IP transmission system, IP transmission device, IP reception device, and IP transmission method

Abstract

To retransmit a broadcast signal of higher quality while suppressing a delay occurring when retransmitting a broadcast signal of a terrestrial digital signal within an allowable range in a system for retransmitting a broadcast signal after IP transmission.SOLUTION: An IP transmission device receives a broadcast signal of digital terrestrial broadcasting, extracts a channel signal from the broadcast signal, and transmits, to an IP receiving device, an IP packet including a digital signal obtained by digitally converting the channel signal, and signal information indicating the reception status of the channel signal, and the IP receiving device obtains the digital signal and the signal information from the IP packet, determines whether to output the channel signal on the basis of the signal information, and outputs the channel signal based on the digital signal in response to a determination result.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an IP transmission system, an IP transmitting device, an IP receiving device, and an IP transmission method. [Background technology]

[0002] 2. Description of the Related Art Conventionally, systems have been proposed for retransmitting terrestrial digital broadcast signals.

[0003] For example, Patent Document 1 (JP 2008-211587 A) discloses the following IP / RF conversion device as a device used in such a system: That is, the IP / RF conversion device includes IP packet receiving devices (32-1 to 32-n) that receive IP packets carrying broadcast TS packets, broadcast TS packet processing devices (34-1 to 34-n) that extract the broadcast TS packets from the IP packets received by the IP packet receiving devices and output them in chronological order on the transmitting side, clock extraction devices (36-1 to 36-n) that extract a synchronization clock required for OFDM modulation from the broadcast TS packets supplied from the broadcast TS packet processing devices and output the synchronization clock and the broadcast TS packets in synchronization with each other, and OFDM modulation devices (38-1 to 38-n) that OFDM-modulate the broadcast TS packets from the clock extraction devices in synchronization with the synchronization clock from the clock extraction devices.

[0004] Furthermore, Patent Document 2 (JP 2011-10186 A) discloses the following digital broadcast retransmission system: That is, the digital broadcast retransmission system includes a packet conversion device that receives a radio frequency signal broadcast from a digital broadcast device, demodulates the radio frequency signal to extract line coding information that has been line coded from the radio frequency signal, packetizes the line coding information, and transmits the packets to a network, and a frequency conversion device that receives the packets from the packet conversion device via the network, extracts the line coding information from the packets, modulates the line coding information to generate a radio frequency signal, and transmits the radio frequency signal to a digital broadcast receiving device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-211587 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-10186 [Patent Document 3] Japanese Patent Application Publication No. 2018-11236 Summary of the Invention [Problem to be solved by the invention]

[0006] There is a need for a technology that goes beyond the technologies described in Patent Documents 1 to 3 and that can retransmit broadcast signals of higher quality while keeping the delay that occurs when retransmitting terrestrial digital broadcast signals within an acceptable range in a system in which broadcast signals are transmitted via IP (Internet Protocol) and then retransmitted.

[0007] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide an IP transmission system, IP transmitting device, IP receiving device, and IP transmission method that are capable of retransmitting broadcast signals of higher quality while keeping the delay that occurs when retransmitting terrestrial digital broadcast signals within an acceptable range in a system in which broadcast signals are transmitted via IP and then retransmitted. [Means for solving the problem]

[0008] The IP transmission system of the present disclosure comprises an IP transmitting device and an IP receiving device, wherein the IP transmitting device receives a terrestrial digital broadcast signal, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating the reception status of the channel signal, and the IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result.

[0009] The IP transmission device of the present disclosure includes a receiving unit that receives a terrestrial digital broadcast signal, an extraction unit that extracts a channel signal from the broadcast signal received by the receiving unit, a signal information generation unit that generates signal information indicating the reception status of the channel signal extracted by the extraction unit, an IP packet generation unit that generates a digital signal obtained by digitally converting the channel signal and an IP packet including the signal information, and an output unit that outputs the IP packet generated by the IP packet generation unit.

[0010] The IP receiving device of the present disclosure comprises a receiving unit that receives from an IP transmitting device an IP packet containing a digital signal obtained by digitally converting a channel signal in terrestrial digital broadcasting and signal information indicating the reception status of the channel signal at the IP transmitting device; an acquisition unit that acquires the digital signal from the IP packet received by the receiving unit; a judgment unit that acquires the signal information from the IP packet received by the receiving unit and determines whether or not to output the channel signal based on the acquired signal information; and an output unit that outputs the channel signal based on the digital signal acquired by the acquisition unit depending on the judgment result by the judgment unit.

[0011] The IP transmission method disclosed herein is an IP transmission method in an IP transmission system including an IP transmitting device and an IP receiving device, and includes the steps of: the IP transmitting device receiving a terrestrial digital broadcast signal, extracting a channel signal from the received broadcast signal, and transmitting an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating the reception status of the channel signal; and the IP receiving device acquiring the digital signal and the signal information from the IP packet received from the IP transmitting device, determining whether or not to output the channel signal based on the acquired signal information, and outputting the channel signal based on the digital signal according to the determination result.

[0012] One aspect of the present disclosure can be realized not only as an IP transmission device equipped with such a characteristic processing unit, but also as an IP transmission method having such characteristic processing steps, as a program for causing a computer to execute such steps, or as a semiconductor integrated circuit that realizes part or all of the IP transmission device.

[0013] Furthermore, one aspect of the present disclosure can be realized not only as an IP receiving device equipped with such a characteristic processing unit, but also as an IP receiving method having such characteristic processing steps, as a program for causing a computer to execute such steps, or as a semiconductor integrated circuit that realizes part or all of the IP receiving device. [Effects of the Invention]

[0014] According to the present disclosure, in a system in which a broadcast signal is transmitted via IP and then retransmitted, it is possible to retransmit a broadcast signal of higher quality while keeping the delay that occurs when retransmitting a terrestrial digital broadcast signal within an acceptable range. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating a configuration of an IP transmission system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating an example of IP packet transmission in the IP transmission system according to the embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram illustrating a configuration of an IP transmission device according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating a configuration of an IP receiving device according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a flowchart illustrating an example of an operation procedure when an IP transmission device according to an embodiment of the present disclosure transmits an IP packet. [Figure 6] FIG. 6 is a flowchart defining an example of an operation procedure when the IP receiving device according to the embodiment of the present disclosure outputs a channel signal. [Figure 7] FIG. 7 is a diagram illustrating an example of a sequence of IP packet transmission processing in the IP transmission system according to the embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram illustrating an example of IP packet transmission in an IP transmission system according to a modified example of the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] First, the contents of the embodiments of the present disclosure will be listed and described.

[0017] (1) An IP transmission system according to an embodiment of the present disclosure includes an IP transmitting device and an IP receiving device, wherein the IP transmitting device receives a broadcast signal of terrestrial digital broadcasting, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating the reception status of the channel signal. The IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result.

[0018] In this way, by transmitting IP packets containing digital signals obtained by digitally converting channel signals and signal information indicating the reception status of the channel signals, determining whether to output the channel signals based on the signal information contained in the transmitted IP packets, and outputting the channel signals based on the determination result, delays are reduced compared to systems that demodulate and re-modulate modulated signals, and output of the channel signals can be stopped, for example, when the IP transmitting device breaks down or the broadcast signal is paused, thereby reducing degradation in the quality of the retransmitted broadcast signals. Therefore, in a system that transmits broadcast signals via IP and then retransmits them, it is possible to retransmit broadcast signals of higher quality while keeping delays that occur when retransmitting terrestrial digital broadcast signals within an acceptable range.

[0019] (2) The IP transmitting device may transmit, as the reception status, an IP packet including the signal information indicating the signal quality of the channel signal to the IP receiving device.

[0020] With this configuration, signal information indicating a more accurate reception status can be transmitted to the IP receiving device.

[0021] (3) The IP transmitting device may transmit, as the reception status, an IP packet including the signal information indicating the control content of automatic gain control for the channel signal to the IP receiving device.

