JP2012156819A - Video signal transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement a function equivalent to the case where a camera having a cable is used, by certainly transmitting control information such as a camera control signal.SOLUTION: A video signal transmission system 1 comprises: a main system in which a main line/send back transmission parts 22-1 to 22-N of terminal devices 2-1 to 2-N perform multi-value modulation by such as 16QAM of a video signal of a main line video and transmit it by an OFDM signal by using a data carrier, and perform multi-value modulation by such as BPSK whose required CNR is low of control information such as a camera control signal and transmit it by the OFDM signal by using an AC carrier; and a send back system in which a send back transmission processing part 35 of a base station device 3 performs multi-value modulation by such as BPSK whose required CNR is low of a video signal of a send back video and the control information, and transmits them by the OFDM signal by using the data carrier.

Description

  The present invention relates to a video signal transmission system, and in particular, main line transmission from a photographing side to a base station side, such as a wireless camera or an FPU (Field Pick-up Unit) device, and return transmission from the base station side to the photographing side. The present invention relates to a transmission technique for a captured video signal and control information.

  2. Description of the Related Art Conventionally, wireless cameras or FPU devices have been used in place of cameras with cables at shooting sites such as sports broadcasts, music programs, and drama shooting. Compared with a camera with a cable, the wireless camera not only increases the flexibility of the camera angle and shooting position by improving the camera work, but also saves the trouble of laying and removing the cable, simplifying the setup preparation, and the photographer Various effects such as improvement of safety for performers and spectators including themselves can be produced. Therefore, development of a new wireless transmission system is underway for the purpose of realizing a wireless camera that wirelessly transmits high-definition television signals with low delay and high line reliability.

  Video signal transmission systems using such wireless cameras or FPU devices include main line transmission and return transmission. The main line system is a system that mainly transmits high-definition video, etc., taken by a camera (hereinafter referred to as “terminal side”) to a secondary adjustment room (hereinafter referred to as “base station side”). Is a system that mainly transmits control information such as camera control signals, tally signals, and genlock signals (ternary synchronization signals) on the terminal side from the base station side to the terminal side. Such wireless cameras and the like are required to realize these two systems of transmission.

  A conventional wireless camera or the like used in Japan is a device that performs only main line transmission (see, for example, Patent Document 1), or a conventional transmission camera with a cable as a transmission signal of a return system. Many devices receive only simple control signals, not control signals.

JP 2002-84252 A

  Such a conventional wireless camera has advantages in terms of improvement of camera work, simplification of setup preparation, and safety, but is inferior in function as compared with a camera with a cable. In general, in a video signal transmission system using a camera, control information such as a camera control signal and a tally signal is a signal necessary for adjusting a main line video signal for broadcasting, and is interrupted compared to main line transmission. Transmission is essential. In a camera with a cable, such control information can be reliably transmitted via a cable. However, in a wireless camera, a mechanism for reliably transmitting control information has not been established. Therefore, it has been desired that the wireless camera has a function equivalent to that of a camera with a cable.

  In order for the wireless camera to have the same function as a camera with a cable, the wireless camera receives a low-delay video signal and sends / receives a camera control signal (for example, transmission of control information from the controller to the camera, camera ACK signal from camera to controller, camera setting information, etc.), genlock signal for camera synchronization, income signal for communication between cameraman and operator (eg, cameraman to demodulator side) And a control function for transmitting control information such as a tally signal indicating that a photographed image of the camera is selected for broadcasting. However, in order to realize these functions, it is necessary to have a mechanism for bidirectional transmission (main line system / sending system) between the terminal side and the base station side, and a desired signal is extracted from signals in both directions. A generation mechanism is also required.

  Therefore, the present invention has been made to solve the above-described problems, and the purpose of the present invention is to reliably transmit control information such as camera control signals and to realize functions equivalent to those using a camera with a cable. It is to provide a video signal transmission system.

  In order to solve the above-described problem, the video signal transmission system according to claim 1 of the present invention is a video signal transmission including a terminal device that transmits a video signal and a base station device that receives the video signal from the terminal device. In the system, the terminal apparatus modulates the video signal and control information used in the video signal transmission system, transmits the modulated signal as an OFDM signal to the base station apparatus, and the video signal transmitted from the base station apparatus, and The base station apparatus includes a terminal-side transmission unit that receives and demodulates an OFDM signal of control information used in the video signal transmission system and separates the video signal and various information constituting the control information. The video signal and control information transmitted from the terminal device are received and demodulated, the video signal and the control information are extracted, and the control information is separated into various types of information. A base station side transmission unit that modulates a video signal to be transmitted to the terminal device and control information used in the video signal transmission system, and transmits the modulated signal to the terminal device as an OFDM signal, and the terminal side transmission unit includes: The video signal to be transmitted to the base station apparatus is multi-level modulated by a predetermined modulation method and transmitted by an OFDM signal using a data carrier, and the control information is less than the predetermined modulation method. Multi-level modulation is performed by a modulation method of the number of values, and transmission is performed by an OFDM signal using an AC carrier.

