JP6981768B2 - Transmission system, transmitter, and receiver - Google Patents

Description

The present invention relates to a transmission system, a transmission device, and a reception device.

As a technique for transmitting a terrestrial digital broadcast signal via an IP (Internet Protocol) network, for example, there is a technique disclosed in Document 1.

In the technique disclosed in Patent Document 1, the transmitting device extracts digital data from the RF signal of the terrestrial digital broadcasting signal, converts it into a transmission line signal and sends it to the IP network, and the receiving device receives the binary from the IP network. The data is reconverted into a digital broadcast signal and output without performing interleaving processing.

According to such a technology, when transmitting terrestrial digital broadcasting, an expensive circuit having high linearity required for an analog transmission method becomes unnecessary, and when demodulating and transmitting via an IP network, The delay that occurs can be reduced.

Further, in the technique disclosed in Non-Patent Document 1, the received signal is used as a frequency-modulated wave, and the light output from the laser diode is frequency-modulated and output to the transmission line.

According to the technique disclosed in Non-Patent Document 1, the IF signal of satellite broadcasting exceeding 1 GHz can be frequency-multiplexed and transmitted as it is.

Japanese Unexamined Patent Publication No. 2012-60303

NTT Technology Journal 2007.5 Wide area video distribution using FM batch conversion technology

By the way, since the technique disclosed in Patent Document 1 utilizes a method optimized for OFDM (Orthogonal Frequency Division Multiplex) modulation used in terrestrial digital broadcasting, other modulation methods, for example, In the case of baseband signals having different standards such as mAPSK (Amplitude Phase Shift Keying (m is a phase value)) and nPSK (Phase Shift Keying (n is a phase value)), there is a problem that data cannot be extracted.

Further, in each phase phase shift keying and amplitude phase shift keying modulation, the transmission capacity is increased by increasing the baud rate instead of the frequency division multiplexing method such as multi-value modulation such as nQAM and OFDM modulation. To increase. For this reason, if an attempt is made to directly transmit the data of the received analog signal converted into analog digital, there is a problem that the transmission capacity increases as compared with the above-mentioned transmission method due to the relationship between the dynamic range in which the signal can be restored and the sampling rate. ..

Further, in the technique disclosed in Technical Document 1, since frequency modulation is analog modulation, demodulation cannot be performed when the light intensity is lowered, so that there is a problem that the transmission distance is shortened. Therefore, since it is necessary to arrange the head-end device near the receiving device, there is a problem that a large number of head-end devices are required and the cost is high.

Further, since frequency modulation expands the frequency band to infinity in principle, there is a problem that if the variation of the modulated wave is large, the band of the transmission line is largely occupied.

Furthermore, when transmitting using IP linear broadcasting, a set-top box is required for the receiving device, and a television receiver and two receiving devices must be arranged for each television receiver, which is expensive. There is a problem that it becomes a complicated system.

The present invention has been made in view of the above points, and an object of the present invention is to provide a transmission system, a transmission device, and a reception device capable of efficiently transmitting satellite broadcast signals via an IP network.

In order to solve the above problems, the present invention relates to a transmission system for transmitting a satellite broadcast signal from a transmitting device to a receiving device via an IP network, wherein the transmitting device includes an input means for inputting the satellite broadcasting signal and the above. The demodulating means for demodulating the satellite broadcast signal input from the input means to obtain digital data, the packetizing means for packetizing the digital data obtained by the demodulating means, and the packet obtained by the packetizing means. On the other hand, an additional means for adding synchronization information indicating the order and timing of reproduction based on RTP (Real-time Transport Protocol) and the packet to which the synchronization information is added by the addition means are delivered via the IP network. The receiving device has a receiving means for receiving the packet transmitted via the IP network and the packet received by the receiving means based on the synchronization information. A data conversion means that converts the data into digital data after synchronization, a modulation means that modulates the digital data obtained by the data conversion means by a predetermined modulation method to obtain a baseband signal, and the baseband signal into an analog signal. a digital-to-analog converter means for converting said digital converts the frequency of the resulting analog signal by the analog conversion means, possess a frequency conversion means for obtaining the original of the satellite broadcasting signal, wherein the adding means, RTCP (Real -Time Control Protocol) to generate the synchronization information indicating the transmission time for calculating the inter-packet jitter and clock skew of the packet, and the data conversion means will clock skew the packet based on the synchronization information. And after adjusting the inter-packet jitter, it is converted to digital data, the synchronization information includes the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet, and the clock skew is the RTCP packet. It is characterized in that it is calculated from the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time.
With such a configuration, the satellite broadcast signal can be efficiently transmitted via the IP network. In addition, real-time data of analog signals can be accurately reproduced.