[0022] With this configuration, signal information can be generated without demodulating the modulated signal, so that signal information indicating a change in the reception status of the channel signal can be transmitted to the IP receiving device at an earlier stage.

[0023] (4) The apparatus may include a first IP transmitting device and a second IP transmitting device, wherein the first IP transmitting device extracts the channel signal corresponding to a predetermined channel and transmits to the IP receiving device a first IP packet including the digital signal obtained by digitally converting the extracted channel signal and first signal information indicating the reception status of the channel signal; the second IP transmitting device extracts the channel signal corresponding to the predetermined channel and transmits to the IP receiving device a second IP packet including the digital signal obtained by digitally converting the extracted channel signal and second signal information indicating the reception status of the channel signal; and the IP receiving device may output either the channel signal based on the digital signal in the first IP packet or the channel signal based on the digital signal in the second IP packet based on the first signal information and the second signal information.

[0024] Such a configuration can further realize redundancy in the receiving path of the broadcast signal.

[0025] (5) An IP transmission device according to an embodiment of the present disclosure includes a receiving unit that receives a terrestrial digital broadcast signal, an extraction unit that extracts a channel signal from the broadcast signal received by the receiving unit, a signal information generation unit that generates signal information indicating the reception status of the channel signal extracted by the extraction unit, an IP packet generation unit that generates a digital signal obtained by digitally converting the channel signal and an IP packet including the signal information, and an output unit that outputs the IP packet generated by the IP packet generation unit.

[0026] In this way, by configuring the system to output IP packets containing digital signals obtained by digitally converting channel signals and signal information indicating the reception status of the channel signals, the IP receiving device can determine whether to output the channel signals based on the signal information included in the IP packets and output the channel signals according to the determination result. This allows the IP receiving device to stop outputting the channel signals in cases such as when the IP transmitting device breaks down or when the broadcast signal is paused, while suppressing delays compared to systems that demodulate and re-modulate modulated signals, thereby suppressing deterioration in the quality of the retransmitted broadcast signals. Therefore, in a system that transmits broadcast signals via IP and then retransmits them, it is possible to retransmit broadcast signals of higher quality while keeping delays that occur when retransmitting terrestrial digital broadcast signals within an acceptable range.

[0027] (6) An IP receiving device according to an embodiment of the present disclosure includes a receiving unit that receives from an IP transmitting device an IP packet containing a digital signal obtained by digitally converting a channel signal in terrestrial digital broadcasting and signal information indicating the reception status of the channel signal in the IP transmitting device; an acquiring unit that acquires the digital signal from the IP packet received by the receiving unit; a judgment unit that acquires the signal information from the IP packet received by the receiving unit and determines whether or not to output the channel signal based on the acquired signal information; and an output unit that outputs the channel signal based on the digital signal acquired by the acquisition unit according to the judgment result by the judgment unit.

[0028] In this way, the system receives IP packets containing digital signals obtained by digitally converting channel signals and signal information indicating the reception status of the channel signals at the IP transmission device, determines whether to output the channel signals based on the signal information contained in the received IP packets, and outputs the channel signals according to the determination result. This configuration reduces delays compared to systems that demodulate and re-modulate modulated signals, and can stop the output of the channel signals in cases such as when the IP transmission device breaks down or when the broadcast signal is paused, thereby reducing degradation in the quality of the retransmitted broadcast signals. Therefore, in a system that transmits broadcast signals via IP and then retransmits them, it is possible to retransmit broadcast signals of higher quality while keeping the delay that occurs when retransmitting terrestrial digital broadcast signals within an acceptable range.

[0029] (7) An IP transmission method according to an embodiment of the present disclosure is an IP transmission method in an IP transmission system including an IP transmitting device and an IP receiving device, and includes the steps of: the IP transmitting device receiving a broadcast signal of terrestrial digital broadcasting, extracting a channel signal from the received broadcast signal, and transmitting an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating the reception status of the channel signal; and the IP receiving device acquiring the digital signal and the signal information from the IP packet received from the IP transmitting device, determining whether or not to output the channel signal based on the acquired signal information, and outputting the channel signal based on the digital signal according to the determination result.

[0030] In this way, by transmitting IP packets containing digital signals obtained by digitally converting channel signals and signal information indicating the reception status of the channel signals, determining whether to output the channel signals based on the signal information contained in the transmitted IP packets, and outputting the channel signals according to the determination result, delays can be reduced compared to systems that demodulate and re-modulate modulated signals, and the output of the channel signals can be stopped, for example, when the IP transmission device breaks down or the broadcast signal is paused, thereby reducing deterioration in the quality of the retransmitted broadcast signals. Therefore, in a system that transmits broadcast signals via IP and then retransmits them, it is possible to retransmit broadcast signals of higher quality while keeping the delay that occurs when retransmitting terrestrial digital broadcast signals within an acceptable range.

[0031] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0032] [Configuration and basic operation] Fig. 1 is a diagram illustrating a configuration of an IP transmission system according to an embodiment of the present disclosure. Referring to Fig. 1, an IP transmission system 301 includes a plurality of IP transmission devices 101 and a plurality of IP reception devices 201. For example, the IP reception device 201 is provided in a cable television station. Furthermore, for example, the IP transmission device 101 is provided in a location different from the cable television station.

[0033] The IP transmitting device 101 receives a terrestrial digital broadcasting signal, for example, including a stream. Hereinafter, the terrestrial digital broadcasting signal will also be referred to as a terrestrial signal. For example, the terrestrial signal includes multiple channel signals corresponding to multiple channels. The stream includes program information, etc. The program information includes, for example, audio information, video information, EPG (Electronic Program Guide) information, SI (Service Information), and subtitle information. The audio information and video information are compressed and encrypted, for example, according to a predetermined method. Note that the terrestrial signal may include one channel signal corresponding to one channel.

[0034] The IP transmitting device 101 extracts a channel signal corresponding to a specific channel from the received terrestrial signal. For example, the channel signal to be extracted by the IP transmitting device 101 is predetermined for each IP transmitting device 101. Hereinafter, the channel corresponding to the channel signal to be extracted by the IP transmitting device 101 is also referred to as the target channel. The IP transmitting device 101 generates an IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating the reception status of the channel signal. The IP transmitting device 101 transmits the generated IP packet to one or more IP receiving devices 201 via the IP network 151.

[0035] For example, an IP packet output by the IP transmitting device 101 is converted into an optical signal in the IP network 151 and transmitted to the IP receiving device 201 by wavelength division multiplexing communication.

[0036] The IP receiving device 201 receives IP packets via the IP network 151. The IP receiving device 201 acquires the digital signal and signal information from the received IP packets, and determines whether or not to output a channel signal based on the acquired signal information. Depending on the determination result, the IP receiving device 201 outputs a channel signal based on the digital signal acquired from the received IP packets to the multiplexer 161.

[0037] The multiplexer 161 multiplexes the channel signals output from each IP receiving device 201 and transmits the multiplexed signal to each subscriber's home via the cable television network.

[0038] FIG. 2 is a diagram illustrating an example of IP packet transmission in an IP transmission system according to an embodiment of the present disclosure. FIG. 2 illustrates IP transmitters 101A and 101B, which are IP transmitters 101, and IP receiver 201A, which is IP receiver 201. IP transmitter 101A is an example of a first IP transmitter, and IP transmitter 101B is an example of a second IP transmitter. For example, IP receiver 201 operates in a normal mode or a redundant mode. IP receiver 201A operates in the normal mode. The redundant mode will be described in detail later. Referring to FIG. 2, IP network 151 includes switch devices 152A and 152B.

[0039] The IP transmission devices 101A and 101B receive, via an antenna 111, a terrestrial signal transmitted from a radio tower (not shown) for relaying a stream from a broadcast station.

[0040] The IP transmission device 101A extracts the channel signal chX of the target channel, channel X, from the terrestrial signal received via the antenna 111.