  The video signal transmission system according to a second aspect of the present invention is the video signal transmission system according to the first aspect, wherein the terminal-side transmission unit assigns priorities according to types of various information constituting the control information. Set and transmit control information with high priority in the OFDM signal using an AC carrier arranged in a predetermined range near the center of the carrier axis in the OFDM frame, and control information with low priority in the OFDM frame Transmission using an OFDM signal using an AC carrier arranged in a predetermined range near the end of the carrier axis.

  The video signal transmission system according to a third aspect of the present invention is the video signal transmission system according to the second aspect, wherein the terminal-side transmission unit assigns priorities according to the types of various information constituting the control information. Set and add error correction with a lower coding rate than control information with lower priority to control information with higher priority, and to a modulation system with a multi-value number smaller than a predetermined modulation method for the video signal Multi-level modulation and transmit with an OFDM signal using an AC carrier arranged in a predetermined range near the center of the carrier axis in the OFDM frame, and control information with lower priority than control information with higher priority In addition, error correction with a high coding rate is added, multi-level modulation is performed with a modulation scheme having a higher multi-level number than the modulation scheme for the control information with high priority, and the end of the carrier axis in the OFDM frame Transmitting at OFDM signal using the AC carriers arranged in a predetermined range of the near, characterized in that.

  The video signal transmission system according to claim 4 of the present invention is the video signal transmission system according to any one of claims 1 to 3, wherein the terminal-side transmission unit forms various information constituting the control information. The priority is set according to the type of control information, and the control information with high priority is transmitted more than the predetermined minimum transmission amount, and when the transmission amount of control information with low priority decreases, the priority is high. When the transmission amount of control information is increased and the transmission amount of control information with low priority is increased, the transmission amount of control information with high priority is reduced so as not to fall below the predetermined minimum transmission amount. Features.

  A video signal transmission system according to a fifth aspect of the present invention is the video signal transmission system according to any one of the first to fourth aspects, wherein the plurality of terminal devices respectively transmit the video signal, and the plurality of the plurality of terminal devices. A base station device that receives the video signal from each terminal device, and the base station-side transmission unit transmits the control information addressed to each terminal device with identification information for distinguishing each terminal device. It is characterized by.

  As described above, according to the present invention, it is possible to reliably transmit control information such as a camera control signal, and it is possible to realize a function equivalent to that when a camera with a cable is used.

1 is a block diagram showing an overall configuration of a video signal transmission system according to an embodiment of the present invention. It is a figure which shows the example of the transmission signal between the terminal side and the base station side in a video signal transmission system. It is a block diagram which shows the structure of the main line / send-back transmission part in a terminal device. 6 is a flowchart illustrating a part of processing by an OFDM (Orthogonal Frequency Division Multiplexing) signal generation unit of the main line / send-back transmission unit in the terminal device according to the first embodiment. It is a block diagram which shows the structure of the demultiplexing part in a base station apparatus. 6 is a flowchart illustrating a part of processing by an OFDM signal generation unit of a main line / send-back transmission unit in the terminal device according to the second embodiment. It is a figure which shows the example of arrangement | positioning of the camera control signal and income signal which were allocated to AC (Auxiliary Channel) carrier of the OFDM frame in Example 2. FIG. It is a figure which shows the example of arrangement | positioning of the AC carrier in an OFDM frame. 12 is a flowchart illustrating a part of processing by an OFDM signal generation unit of a main line / send-back transmission unit in the terminal device according to the third embodiment. It is a figure which shows the characteristic of BER (Bit Error Rate: Bit error rate) and CNR (Carrier to Noise Ratio) for every modulation system. 14 is a flowchart illustrating a part of processing by an OFDM signal generation unit of a main line / send-back transmission unit in the terminal device according to the fourth embodiment. It is a figure which shows the example of arrangement | positioning of the camera control signal and the income signal allocated to the AC carrier of the OFDM frame in Example 4. It is a block diagram which shows the structure of the main line / sending-back transmission part in the terminal device of a modification.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
[Overall configuration of video signal transmission system]
FIG. 1 is a block diagram showing the overall configuration of a video signal transmission system according to an embodiment of the present invention. The video signal transmission system 1 is a system for transmitting main line video and the like taken by the wireless cameras 20-1 to 20-N, and includes N terminal devices 2-1 to 2-N provided on the terminal side. And one base station apparatus 3 provided on the base station side. A MIMO (Multiple Input Multiple Output) transmission environment using a plurality of transmission antennas and a plurality of reception antennas between the N terminal apparatuses 2-1 to 2-N and one base station apparatus 3 Is constructed, and various data such as main line images are transmitted wirelessly. Further, as described above, the transmission path of the video signal transmission system 1 includes a main line system that performs transmission from the terminal side to the base station side, and a send-back system that performs transmission from the base station side to the terminal side. Note that the video signal transmission system 1 described below is shown by taking a MIMO transmission environment as an example, but the present invention is not limited to the MIMO transmission environment. The video signal transmission system 1 is shown as a system that wirelessly transmits various data between the terminal devices 2-1 to 2-N including the cameras 20-1 to 20-N and the base station device 3, but the main line It may be a system constituted by a plurality of FPU devices that relay transmission of video and the like.

