JP2016208121A - Synchronous broadcasting system, distribution device and transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology which implements synchronization of audio signals by adjusting transmission timing in simple configuration.SOLUTION: A distribution device (2) acquires time information representing a predetermined standard time, defines timing in a fixed cycle that is an integer multiple of a cycle of an audio frame and identified by the time information, as designation timing and transmits previously designated synchronization information while adding it to the audio frame in every designated timing. A transmission device (3, 4) acquires the same time information as the time information that is acquired by the distribution device, defines a delay time from designation timing that is identified by the time information to reception of an audio frame to which synchronization information is added as a path delay time, defines a time obtained by subtracting the path delay time from a preset delay time that is set equal to or greater than a maximum value of delay which may occur in a process of distribution from the distribution device to the transmission device, as an adjustment delay time and uses the audio frame that is received from the distribution device, for synchronous broadcasting while delaying the audio frame just for the adjustment delay time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for synchronizing audio signals in each transmission apparatus in synchronized broadcasting of audio signals.

  Conventionally, synchronous broadcasting in which audio broadcast waves of the same program are transmitted from a plurality of transmitting stations at the same frequency is known. In synchronous broadcasting, the occurrence of a reception failure is prevented by adjusting the transmission timing at each transmitting station so that the delays of each arriving wave match in a place where a plurality of arriving waves coexist. Further, such adjustment of the transmission timing at each transmitting station has been performed on the premise that a transmission line is used for distribution from the distribution source of the program to each transmitting station, and that the transmission delay hardly varies.

  In recent years, it has been considered to use an IP transmission network instead of a wireless transmission line or to use a wireless transmission line and an IP transmission network together for distribution from a distribution source to each transmitting station. However, when an IP transmission network is used for distribution to each transmitting station, unlike a wireless transmission line, the transmission delay to each transmitting station may fluctuate greatly, and the transmission timing corresponding to the variation in the transmission delay It is necessary to make adjustments.

  On the other hand, as a technique to adjust the transmission timing at the transmitting station according to the situation, a facility for receiving the incoming wave is provided at the point where the incoming wave from the two transmitting stations coexists, and transmitted from both transmitting stations. There has been proposed a technique of receiving signals having phases different from each other by 180 degrees and adjusting the transmission timing of one transmitting station so that the received signal becomes zero (see Patent Document 1).

JP-A-9-284240

  However, in the prior art, it is necessary to install a facility for receiving an incoming wave separately from the transmitting station, or to transmit a special signal for measurement from each transmitting station, which complicates the apparatus configuration. there were.

  The present invention has been made in view of these problems, and an object of the present invention is to provide a technique for realizing synchronization of audio signals by adjusting transmission timing with a simple configuration.

  The synchronous broadcast system of the present invention distributes a digitized audio signal using a predetermined audio frame, and receives the audio frame distributed from the distribution device and extracts the audio extracted from the audio frame And a plurality of transmission devices that perform synchronous broadcasting of signals using radio waves of the same frequency.

  The distribution device acquires time information representing a predetermined standard time, and is designated in advance at each designated timing, with a timing of an integer multiple of the period of the audio frame and a fixed cycle specified by the time information as the designated timing. The synchronized information is added to the audio frame and distributed.

  The transmission device acquires the same time information as that acquired by the distribution device, and the delay time from the designated timing specified by the time information to the reception of the audio frame to which the synchronization information is added is defined as the path delay time. The audio frame received from the distribution device is adjusted by adjusting the delay time as the time obtained by subtracting the route delay time from the set delay time set to be greater than or equal to the maximum delay that can occur in transmission from the distribution device to the transmission device. Delayed by time and used for synchronous broadcasting.

  In other words, in the present invention, each of the distribution device and the transmission device receives the same time information, and is set from the specified timing regardless of how the path delay time changes based on the specified timing specified from this time information. Synchronous broadcast radio waves are transmitted at the timing delayed by the delay time.

  As described above, according to the present invention, each transmission device can be configured with a simple configuration without providing a special facility other than a distribution device or a transmission device or transmitting a special signal other than a signal for synchronous broadcasting. It is possible to synchronize the audio frames distributed from the distribution device, and hence the audio signals used for the synchronous broadcasting.