[0041] The IP transmitting device 101A generates a digital signal DX by digitally converting the extracted channel signal chX, and signaling information FX indicating the reception status of the channel signal chX. The IP transmitting device 101A transmits an IP packet PAX1 including the digital signal DX and signaling information FX to the IP receiving device 201A via the switching device 152A. The IP transmitting device 101A also transmits an IP packet PAX2 including the digital signal DX and signaling information FX to the IP receiving device 201A via the switching device 152B. The signaling information FX is an example of first signaling information. The IP packets PAX1 and PAX2 are examples of first IP packets.

[0042] The IP transmission device 101B extracts, from the terrestrial signal received via the antenna 111, a channel signal chY of the target channel Y, which is different from the X channel.

[0043] The IP transmitting device 101B generates a digital signal DY by digitally converting the extracted channel signal chY, and signaling information FY indicating the reception status of the channel signal chY. The IP transmitting device 101B transmits an IP packet PAY1 including the digital signal DY and signaling information FY to the IP receiving device 201A via the switching device 152A. The IP transmitting device 101B also transmits an IP packet PAY2 including the digital signal DY and signaling information FY to the IP receiving device 201A via the switching device 152B. The signaling information FY is an example of second signaling information. The IP packets PAY1 and PAY2 are examples of second IP packets.

[0044] The IP receiver 201A receives the IP packets PAX1 and PBY1 via the switch device 152A, and also receives the IP packets PAX2 and PBY2 via the switch device 152B.

[0045] The IP receiving device 201A acquires the digital signal DX and signal information FX from the received IP packet PAX1 or IP packet PAX2. Based on the acquired signal information FX, the IP receiving device 201A determines whether or not to output the channel signal chX. If the IP receiving device 201A determines that the channel signal chX should be output, it outputs the channel signal chX obtained by converting the digital signal DX to analog to the multiplexer 161.

[0046] In addition, the IP reception device 201A acquires the digital signal DY and the signal information FY from the received IP packet PAY1 or IP packet PAY2. The IP reception device 201A determines whether to output the channel signal chY based on the acquired signal information FY. When it is determined that the channel signal chY should be output, the IP reception device 201A outputs the channel signal chY obtained by analog-converting the digital signal DY to the combiner 161.

[0047] <IP transmission device> FIG. 3 is a diagram showing the configuration of an IP transmission device according to an embodiment of the present disclosure. Referring to FIG. 3, the IP transmission device 101 includes a reception unit 11, an extraction unit 12, an amplification unit 13, an AD (Analog to Digital) conversion unit 14, a detection unit 15, a filter unit 16, a signal information generation unit 17, an IP packet generation unit 18, an output unit 19, and a storage unit 20. The output unit 19 includes IP packet output units 19A and 19B. The storage unit 20 is, for example, a non-volatile memory.

[0048] (Reception unit) The reception unit 11 receives a terrestrial wave signal. More specifically, for example, the reception unit 11 receives an RF (Radio Frequency) band terrestrial wave signal modulated by OFDM (Orthogonal Frequency Division Multiplexing) via the antenna 111.

[0049] The reception unit 11 generates a baseband signal by down-converting the received terrestrial wave signal using a direct conversion method. The reception unit 11 outputs the generated baseband signal to the extraction unit 12.

[0050] (Extraction unit) The extraction unit 12 extracts the channel signal of the target channel from the terrestrial wave signal received by the reception unit 11. More specifically, the extraction unit 12 extracts the channel signal of the target channel from the baseband signal received from the reception unit 11. The extraction unit 12 outputs the extracted channel signal to the amplification unit 13.

[0051] Specifically, the extraction unit 12 in the IP transmission device 101A extracts the channel signal chX from the baseband signal received from the reception unit 11 and outputs it to the amplification unit 13. In addition, the extraction unit 12 in the IP transmission device 101B extracts the channel signal chY from the baseband signal received from the reception unit 11 and outputs it to the amplification unit 13.

[0052] (Amplification section) The amplifier 13 amplifies the channel signal received from the extractor 12. For example, the amplifier 13 performs automatic gain control on the channel signal. More specifically, the amplifier 13 receives a control signal from the detector 15 as described below, and changes the gain in accordance with the received control signal to amplify the channel signal so that the level of the channel signal becomes a predetermined value. The amplifier 13 outputs the amplified channel signal to the AD converter 14.

[0053] (AD conversion section) The AD conversion unit 14 generates a digital signal by digitally converting the channel signal received from the amplification unit 13, and outputs the generated digital signal to the detection unit 15 and the filter unit 16. More specifically, the AD conversion unit 14 includes an ADC (Analog to Digital Converter). The AD conversion unit 14 generates a digital signal at each sampling timing of the ADC and outputs the digital signal to the detection unit 15 and the filter unit 16.

[0054] Specifically, the AD conversion unit 14 in the IP transmission device 101A receives the amplified channel signal chX from the amplifier unit 13, digitally converts the received channel signal chX to generate a digital signal DX, and outputs the digital signal DX to the detection unit 15 and the filter unit 16. Also, the AD conversion unit 14 in the IP transmission device 101B receives the amplified channel signal chY from the amplifier unit 13, digitally converts the received channel signal chY to generate a digital signal DY, and outputs the digital signal DY to the detection unit 15 and the filter unit 16.

[0055] (Detection section) The detection unit 15 generates a control signal for adjusting the gain of the amplification unit 13 so that the level indicated by the digital signal received from the AD conversion unit 14 becomes a predetermined value, and outputs the generated control signal to the amplification unit 13.

[0056] (filter section) For example, the filter unit 16 includes an FIR (Finite Impulse Response) filter. The filter unit 16 performs filtering to attenuate signal components of channels other than the target channel in the frequency components indicated by the digital signal generated by the AD conversion unit 14, and outputs the filtered digital signal to the signal information generation unit 17 and the IP packet generation unit 18.

[0057] Specifically, the filter unit 16 in the IP transmission device 101A receives the digital signal DX from the AD conversion unit 14, attenuates signal components of channels other than the X channel in the frequency components indicated by the received digital signal DX, and outputs the result to the signal information generation unit 17 and the IP packet generation unit 18. Also, the filter unit 16 in the IP transmission device 101B receives the digital signal DY from the AD conversion unit 14, attenuates signal components of channels other than the Y channel in the frequency components indicated by the received digital signal DY, and outputs the result to the signal information generation unit 17 and the IP packet generation unit 18.

[0058] (Signal information generation section) The signal information generating unit 17 generates signal information indicating the reception status of the channel signal extracted by the extracting unit 12. The signal information generating unit 17 outputs the generated signal information to the IP packet generating unit .

[0059] For example, the signal information generating unit 17 generates signal information indicating the signal quality of the channel signal as the reception status of the channel signal.

[0060] More specifically, the signal information generator 17 demodulates the OFDM-modulated signal indicated by the digital signal received from the filter unit 16 at a generation timing according to a predetermined cycle to generate demodulated data, and measures the CNR (Carrier-to-Noise Ratio) of the digital signal using the demodulated data. The signal information generator 17 also measures the BER (Bit Error Rate) of the digital signal using the demodulated data. The signal information generator 17 also calculates an average value L of the level indicated by the digital signal received from the filter unit 16 over a predetermined period at the generation timing.

[0061] Furthermore, for example, the signal information generating unit 17 generates signal information indicating the control content of the automatic gain control for the channel signal as the reception status of the channel signal. More specifically, the signal information generating unit 17 acquires the control signal output from the detecting unit 15 to the amplifying unit 13 at the above generation timing, and acquires the control content of the automatic gain control indicated by the control signal, such as the gain value.

[0062] The signal information generating unit 17 generates signal information including the measured CNR and BER, the calculated average value L, and the acquired gain value, and outputs the generated signal information to the IP packet generating unit 18.

[0063] Specifically, the signal information generation unit 17 in the IP transmission device 101A generates signal information FX indicating the signal quality of the channel signal chX and the control details of the automatic gain control for the channel signal chX, and outputs the generated signal information FX to the IP packet generation unit 18. Also, the signal information generation unit 17 in the IP transmission device 101B generates signal information FY indicating the signal quality of the channel signal chY and the control details of the automatic gain control for the channel signal chY, and outputs the generated signal information FY to the IP packet generation unit 18.