  Hereinafter, while having two transmission antennas as the main line system and N terminal devices 2-1 to 2-N having one reception antenna as the return system, and four reception antennas as the main line system, A video signal transmission system 1 using a wireless camera that performs bidirectional transmission with a base station apparatus 3 having four transmission antennas as a sending back system will be described as an example. The control information refers to information related to the video signal used in the video signal transmission system 1 such as a camera control signal, a genlock signal, and an intercom signal, and the main line video signal includes the audio signal. Shall.

[Summary of the Invention]
First, an outline of the invention will be described. FIG. 2 is a diagram showing an example of a transmission signal between the terminal side and the base station side in the video signal transmission system 1 shown in FIG. In a main line system that wirelessly transmits various data from the terminal side to the base station side, a video signal of the main line video that is a captured camera video and control information (camera control signal, intercom signal, etc.) are transmitted. In this main line system, high-definition and large-capacity transmission is required for the video signal of the captured high-definition video. The control information is required to be transmitted with high line reliability.

  On the other hand, in a sending back system that wirelessly transmits various data from the base station side to the terminal side, a sending back video signal and control information (camera control signal, intercom signal, genlock signal, tally signal, etc.) are transmitted. In this sending back system, the video signal and control information of the sending back video are not required to be transmitted at a capacity as high as that of the camera video in the main line system, but are required to be transmitted with high line reliability, which is less likely to be interrupted than the main line system. This is because the video signal is synchronized in the video signal transmission system 1 on the basis of control information transmitted from the base station side to the terminal side, and various processes and adjustments are performed in order to use the video signal as a broadcast. It is because it is made.

  The present invention is based on the premise that various data transmitted and received in the main line system and the return line system are transmitted wirelessly. In the main line system, the video signal of the main line video uses a data carrier, and the control information uses an AC carrier. Transmission is performed using an OFDM signal. Further, the present invention pays attention to the difference between the main line system and the sending back system, and is characterized in that transmission is performed by a method suitable for various data characteristics. Thereby, control information such as a camera control signal can be reliably transmitted, and functions equivalent to those using a camera with a cable can be stably realized.

  In the first embodiment shown below, in the main line system, the video signal of the main line video is subjected to multi-level modulation by 16QAM (Quadrature Amplitude Modulation) or the like, and is transmitted as an OFDM signal using a data carrier. , Multi-level modulation using BPSK (Binary Phase Shift Keying) or the like having a low required CNR (multi-level modulation using a modulation scheme having a smaller number of data (multi-level number) that can be transmitted per signal point than 16QAM), and AC The transmission is performed using an OFDM signal using a carrier. Further, the first embodiment is characterized in that, in the sending back system, the video signal and the control information of the sending back video are subjected to multi-level modulation by BPSK or the like having a low required CNR, and transmitted by an OFDM signal using a data carrier. . As a result, the transmission rate can be increased for the main line video signal in the main line system, and the transmission rate can be reduced for the main line control information and the return video signal and control information in the return system. And high line reliability can be realized.

  Further, in the second embodiment, in the main line system of the first embodiment, when the control information is subjected to multilevel modulation with BPSK or the like having a low required CNR and transmitted as an OFDM signal using an AC carrier, the control information is further reduced. The priority is set according to the type of the control signal, and the control information having a high priority is transmitted in the OFDM signal using the AC carrier arranged at the center of the carrier axis in the OFDM frame (a predetermined range near the center of the carrier number). Transmitting low-priority control information with an OFDM signal using an AC carrier arranged at the end of the carrier axis in the OFDM frame (a predetermined range with a small carrier number and a predetermined range with a large carrier number) To do. In general, it is known that the signal quality is high in the region near the center of the carrier axis in the OFDM frame, and the signal quality is low in the region near the end of the carrier axis. This is because FFT (Fast Fourier Transform) and IFFT (Inverse Fast Fourier Transform) corresponding to the width of the carrier axis of one OFDM frame is performed, so that an error due to conversion occurs in the region near the end of the OFDM frame, resulting in distortion. Because it appears. Also, attenuation is likely to occur in the region near the end of the OFDM frame, and it is likely to be affected by interference waves from adjacent bands, and further, propagation path estimation errors are likely to occur at the end where there is no pilot carrier. It is. According to the second embodiment, for example, a camera control signal that needs to ensure high reliability is set to have a higher priority than an income signal, and the camera control signal is transmitted to an AC carrier near the center on the carrier axis in the OFDM frame. By disposing in this way, it is possible to reliably transmit a camera control signal that needs to ensure high reliability.