  The distribution device of the present invention includes an audio frame generation unit, a time information acquisition unit, a synchronization information addition unit, a distribution unit, and a transmission device. The audio frame generation unit generates an audio frame from the input audio signal. The time information acquisition unit acquires time information representing a predetermined standard time. The synchronization information adding unit adds the synchronization information designated in advance to the audio frame at each designated timing, with the timing of a fixed period specified by the integral multiple of the cycle of the audio frame and the time information as the designated timing. The distribution unit distributes the audio frame to which the synchronization information is added by the synchronization information adding unit to a plurality of transmission apparatuses. Each transmission apparatus distributes the audio frame supplied from the distribution unit to the transmission apparatus via a transmission network designated in advance.

  Furthermore, the transmission apparatus of the present invention includes a distribution frame acquisition unit, a second time information acquisition unit, a delay synchronization unit, and a modulation transmission unit. The distribution frame acquisition unit acquires an audio frame distributed from the distribution device. The second time information acquisition unit acquires the same time information as that acquired by the first time information acquisition unit of the distribution apparatus. The delay synchronization unit uses a delay time from the specified timing specified by the time information acquired by the second time information acquisition unit to the reception of the audio frame to which the synchronization information is added as a path delay time. The audio frame acquired by the distribution frame acquisition unit is adjusted delay using the time obtained by subtracting the path delay time from the set delay time set above the maximum delay that can occur during the transmission to the transmitter. Delay by time. The modulation transmission unit transmits a radio wave for synchronous broadcasting based on the audio frame delayed by the delay synchronization unit.

According to the distribution apparatus and the transmission apparatus of the present invention configured as described above, the distribution apparatus and the transmission apparatus of the present invention can be suitably used when configuring the above-described synchronous broadcasting system of the present invention.
In addition, the code | symbol in the parenthesis described in the claim shows the correspondence with the specific means as described in embodiment mentioned later as one aspect, Comprising: The technical scope of this invention is limited is not.

It is a block diagram which shows the structure of a synchronous broadcast system. It is explanatory drawing which shows the format of AES / EBU specification. It is a block diagram which shows the structure of a synchronous information addition part. It is a timing diagram which shows operation | movement of a synchronous information addition part. It is a block diagram which shows the structure of a delay synchronizer. It is a timing diagram which shows operation | movement of a delay synchronizer.

Embodiments to which the present invention is applied will be described below with reference to the drawings.
[System configuration]
A synchronous broadcast system 1 shown in FIG. 1 includes a distribution device 2 and a plurality of transmission devices 3 and 4. The distribution apparatus 2 distributes audio frames in an AES / EBU standard format (hereinafter referred to as “AES / EBU format”) standardized by IEC 60958 or the like to the transmission apparatuses 3 and 4 via each transmission network. The transmission apparatus 3 performs synchronous broadcasting according to the audio signal extracted from the audio frame received via the transmission network A, and the transmission apparatus 4 according to the audio signal extracted from the audio frame received via the transmission network B. In the figure, the transmission apparatuses 3 and 4 are provided, but three or more transmission apparatuses may be provided. Further, the transmission network A and the transmission network B are configured by, for example, a wireless transmission network or an IP transmission network, but are not limited to the wireless transmission network or the IP transmission network.

[AES / EBU format]
The AES / EBU format is a format for sequentially transmitting audio data obtained by converting an audio signal into digital data. As shown in FIG. 2, the sub-frame of the minimum unit is composed of 32 bits, 4 bits of preamble, 4 bits of auxiliary data, 20 bits of audio data, each 1 bit validity indication flag (V), It consists of user data (U), channel status (C), and parity bit (P). The auxiliary data is used when the audio data is represented by 24 bits. However, the audio data is stored so that the 27th bit side in the frame is the MSB.

Two subframes constitute one frame, and 192 frames constitute one block.
Two subframes constituting one frame are composed of a channel 1 used for data transmission of the left channel of stereo sound and a channel 2 used for data transmission of the right channel of stereo sound. That is, the frame transmission speed is 64 times the sampling frequency of the audio data. The sampling frequency is selected from 48 kHz, 44.1 kHz, and 32 kHz, for example.

  There are three types of subframe preambles (X, Y, Z). The pattern “Z” is used for the preamble of the subframe located at the head of the block (that is, channel 1), and the pattern “X” is used for the preambles of the other channel 1 subframes. The pattern “Y” is used for the preamble of the subframe of channel 2. By extracting these preambles, the beginning of each subframe can be extracted, and by identifying the preamble pattern, the beginning of the subframe, the beginning of the frame, and the like can be identified.