[0064] (IP packet generation unit) The IP packet generator 18 generates IP packets containing digital signals obtained by digitally converting the channel signals and signal information.

[0065] More specifically, the IP packet generation unit 18 receives a digital signal from the filter unit 16 and stores the received digital signal in a buffer in the storage unit 20. The IP packet generation unit 18 also receives signal information from the signal information generation unit 17 and stores the received signal information in the storage unit 20. Every time the IP packet generation unit 18 receives signal information from the signal information generation unit 17, it updates the signal information stored in the storage unit 20 with the newly received signal information.

[0066] The IP packet generator 18 acquires a plurality of digital signals and signal information from the storage unit 20 at packet generation timings that conform to a predetermined cycle, and generates IP packets addressed to the IP receiver 201, with the acquired plurality of digital signals and signal information stored in the payload. The IP packet generator 18 outputs the generated IP packets to the IP packet output units 19A and 19B.

[0067] Specifically, the IP packet generator 18 in the IP transmitter 101A generates IP packets PAX1 and PAX2 addressed to the IP receiver 201, each of which has a payload containing a plurality of digital signals DX and signaling information FX, and outputs the generated IP packets PAX1 and PAX2 to the IP packet output units 19A and 19B. Also, the IP packet generator 18 in the IP transmitter 101B generates IP packets PAY1 and PAY2 addressed to the IP receiver 201, each of which has a payload containing a plurality of digital signals DY and signaling information FY, and outputs the generated IP packets PAY1 and PAY2 to the IP packet output units 19A and 19B.

[0068] (output section) The output unit 19 outputs the IP packet generated by the IP packet generation unit 18 .

[0069] More specifically, the IP packet output unit 19A in the IP transmission device 101A transmits the IP packet PAX1 received from the IP packet generation unit 18 to the IP reception device 201A via the switch device 152A. The IP packet output unit 19B in the IP transmission device 101A transmits the IP packet PAX2 received from the IP packet generation unit 18 to the IP reception device 201A via the switch device 152B.

[0070] Also, the IP packet output unit 19B in the IP transmission device 101B transmits the IP packet PAY1 received from the IP packet generation unit 18 to the IP reception device 201A via the switch device 152A. The IP packet output unit 19B in the IP transmission device 101B transmits the IP packet PAY2 received from the IP packet generation unit 18 to the IP reception device 201A via the switch device 152B.

[0071] <IP reception device> FIG. 4 is a diagram showing the configuration of an IP reception device according to an embodiment of the present disclosure. Referring to FIG. 4, the IP reception device 201 includes a reception unit 31, a selection unit 32, an acquisition unit 33, a determination unit 34, switches 35A and 35B, and an output unit 36. The reception unit 31 includes IP packet reception units 31A and 31B. The selection unit 32 includes IP packet selection units 32A and 32B. The acquisition unit 33 includes signal acquisition units 33A and 33B. The output unit 36 includes signal output units 36A and 36B. One end of the switch 35A is connected to the signal acquisition unit 33A, and the other end of the switch 35A is connected to the signal output unit 36A. One end of the switch 35B is connected to the signal acquisition unit 33B, and the other end of the switch 35B is connected to the signal output unit 36B. Hereinafter, each of the switches 35A and 35B is also referred to as the switch 35.

[0072] (Reception unit) The reception unit 31 receives an IP packet including a digital signal obtained by digitally converting a channel signal in terrestrial digital broadcasting and signal information indicating the reception status of the channel signal in the IP transmission device 101 from the IP transmission device 101.

[0073] More specifically, the IP packet receiving unit 31A receives the IP packet PAX1 from the IP transmitting device 101A via the switch device 152A, and outputs the received IP packet PAX1 to the IP packet selecting unit 32A. The IP packet receiving unit 31A receives the IP packet PAY1 from the IP transmitting device 101B via the switch device 152A, and outputs the received IP packet PAY1 to the IP packet selecting unit 32B.

[0074] Furthermore, the IP packet receiving unit 31B receives the IP packet PAX2 from the IP transmitting device 101A via the switch device 152B, and outputs the received IP packet PAX2 to the IP packet selecting unit 32A. The IP packet receiving unit 31B receives the IP packet PAY2 from the IP transmitting device 101B via the switch device 152B, and outputs the received IP packet PAY2 to the IP packet selecting unit 32B.

[0075] (Selection section) The selector 32 receives from the receiver 31 a plurality of IP packets that have been transmitted by the IP transmitter 101 and have passed through a plurality of different transmission paths in the IP network 151, and outputs one of the received IP packets to the acquirer 33 and the determiner 34. For example, of an IP packet P1 received by the receiver 31 from the IP transmitter 101 via the switch device 152A and an IP packet P2 received by the receiver 31 from the IP transmitter 101 via the switch device 152B, the selector 32 preferentially outputs the IP packet P1 to the acquirer 33 and the determiner 34. If the IP packet P1 is lost, the selector 32 outputs the IP packet P2 to the acquirer 33 and the determiner 34 instead of the IP packet P1.

[0076] More specifically, the IP packet selector 32A receives IP packets PAX1 and PAX2 from the IP packet receivers 31A and 31B, respectively. The IP packet selector 32A checks the sequence numbers of the received IP packets PAX1 and PAX2 to determine whether the IP packet PAX1 is missing and whether the IP packet PAX2 is missing. If the IP packet selector 32A determines that the IP packet PAX1 is not missing, it outputs the IP packet PAX1 received from the IP packet receiver 31A to the signal acquirer 33A and the determination unit 34. On the other hand, if the IP packet selector 32A determines that the IP packet PAX1 is missing and that the IP packet PAX2 is not missing, it outputs the IP packet PAX2 received from the IP packet receiver 31B, instead of the IP packet PAX1, to the signal acquirer 33A and the determination unit 34. For example, if the IP packet selector 32A determines that both the IP packets PAX1 and PAX2 are missing, it issues an alert notification. Hereinafter, the IP packet output by the IP packet selector 32A to the signal acquirer 33A and the decision unit 34 will also be referred to as an "output IP packet PAX."

[0077] Furthermore, the IP packet selector 32B receives IP packets PAY1 and PAY2 from the IP packet receivers 31A and 31B, respectively. The IP packet selector 32B checks the sequence numbers of the received IP packets PAY1 and PAY2 to determine whether the IP packet PAY1 is missing and whether the IP packet PAY2 is missing. If the IP packet selector 32B determines that the IP packet PAY1 is not missing, it outputs the IP packet PAY1 received from the IP packet receiver 31A to the signal acquirer 33B and the determination unit 34. On the other hand, if the IP packet selector 32B determines that the IP packet PAY1 is missing and that the IP packet PAY2 is not missing, it outputs the IP packet PAY2 received from the IP packet receiver 31B, instead of the IP packet PAY1, to the signal acquirer 33B and the determination unit 34. For example, if the IP packet selector 32B determines that both the IP packets PAY1 and PAY2 are missing, it issues an alert notification. Hereinafter, the IP packet output by the IP packet selection unit 32B to the signal acquisition unit 33B and the determination unit 34 will also be referred to as an "output IP packet PAY."

[0078] (Acquisition Department) The acquisition unit 33 acquires a digital signal from the IP packet received by the reception unit 31 .

[0079] More specifically, the signal acquirer 33A receives the output IP packet PAX from the IP packet selector 32A, acquires the digital signal DX from the payload of the received output IP packet PAX, and outputs the acquired digital signal DX to the switch 35A.

[0080] Furthermore, the signal acquirer 33B receives the output IP packet PAY from the IP packet selector 32B and acquires the digital signal DY from the payload of the received output IP packet PAY. The signal acquirer 33B outputs the acquired digital signal DY to the switch 35B.