Further, the present invention is characterized in that the modulation means and the demodulation means perform modulation and demodulation by each phase shift keying and each phase amplitude phase shift keying.
According to such a configuration, for example, an advanced BS / CS satellite broadcasting signal can be efficiently transmitted via an IP network.

Further, in the present invention, the transmitting device selects one or a plurality of transponders from a plurality of transponders included in the satellite broadcast signal, converts them into the packet, transmits the packet, and transmits the transponder via the IP network. The apparatus is characterized in that a broadcast signal corresponding to one or a plurality of transponders is generated from the packet transmitted from the transmission device via the IP network and synthesized by a synthesis means.
According to such a configuration, a satellite broadcast signal having a plurality of transponders can be efficiently transmitted via an IP network.

Further, the present invention is characterized in that it is arranged after the frequency conversion means and has a distribution means for distributing the satellite broadcast signal.
According to such a configuration, satellite broadcasting signals can be supplied to a plurality of television receivers.

Further, the present invention is characterized in that the distribution means distributes an electric signal corresponding to the satellite broadcast signal.
According to such a configuration, a satellite broadcast signal can be supplied to a plurality of television receivers with a simple configuration.

Further, the present invention is characterized in that the distribution means converts an electric signal corresponding to the satellite broadcast signal into an optical signal and distributes the optical signal.
According to such a configuration, satellite broadcasting signals can be supplied to a plurality of television receivers while reducing signal deterioration.

Further, the present invention relates to an input means for inputting the satellite broadcast signal and the input means input from the input means in the transmission device of the transmission system for transmitting the satellite broadcast signal from the transmission device to the reception device via the IP network. RTP (Real- An additional means for adding synchronization information indicating the order and timing of reproduction based on the time Transport Protocol), and a transmission means for transmitting the packet to which the synchronization information is added by the addition means via the IP network. It has a, said adding means generates said synchronization information indicating the transmission time for calculating at said receiving device jitter and clock skew between packets of the packet based on the RTCP (Real-time Control Protocol) , wherein The synchronization information is characterized by including the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet.
With such a configuration, the satellite broadcast signal can be efficiently transmitted via the IP network. In addition, real-time data of analog signals can be accurately reproduced.

Further, the present invention relates to a receiving means for receiving a packet transmitted via the IP network in the receiving device of a transmission system for transmitting a satellite broadcast signal from the transmitting device to the receiving device via the IP network, and the receiving means. The data conversion means for converting the packet received by the means into digital data after synchronizing the packets based on the synchronization information indicating the order and timing of reproduction based on the RTP (Real-time Transport Protocol), and the data conversion means. A modulation means that modulates the obtained digital data by a predetermined modulation method to obtain a baseband signal, a digital-analog conversion means that converts the baseband signal into an analog signal, and an analog signal obtained by the digital-analog conversion means. converts the frequency of, possess a frequency conversion means for obtaining the original of the satellite broadcasting signal, wherein the data means digital data after adjusting the clock skew and packet jitter of the packet based on the synchronization information The synchronization information includes the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet, and the clock skew is the packet interval jitter, the latest transmission report time in the RTCP packet. It is characterized in that it is calculated from the stamp and the elapsed time of the latest transmission report.
With such a configuration, the satellite broadcast signal can be efficiently transmitted via the IP network. In addition, real-time data of analog signals can be accurately reproduced.

