JP5313195B2 - RF-IP transmission / reception method and RF-IP transmission / reception apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform retransmission without missing of a part of data put on broadcast waves in the retransmission. <P>SOLUTION: The RF-IP transmitting/receiving method includes steps of: receiving the broadcast waves to perform frequency conversion on them into a base band; performing A/D conversion of converted modulated waves by a sampling clock generated by a receiving part; generating a time stamp by utilizing the sampling clock; using the A/D converted sampling data as RTP (Real Time Transport Protocol) data, further describing a count value counted by the sampling clock in an RTP time stamp, and performing RTP encapsulation to the count value to be transmitted to an IP network; and receiving a capsule from the IP network to be decapsulated, regenerating the sampling clock using the counter value described in the RTP time stamp, reading the decapsulated data by the regenerated sampling clock to perform D/A conversion to the data, and converting the D/A converted broadcast waves into a frequency in broadcast to be retransmitted. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention transmits various broadcast waves such as television broadcast waves, independent broadcast waves, and satellite broadcast waves, particularly terrestrial digital television broadcast waves, as RF signals to remote locations using the IP network (IP: Internet Protocol). The present invention relates to an RF-IP transmission / reception method and an RF-IP transmission / reception apparatus suitable for performing the above.

  Retransmission refers to a cable broadcaster such as a CATV provider or a telecommunications service use broadcaster receiving various broadcast waves (ON-AIR waves) and broadcasting them again to a cable broadcast or a cable service use broadcast. Giving consent to the resending request that has been applied by the business operators is referred to as resending consent.

  To retransmit a digital terrestrial television broadcast to a remote location, you must retransmit “all broadcast programs”, which are the basic conditions for resending consent, “as is”, “simultaneously with the broadcast”, and “from the start to the end of the broadcast”. I must.

  As a method for CATV operators to retransmit terrestrial digital television broadcast waves (OFDM modulated waves, OFDM: Orthogonal Frequency Division Multiplexing) to remote locations, for example, the broadcast waves received at the CATV center are demodulated and TS (Transport Stream), send it to the IP network, send it to the remote location, and extract the OFDM data from the received TS at the remote location and re-convert it into an OFDM signal (IP / RF conversion) Thus, there is a method for enabling the subscriber to receive (Patent Documents 1 and 2).

JP2007-274606 JP2008-211587

  In the retransmission of terrestrial digital television broadcasting, in order to perform “as is” as in the basic provisions of the agreement, a part of signals (data) in the OFDM modulated wave of terrestrial digital television broadcasting, for example, earthquake motion warning information is included. It is necessary not to be lost at the time of retransmission. Earthquake motion warning information is additional information newly established as one of the information transmitted by AC (Auxiliary Channel) signal by the revision of ARIB STD-31 (standard for transmission system of digital terrestrial television broadcasting).

  The invention of Patent Document 1 is intended to retransmit terrestrial digital television broadcasts over an IP network, but aims to realize an emergency warning broadcast system when retransmitted over an IP network. It does not improve the lack of some data in the wave. In particular, AC (Auxiliary Channel) signals such as earthquake motion warning information cannot be transmitted.

  The invention of Patent Document 2 also retransmits digital terrestrial television broadcasting over an IP network. However, it is possible to inexpensively transmit a synchronization clock necessary for reproducing an OFDM modulated wave RF signal from the retransmitted TS. It can be executed, and does not improve the loss of some data during retransmission.

  In a retransmission system using an IP network so far, some data in the OFDM modulated wave may be lost at the time of retransmission, and it is difficult to retransmit the OFDM modulated wave “as is” as described in the above basic clause. Was in the situation.

  The RF-IP transmission / reception method and apparatus according to the present invention provide a modulated wave of a broadcast wave (for example, when a broadcast wave such as a television broadcast wave, a voluntary broadcast wave, and a satellite broadcast wave is retransmitted using an IP network (for example, In this case, a part of the data included in the OFDM modulation wave in the case of the terrestrial digital television broadcast wave) is retransmitted without being lost.