  Further, in the third embodiment, in the main line system of the first embodiment, when the control information is subjected to multi-level modulation by a predetermined modulation method and transmitted by an OFDM signal using an AC carrier, the type of control information is further increased. Priority is set, multi-level modulation is performed on control information with high priority by BPSK or the like having low required CNR, and control information with low priority is required with respect to control information with higher priority than control information with high priority. High-level QPSK (Quadrature Phase Shift Keying) or multi-level modulation by 16QAM (multi-level modulation using a modulation scheme with a larger number of data (multi-level number) that can be transmitted per signal point than BPSK) And Thereby, for example, by setting a camera control signal that needs to ensure high reliability as control information having a higher priority than the income signal, the transmission rate can be made lower than the income signal having a lower priority. Therefore, it is possible to reliably transmit a camera control signal having a high priority.

  Further, in the fourth embodiment, in the main line system of the first embodiment, when the control information is multi-level modulated by BPSK or the like having a low required CNR and transmitted by an OFDM signal using an AC carrier, the control information is further increased. Priority is set according to the type of control, the minimum setting amount of AC carrier that can be transmitted is secured for control information with high priority, and control with high priority is performed according to the transmission amount of control information with low priority The transmission amount of information is controlled within a range equal to or greater than the minimum set amount. Thus, for example, when a camera control signal that needs to ensure high reliability is set to have a higher priority than an intercom signal, and the amount of intercom signal transmission is small, the camera control signal is When an AC carrier is used for transmission as an OFDM signal and the amount of intercom signal transmission is large, the camera control signal can be transmitted as an OFDM signal using an amount of AC carrier that does not fall below the minimum set amount. Therefore, the camera control signal can be transmitted at a transmission rate equal to or higher than a predetermined value determined by the minimum set amount.

  Moreover, the modification of Examples 1-4 is characterized in that in the main line system, a video signal and control information of the main line video are multiplexed to generate a TS signal, and the TS signal is transmitted in an arbitrary signal format. . In addition, this modification is characterized in that in the sending back system, the TS signal is generated by multiplexing the video signal and the control information of the sending back video, and the TS signal is transmitted in an arbitrary signal format. As a result, high line reliability can be realized and transmitted reliably for the main line control information and the video signal and control information of the return video in the return system.

[Example 1]
First, Example 1 will be described. In the first embodiment, as shown in FIG. 1, the main line video signal and control information in the N cameras 20-1 to 20-N, which are main line transmissions, and N transmissions, which are transmission lines, are transmitted. This is an example in which the video signal and the control information of the return video to the cameras 20-1 to 20-N are transmitted by the OFDM signal. The OFDM signal format is an OFDM signal format according to ARIB STD-B43. Specifically, in the first embodiment, as described above, in the main line system, the video signal of the main line video is subjected to multi-level modulation by 16QAM or the like, and is transmitted as an OFDM signal using a data carrier, and is also used as control information. On the other hand, multilevel modulation is performed by BPSK or the like having a low required CNR, and transmission is performed with an OFDM signal using an AC carrier. In the sending back system, the video signal and the control information of the sending back video are subjected to multi-level modulation using BPSK or the like having a low required CNR, and transmitted by using an OFDM signal using a data carrier.

[Terminal side]
Referring to FIG. 1, on the terminal side, terminal device 2-1 includes camera (HDTV camera) 20-1, income 21-1, main line / send-back transmission unit (terminal-side transmission unit) 22-1, and transmission unit 23. -1 and a receiving unit 24-1. The camera 20-1 is a wireless camera, and an image of a subject is taken by an operator's operation. The income 21-1 is a device for exchanging voice information between a cameraman who operates the camera 20-1 and an operator on the base station side.

  The transmission unit 23-1 has two transmission antennas Tx 1 and Tx 2 for performing transmission on the main line system, and an OFDM signal (2) including a video signal of main line video and control information from the main line / send-back transmission unit 22-1. System OFDM signals, that is, OFDM signals transmitted from the first transmission antenna and OFDM signals transmitted from the second transmission antenna). Then, the transmission unit 23-1 performs D / A conversion on each of the two systems of OFDM signals into analog signals, frequency-converts the analog signals into RF band signals, amplifies the signals to a certain level, and then converts the RF signals. Filter. The filtered transmission signal is radiated as a radio wave via two transmission antennas.

  The receiving unit 24-1 has one receiving antenna for performing transmission in the return system, and sends back video and control information for the N terminal apparatuses 2-1 to 2-N transmitted from the base station apparatus 3. Is received via one receiving antenna. Then, the receiving unit 24-1 filters the received signal, amplifies the RF signal after the filter process, frequency-converts the RF band signal, and converts the analog signal after the frequency conversion into a digital signal. The converted and output MIMO signal including the return video and control information for the N terminal devices 2-1 to 2-N is output to the main line / send-back transmission unit 22-1. The configuration of the terminal devices 2-2 to 2-N is the same as that of the terminal device 2-1.