According to the present invention, it is possible to provide a transmission system, a transmission device, and a reception device capable of efficiently transmitting a satellite broadcast signal via an IP network.

It is a figure which shows the structural example of the transmission system which concerns on embodiment of this invention. It is a figure which shows the detailed configuration example of the transmission apparatus shown in FIG. It is a figure which shows the detailed configuration example of the receiving apparatus shown in FIG. It is a figure which shows the structural example of the advanced BS / CS sanitary broadcasting signal. It is a figure which shows an example of the signal point arrangement of PSK and APSK modulation / demodulation. It is a figure which shows an example of the RTP packet transmitted from the transmission device. It is a figure which shows an example of the RTCP packet transmitted from the transmission device. It is a figure which shows an example of the packet transmitted from a transmission device. It is a figure which shows an example of the signal output from the D / A conversion part shown in FIG. It is a figure which shows an example of the operation of the synthesis part shown in FIG. This is a configuration example in which a plurality of television receivers are connected to the subsequent stage of the receiver. This is another configuration example in which a plurality of television receivers are connected to the subsequent stage of the receiver. This is still another configuration example in which a plurality of television receivers are connected to the subsequent stage of the receiver.

Next, an embodiment of the present invention will be described.

(A) Explanation of the configuration of the embodiment of the present invention FIG. 1 is a diagram showing a configuration example of a transmission system according to the embodiment of the present invention. As shown in FIG. 1, the transmission system 1 according to the embodiment of the present invention includes a transmission device 10, an IP (Internet Protocol) network 30, a reception device 50-1 to 50-n (n> 1), and a television receiver. It has 70-1 to 70-n.

Here, the transmitting device 10 is arranged in, for example, a signal distribution center, demodulates the satellite broadcast signal received by the antenna and converts it into digital data, and after packetizing it, the receiving device 50-1 to the receiving device 50-1 through the IP network 30. It is transmitted to 50-n.

The IP network 30 is composed of, for example, an IP network capable of transmitting about several M to several Gbps, and transmits packets transmitted from the transmitting device 10 to each of the receiving devices 50-1 to 50-n.

The receiving devices 50-1 to 50-n are arranged in, for example, a management room of each home or an apartment house, receive a packet transmitted via the IP network 30, and generate an original satellite broadcast signal. It is supplied to the television receivers 70-1 to 70-n.

The television receivers 70-1 to 70-n input satellite broadcast signals supplied from the receivers 50-1 to 50-n, reproduce video signals, audio signals, and data signals contained in the broadcast signals. Along with displaying on the display unit, sound is emitted from the speaker.

FIG. 2 is a diagram showing a detailed configuration example of the transmission device 10 shown in FIG. As shown in FIG. 2, the transmission device 10 has an antenna 11, a distribution unit 12, a transmission unit 13-1 to 13-m (m> 1), and a HUB 18.

Here, the antenna 11 is configured by, for example, a parabolic antenna, receives a satellite broadcast signal transmitted from an artificial satellite (not shown), converts it into an electric signal, and supplies it to the distribution unit 12.

The distribution unit 12 distributes and supplies the electric signal supplied from the antenna 11 to the transmission units 13-1 to 13-m.

The transmission units 13-1 to 13-m demodulate the electric signal (satellite broadcast signal) supplied from the distribution unit 12, packetize the digital data obtained, and transmit the digital data via the HUB 18. Since the transmission units 13-1 to 13-m all have the same configuration, the transmission unit 13-1 will be described below as an example.

The transmission unit 13-1 has an RF (Radio Frequency) tuner 14, a demodulation processing unit 15, an IP (Internet Protocol) packet generation unit 16, and a transmission processing unit 17.

Here, the RF tuner 14 extracts a signal of a desired transponder from the RF signal supplied from the distribution unit 12, converts it into an intermediate frequency signal, and then performs A / D (Analog to Digital) conversion and outputs the signal.