The RF-IP transmission / reception method of the present invention encapsulates a broadcast wave being broadcast and sends it to an IP network as an Ethernet frame (“Ethernet” is a registered trademark), which is encapsulated in an Ethernet frame transmitted over the IP network. In the RF-IP transmission / reception method for converting the received signal into a broadcast wave and transmitting it to the receiver, the broadcast wave is received by the RF-IP transmitter, and the carrier of the broadcast wave is generated by the RF-IP transmitter An A / D conversion step for A / D conversion with a clock; an RTP time stamp generation step for generating an RTP time stamp (time information) (RTP: Real Time Transport Protocol) using the sampling clock; and the A / D The sampling data that has been A / D converted in the conversion process is placed on the Ethernet frame as RTP data, and the count value counted by the sampling clock is used as the RTP timetable. RTP encapsulation process for generating an Ethernet frame as described in a network, a sending process for sending the Ethernet frame to an IP network, and receiving the Ethernet frame sent to the IP network by an RF-IP receiver A decapsulation process for extracting an RTP time stamp included in a frame, an RTP time stamp regeneration process for extracting the RTP time stamp, and a counter value counted by the sampling clock described in the RTP time stamp are used. A sampling clock regenerating step for regenerating the sampling clock, and the sampling data decapsulated in the decapsulating step is read out by the sampling clock regenerated in the sampling clock regenerating step to perform D / A conversion D / A to do And conversion process is a method that includes the D / in A conversion process sends a broadcast wave that has been converted D / A (retransmitting) feed step.

  The RF-IP transmission / reception method of the present invention is the RF-IP transmission / reception method, wherein the carrier of the broadcast wave received by the RF-IP transmission device before the A / D conversion step in the RF-IP transmission device An RF down-conversion process that converts to a frequency, and after the D / A conversion process in the RF-IP receiver, the D / A converted broadcast wave is converted to the frequency of the broadcast wave received by the RF-IP transmitter It can also be set as the method provided with the up-conversion process.

  The RF-IP transmission / reception method of the present invention may be a method in which, in the RF-IP transmission / reception method, the encapsulation step is performed by placing a sampling clock using the RTP protocol.

  The RF-IP transmission / reception apparatus of the present invention includes an RF-IP transmission apparatus that encapsulates a broadcast wave being broadcast and sends it as an Ethernet frame to an IP transmission network, and an encapsulation in an Ethernet frame transmitted over the IP network. In an RF-IP transmission / reception apparatus including an RF-IP reception apparatus that converts a signal into a broadcast wave and transmits the signal to a receiver, the RF-IP transmission apparatus includes a sampling clock generation unit and a broadcast wave carrier as the sampling clock. An A / D conversion unit that performs A / D conversion using the sampling clock generated by the generation unit, an RTP time stamp generation unit that generates a time stamp using the sampling clock, and an A / D converter by the A / D conversion unit The converted sampling data is placed on the Ethernet frame as RTP data, and the count value counted by the sampling clock is used as the RTP time stamp. An RTP encapsulating unit that generates an Ethernet frame and a sending unit that sends out the encapsulated Ethernet frame to an IP network, and the RF-IP receiver is a capsule that has been transmitted over the IP network. A decapsulation unit that decapsulates the Ethernet frame that has been converted, an RTP time stamp regeneration unit that extracts an RTP time stamp included in the decapsulated Ethernet frame, and an RTP time stamp of the Ethernet frame. A sampling clock regenerator that regenerates the sampling clock using a counter value counted by a sampling clock that is present, and reads the sampling data decapsulated by the decapsulator by the regenerated sampling clock. D / A change A D / A converting unit for conversion, and a sending unit for sending out the broadcast wave D / A converted by the D / A converting unit.

  The RF-IP transmission / reception apparatus according to the present invention is an RF down-conversion apparatus in which, in the RF-IP transmission / reception apparatus, the RF-IP transmission apparatus performs frequency conversion of a received broadcast wave to baseband before the A / D conversion unit. And an RF up-converter for converting the D / A converted broadcast wave into the frequency of the broadcast wave received by the RF-IP transmitter after the D / A conversion unit. It can be provided with a part.