(Terminal side: Main line / Return transmission unit)
The main line / send-back transmission unit 22-1 will be described in detail. FIG. 3 is a block diagram illustrating a configuration of the main line / send-back transmission unit 22-1 in the terminal device 2-1 illustrated in FIG. The main line / send-back transmission unit 22-1 includes a demultiplexing unit 221, an OFDM signal generation unit 222, and a send-back demodulation unit 223. The demultiplexing unit 221 includes a multiplexing unit 224 and a demultiplexing unit 225. The main line / send-back transmission unit 22-1 performs main line processing by the multiplexing unit 224 and the OFDM signal generation unit 222 of the demultiplexing unit 221, and performs return processing by the demultiplexing unit 225 of the demultiplexing unit 221 and the return demodulation. This is performed by the unit 223.

(Main line processing)
The multiplexing unit 224 of the demultiplexing unit 221 inputs the camera control signal from the camera 20-1, and also inputs the income signal (voice information transmitted from the cameraman to the operator on the base station side) from the income 21-1. These signals are TS multiplexed and output to the OFDM signal generator 222 as control information.

  The OFDM signal generation unit 222 will be described. FIG. 4 is a flowchart illustrating a part of the processing performed by the OFDM signal generation unit 222 according to the first embodiment. The OFDM signal generation unit 222 receives the video signal of the main line video from the camera 20-1, and also receives control information from the demultiplexing unit 221 (step S401). Then, the OFDM signal generation unit 222 determines whether or not the processing target is a main line video signal (step S402), and determines that the processing target is a main line video signal (step S402: Y). Then, the video signal of the main line video is subjected to signal processing such as compression by error correction coding or the like, multi-value modulated by 16QAM or the like, and arranged on the data carrier of the OFDM frame (step S403). If it is determined in step S402 that the processing target is not a main line video signal (step S402: N), the OFDM signal generation unit 222 determines whether the processing target is control information (step S404).

  When the OFDM signal generation unit 222 determines in step S404 that the processing target is control information (step S404: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the control information by error correction coding or the like, and obtains the required CNR. Multi-level modulation is performed using BPSK or the like having a low A and placed on the AC carrier of the OFDM frame (step S405). If the OFDM signal generation unit 222 determines that the processing target is not control information after Step S403 or Step S405 or in Step S404 (Step S404: N), the OFDM signal generation unit 222 ends the process and proceeds to Step S401. Then, the OFDM signal generation unit 222 generates an OFDM signal, separates the OFDM signal for each system of two transmission antennas, and outputs the two systems of OFDM signals to the transmission unit 23-1.

(Return system processing)
Returning to FIG. 3, the send back demodulator 223 receives the MIMO signal including the send back video and control information for the terminal devices 2-1 to 2 -N from the receiver 24-1, demodulates the MIMO signal, and demodulates the TS signal. And a TS signal including the return video and control information for the terminal devices 2-1 to 2-N is output to the demultiplexing unit 225 of the demultiplexing unit 221.

  The demultiplexing unit 225 of the demultiplexing unit 221 receives a TS signal including a return video and control information for the terminal devices 2-1 to 2-N from the return demodulation unit 223, and is added to the return video and the control information. A serial number assigned for each of 20-1 to 20-N is extracted, and based on the serial number, a TS signal including return video and control information for the terminal devices 2-1 to 2-N is converted into a terminal device 2-1. -N is separated for each of -N, and further separated from the control information into a video signal of a return video, a camera control signal, an intercom signal, a genlock signal, and a tally signal, and the corresponding signals are separated into the camera 20-1 and the intercom 21. Output to -1 etc. The serial number is used to identify the cameras 20-1 to 20-N (or terminal devices 2-1 to 2-N) added as attached information to the video signal and control information of the return video on the base station side. Identification information.

[Base station side]
Referring to FIG. 1, on the base station side, base station apparatus 3 includes main line / send-back transmission / reception units 30-1 to 30-4, signal demultiplexing units 31 and 32, demodulation units 33-1 to 33-N, and multiplexing. A separation unit 34, a return transmission processing unit 35, camera controllers 36-1 to 36-N, and incomes 37-1 to 37-N are provided. The demodulating units 33-1 to 33-N, the demultiplexing unit 34, and the return transmission processing unit 35 constitute a base station side transmission unit.