The demodulation processing unit 15 demodulates the signal of the predetermined transponder supplied from the RF tuner 14 by, for example, PSK (Phase Shift Keying) and APSK (Amplitude and Phase Shift Keying), and outputs the obtained digital data.

The IP packet generation unit 16 packetizes the digital data supplied from the demodulation processing unit 15, and outputs the digital data by adding the synchronization information specified by the RTP.

The transmission processing unit 17 adds an IP header to the packet output from the IP packet generation unit 16, and also adds a TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) header and outputs the packet.

The HUB 18 multiplexes the packets supplied from the transmission units 13-1 to 13-m and sends them out to the IP network 30.

FIG. 3 is a diagram showing a configuration example of the receiving devices 50-1 to 50-n shown in FIG. Since the receiving devices 50-1 to 50-n have the same configuration, the receiving device 50-1 will be taken as an example below, and will be described as the receiving device 50 for the sake of simplicity.

As shown in FIG. 3, the receiving device 50 includes a transmission processing unit 51, receiving units 52-1 to 52-m, and a combining unit 57.

Here, the transmission processing unit 51 receives the packet transmitted via the IP network 30 at a different port for each transponder, and supplies the packet to each of the corresponding receiving units 52-1 to 52-m. More specifically, the packet transmitted from the transmitting unit 13-1 is supplied to the receiving unit 52-1, and similarly, the packet transmitted from the transmitting units 13-2 to 13-m is supplied to the receiving unit 52-2 to 13-m. Supply to 52-m respectively.

The receiving units 52-1 to 52-m generate and output transponder signals from the packets supplied from the transmission processing unit 51, respectively. Since the receiving units 52-1 to 52-m have the same configuration, the receiving unit 52-1 will be described below as an example.

The receiving unit 52-1 includes an IP packet receiving unit 53, a modulation processing unit 54, a D / A (Digital to Analog) conversion unit 55, and a synchronous clock reproduction unit 56.

The IP packet receiving unit 53 converts the packet supplied from the transmission processing unit 51 into digital data after adjusting the order and timing based on the RTP, and outputs the packet.

The modulation processing unit 54 performs modulation processing such as PSK and APSK on the digital data supplied from the IP packet reception unit 53 and outputs the data.

The D / A conversion unit 55 converts the digital signal supplied from the modulation processing unit 54 into an analog signal and outputs it.

After releasing the IP packet and the UDP packet, the synchronous clock reproduction unit 56 changes the order of the packets by referring to the sequence number included in the RTP packet as necessary, and also refers to the time stamp information to clock. To play. Further, the synchronous clock reproduction unit 56 calculates the clock skew from the jitter information in the RTCP packet and the transmission time stamp, and reproduces the synchronous clock.

The synthesizing unit 57 multiplexes the broadcast signals corresponding to each transponder output from the receiving units 52-1 to 52-m, up-converts them, and generates and outputs the original satellite broadcast signal.

(B) Explanation of the operation of the embodiment of the present invention Next, the operation of the embodiment of the present invention will be described. The antenna 11 shown in FIG. 2 receives, for example, a BS left-handed signal and a CS left-handed signal as shown in FIG. 4 from an artificial satellite (not shown). In the example of FIG. 4, the BS left-handed signal has a band of 2224.41 to 2680.87 MHz and has 12 transponders. Further, the CS left-handed signal has a band of 2708.75 to 3223.25 MHz and has 13 transponders.

The distribution unit 12 distributes an electric signal including a broadcast signal as shown in FIG. 4 supplied from the antenna 11 and supplies the electric signals to the transmission units 13-1 to 13-m, respectively.

The transmission units 13-1 to 13-m correspond to each of at least a part of the transponders shown in FIG. 4, and the signal of each transponder is packetized and output. For example, the transmission unit 13-1 executes processing on the signal of the transponder to which the symbol “8” of the BS left-handed signal is assigned. Since the operations of the transmission units 13-1 to 13-m are the same, the operation of the transmission unit 13-1 will be described below as an example.