The RF-IP transmission / reception method of the present invention has the following effects.
(1) A clock signal (synchronization signal) for converting an RF modulated wave into an Ethernet frame by the RF-IP transmitter, and a clock signal used for reproducing an Ethernet frame transmitted over the IP network as a broadcast wave Since they are the same, even if an asynchronous IP network is used, a part of the data in the modulated wave is retransmitted without being lost, and the synchronization reference condition can be satisfied.
(2) Even when retransmitting in the IP network, when modulating with the RF-IP transmitting device and demodulating with the RF-IP receiving device, in addition to the delay time in the IP network, the modulation / demodulation time Since it takes about 1 second (500 ms for modulation and 500 ms for demodulation), there is a time delay in retransmission, but in the present invention, there is no time delay due to them because of no modulation / demodulation, and the retransmission time is almost IP. Since only the delay time on the network is required, the delay time can be shortened by about 1 second compared with the modulation / demodulation method, and the early arrival time of the emergency earthquake bulletin used in terrestrial digital television broadcasting is increased.
(3) Before the A / D conversion process in the RF-IP transmitter, the RF-IP receiver includes an RF down-conversion process for frequency-converting the broadcast wave carrier received by the RF-IP transmitter to baseband. When an RF up-conversion process is performed to convert the D / A converted RF modulated wave into the frequency of the broadcast wave received by the RF-IP transmitter, the AD converter unit reduces the frequency by the D / A conversion. Therefore, it is not necessary to use a high sampling rate, and it is possible to avoid a high bit rate of the IP signal transmitted to the IP network.
(4) When the Ethernet frame generation process is a method of placing a sampling clock using the RTP protocol, the sampling clock can be processed more efficiently.

1 is a schematic diagram of an RF-IP transceiver device according to the present invention. (A) is a block diagram of an RF-IP transmitting apparatus in the RF-IP transmitting / receiving apparatus of the present invention, and (b) is a block diagram of an RF-IP receiving apparatus in the apparatus.

(RF-IP transceiver)
An example of the RF-IP transceiver apparatus of the present invention is shown in FIGS. As described above, the RF-IP transmission / reception apparatus of the present invention can be used for retransmission of various broadcast waves. However, the one shown in FIGS. 1 and 2 is an RF-IP for retransmitting a terrestrial digital television broadcast. It is an example of a transmission / reception apparatus.

  The RF-IP transmission / reception apparatus in FIG. 1 receives an OFDM-modulated terrestrial digital television broadcast signal broadcast in the UHF band by the RF-IP transmission apparatus 1 and generates it by the RF-IP transmission unit 3 of the apparatus 1. Is encapsulated by the UDP / IP RTP protocol (UDP: User Datagram Protocol, RTP: Real-time Transport Protocol) and output to the IP network as an Ethernet frame, and the Ethernet frame transmitted by the IP network is an RF-IP receiver. 2, the encapsulated signal in the Ethernet frame is re-generated into the same broadcast wave as the OFDM-modulated digital terrestrial television broadcast signal in the RF-IP receiving unit 4 of the receiver 2, and the CATV network It is sent out to gap fillers.

(RF-IP transmitter)
The RF-IP transmitter 1 (FIG. 1) encapsulates the received broadcast wave and sends it to the IP network as an Ethernet frame, and distributes the received broadcast wave according to its carrier frequency (RF-). DIV), a plurality of RF-IP transmission units 3 for individually processing each distributed broadcast wave, and a Gigabit Ethernet switch (GbESW). Although the number of RF-IP transmission units shown in FIG. 1 is 8, this is merely an example, and there may be more or less than that. There are various GbESW ports such as 8, 16, 24.