  When the main line / send-back transmission / reception units 30-1 to 30-4 function as main line reception units, the main line / send-back transmission / reception units 30-1 to 30-4 perform filter processing, amplification processing, and frequency conversion processing on a signal received through a corresponding reception antenna. And output to the signal demultiplexing unit 31. On the other hand, when the main line / send-back transmission / reception units 30-1 to 30-4 function as a transmission unit of the return system, the return / video and control from the signal demultiplexing unit 31 to the N terminal apparatuses 2-1 to 2-N. An OFDM signal including information is input, and D / A conversion processing, frequency conversion processing, amplification processing, filter processing, and the like are performed on the input OFDM signal. The transmission signal after the filter processing is radiated as a radio wave via one corresponding transmission antenna.

  When functioning as a main line system, the signal demultiplexing unit 31 receives four systems of OFDM signals from the main line / send-back transmission / reception units 30-1 to 30-4, wavelength-multiplexes them, converts them into optical signals, The signal is output to the signal demultiplexing unit 32. The signal demultiplexing unit 32 receives the optical signal from the signal demultiplexing unit 31, converts the optical signal into a multiplexed OFDM signal, and outputs the converted OFDM signals to the demodulation units 33-1 to 33-N, respectively. .

  When the signal demultiplexing unit 32 functions as a sending back system, an OFDM signal including a sending back video signal and control information is input from the sending back processing unit 35, and these are wavelength-multiplexed and converted into an optical signal. The signal is output to the signal demultiplexing unit 31. The signal demultiplexing unit 31 receives the optical signal from the signal demultiplexing unit 32, converts the optical signal into an OFDM signal, demultiplexes the converted OFDM signal into four systems, and transmits the main line / send-back transmission / reception units 30-1 to 30-30. -4.

  The demodulating units 33-1 to 33-N receive the IF signal of the OFDM signal in which the four systems are multiplexed from the signal demultiplexing unit 32, perform A / D conversion processing and the like, and demodulate each OFDM signal to perform MIMO demodulation Thus, the main line video signal and control information in the corresponding terminal devices 2-1 to 2-N are generated. Then, the demodulating units 33-1 to 33-N extract the main line video signal from the data carrier of the corresponding OFDM frame, perform signal processing such as demodulation processing and error correction decoding, and the corresponding main line video signal. , The control information is extracted from the AC carrier, the signal processing such as demodulation processing is performed, and the corresponding control information is output to the demultiplexing unit 34.

(Base station side: Demultiplexer)
The demultiplexing unit 34 will be described in detail. FIG. 5 is a block diagram showing a configuration of the demultiplexing unit 34 in the base station apparatus 3 shown in FIG. The demultiplexing unit 34 includes a demultiplexing unit 341 and a multiplexing unit 342. The demultiplexing unit 34 performs main line processing by the demultiplexing unit 341, and sends back processing by the multiplexing unit 342.

(Main line processing)
The demultiplexing unit 341 of the demultiplexing unit 34 receives the corresponding control information from the demodulating units 33-1 to 33-N, respectively, and from the multiplexed control information to the camera control signal and the income signal (from the cameraman to the operator on the base station side) Audio information to be transmitted) is extracted, and camera control signals are output to the corresponding camera controllers 36-1 to 36 -N, respectively. In addition, the separation unit 341 outputs an income signal to the corresponding incomes 37-1 to 37-N, respectively.

(Return system processing)
The multiplexing unit 342 receives the video signal and the genlock signal of the return video, inputs the corresponding camera control signals from the camera controllers 36-1 to 36-N, and further supports the incoming signals 37-1 to 37-N. The incoming intercom signal (voice information transmitted from the operator on the base station side to the cameraman) is input. The multiplexing unit 342 adds the camera 20-1 to 20 -N (or the additional information) to the video signal of the return video and the genlock signal, camera control signal, and income signal for each of the terminal devices 2-1 to 2 -N. A serial number for identifying the terminal devices 2-1 to 2-N) is added, these video signals and the like are multiplexed, and the multiplexed TS signal is sent back and output to the transmission processing unit 35. The camera control signal is treated as a sampled signal because the protocol and packet format differ depending on the manufacturer of the cameras 20-1 to 20-N.

  Returning to FIG. 1, the return transmission processing unit 35 of the base station device 3 inputs the video signal of the return video and the TS signal of the control information to the N terminal devices 2-1 to 2-N from the demultiplexing unit 34. Then, the input TS signal is subjected to multi-level modulation using BPSK or the like having a low required CNR, and is arranged on the data carrier of the OFDM frame. Then, the return transmission processing unit 35 generates an OFDM signal and outputs it to the signal demultiplexing unit 32.