The RF tuner 14 extracts, for example, a transponder signal assigned the reference numeral “8” shown in FIG. 4 from an electric signal supplied from the distribution unit 12, converts the frequency to an intermediate frequency, and makes the signal level constant. A / D conversion is performed and output.

The demodulation processing unit 15 performs, for example, PSK and APSK demodulation on the signal supplied from the RF tuner 14, and outputs the obtained digital data. More specifically, the demodulation processing unit 15 performs PSK and APSK demodulation on the RF signal to which PSK and APSK modulation are performed based on the signal point arrangement as shown in FIG. 5, for example, and the demodulation processing unit 15 performs PSK and APSK demodulation in FIG. It is converted to 4-bit data shown next to the signal point and output. The signal point arrangement shown in FIG. 5 is an example, and other arrangements may be used. That is, the present invention is not limited to 4 bits.

The IP packet generation unit 16 packets the digital data supplied from the demodulation processing unit 15 into packets, adds synchronization information, and outputs the data. More specifically, the IP packet generation unit 16 divides the digital data supplied from the demodulation processing unit 15 into predetermined lengths, generates "payload data" constituting the packet shown in FIG. 6, and arbitrarily. A "sequence number" indicating the order of packets to be counted by the synchronization clock and a "time stamp" indicating the sampling rate are added to. Further, in the RTCP packet, as shown in FIG. 7, "packet interval jitter" is added, and "latest transmission report time stamp (LSR)" and "latest transmission report elapsed time (DSLR)" are added to receive the packet. The clock skew can be calculated on the side.

As shown in FIG. 8, the transmission processing unit 17 adds a UDP packet and an IP packet 81 to the data to which the RTP packet 83 supplied from the IP packet generation unit 16 is added, and outputs the data.

Packets as shown in FIG. 6 output from transmission units 13-1 to 13-m are multiplexed by HUB 18 and transmitted to the IP network 30.

The data transmitted from the transmitting device 10 is transmitted to the receiving devices 50-1 to 50-n by multicast or unicast, for example. Since the operations of the receiving devices 50-1 to 50-n are the same, in the following, the receiving device 50-1 will be taken as an example, and the receiving device 50-1 will be used as the receiving device 50, and the operation will be performed with reference to FIG. explain.

The transmission processing unit 51 receives the packets transmitted from each of the transmission units 13-1 to 13-m shown in FIG. 2 by the corresponding ports and supplies them to the reception units 52-1 to 52-m. Since the operations of the receiving units 52-1 to 52-m are the same, the receiving unit 52-1 will be described below as an example.

The receiving unit 52-1 inputs a packet supplied from the transmission processing unit 51 (for example, a packet transmitted from the transmitting unit 13-1 shown in FIG. 2).

The IP packet receiving unit 53 of the receiving unit 52-1 supplies the packet data supplied from the transmission processing unit 51 to the synchronous clock reproduction unit 56. After releasing the IP packet and the UDP packet, the synchronous clock reproduction unit 56 refers to the sequence number included in the RTP packet 83 to change the packet order as necessary, and also refers to the time stamp information. Play the clock. Further, the clock skew is calculated from the jitter information in the RTCP packet and the transmission time stamp, and the synchronous clock is reproduced. As a result, the IP packet receiving unit 53 outputs the packet data 84 shown in FIG. 6 in the same order and timing as at the time of transmission.

The modulation processing unit 54 performs, for example, PSK and APSK modulation on the digital data output from the IP packet reception unit 53, and outputs the obtained data. More specifically, the modulation processing unit 54 divides the digital data output from the IP packet receiving unit 53 into 4 bits, and divides the 4-bit data into, for example, PSK and PSK based on the signal point arrangement shown in FIG. APSK modulation is applied and output.

The D / A conversion unit 55 converts the digital signal supplied from the modulation processing unit 54 into an analog signal and outputs it. As a result, from the D / A conversion unit 55 of each of the receiving units 52-1 to 52-m, for example, the signals (1) to (m) as shown in FIG. 9 (signals corresponding to each transponder). Is output. In the example of FIG. 9, each transponder has the same frequency band.