  As shown in FIG. 2, each RF-IP transmission unit 3 of the RF-IP transmission apparatus 1 in FIG. 1 includes an RF down-conversion unit 3a, an A / D conversion unit 3b, a sampling clock generation unit 3c, and an RTP time stamp generation. 3d, RTP encapsulation 3e, Gigabit Ethernet transmission unit (GbEPHY) 3f, and data buffer 3g.

  The RF down-conversion unit 3a shown in FIG. 2 is not for demodulating the digital terrestrial television signal broadcast in the UHF band but converting the digital terrestrial television signal into a digital signal. In order to reduce the data rate in consideration of transmission, broadcast wave carriers transmitted in the UHF band are frequency-converted to baseband (0 to 6 MHz).

  The A / D conversion unit 3b in FIG. 2 quantizes the broadcast wave carrier frequency-converted by the RF down-conversion unit 3a with a sampling clock (frequency unknown) that satisfies the sampling theorem. The number of quantization bits can be a desired number, for example, about 10 to 16 bits.

  The sampling clock generation unit 3c in FIG. 2 generates a clock used for sampling in the A / D conversion unit 3b, and is generated using, for example, a VCXO (voltage controlled crystal oscillator).

  The RTP time stamp (time information for time synchronization) generation unit 3d in FIG. 2 is necessary when the sampling clock used for A / D conversion is D / A converted on the receiving side, so the UDP / IP RTP protocol is used. Is used to transmit the count value (clock information) counted by the sampling clock in the RTP time stamp area (32 bits).

  The RTP encapsulation unit (UDP / IP RTP packet generation unit) 3e places the sampling data after the A / D conversion on the payload data portion of the RTP data transfer packet, and uses the count value counted by the sampling clock as the RTP time stamp. It is described and encapsulated to generate a UDP / IP RTP protocol Ethernet frame (eg 1000baseTX).

  The Gigabit Ethernet transmission unit 3f outputs the Ethernet frame generated by the RTP encapsulation unit 3e through an Ethernet physical layer device.

  The data buffer is a memory area for temporarily storing the A / D converted data.

(RF-IP receiver)
The RF-IP receiver 2 in FIG. 1 receives a broadcast wave (Ethernet frame) sent over an IP network, and converts the broadcast wave to a broadcast wave having the same frequency as the OFDM-modulated terrestrial digital television signal. An RF distribution unit (RF DIV) that distributes received broadcast waves according to carrier frequency, and multiple RF-IP receptions that individually process each distributed broadcast wave and convert it to the original frequency broadcast wave Unit 4 and Gigabit Ethernet switch (GbESW) are provided.

  As shown in FIG. 2, the RF-IP receiving unit 4 in FIG. 1 includes a Gigabit Ethernet receiving unit (GbEPHY) 4a, an RTP decapsulating unit 4b, an RTP time stamp regenerating unit 4c, a sampling clock regenerating unit 4d, An A conversion unit 4e, an RF up-conversion unit 4e, and a data buffer 4g are provided.

  The RTP Gigabit Ethernet receiver 4a in FIG. 2 receives an Ethernet frame through a LAN cable or the like that is an Ethernet physical layer device.

  The decapsulation unit 4b shown in FIG. 2 extracts sampling data from the payload data portion of the RTP data packet included in the received encapsulated Ethernet frame.

  The RTP time stamp regenerating unit 4c in FIG. 2 regenerates the time stamp that is put on the time stamp area of the received Ethernet frame.

  The sampling clock regeneration unit 4d in FIG. 2 regenerates the sampling clock using the counter value counted by the sampling clock described in the RTP time stamp and VCXO.

  2 reads out the sampling data buffered in the data buffer 4g by the RTP decapsulation unit 4b using the sampling clock regenerated by the sampling clock regeneration unit 4d, and performs D / A conversion. A conversion is performed.

  The RF up-conversion unit 4f in FIG. 2 performs frequency conversion on the D / A converted OFDM carrier to the frequency originally transmitted.

  The data buffer 4g in FIG. 2 accumulates the sampling data extracted by the RTP decapsulation unit 4b.