[Distributor]
Returning to FIG. 1, the distribution device 2 includes an audio frame generation unit 21, a first time information acquisition unit 22, a synchronization information addition unit 23, a distribution unit 24, a transmission device 25, and a transmission device 26. .

  The audio frame generation unit 21 acquires an audio signal generated for audio broadcasting, and generates an AES / EBU format audio frame. The acquisition source of the audio signal may be, for example, a studio that creates an audio broadcast program, a server that stores an audio signal of a recorded program, or the like.

  The first time information acquisition unit 22 acquires time information indicating a predetermined standard time. Here, a well-known GPS receiver is used, and as a time information, a 1-second pulse signal that is a pulse signal having a 1-second cycle and a GPS time representing the generation time of the 1-second pulse signal are acquired.

  The synchronization information addition unit 23 adds synchronization information generated based on the time information acquired by the first time information acquisition unit 22 to the audio frame generated by the audio frame generation unit 21. Details of the synchronization information adding unit 23 will be described later.

  The distribution unit 24 distributes the audio frame to which the synchronization information supplied from the synchronization information adding unit 23 is added to a plurality of audio frames and supplies the audio frames to the transmission device 25 and the transmission device 26, respectively. The transmission device 25 distributes the audio frame to which the synchronization information supplied from the distribution unit 24 is added to the transmission device 3 via the transmission network A. The transmission device 26 distributes the audio frame to which the synchronization information supplied from the distribution unit 24 is added to the transmission device 4 via the transmission network B.

As shown in FIG. 3, the synchronization information adding unit 23 includes a digital audio input unit 231, a frame synchronization detecting unit 232, and a synchronization information adding unit 233.
The digital audio input unit 231 supplies the input audio frame to the frame synchronization detection unit 232 and stores it in the delay buffer memory. The frame synchronization detection unit 232 detects the start timing of the subframe by detecting the preamble from the audio frame, and further identifies the preamble pattern so that the block synchronization signal indicating the start of the block is transmitted to the synchronization information addition unit. 233. As shown in FIG. 4, the synchronization information adding unit 233 is based on the 1-second pulse signal and the block synchronization signal, and the buffer memory of the digital audio input unit 231 so that the head of the block coincides with the timing of the 1-second pulse signal. Using a region of user data (U) in a predetermined number of consecutive subframes (hatched portion in FIG. 4) including at least the head of the block that matches the timing of the 1 second pulse signal Write synchronization information. Alternatively, the synchronization information is written using the least significant bit of the audio data area of the audio frame instead of the user data (U) area. Then, the audio frame to which the synchronization information is added is output.

[Transmitter]
Returning to FIG. 1, the transmission device 3 includes a distribution frame acquisition unit 31, a second time information acquisition unit 32, a delay synchronization unit 33, and a modulation transmission unit 34.

The distribution frame acquisition unit 31 acquires an audio frame to which synchronization information distributed from the distribution device 2 via the transmission network A is added and supplies the audio frame to the delay synchronization unit 33.
The second time information acquisition unit 32 is the same as the first time information acquisition unit 22 constituting the distribution device 2, and thus the description thereof is omitted. Note that the second time information acquisition unit 32 supplies the acquired time information to the delay synchronization unit 33.

  The delay synchronization unit 33 is based on the audio frame to which the synchronization information acquired by the distribution frame acquisition unit 31 is added and the time information acquired by the second time information acquisition unit 32. However, the delay is adjusted so as to be delayed by a preset delay time with respect to the 1-second pulse signal, and the audio frame is output. Details of the delay synchronization unit 33 will be described later.

The modulation transmission unit 34 modulates a carrier wave having a predetermined frequency by an audio signal extracted from the audio frame, and transmits a synchronous broadcast broadcast wave toward a broadcast area covered by the own apparatus.
As shown in FIG. 5, the delay synchronization unit 33 includes a digital audio input unit 331, a frame synchronization detection unit 332, a synchronization information extraction unit 333, and a delay control unit 334.