  As described above, according to the video signal transmission system 1 of the first embodiment, in the main line system, the main line / send-back transmission units 22-1 to 22-N of the terminal devices 2-1 to 2-N are connected to the main line video. The signal is multi-level modulated by 16QAM, etc., and transmitted as an OFDM signal using a data carrier. The control information is multi-level modulated by BPSK or the like having a low required CNR, and converted to an OFDM signal using an AC carrier. To transmit. Further, in the return system, the return transmission processing unit 35 of the base station apparatus 3 performs multi-level modulation on the video signal and control information of the return video using BPSK or the like having a low required CNR, and uses the data carrier as an OFDM signal. Transmitted. As a result, the transmission rate can be increased for the main line video signal in the main line system, and the transmission rate can be reduced for the main line control information and the return video signal and control information in the return system. And high line reliability can be realized. Further, in the return system, it is possible to realize transmission while maintaining high line reliability at a lower rate than in the main line system. In other words, it is possible to reliably transmit control information such as camera control signals and realize the same functions as when using a camera with a cable, and it is difficult to achieve with a conventional wireless camera. In addition, camera synchronization using a genlock signal, low-delay main line system and wireless transmission of video in the return system, intercom communication, and the like are possible.

[Example 2]
Next, Example 2 will be described. In the second embodiment, as described above, in the main line system of the video signal transmission system 1 of the first embodiment, the control information is subjected to multi-level modulation by BPSK or the like having a low required CNR, and is transmitted as an OFDM signal using an AC carrier. In addition, priority is set according to the type of control information, and control information with high priority (in this example, camera control signal) is placed in a predetermined range near the center of the carrier axis in the OFDM frame. Using an AC carrier that has been transmitted, and using low-priority control information (in this example, an incoming signal) using an AC carrier arranged in a predetermined range near the end of the carrier axis in the OFDM frame And transmitting with an OFDM signal.

[Terminal side]
Referring to FIG. 1, when the first and second embodiments are compared, the first and second embodiments are the same in that the same terminal devices 2-1 to 2-N are provided. Terminal apparatuses 2-1 to 2-N are different in that they include main line / send-back transmission units 22-1 to 22-N different from the first embodiment. Specifically, referring to FIG. 3, the main line / send-back transmission unit 22-1 of the second embodiment includes an OFDM signal generation unit 222 different from that of the first embodiment. Hereinafter, the terminal device 2-1 will be described. The configuration of the terminal devices 2-2 to 2-N is the same as that of the terminal device 2-1.

  The camera 20-1, the intercom 21-1, the transmitting unit 23-1, the receiving unit 24-1, and the demultiplexing unit 221 and the sending back demodulating unit 223 in the main line / sending transmission unit 22-1 have the same functions as those in the first embodiment. Since it has already been described, it is omitted here.

(Terminal side: Processing by the OFDM signal generator of the main line / send-back transmission unit (main line processing))
Of the main line processing on the terminal side, the OFDM signal generation unit 222 of the main line / send-back transmission unit 22-1 will be described in detail. FIG. 6 is a flowchart illustrating a part of the processing by the OFDM signal generation unit 222 in the terminal device 2-1 according to the second embodiment. The OFDM signal generation unit 222 receives the video signal of the main line video from the camera 20-1, and also receives control information from the demultiplexing unit 221 (step S601), and the multiplexed control information is converted into a camera control signal and an income signal. Separate (step S602). Then, the OFDM signal generation unit 222 sets a high priority for the camera control signal and sets a low priority for the income signal (step S603).

  The OFDM signal generation unit 222 determines whether or not the processing target is a main line video signal (step S604), and determines that the processing target is a main line video signal (step S604: Y). The video signal is subjected to signal processing such as compression by error correction coding or the like, multi-level modulated by 16QAM or the like, and arranged on the data carrier of the OFDM frame (step S605). On the other hand, when the OFDM signal generation unit 222 determines in step S604 that the processing target is not a main line video signal (step S604: N), the processing target is a camera control signal (high priority is set in the control information). Is determined (step S606). Note that the priority level may be determined by a threshold (the same applies to the third and fourth embodiments).

  When the OFDM signal generation unit 222 determines in step S606 that the processing target is a camera control signal (step S606: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the camera control signal by error correction coding or the like, Multi-level modulation is performed with BPSK or the like having a low required CNR, and it is arranged on an AC carrier in a predetermined range near the center of the carrier axis in the OFDM frame (step S607). On the other hand, when the OFDM signal generation unit 222 determines in step S606 that the processing target is not a camera control signal (N in step S606), the processing target is an income signal in the control information (an income with a low priority). Signal) is determined (step S608). If the OFDM signal generation unit 222 determines in step S608 that the processing target is an income signal (step S608: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the income signal by error correction coding or the like to obtain the required CNR. Multi-level modulation is performed using BPSK or the like having a low A and placed on an AC carrier in a predetermined range near the end of the carrier axis in the OFDM frame (step S609).

  If the OFDM signal generation unit 222 determines that the processing target is not an income signal after step S605, step S607, or step S609 or in step S608 (step S608: N), the process ends and proceeds to step S601. To do. Then, the OFDM signal generation unit 222 generates an OFDM signal, separates the OFDM signal for each system of two transmission antennas, and outputs the two systems of OFDM signals to the transmission unit 23-1.