The synthesizer 57 sets the transponders of the analog signals output from each of the receiving units 52-1 to 52-m to the original frequency, that is, as shown in the upper part of FIG. Perform frequency conversion so that they do not overlap. Further, the synthesizing unit 57 synthesizes the analog signal subjected to the frequency conversion in this way as shown in the middle stage of FIG. In the middle example of FIG. 10, the transponder is arranged in the range of about 0 Hz to about 1 GHz. Next, as shown in the lower part of FIG. 10, the synthesis unit 57 performs frequency conversion so as to have the same frequency band as the original satellite broadcast signal. In the lower example of FIG. 10, the transponder is arranged in the range of about 2.2 GHz to about 3.2 GHz. The original satellite broadcast signal thus obtained is supplied to the television receiver 70-1.

The television receiver 70-1 can reproduce the satellite broadcast signal supplied from the receiving device 50-1 in the same manner as when it is received from the artificial satellite using the antenna.

As described above, in the embodiment of the present invention, since the digital signal is transmitted from the transmitting device to the receiving device, the transmission distance is dramatically extended as compared with the case of transmitting an analog signal. be able to.

Further, in the embodiment of the present invention, since the transmission device 10 transmits the data obtained by the demodulation process, the transmission capacity can be reduced.

Further, in the embodiment of the present invention, the packets are rearranged by RTP / RTCP and the reproduction timing is adjusted, so that the audio and video can be reproduced without delay.

(C) Description of Modified Embodiment It goes without saying that the above embodiment is an example and the present invention is not limited to the above-mentioned case. For example, in the embodiment shown in FIG. 1, one television receiver 70-1 to 70-n is connected to the receiving devices 50-1 to 50-n, but a plurality of television receivers are connected. The machine may be connected. For example, the receiving device may be installed in the management room of the apartment house, and the satellite broadcast signal may be distributed to the television receivers (s) arranged in each resident's room.

More specifically, for example, as shown in FIGS. 11 to 13, a plurality of television receivers may be connected to the subsequent stage of the receiving device 50-1. In the example of FIG. 11, a distributor 61-1 is provided after the receiver 50-1, and the electric signal distributed by the distributor 61-1 is transmitted to the television receivers 701-1 to 70-1-p. An example of supplying to (p> 1) is shown. Although the receiving device 50-1 shown in FIG. 1 is taken as an example in FIG. 11, it goes without saying that the receiving devices 50-2 to 50-n may have the same configuration as that of FIG. Nor.

FIG. 12 shows an example of distributing an optical signal. That is, in the example of FIG. 12, an E / O62-1 that converts an electric signal into an optical signal is arranged after the receiving device 50-1, and the optical output of the E / O62-1 is distributed by the optical distributor 63-1. Then, after converting the optical signal into an electric signal by O / E64-1 to 64-p (p> 1), which converts the optical signal into an electric signal, it is supplied to the television receiver 701-1 to 70-1-p. ing. Although the receiving device 50-1 shown in FIG. 1 is taken as an example in FIG. 12, it goes without saying that the receiving devices 50-2 to 50-n may have the same configuration as that of FIG. Nor.

FIG. 13 shows another example of distributing an optical signal. That is, in the example of FIG. 13, the distributor 63-1 that distributes the electric signal is arranged after the receiving device 50-1, and the electric signal distributed by the distributor 63-1 is converted into an optical signal E / O62. -1 to 62-q are arranged, and the optical signal output from E / O62-1 is amplified by the multi-port optical amplifier 65-1 and then distributed, and O / E64-1 to 64-p (p> 1). After being converted into an electric signal by the above, it is supplied to the television receivers 701-1 to 70-1-p. Although the receiving device 50-1 shown in FIG. 1 is taken as an example in FIG. 13, it goes without saying that the receiving devices 50-2 to 50-n may have the same configuration as that of FIG. Nor. Further, in the example of FIG. 13, only the latter part of E / O62-1 is illustrated for the sake of simplification of the drawing, but the latter part of E / O62-2 to 62-q is the same as E / O62-1. Can be configured as.

In addition, in FIGS. 11 to 13, regarding the receiving device 50-1, the distributor 61-1, the E / O 62-1 to 62-q, the optical distributor 63-1 and the like, for example, the management room of the apartment house. Or, it can be placed in a sub-center of a CATV system.

Further, for the configurations of FIGS. 11 to 13, the existing in-house wiring of the apartment house, the existing optical network system, and the existing electric network system are diverted, and the electric signal of the present invention or the electric signal of the present invention is applied to these wirings or networks. An optical signal may be transmitted.

Further, in the above embodiment, the BS left-handed signal and the CS left-handed signal shown in FIG. 4 are processed, but satellite broadcasting other than these may be processed. Further, the transponder shown in FIG. 4 is an example, and transponders other than these may be targeted.

Further, in the embodiment shown in FIG. 2, the satellite broadcast signal received by the antenna 11 is processed, but the satellite broadcast signal may be received by means other than the antenna 11.

Further, the method for synthesizing the transponders shown in FIGS. 9 and 10 is an example, and the transponders may be synthesized by other methods. For example, the signals of about 2.2 to about 3.2 GHz shown in the lower part of FIG. 10 are output from the D / A conversion unit 55 of the receiving units 52-1 to 52-m, respectively, and synthesized by the synthesis unit 57. You may. Alternatively, the 0 to 1 GHz signal shown in the upper part of FIG. 10 is output from the D / A conversion unit 55 of the receiving units 52-1 to 52-m, and synthesized by the synthesizer unit 57 as shown in the middle part of FIG. After that, it may be converted as shown in the lower part of FIG. 10 by frequency conversion.

Further, the signal point arrangement shown in FIG. 5 is an example, and other arrangements may be used. For example, the radii of the inner and outer circles may differ from those shown in FIG. Alternatively, the correspondence between each signal point and the 4-bit data may be changed. Further, although the examples of FIG. 5 are PSK and APSK, other signal points such as quadrature amplitude modulation may be arranged other than the 16-phase amplitude phase shift keying and each phase phase shift keying. This indicates that the digital data does not have to be 4-bit data.

Further, in the above embodiment, RTP / RTCP is used as a protocol for specifying the sorting of packets and the reproduction timing, but other protocols may be used.

Further, in the above embodiments, as the modulation and demodulation, PSK and APSK have been described as examples, but other modulation and demodulation methods may be used. Of course, quadrature modulation in which I / Q data is output may be used.

Further, control information such as information defining the signal point arrangement shown in FIG. 5 and information indicating the coding rate at the time of coding is added to the packet transmitted from the transmitting device 10 and transmitted. You may do it.

Further, in the above embodiment, the case where the television receivers 70-1 to 70-n are connected has been described as an example, but a measuring instrument (for example, a device for measuring the state of the constellation or the received signal) may be used. You may try to connect.

1 Transmission system 10 Transmitter 11 Antenna 12 Distributor 13-1 to 13-m Transmission unit 14 RF tuner (input means)
15 Demodulation processing unit (demodulation means)
16 IP packet generator (packetizing means, additional means)
17 Transmission processing unit (transmission means)
18 HUB
30 IP network 50-1 to 50-n receiving device 51 Transmission processing unit (receiving means)
52-1 to 52-m receiving unit 53 IP packet receiving unit (data conversion means)
54 Modulation processing unit (modulation means)
55 D / A converter (digital-to-analog converter)
56 Synchronous clock playback unit 57 Synthesis unit (frequency conversion means, synthesis means)
70-1 to 70-n television receiver

Claims (8)