[0081] (Judgment Department) The determination unit 34 acquires signal information from the IP packet received by the receiving unit 31, and performs a determination process to determine whether or not to output a channel signal based on the acquired signal information. The determination unit 34 controls the opening and closing of the switch 35 according to the determination result.

[0082] More specifically, the determination unit 34 receives the output IP packet PAX from the IP packet selection unit 32A and acquires the signal information FX from the received output IP packet PAX. Based on the acquired signal information FX, the determination unit 34 determines whether or not to output the channel signal chX, and controls the opening and closing of the switch 35A based on the determination result. For example, the determination unit 34 compares the CNR indicated by the signal information FX with a predetermined threshold value Th1, compares the BER indicated by the signal information FX with a predetermined threshold value Th2, compares the average value L indicated by the signal information FX with a predetermined threshold value Th3, and compares the gain value indicated by the signal information FX with a predetermined threshold value Th4.

[0083] If the CNR is less than the threshold value Th1, the BER is less than the threshold value Th2, the average value L is equal to or greater than the threshold value Th3, and the gain value is less than the threshold value Th4, the decision unit 34 decides that the channel signal chX should be output. In this case, the decision unit 34 switches the switch 35A to the on state or maintains the on state of the switch 35A. As a result, as will be described later, the output of the channel signal chX by the signal output unit 36A is turned on. On the other hand, if the CNR is equal to or greater than the threshold value Th1, the BER is equal to or greater than the threshold value Th2, the average value L is less than the threshold value Th3, or the gain value is equal to or greater than the threshold value Th4, the decision unit 34 decides that the channel signal chX should not be output. In this case, the decision unit 34 switches the switch 35A to the off state or maintains the off state of the switch 35A. As a result, as will be described later, the output of the channel signal chX by the signal output unit 36A is turned off.

[0084] Furthermore, the determination unit 34 receives the output IP packet PAY from the IP packet selection unit 32B and acquires signal information FY from the received output IP packet PAY. Based on the acquired signal information FY, the determination unit 34 determines whether or not to output the channel signal chY, and controls the opening and closing of the switch 35B based on the determination result. For example, the determination unit 34 compares the CNR indicated by the signal information FY with a predetermined threshold Th5, compares the BER indicated by the signal information FY with a predetermined threshold Th6, compares the average value L indicated by the signal information FY with a predetermined threshold Th7, and compares the gain value indicated by the signal information FY with a predetermined threshold Th8. Note that the threshold Th5 may be the same as or different from the threshold Th1. The threshold Th6 may be the same as or different from the threshold Th2. The threshold Th7 may be the same as or different from the threshold Th3. The threshold Th8 may be the same as or different from the threshold Th4.

[0085] If the CNR is less than the threshold value Th5, the BER is less than the threshold value Th6, the average value L is equal to or greater than the threshold value Th7, and the gain value is less than the threshold value Th8, the decision unit 34 decides that the channel signal chY should be output. In this case, the decision unit 34 switches the switch 35B to the on state or maintains the on state of the switch 35B. As a result, as will be described later, the output of the channel signal chY by the signal output unit 36B is turned on. On the other hand, if the CNR is equal to or greater than the threshold value Th5, the BER is equal to or greater than the threshold value Th6, the average value L is less than the threshold value Th7, or the gain value is equal to or greater than the threshold value Th8, the decision unit 34 decides that the channel signal chY should not be output. In this case, the decision unit 34 switches the switch 35B to the off state or maintains the off state of the switch 35B. As a result, as will be described later, the output of the channel signal chY by the signal output unit 36B is turned off.

[0086] (output section) The output unit 36 ​​outputs a channel signal based on the digital signal acquired by the acquisition unit 33, in accordance with the determination result by the determination unit 34. For example, the output unit 36 ​​includes a DAC (Digital to Analog Converter). The output unit 36 ​​generates a channel signal by converting the digital signal received from the acquisition unit 33 via the switch 35 into an analog signal, and up-converts the generated channel signal to a desired frequency and outputs it.

[0087] More specifically, when the switch 35A is in the on state, the signal output unit 36A receives the digital signal DX from the signal acquisition unit 33A via the switch 35A and generates the channel signal chX by converting the received digital signal DX into an analog signal. The signal output unit 36A up-converts the generated channel signal chX and outputs it to the multiplexer 161.

[0088] Furthermore, when the switch 35B is in the on state, the signal output unit 36B receives the digital signal DY from the signal acquisition unit 33B via the switch 35B and generates the channel signal chY by converting the received digital signal DY into an analog signal. The signal output unit 36B up-converts the generated channel signal chY and outputs it to the multiplexer 161.

[0089] [Operation flow] Each device in the IP transmission system according to the embodiment of the present disclosure includes a computer including a memory, and a processing unit such as a CPU in the computer reads from the memory and executes a program including some or all of the steps in the following flowcharts and sequences. The programs for each of these devices can be installed externally. The programs for each of these devices are distributed in a state stored on a recording medium or via a communication line.

[0090] FIG. 5 is a flowchart illustrating an example of an operation procedure when an IP transmission device according to an embodiment of the present disclosure transmits an IP packet.

[0091] 5, first, the IP transmission device 101 starts receiving a terrestrial signal, and then down-converts the received terrestrial signal to generate a baseband signal (step S11).

[0092] Next, the IP transmission device 101 extracts channel signals from the received terrestrial signal. More specifically, the IP transmission device 101A extracts a channel signal chX of channel X from the baseband signal. Furthermore, the IP transmission device 101B extracts a channel signal chY of channel Y from the baseband signal (step S12).

[0093] Next, the IP transmission device 101 generates a digital signal by digitally converting the extracted channel signal. More specifically, the IP transmission device 101A generates a digital signal DX and performs a filtering process. The IP transmission device 101B generates a digital signal DY and performs a filtering process (step S13).

[0094] Next, the IP transmitter 101 waits for a packet generation timing according to a predetermined cycle (NO in step S14), and when the packet generation timing arrives (YES in step S14), it generates an IP packet addressed to the IP receiver 201. For example, the IP transmitter 101 stores the filtered digital signal in a buffer in the storage unit 20. Furthermore, the IP transmitter 101 generates signal information indicating the signal quality of the channel signal and the control details of the automatic gain control for the channel signal at the generation timing according to the predetermined cycle, and stores the generated signal information in the storage unit 20. The IP transmitter 101 acquires multiple digital signals and signal information from the storage unit 20 at the packet generation timing, and generates an IP packet addressed to the IP receiver 201, including the acquired multiple digital signals and signal information. More specifically, the IP transmitter 101A generates the above-mentioned IP packets PAX1 and PAX2. Furthermore, the IP transmitter 101B generates the above-mentioned IP packets PAY1 and PAY2 (step S15).

[0095] Next, the IP transmitting device 101 outputs the generated IP packets. More specifically, the IP transmitting device 101A transmits the IP packet PAX1 to the IP receiving device 201A via the switching device 152A, and transmits the IP packet PAX2 to the IP receiving device 201A via the switching device 152B. Furthermore, the IP transmitting device 101B transmits the packet PAY1 to the IP receiving device 201A via the switching device 152A, and transmits the IP packet PAY2 to the IP receiving device 201A via the switching device 152B (step S16).

[0096] Next, the IP transmission device 101 waits for a new packet generation timing (NO in step S14).

[0097] FIG. 6 is a flowchart defining an example of an operation procedure when the IP receiving device according to the embodiment of the present disclosure outputs a channel signal.

[0098] 6, first, IP receiving device 201 waits for the arrival of an IP packet (NO in step S21), and upon receiving an IP packet (YES in step S21), acquires a digital signal and signaling information from the received IP packet. More specifically, IP receiving device 201A receives IP packets PAX1 and PAX2 from IP transmitting device 101A via switch device 152, and acquires, for example, digital signal DX and signaling information FX from IP packet PAX1. IP receiving device 201A also receives IP packets PAY1 and PAY2 from IP transmitting device 101B via switch device 152, and acquires, for example, digital signal DY and signaling information FY from IP packet PAY1 (step S22).