  The digital audio input unit 331 supplies the input audio frame to the frame synchronization detection unit 332 and stores it in the delay buffer memory. The frame synchronization detection unit 332 detects the start timing of the subframe by detecting the preamble, and further extracts the start timing of the block by identifying the preamble pattern. The synchronization information extraction unit 333 monitors user data (U) in a predetermined number of subframes from the head timing of the block, and extracts synchronization information added at a timing that matches the 1-second pulse signal in the distribution device 2. . Hereinafter, the block from which the synchronization information is extracted is referred to as a synchronization block (indicated by a block_N in the figure). As shown in FIG. 6, when the 1-second pulse signal is detected, the delay control unit 334 starts the synchronization block detected until the set delay time elapses from the 1-second pulse signal to the set delay time. The audio frame is read from the buffer memory of the digital audio input unit 331 and output so as to coincide with the delayed timing.

  The transmission device 4 includes a distribution frame acquisition unit 41, a second time information acquisition unit 42, a delay synchronization unit 43, and a modulation transmission unit 44. The distribution frame acquisition unit 41 acquires an audio frame distributed from the distribution device 2 via the transmission network B and supplies it to the delay synchronization unit 43. The other configurations 42 to 44 have the same configurations as the second time information acquisition unit 32, the delay synchronization unit 33, and the modulation transmission unit 34 of the transmission device 3, respectively.

[Operation]
In the synchronous broadcasting system 1, in the distribution device 2, the synchronization information is written at the same timing as the 1-second pulse signal. However, the audio frames received by the transmission apparatuses 3 and 4 are distributed at a timing delayed from the 1-second pulse signal by the transmission delay of the path from the distribution apparatus 2 to the transmission apparatuses 3 and 4. In the transmission apparatuses 3 and 4, the path delay times of the transmission networks A and B vary, and the delay time is not necessarily constant, and the path delay time also changes dynamically according to the transmission path used. Can be considered. That is, the path delay time differs depending on the transmission network for each transmission apparatus. However, any of the transmission apparatuses 3 and 4 performs delay adjustment so that the synchronization block is output at a timing delayed from the reference 1-second pulse signal by the set delay time regardless of the magnitude of the path delay time. Thereby, the broadcast wave of synchronous broadcasting is transmitted from each transmission device at the same timing.

[effect]
As described above, the synchronous broadcasting system 1 has a simple configuration without providing a special facility other than the distribution device 2 and the transmission devices 3 and 4 and transmitting a special signal other than the audio frame. The audio frames distributed from the distribution device 2 and thus the audio signals used for the synchronous broadcast can be synchronized between the transmission devices 3 and 4.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this invention can take a various form, without being limited to the said embodiment.

  (1) In the above embodiment, the AES / EBU format is adopted as the audio frame. However, the present invention is not limited to this, and an integer multiple of the frame period of the audio frame matches the cycle of the 1-second pulse signal, and Any format that can add synchronization information may be used.

  (2) In the above embodiment, the synchronization information is added using the user data area of the audio frame, but the present invention is not limited to this. For example, the LSB (least significant bit) of the audio data area may be used instead of the user data area. That is, in the case of LSB, since the waveform of the audio signal is not greatly changed, the synchronization information can be added without giving the viewer a sense of incongruity.

  (3) In the above embodiment, the synchronization information only indicates the presence of the synchronization block, but may indicate the GPS time. In this case, even when the set delay time is longer than the cycle of the 1-second pulse signal, the GPS time of the synchronization information is compared with the GPS time of the 1-second pulse signal obtained by the second time information acquisition unit 42. The 1-second pulse signal to be used as a reference for timing adjustment can be specified. In addition, the configuration example using GPS time as time information has been shown. For example, not only the GPS time generated by receiving a signal from a GPS satellite but also a signal from a satellite such as a quasi-zenith satellite is generated. The same effect can be obtained by using time information that is generated by receiving standard time signals using long waves that transmit time information that is used, and time information that is used for radio clocks, etc. .

  (4) The functions of one component in the above embodiment may be distributed to a plurality of components, or the functions of a plurality of components may be integrated into one component. Further, at least a part of the configuration of the above embodiment may be replaced with a known configuration having the same function. Moreover, you may abbreviate | omit a part of structure of the said embodiment. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of the other embodiment. In addition, all the aspects included in the technical idea specified only by the wording described in the claim are embodiment of this invention.

  (5) In addition to the above-described synchronous broadcast system, distribution device, and transmission device, the present invention includes a device having a configuration of a synchronization information addition unit that is a main part of the distribution device, and a delay synchronization unit that is a main part of the transmission device. The present invention can be realized in various forms such as an apparatus having the configuration described above.