In a transmission system that transmits satellite broadcast signals from a transmitter to a receiver via an IP network.
The transmitter is
An input means for inputting the satellite broadcast signal and
A demodulation means for demodulating the satellite broadcast signal input from the input means to obtain digital data, and a demodulation means.
A packetizing means for packetizing the digital data obtained by the demodulation means, and a packetizing means.
An additional means for adding synchronization information indicating the order and timing of reproduction based on RTP (Real-time Transport Protocol) to the packet obtained by the packetizing means.
It has a transmission means for transmitting the packet to which the synchronization information is added by the addition means via the IP network.
The receiving device is
A receiving means for receiving the packet transmitted via the IP network, and
A data conversion means for synchronizing the packet received by the receiving means based on the synchronization information and then converting it into digital data.
A modulation means for obtaining a baseband signal by modulating the digital data obtained by the data conversion means by a predetermined modulation method.
A digital-to-analog conversion means for converting the baseband signal into an analog signal,
It said digital converts the frequency of the resulting analog signal by the analog conversion means, possess a frequency conversion means for obtaining the original of the satellite broadcast signal, a,
The additional means generates the synchronization information indicating the transmission time for calculating the inter-packet jitter and the clock skew of the packet based on RTCP (Real-time Control Protocol).
The data conversion means adjusts the clock skew and the inter-packet jitter of the packet based on the synchronization information, and then converts the data into digital data.
The synchronization information includes the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet.
The clock skew is calculated from the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet.
A transmission system characterized by that. The transmission system according to claim 1, wherein the modulation means and the demodulation means perform modulation and demodulation by each phase shift keying and each phase amplitude phase shift keying. The transmitting device selects one or a plurality of transponders from a plurality of transponders included in the satellite broadcast signal, converts them into the packet, and transmits the packet via the IP network.
The receiving device generates a broadcast signal corresponding to one or a plurality of transponders from the packet transmitted from the transmitting device via the IP network, and synthesizes the broadcast signal by a synthesizing means.
The transmission system according to claim 1 or 2. The transmission system according to any one of claims 1 to 3 , wherein the transmission system is arranged after the frequency conversion means and has a distribution means for distributing the satellite broadcast signal. The transmission system according to claim 4 , wherein the distribution means distributes an electric signal corresponding to the satellite broadcast signal. The transmission system according to claim 4 , wherein the distribution means converts an electric signal corresponding to the satellite broadcast signal into an optical signal and distributes the optical signal. In the transmission device of a transmission system that transmits a satellite broadcast signal from a transmission device to a reception device via an IP network.
An input means for inputting the satellite broadcast signal and
A demodulation means for demodulating the satellite broadcast signal input from the input means to obtain digital data, and a demodulation means.
A packetizing means for packetizing digital data obtained by the demodulation means, and a packetizing means.
An additional means for adding synchronization information indicating the order and timing of reproduction based on RTP (Real-time Transport Protocol) to the packet obtained by the packetizing means.
The packet in which the synchronization information is added by said adding means, have a, and transmitting means for transmitting through said IP network,
The additional means generates the synchronization information indicating the transmission time for calculating the inter-packet jitter and clock skew of the packet in the receiving device based on RTCP (Real-time Control Protocol).
The synchronization information includes the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet.
A transmitter characterized by that. In the receiving device of a transmission system that transmits a satellite broadcast signal from a transmitting device to a receiving device via an IP network.
A receiving means for receiving a packet transmitted via the IP network, and
A data conversion means for synchronizing the packet received by the receiving means based on synchronization information indicating the order and timing of reproduction based on RTP (Real-time Transport Protocol) and then converting it into digital data.
A modulation means that obtains a baseband signal by modulating the digital data obtained by the data conversion means by a predetermined modulation method.
A digital-to-analog conversion means for converting the baseband signal into an analog signal,
It said digital converts the frequency of the resulting analog signal by the analog conversion means, possess a frequency conversion means for obtaining the original of the satellite broadcast signal, a,
The data conversion means adjusts the clock skew and the inter-packet jitter of the packet based on the synchronization information, and then converts the data into digital data.
The synchronization information includes the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet.
The clock skew is calculated from the packet interval jitter, the latest transmission report time stamp, and the latest transmission report elapsed time in the RTCP packet.
A receiver characterized by that.

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