[0099] Next, the IP receiving device 201 determines whether to output the channel signal based on the signal information. More specifically, the IP receiving device 201A determines whether to output the channel signal chX based on the results of comparing the CNR indicated by the signal information FX with threshold value Th1, the results of comparing the BER indicated by the signal information FX with threshold value Th2, the results of comparing the average value L indicated by the signal information FX with threshold value Th3, and the results of comparing the gain value indicated by the signal information FX with threshold value Th4. The IP receiving device 201A also determines whether to output the channel signal chY based on the results of comparing the CNR indicated by the signal information FY with threshold value Th5, the results of comparing the BER indicated by the signal information FY with threshold value Th6, the results of comparing the average value L indicated by the signal information FY with threshold value Th7, and the results of comparing the gain value indicated by the signal information FY with threshold value Th8 (step S23).

[0100] Next, if the IP receiving device 201A determines that the channel signal chX should be output (YES in step S24), it turns on the output of the channel signal chX by switching the switch 35A to the on state or maintaining the switch 35A in the on state (step S25), and waits for the arrival of a new IP packet (NO in step S21).

[0101] On the other hand, if the IP receiving device 201A determines that the channel signal chX should not be output (NO in step S24), it turns off the output of the channel signal chX by switching the switch 35A to the off state or by maintaining the switch 35A in the off state (step S26), and waits for the arrival of a new IP packet (NO in step S21).

[0102] Furthermore, if the IP receiving device 201A determines that the channel signal chY should be output (YES in step S24), it turns on the output of the channel signal chY by switching the switch 35B to the on state or by maintaining the switch 35B in the on state (step S25), and waits for the arrival of a new IP packet (NO in step S21).

[0103] On the other hand, if the IP receiving device 201A determines that the channel signal chY should not be output (NO in step S24), it turns off the output of the channel signal chY by switching the switch 35B to the off state or by maintaining the switch 35B in the off state (step S26), and waits for the arrival of a new IP packet (NO in step S21).

[0104] FIG. 7 is a diagram illustrating an example of a sequence of IP packet transmission processing in the IP transmission system according to the embodiment of the present disclosure.

[0105] Referring to FIG. 7, first, IP transmission devices 101A and 101B receive terrestrial signals via antenna 111 (step S31).

[0106] Next, the IP transmission device 101A extracts the channel signal chX from the terrestrial signal (step S32).

[0107] Furthermore, the IP transmission device 101B extracts the channel signal chY from the terrestrial signal (step S33).

[0108] Next, the IP transmission device 101A generates a digital signal DX by digitally converting the channel signal chX (step S34).

[0109] Furthermore, the IP transmission device 101B generates a digital signal DY by digitally converting the channel signal chY (step S35).

[0110] Next, the IP transmitting device 101A generates signal information FX indicating the signal quality of the channel signal chX and the control content of the automatic gain control for the channel signal chX (step S36).

[0111] Furthermore, the IP transmission device 101B generates signal information FY indicating the signal quality of the channel signal chY and the control content of the automatic gain control for the channel signal chY (step S37).

[0112] Next, the IP transmitter 101A generates IP packets PAX1 and PAX2 including a plurality of digital signals DX and signal information FX (step S38).

[0113] Furthermore, the IP transmitter 101B generates IP packets PAY1 and PAY2 including a plurality of digital signals DY and signal information FY (step S39).

[0114] Next, the IP transmitter 101A transmits the IP packets PAX1 and PAX2 to the IP receiver 201A via the IP network 151 (step S40).

[0115] Furthermore, the IP transmitting device 101B transmits the IP packets PAY1 and PAY2 to the IP receiving device 201A via the IP network 151 (step S41).

[0116] Next, the IP receiver 201A acquires, for example, the digital signal DX and the signaling information FX from the received IP packet PAX1, and acquires the digital signal DY and the signaling information FY from the received IP packet PAY1 (step S42).

[0117] Next, the IP receiving device 201A performs a determination process to determine whether or not the channel signal chX can be output based on the signal information FX, and performs a determination process to determine whether or not the channel signal chY can be output based on the signal information FY (step S43).

[0118] Next, the IP receiving device 201A continues to output the channel signal chX by, for example, maintaining the on state of the switch 35A in accordance with the determination result of the determination process based on the signal information FX (step S44).

[0119] Next, the IP receiving device 201A stops outputting the channel signal chY by switching the switch 35B to the OFF state, for example, in accordance with the determination result of the determination process based on the signal information FY (step S45).

[0120] <Modification> 8 is a diagram showing an example of IP packet transmission in an IP transmission system according to a modified example of the embodiment of the present disclosure. Fig. 8 shows IP transmitters 101C and 101D, which are IP transmitters 101, and an IP receiver 201B, which is an IP receiver 201. Unlike IP receiver 201A, which operates in normal mode, IP receiver 201B operates in redundant mode.

[0121] 8, IP transmission device 101C receives a terrestrial signal via antenna 111C, while IP transmission device 101D receives a terrestrial signal via antenna 111D, which is different from antenna 111C.

[0122] The IP transmission device 101C extracts the channel signal chX from the terrestrial signal received via the antenna 111C. Also, the IP transmission device 101D extracts the channel signal chX from the terrestrial signal received via the antenna 111D. That is, the IP transmission devices 101C and 101D receive the terrestrial signal via different antennas and extract the channel signal of the same channel.

[0123] The IP transmitter 101C generates a digital signal DX and signaling information FX. Hereinafter, the digital signal DX generated by the IP transmitter 101C will also be referred to as a digital signal DXc, and the signaling information FX generated by the IP transmitter 101C will also be referred to as signaling information FXc. The IP transmitter 101C transmits an IP packet PCX1 containing the generated digital signal DXc and signaling information FXc to the IP receiver 201B via the switch device 152A. The IP transmitter 101C also transmits an IP packet PCX2 containing the digital signal DXc and signaling information FXc to the IP receiver 201B via the switch device 152B.

[0124] The IP transmitter 101D generates a digital signal DX and signaling information FX. Hereinafter, the digital signal DX generated by the IP transmitter 101D will also be referred to as a digital signal DXd, and the signaling information FX generated by the IP transmitter 101D will also be referred to as signaling information FXd. The IP transmitter 101D transmits an IP packet PDX1 containing the generated digital signal DXd and signaling information FXd to the IP receiver 201B via the switch device 152A. The IP transmitter 101D also transmits an IP packet PDX2 containing the digital signal DXd and signaling information FXd to the IP receiver 201B via the switch device 152B.

[0125] The IP receiver 201B receives the IP packets PCX1 and PDX1 via the switch device 152A, and also receives the IP packets PCX2 and PDX2 via the switch device 152B.

[0126] The IP receiving device 201B acquires the digital signal DXc and signaling information FXc from the received IP packet PCX1 or IP packet PCX2, and acquires the digital signal DYd and signaling information FYd from the received IP packet PDX1 or IP packet PDX2. Based on the signaling information FXc and FXd, the IP receiving device 201B outputs either the channel signal chX based on the digital signal DXc or the channel signal chX based on the digital signal DXd to the multiplexer 161. This makes it possible to achieve redundancy in the receiving path of the terrestrial signal.

[0127] 4 again, in IP receiving device 201B, IP packet receiving unit 31A receives IP packet PCX1 from IP transmitting device 101C via switch device 152A and outputs it to IP packet selecting unit 32A. IP packet receiving unit 31A receives IP packet PDX1 from IP transmitting device 101D via switch device 152A and outputs it to IP packet selecting unit 32B.

[0128] In addition, in the IP receiving device 201B, the IP packet receiving unit 31B receives the IP packet PCX2 from the IP transmitting device 101C via the switch device 152B and outputs it to the IP packet selecting unit 32A. The IP packet receiving unit 31B receives the IP packet PDX2 from the IP transmitting device 101B via the switch device 152B and outputs it to the IP packet selecting unit 32B.

[0129] In the IP receiving device 201B, the IP packet selecting unit 32A receives the IP packets PCX1 and PCX2 from the IP packet receiving units 31A and 31B, respectively, and outputs one of the received IP packets PCX1 and PCX2 to the signal acquiring unit 33A and the determining unit 34. The IP packet output by the IP packet selecting unit 32A in the IP receiving device 201B to the signal acquiring unit 33A and the determining unit 34 is also referred to as the "output IP packet PCX."

[0130] In addition, in the IP receiving device 201B, the IP packet selecting unit 32B receives the IP packets PDX1 and PDX2 from the IP packet receiving units 31A and 31B, respectively, and outputs one of the received IP packets PDX1 and PDX2 to the signal acquiring unit 33B and the determining unit 34. The IP packet output by the IP packet selecting unit 32B in the IP receiving device 201B to the signal acquiring unit 33B and the determining unit 34 is also referred to as the "output IP packet PDX."

[0131] In the IP receiving device 201B, the signal acquiring unit 33A receives the output IP packet PCX from the IP packet selecting unit 32A, acquires the digital signal DXc from the payload of the received output IP packet PCX, and outputs it to the switch 35A. Also, the signal acquiring unit 33B receives the output IP packet PDX from the IP packet selecting unit 32B, acquires the digital signal DXd from the payload of the received output IP packet PDX, and outputs it to the switch 35B.

[0132] In the IP receiving device 201B, the determination unit 34 receives an output IP packet PCX from the IP packet selection unit 32A and acquires signal information FXc from the received output IP packet PCX. The determination unit 34 also receives an output IP packet PDX from the IP packet selection unit 32B and acquires signal information FXd from the received output IP packet PDX. Based on the signal information FXc and the signal information FXd, the determination unit 34 determines that either the channel signal chX based on the digital signal DXc or the channel signal chX based on the digital signal DXd is the channel signal chX to be output, and controls the opening and closing of the switches 35A and 35B based on the determination result.

[0133] For example, the determining unit 34 determines, with priority, the channel signal chX based on the digital signal DXc of the digital signals DXc and DXd as the channel signal chX to be output.

[0134] More specifically, the decision unit 34 compares the CNR, BER, average value L, and gain value indicated by the signal information FXc with thresholds Th1, Th2, Th3, and Th4, respectively. If a first condition is satisfied, that is, the CNR indicated by the signal information FXc is less than threshold value Th1, the BER indicated by the signal information FXc is less than threshold value Th2, the average value L indicated by the signal information FXc is equal to or greater than threshold value Th3, and the gain value indicated by the signal information FXc is less than threshold value Th4, the decision unit 34 decides that the channel signal chX based on the digital signal DXc should be output. In this case, the decision unit 34 either keeps the switch 35A on and keeps the switch 35B off, or switches the switch 35A on and the switch 35B off. As a result, the signal output unit 36A turns on the output of the channel signal chX based on the digital signal DXc, while the signal output unit 36B turns off the output of the channel signal chX based on the digital signal DXd.

[0135] On the other hand, if the first condition is not satisfied, the decision unit 34 compares the CNR, BER, average value L, and gain value indicated by the signal information FXd with thresholds Th1, Th2, Th3, and Th4, respectively. If a second condition is satisfied—that the CNR indicated by the signal information FXd is less than threshold value Th1, the BER indicated by the signal information FXd is less than threshold value Th2, the average value L indicated by the signal information FXd is equal to or greater than threshold value Th3, and the gain value indicated by the signal information FXd is less than threshold value Th4—the decision unit 34 determines that the channel signal chX based on the digital signal DXd should be output. In this case, the decision unit 34 either switches the switch 35A to the OFF state and switches the switch 35B to the ON state, or maintains the switch 35A in the OFF state and the switch 35B in the ON state. This turns off the output of the channel signal chX based on the digital signal DXc by the signal output unit 36A, and turns on the output of the channel signal chX based on the digital signal DXd by the signal output unit 36B.

[0136] On the other hand, if the first condition and the second condition are not satisfied, the decision unit 34 decides that the channel signal chX based on the digital signal DXc should be output.

[0137] For example, the setting of the channel corresponding to the channel signal extracted by the IP transmitting device 101 can be changed. More specifically, the setting of the target channel of the IP transmitting device 101 and the operation mode of the IP receiving device 201 can be changed. As an example, the administrator of the IP transmission system 301 changes the target channel of the IP transmitting device 101D from channel X to channel Y, and changes the operation mode of the IP transmitting device 101B from redundant mode to normal mode.

[0138] In this case, the IP transmitting device 101D extracts the channel signal chY from the terrestrial signal, and generates a digital signal DY by digitally converting the extracted channel signal chY, as well as signaling information FY indicating the reception status of the channel signal chY. The IP transmitting device 101D then transmits an IP packet PDY1 including the digital signal DY and signaling information FY to the IP receiving device 201B via the switching device 152A, and transmits an IP packet PDY2 including the digital signal DY and signaling information FY to the IP receiving device 201B via the switching device 152B. Also, as described above, the IP transmitting device 101C transmits an IP packet PCX1 to the IP receiving device 201B via the switching device 152A, and transmits an IP packet PCX2 to the IP receiving device 201B via the switching device 152B.

[0139] The IP receiving device 201B receives IP packets PCX1 and PDY1 via the switch device 152A, and receives IP packets PCX2 and PDY2 via the switch device 152B. The IP receiving device 201B acquires a digital signal DX and signaling information FX from the received IP packet PCX1 or IP packet PCX2, and determines whether or not to output the channel signal chX based on the acquired signaling information FX. The IP receiving device 201B also acquires a digital signal DY and signaling information FY from the received IP packet PDY1 or IP packet PDY2, and determines whether or not to output the channel signal chY based on the acquired signaling information FY.

[0140] With this configuration, the user of the IP transmission system 301 can appropriately select a system configuration that prioritizes cost or a system configuration that prioritizes broadcast reliability, using the same hardware.

[0141] In the IP transmission device 101 according to the embodiment of the present disclosure, the signal information generator 17 is configured to generate signal information including the CNR, BER, average value L, and gain value, but this is not limited to this. The signal information generator 17 may also be configured to generate signal information that does not include part of the CNR, BER, average value L, and gain value.

[0142] Furthermore, in the IP transmission system 301 according to the embodiment of the present disclosure, the IP receiving device 201 is configured to receive IP packets from two IP transmitting devices 101, but this is not limiting. The IP receiving device 201 may be configured to receive IP packets from one IP transmitting device 101, perform a determination process based on signal information included in the IP packets, and output a channel signal based on the digital signal included in the IP packets according to the determination result.

[0143] In addition, in the IP transmission device 101 according to the embodiment of the present disclosure, the receiving unit 11 is configured to generate a baseband signal by down-converting the received terrestrial signal using a direct conversion method, but this is not limited to this. The receiving unit 11 may also be configured to generate an intermediate frequency (IF) signal by down-converting the terrestrial signal using a superheterodyne method and output the generated IF signal to the extraction unit 12.

[0144] Furthermore, in the IP receiving device 201 according to the embodiment of the present disclosure, the output unit 36 ​​is configured to generate channel signals by converting digital signals to analog, and then up-convert the generated channel signals to a desired frequency and output them, but this is not limited to this. The output unit 36 ​​may also be configured to up-convert the channel signals by converting them to analog using the functions of an NCO (Numerically Controlled Oscillator) and an interpolator.

[0145] In systems that transmit broadcast signals via IP and then retransmit them, there is a need for technology that can retransmit higher quality broadcast signals while keeping the delay that occurs when retransmitting terrestrial digital broadcast signals within an acceptable range. For example, in cable television broadcasting emergency news, it is necessary to shorten the delay that occurs when retransmitting.

[0146] In the technologies described in Patent Documents 1 and 3, the modulated signal must be demodulated before IP transmission, and then modulated again after IP transmission and retransmitted, resulting in a significant delay when the broadcast signal is retransmitted. For example, in a system that retransmits terrestrial digital broadcast signals, the demodulation and remodulation of the modulated signal takes a particularly long time, resulting in a significant delay.

[0147] Furthermore, in the technology described in Patent Document 2, if the signal quality or level of the received broadcast signal is below a predetermined value, for example, the leakage power to adjacent frequencies due to the channel signal being retransmitted after IP transmission may increase, and the quality of other retransmitted channel signals may decrease.

[0148] In contrast, in the IP transmission system 301 according to the embodiment of the present disclosure, the IP transmitting device 101 receives a broadcast signal of a terrestrial digital broadcast, extracts a channel signal from the received broadcast signal, and transmits an IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating the reception status of the channel signal to the IP receiving device 201. The IP receiving device 201 acquires the digital signal and the signal information from the IP packet received from the IP transmitting device 101, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result.

[0149] In this way, by transmitting IP packets containing digital signals obtained by digitally converting channel signals and signal information indicating the reception status of the channel signals, determining whether to output the channel signals based on the signal information contained in the transmitted IP packets, and outputting the channel signals based on the determination result, delays are reduced compared to systems that demodulate and re-modulate modulated signals, and output of the channel signals can be stopped, for example, when the IP transmitting device breaks down or the broadcast signal is paused, thereby reducing degradation in the quality of the retransmitted broadcast signals. Therefore, in a system that transmits broadcast signals via IP and then retransmits them, it is possible to retransmit broadcast signals of higher quality while keeping delays that occur when retransmitting terrestrial digital broadcast signals within an acceptable range.

[0150] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0151] The above description includes the following additional features. [Appendix 1] IP transmission systems are an IP transmitting device; an IP receiving device; the IP transmitting device receives a broadcast signal of a terrestrial digital broadcast, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating a reception status of the channel signal; the IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result; An IP transmission system, wherein the channel corresponding to the channel signal extracted by the IP transmission device is configurable. [Explanation of symbols]

[0152] 11 Receiving unit 12 Extraction part 13 Amplification section 14 AD conversion section 15 Detector 16 Filter section 17 Signal information generation section 18 IP packet generator 19 Output section 19A, 19B IP packet output section 20 Memory section 31 Receiving unit 31A, 31B IP packet receiving section 32 Selection section 32A, 32B IP packet selection section 33 Acquisition Department 33A,33B Signal acquisition section 34 Judgment section 35A, 35B Switch 36 Output section 36A,36B signal output section 101,101A,101B,101C,101D IP transmitter 111, 111C, 111D antennas 201, 201A, 201B IP receiving device 151 IP network 152A, 152B Switch device 161 Multiplexer 301 IP Transmission System

Claims

1. an IP transmission device; an IP receiving device; the IP transmitting device receives a broadcast signal of a terrestrial digital broadcast, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating a reception status of the channel signal; the IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result; the IP transmitting device transmits to the IP receiving device the IP packet including the digital signal obtained by digitally converting the channel signal corresponding to the target channel that is the channel to be extracted and the signal information; An IP transmission system in which the IP receiving device receives from one of the IP transmitting devices the IP packet including the digital signal obtained by digitally converting the channel signal corresponding to the target channel, and switches between an on state in which the channel signal corresponding to the target channel is output and an off state in which the channel signal corresponding to the target channel is not output, depending on the signal information obtained from the received IP packet.

2. 2. The IP transmission system according to claim 1, wherein the IP transmitting device transmits, as the reception status, an IP packet including the signal information indicating a signal quality of the channel signal to the IP receiving device.

3. 3. The IP transmission system according to claim 1, wherein the IP transmitting device transmits, as the reception status, an IP packet including the signal information indicating the control content of automatic gain control for the channel signal to the IP receiving device.

4. An IP transmission device; an IP receiving device; the IP transmitting device receives a broadcast signal of a terrestrial digital broadcast, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating a reception status of the channel signal; the IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result; the IP transmitting device generates the digital signal by digitally converting the extracted channel signal, stores the generated digital signal in a buffer, and generates the IP packet including the digital signal acquired from the buffer; An IP transmission system in which the IP transmitting device generates demodulated data by demodulating a modulated signal represented by the digital signal in parallel with storing the digital signal in the buffer, and generates the signal information based on the generated demodulated data.

5. An IP transmission device, a receiving unit for receiving a terrestrial digital broadcast signal; an extracting unit that extracts a channel signal from the broadcast signal received by the receiving unit; a signal information generating unit that generates signal information indicating a reception status of the channel signal extracted by the extracting unit; an IP packet generator that generates an IP packet including a digital signal obtained by digitally converting the channel signal and the signal information; an output unit that outputs the IP packet generated by the IP packet generation unit; The IP transmission device further an AD conversion unit that generates the digital signal by digitally converting the channel signal extracted by the extraction unit; the IP packet generation unit accumulates the digital signal generated by the AD conversion unit in a buffer, and generates the IP packet including the digital signal acquired from the buffer; An IP transmitting device in which the signal information generating unit generates demodulated data by demodulating the modulated signal indicated by the digital signal generated by the AD conversion unit in parallel with the accumulation of the digital signal in the buffer by the IP packet generating unit, and generates the signal information based on the generated demodulated data.

6. a receiving unit that receives, from an IP transmitting device, an IP packet including a digital signal obtained by digitally converting a channel signal in terrestrial digital broadcasting and signal information indicating a reception status of the channel signal at the IP transmitting device; an acquisition unit that acquires the digital signal from the IP packet received by the receiving unit; a determination unit that acquires the signal information from the IP packet received by the receiving unit, and determines whether or not to output the channel signal based on the acquired signal information; an output unit that outputs the channel signal based on the digital signal acquired by the acquisition unit in accordance with the determination result by the determination unit, The receiving unit receives, from one of the IP transmitting devices, the IP packet including the digital signal obtained by digitally converting the channel signal corresponding to the target channel that is the channel to be extracted; The output unit switches between an on state in which the channel signal corresponding to the target channel is output and an off state in which the channel signal corresponding to the target channel is not output, depending on the judgment result by the judgment unit.

7. An IP transmission method in an IP transmission system including an IP transmitting device and an IP receiving device, a step in which the IP transmitting device receives a broadcast signal of a terrestrial digital broadcast, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating a reception status of the channel signal; the IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result; In the step of transmitting the IP packet from the IP transmitting device to the IP receiving device, the IP packet including the digital signal obtained by digitally converting the channel signal corresponding to the target channel that is the channel to be extracted and the signal information is transmitted to the IP receiving device; In the step in which the IP receiving device outputs the channel signal, the IP receiving device receives from one of the IP transmitting devices the IP packet containing the digital signal into which the channel signal corresponding to the target channel has been digitally converted, and switches between an on state in which the channel signal corresponding to the target channel is output and an off state in which the channel signal corresponding to the target channel is not output, depending on the signal information obtained from the received IP packet.

8. An IP transmission method in an IP transmission system including an IP transmitting device and an IP receiving device, a step in which the IP transmitting device receives a broadcast signal of a terrestrial digital broadcast, extracts a channel signal from the received broadcast signal, and transmits an IP packet to the IP receiving device, the IP packet including a digital signal obtained by digitally converting the extracted channel signal and signal information indicating a reception status of the channel signal; the IP receiving device acquires the digital signal and the signal information from the IP packet received from the IP transmitting device, determines whether or not to output the channel signal based on the acquired signal information, and outputs the channel signal based on the digital signal according to the determination result; In the step of transmitting the IP packet from the IP transmitting device to the IP receiving device, the IP transmitting device generates the digital signal by digitally converting the extracted channel signal, stores the generated digital signal in a buffer, and generates the IP packet including the digital signal acquired from the buffer; An IP transmission method, in which, in the step in which the IP transmitting device transmits the IP packet to the IP receiving device, the IP transmitting device generates demodulated data by demodulating a modulated signal indicated by the digital signal in parallel with storing the digital signal in the buffer, and generates the signal information based on the generated demodulated data.