    The RF down-conversion unit 3a, the data buffer 3g, the data buffer 4g, and the RF up-conversion unit 4f in FIG. 2 are not necessarily required. Therefore, it is possible to realize efficiency and simplification of control parts of the RF-IP transmitter 1 and the RF-IP receiver 2. In addition, by providing the data buffer 3g and the data buffer 4g, the A / D converted sampling data can be placed on the RTP data transfer packet at an appropriate timing, and the decapsulated sampling data can be applied at an appropriate timing. Reading and D / A conversion can be performed using the sampling clock.

(RF-IP transmission / reception method 1)
The RF-IP transmission / reception method of the present invention can be used for retransmission of various broadcast waves. The case of retransmitting terrestrial digital television waves will be described below.
(1) The RF-IP transmitter 1 (FIG. 1) receives a broadcast terrestrial digital television broadcast signal.
(2) In the RF down-conversion unit 3a (FIG. 2) of the RF-IP transmission unit 3 of the RF-IP transmission apparatus 1, the frequency of the broadcast wave carrier of the received terrestrial digital television broadcast signal is converted to baseband.
(3) In the A / D conversion unit 3b (FIG. 2) of the RF-IP transmission unit 3, the frequency-converted broadcast wave carrier is generated by the sampling clock generation unit 3c (FIG. 2) of the RF-IP transmission unit 3. Quantize with the sampling clock.
(4) RF-IP transmission In the RTP encapsulation unit 3e of the RF-IP unit 3, a time stamp is generated using the sampling clock, and the sampling data after the A / D conversion is placed on an RTP data transfer packet. An Ethernet frame is generated by encapsulating the count value counted by the sampling clock in the RTP time stamp. At this time, a sampling clock can also be loaded using the RTP protocol. Thus, by transmitting the sampling clock using the existing RTP protocol, it is not necessary to set a new protocol for transmitting the sampling clock, and it is possible to improve the efficiency of control.
(5) The Ethernet frame is sent out from the Gigabit Ethernet sending unit 3f in the RF-IP sending unit 3 to the IP network (FIGS. 1 and 2).
(6) The encapsulated Ethernet frame transmitted through the IP network is received by the Gigabit Ethernet receiver 4a (FIG. 2) of the RF-IP receiver unit 4 of the RF-IP receiver 2.
(7) The RTP decapsulation unit 4b (FIG. 2) of the RF-IP receiving unit 4 extracts (regenerates) the time stamp included in the received Ethernet frame.
(8) The sampling clock regeneration unit 4d (FIG. 2) of the RF-IP receiving unit 4 reproduces the sampling clock using the counter value counted by the sampling clock described in the RTP time stamp of the Ethernet frame. To do.
(9) In the D / A converter 4e (FIG. 2) of the RF-IP receiving unit 4, the decapsulated sampling data is read out by the regenerated sampling clock and D / A converted.
(10) In the RF up-conversion unit 4f (FIG. 2) of the RF-IP receiving unit 4, the D / A converted broadcast wave carrier is frequency-converted to the broadcast wave frequency, and downstream (subscription in the case of CATV) To the person side).

DESCRIPTION OF SYMBOLS 1 RF-IP transmitter 2 RF-IP receiver 3 RF-IP transmission unit 3a RF down-conversion unit 3b A / D conversion unit 3c Sampling clock generation unit 3d RTP time stamp (time information) generation unit 3e RTP encapsulation unit ( UDP / IP RTP packet generator)
3f Gigabit Ethernet transmitter (GbEPHY)
3g Data buffer 4 RF-IP receiver 4a Gigabit Ethernet receiver (GbEPHY)
4b RTP decapsulation unit 4c RTP time stamp regeneration unit 4d sampling clock regeneration unit 4e D / A conversion unit 4f RF up-conversion unit 4g data buffer unit

Claims (3)