  DESCRIPTION OF SYMBOLS 1 ... Synchronous broadcasting system 2 ... Distribution apparatus 3, 4 ... Transmission apparatus 21 ... Audio | voice frame production | generation part 22 ... 1st time information acquisition part 32, 42 ... 2nd time information acquisition part 23 ... Synchronization information addition part 24 ... Distribution Units 25, 26 ... transmission device 31, 41 ... distribution frame acquisition unit 33, 43 ... delay synchronization unit 34, 44 ... modulation transmission unit 231, 331 ... digital audio input unit 232, 332 ... frame synchronization detection unit 233 ... addition of synchronization information Unit 333 ... synchronization information extraction unit 334 ... delay control unit

Claims (9)

A distribution device (2) for distributing a digitized audio signal using a predetermined audio frame;
A plurality of transmission devices (3, 4) for receiving the audio frame distributed from the distribution device and synchronously broadcasting an audio signal extracted from the audio frame using radio waves of the same frequency;
With
The distribution device includes:
Time information representing a predetermined standard time is acquired, and a predetermined period of time that is an integer multiple of the period of the audio frame and specified by the time information is used as a designated timing. Information is added to the audio frame and distributed,
The transmitter is
The same time information as that acquired by the distribution device is acquired, and the delay time from the specified timing specified by the time information to the acquisition of the audio frame to which the synchronization information is added is defined as a path delay time. Received from the distribution device as an adjustment delay time, which is a time obtained by subtracting the path delay time from the set delay time set to be equal to or greater than the maximum delay that can occur in the process of distribution from the distribution device to the transmission device. A synchronous broadcast system, wherein an audio frame is delayed for the adjustment delay time and used for the synchronous broadcast.   The synchronous broadcasting system according to claim 1, wherein the audio frame has a format of AES / EBU standard.   The synchronous broadcasting system according to claim 2, wherein the synchronization information is added using a user data area of the audio frame.   The synchronous broadcasting system according to claim 2, wherein the synchronization information is added using a least significant bit of an audio data area of the audio frame.   5. The synchronous broadcasting system according to claim 1, wherein the synchronization information is information of a plurality of bits representing the time of the designated timing. The period of the designated timing is set longer than the set delay time,
5. The synchronous broadcasting system according to claim 1, wherein the synchronization information is at least one bit information indicating that the synchronization information is distributed at the designated timing. 6.   The said time information consists of GPS time showing the generation time of the 1 second pulse signal obtained from a GPS receiver, and this 1 second pulse signal, The Claim 1 thru | or 6 characterized by the above-mentioned. Synchronous broadcasting system. A distribution device that distributes a digitized audio signal using a predetermined audio frame to a plurality of transmission devices that perform synchronous broadcasting using radio waves of the same frequency,
An audio frame generation unit (21) for generating the audio frame;
A time information acquisition unit (22) for acquiring time information representing a predetermined standard time;
A synchronization information adding unit (23) which adds a predetermined synchronization information to the audio frame at each specified timing, with a timing of an integer multiple of the cycle of the audio frame and a fixed cycle specified by the time information as the specified timing. )When,
A distribution unit (24) for distributing the audio frame to which the synchronization information is added by the synchronization information adding unit;
A plurality of transmission devices (25, 26) for distributing the audio frames supplied from the distribution unit to the transmission device via a transmission network designated in advance;
A distribution apparatus comprising: A transmission device that receives audio frame distribution from the distribution device according to claim 8 and performs synchronous broadcasting,
A distribution frame acquisition unit (31, 41) for acquiring the audio frame distributed from the distribution device;
A second time information acquisition unit (32, 42) for acquiring the same time information as that acquired by the first time information acquisition unit of the distribution device;
A delay time from the specified timing specified by the time information acquired by the second time information acquisition unit to reception of the audio frame to which the synchronization information is added is defined as a path delay time, The audio frame acquired by the distribution frame acquisition unit is defined as a time obtained by subtracting the path delay time from a set delay time set to be equal to or greater than the maximum delay value that can occur in the process of distribution to the transmission device. A delay synchronizer (33, 43) for delaying by the adjustment delay time;
Modulation transmitters (34, 44) for transmitting radio waves for synchronous broadcasting based on the audio frames delayed by the delay synchronization unit;
A transmission device comprising: