rate) greatly changes, the clock jitter correction value calculation and the calculation are performed. Since the clock jitter correction value convergence judgment is masked, for example, even if the broadcast program switches and the received stream changes from an HD stream (20 Mbps) to an SD stream (6 Mbps), a system that does not greatly deviate from the clock jitter correction value is stable. There is an effect that can be operated.
- the correction of the clock jitter value is masked a predetermined number of times. This is for the following reason.
- the power of the memory 53 (FIG. 5) is also read based on the time stamp information added to the beginning of the TS. Therefore, when the average reception rate of the TS greatly changes, the control points in the memory 53 change as described in the sixth embodiment. Therefore, in the seventh embodiment, when the received TS rate greatly changes, the system is operated stably by masking the calculation of the clock jitter correction value until the control point in the memory 53 is stabilized. It can be configured as follows.
- the force configured to mask the operation of calculating the clock jitter correction value based on the amplitude of the clock jitter value dSUM is not limited to this.
- the operation illustrated in FIG. As shown in the flow (steps S141-S144), if the overflow or underflow of the memory 53 (Fig. 5) is detected during the calculation of the clock jitter correction value, the predetermined number of times and the clock jitter correction value Is configured to mask the calculation of In this case, it is possible to stably control the system in which the clock jitter correction value does not largely deviate.
- Embodiment 17 described above a case where a 4-byte time stamp is added to the beginning of a 188-byte TS and transmitted as shown in FIG. 4 has been described.
- the scope of the device (wireless receiver) and data receiving method is not limited to such cases.
- a 2-byte time stamp is added, or a random error that occurs during wireless transmission is corrected.
- a change such as adding an error correction code such as Reed's Solomon code after the 192 bytes of data shown in FIG. 4 may be made.
- the error correction code may be added to only the TS, or may be added to each of the time stamp and the TS.
- the number of TSs with time stamps is set to a predetermined number (7 TSs).
- a wireless packet may be configured by collecting TSs, or a wireless packet may be configured by collecting six or less TSs.
- the length of the packet to be transmitted may be changed according to the packet error rate in the wireless section. For example, when the packet error rate is high, TS can be transmitted and received efficiently if the wireless packet length is shortened and the overhead due to retransmission control is controlled as small as possible.
- the wireless receiving device 50 handles a maximum of two TSs
- the data receiving device (wireless receiving device) and the data receiving method of the present invention are described. The scope of application is not limited to such a case.
- Three or more TSs can be handled at the same time.
- a storage area for the maximum number of TSs to be handled is secured in the memory 53 (FIG. 5), and each storage area is stored. If the read timing of the TS stored in the memory 53 (Fig. 5) is generated using the TS data read timing generation circuit 521 (Fig. 6) corresponding to the TS, clock recovery (clock jitter) is performed for each received TS. Correction) can be performed.
- the average transmission rate of the received packet is stored in the memory 53.
- the data receiving device (wireless receiving device) and the applicable range of the data receiving method of the present invention are not limited to such a case.
- the number of packets when writing the TS in the received wireless packet to the memory 53 may also be calculated.
- the average transmission rate of the received packet may be obtained when it is directly received by the wireless LAN module 51 (FIG. 5).
- the power receiving apparatus (wireless receiving apparatus) of the present invention has been described in the case where a MAC address or an IP address is used for device identification of a transmitter (wireless transmitting apparatus).
- the applicable range of the data receiving method are not limited to such a case, and other device-specific information may be used as long as the information is determined one-to-one with the transmitter.
- the measurement time is set to the period of 1 GOP (0.5 seconds).
- the applicable range of the receiving device (wireless receiving device) and the data receiving method is not limited to such a case, and the measurement time may be set to another value such as 1 second or 2 seconds.
- Embodiments 17 to 17 the case where the time correction interval of the time measurement counter 5213 (FIG. 8) in the TS data read timing generation circuit 52 1 (FIG. 6) is set to 100 ms has been described.
- the application range of the data receiving device (wireless receiving device) and the data receiving method of the present invention is not limited to such a case, and may be set to another value such as 10 ms or 200 ms. Oscillator, or may be determined based on the accuracy of the oscillator
- Embodiments 17 to 17 the case has been described where the TS of the MPEG2 system is transmitted via a wireless network having jitter.
- the data receiving apparatus wireless receiving apparatus
- the application range of the receiving method is not limited to such a case.
- PES Packetized Elementary Stream
- Embodiments 17 to 17 the case where the wired network is a system compliant with the IEEE 1394 standard and the wireless network is a system compliant with the IEEE 802.11a standard has been described.
- the application range of the data receiving device (wireless receiving device) and the data receiving method is not limited to such a case.
- the data receiving apparatus and the data receiving method according to the present invention include a network related to IEEE802.11, in which network jitter (clock jitter) is not guaranteed when data is transmitted and received, such as a wireless network, a network using Ethernet,
- the present invention can be applied to other wireless networks such as a network using ultra wide band (UWB) communication, a network using Bluetooth, and the like.
- the data receiving apparatus and the data receiving method of the present invention can be applied to a wired network such as high-speed power line communication (PLC: Power Line Control) or communication using an RF line.
- PLC Power Line Control
- the power receiving apparatus (wireless receiving apparatus) according to the present invention has been described in the case where the wireless transmitting / receiving apparatus constitutes a part of a wired network conforming to the IEEE1394 standard.
- the applicable range of the data reception method is not limited to such a case.
- a wireless transmission / reception device to which TS is directly input, or a radio to which analog video signal or digital video signal is input with built-in MPEG2 encoder It can be applied to a network composed of transmitting and receiving devices.
- the present invention can be applied to an audio visual home network system using a jittery network such as a wireless LAN, a video monitoring system that distributes a video stream, and the like.
- a jittery network such as a wireless LAN, a video monitoring system that distributes a video stream, and the like.
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Abstract
Description
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JP2006508505A JP4361561B2 (ja) | 2004-03-10 | 2005-02-02 | データ受信装置及びデータ受信方法 |
EP05704354A EP1724960A4 (en) | 2004-03-10 | 2005-02-02 | DATA RECEIVING DEVICE AND DATA RECEIVING METHOD |
US10/588,380 US7756233B2 (en) | 2004-03-10 | 2005-02-02 | Data receiving device and data receiving method |
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WO2009118885A1 (ja) * | 2008-03-28 | 2009-10-01 | パイオニア株式会社 | 受信装置、その制御方法、プログラム及び記憶媒体 |
WO2009118884A1 (ja) * | 2008-03-28 | 2009-10-01 | パイオニア株式会社 | 送信装置、受信装置、及びコンテンツ再生システム |
JP2010098519A (ja) * | 2008-10-16 | 2010-04-30 | Oki Electric Ind Co Ltd | クロック再生システムおよび方法 |
WO2013179932A1 (ja) * | 2012-05-28 | 2013-12-05 | ソニー株式会社 | 信号処理装置、及び、信号処理方法 |
JP2013247542A (ja) * | 2012-05-28 | 2013-12-09 | Sony Corp | 信号処理装置、及び、信号処理方法 |
CN104350758A (zh) * | 2012-05-28 | 2015-02-11 | 索尼公司 | 信号处理装置和信号处理方法 |
CN104350758B (zh) * | 2012-05-28 | 2019-01-15 | 索尼公司 | 信号处理装置和信号处理方法 |
KR101577708B1 (ko) * | 2014-04-29 | 2015-12-15 | 주식회사 펀진 | 패킷분석 장치 |
Also Published As
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US20070140398A1 (en) | 2007-06-21 |
US7756233B2 (en) | 2010-07-13 |
EP1724960A1 (en) | 2006-11-22 |
EP1724960A4 (en) | 2008-03-05 |
JP4361561B2 (ja) | 2009-11-11 |
JPWO2005088888A1 (ja) | 2007-08-09 |
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