The broadcast wave being broadcast is encapsulated in the RF-IP transmission unit of the RF-IP transceiver and sent to the IP network as an Ethernet frame, and the encapsulated signal in the Ethernet frame transmitted over the IP network is In the RF-IP receiving unit of the RF-IP transmitting / receiving apparatus, an RF-IP transmitting / receiving method for converting to a broadcast wave and transmitting to a receiver,
The RF-IP transmission unit includes the following steps (1) to (6):
(1) an RF down-conversion process for converting a received broadcast wave carrier to a frequency near the baseband;
(2) a sampling clock generation step for generating a sampling clock;
(3) A / D conversion converting step of A / D converting the frequency-converted broadcast wave carrier by A / D conversion with the sampling clock;
(4) an RTP time stamp generating step of generating an RTP time stamp using the sampling clock;
(5) an RTP encapsulation step of placing the sampling data after the A / D conversion in an RTP data transfer packet, encapsulating the count value counted by the sampling clock in the RTP timestamp and generating an Ethernet frame; ,
(6) a sending step of sending the Ethernet frame from the RF-IP transmission unit to the IP network;
The RF-IP receiving unit includes the following steps (7) to (13):
(7) An Ethernet frame receiving step of receiving the Ethernet frame transmitted through the IP network at a receiving unit of the RF-IP receiving unit of the RF-IP transceiver device ;
(8) a time stamp regeneration step of extracting (regenerating) an RTP time stamp included in the Ethernet frame;
(9) a decapsulation step of extracting an RTP time stamp included in the decapsulated Ethernet frame;
(10) a sampling clock regeneration step of regenerating the sampling clock using a counter value counted by the sampling clock described in the RTP time stamp of the Ethernet frame;
(11) A D / A conversion step of reading and D / A converting the sampling data decapsulated in the decapsulation step by the sampling clock regenerated in the sampling clock regeneration step;
(12) an RF up-conversion step of frequency-converting the D / A converted broadcast wave carrier to a broadcast wave frequency; and (13) a step of sending the up-converted RF signal from the RF-IP receiving unit to the receiver side. An RF-IP transmission / reception method characterized by comprising:   2. The RF-IP transmission / reception method according to claim 1, wherein the encapsulation step is performed by mounting a sampling clock using the RTP protocol. An RF-IP transmitter that encapsulates the broadcast wave being broadcast and sends it to the IP network as an Ethernet frame, and converts the encapsulated signal in the Ethernet frame transmitted over the IP network into a broadcast wave for the receiver An RF-IP transmission / reception device including an RF-IP reception device for transmitting,
The RF-IP transmitter has the following configurations (1) to (6),
(1) an RF down-converter for converting the received broadcast wave carrier to a frequency near the baseband;
(2) a sampling clock generator for generating a sampling clock;
(3) an A / D conversion unit that quantizes the frequency-converted broadcast wave carrier with the sampling clock and performs A / D conversion;
(4) an RTP time stamp generation unit that generates a time stamp using the sampling clock;
(5) An RTP capsule for generating an Ethernet frame by placing the sampling data after A / D conversion in the A / D conversion unit on an RTP data transfer packet and writing the count value counted by the sampling clock in the RTP time stamp Equipped with
(6) Send the encapsulated Ethernet frame to an IP network;
The RF-IP receiver includes the following configurations (7) to (13):
(7) a Gigabit Ethernet receiver that receives the Ethernet frame transmitted over the IP network;
(8) a decapsulation unit that extracts an RTP time stamp included in the encapsulated Ethernet frame transmitted over the IP network;
(9) an RTP timestamp regenerator for extracting an RTP timestamp included in the decapsulated Ethernet frame;
(10) a sampling clock regenerator that regenerates the sampling clock using a counter value counted by the sampling clock described in the RTP time stamp of the Ethernet frame;
(11) A D / A conversion unit that reads out the sampling data decapsulated by the decapsulation unit using the sampling clock regenerated by the sampling clock regeneration unit and performs D / A conversion;
(12) An RF up-conversion unit that frequency-converts the D / A converted broadcast wave carrier to a broadcast wave frequency,
(13) An RF-IP transmission / reception apparatus that sends the up-converted broadcast wave to a receiver.

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