  FIG. 7 is a diagram illustrating an arrangement example of camera control signals and income signals allocated to the AC carrier of the OFDM frame in the second embodiment, and FIG. 8 is a diagram illustrating an arrangement of the AC carrier in the OFDM frame. As shown in FIG. 8, the AC carrier in the 1K full mode is 1, 2, 3,..., 7, 9,. ., 855, the number of which is 66. As shown in FIG. 7, the arrangement region of the AC carrier includes a predetermined range α (α region) near the center of the carrier axis in the OFDM frame, and predetermined ranges β1 (β1 region) and β2 (β2 region) near the end. These are divided into two categories in advance. For example, carrier numbers 111 to 790 are set as an α region, carrier numbers 1 to 87 are set as a β1 region, and carrier numbers 825 to 855 are set as a β2 region.

  Therefore, in step S607 of the flowchart shown in FIG. 6, the OFDM signal generation unit 222 sends the camera control signal to an AC carrier in a predetermined range (α region shown in FIG. 7) near the center of the carrier axis in the OFDM frame. Deploy. Further, in step S609, the OFDM signal generation unit 222 places the income signal on an AC carrier in a predetermined range (β1 region and β2 region shown in FIG. 7) near the end of the carrier axis in the OFDM frame.

  Note that the processing of the sending back system on the terminal side is the same as that in the first embodiment, and thus the description thereof is omitted. Further, since the processing on the base station side is the same as that in the first embodiment, the description thereof is omitted. In this case, when extracting the control information from the AC carrier, the demodulation units 33-1 to 33-N extract the camera control signal from the region α shown in FIG. 7 and extract the income signal from the region β1 and the region β2. To do.

  As described above, according to the video signal transmission system 1 of the second embodiment, in the main line system, the main line / send-back transmission units 22-1 to 22-N of the terminal devices 2-1 to 2-N are the types of control information. Priority is set according to, and control information with high priority (in this example, a camera control signal) is converted into an OFDM signal using an AC carrier arranged in a predetermined range near the center of the carrier axis in the OFDM frame. Control information with a low priority (in this example, an incoming signal) is transmitted as an OFDM signal using an AC carrier arranged in a predetermined range near the end of the carrier axis in the OFDM frame. . Thereby, in addition to the same effects as those of the first embodiment, the camera control signal which is the control information with high priority can be reliably transmitted with high reliability. This is because the signal quality is higher in the region near the center of the carrier axis in the OFDM frame where the camera control signal is arranged than in the region near the end.

Example 3
Next, Example 3 will be described. In the third embodiment, as described above, in the main line system of the first embodiment, when control information is subjected to multi-level modulation by a predetermined modulation method and transmitted by an OFDM signal using an AC carrier, the control information is further controlled. Priority is set according to the type of information, and multi-level modulation is performed on control information with high priority (in this example, a camera control signal) using BPSK or the like having a low required CNR. In the example, the required CNR is higher than the control information with high priority, and the multilevel modulation by QPSK or 16QAM or the like capable of transmitting a large amount of information at a time is performed.

[Terminal side]
Referring to FIG. 1, when the first and third embodiments are compared, the first and third embodiments are the same in that the same terminal devices 2-1 to 2-N are provided. Terminal apparatuses 2-1 to 2-N are different in that they include main line / send-back transmission units 22-1 to 22-N different from the first embodiment. Specifically, referring to FIG. 3, the main line / send-back transmission unit 22-1 of the third embodiment includes an OFDM signal generation unit 222 different from that of the first embodiment. Hereinafter, the terminal device 2-1 will be described. The configuration of the terminal devices 2-2 to 2-N is the same as that of the terminal device 2-1.

  The camera 20-1, the intercom 21-1, the transmitting unit 23-1, the receiving unit 24-1, and the demultiplexing unit 221 and the sending back demodulating unit 223 in the main line / sending transmission unit 22-1 have the same functions as those in the first embodiment. Since it has already been described, it is omitted here.

(Terminal side: Processing by the OFDM signal generator of the main line / send-back transmission unit (main line processing))
Of the main line processing on the terminal side, the OFDM signal generation unit 222 of the main line / send-back transmission unit 22-1 will be described in detail. FIG. 9 is a flowchart illustrating a part of the processing performed by the OFDM signal generation unit 222 in the terminal device 2-1 according to the third embodiment. Steps S901 to S903 are the same as steps S601 to S603 shown in FIG. The OFDM signal generation unit 222 sets a high priority to the camera control signal in the control information, and sets a low priority to the income signal.

  The OFDM signal generation unit 222 determines whether or not the processing target is a main line video signal (step S904), and determines that the processing target is a main line video signal (step S904: Y). The video signal is subjected to signal processing such as compression by error correction coding or the like, and multi-level modulated by 16QAM (step S905). Then, the video signal of the multiline modulated main line video is arranged on the data carrier of the OFDM frame. On the other hand, when the OFDM signal generation unit 222 determines in step S904 that the processing target is not a main line video signal (step S904: N), the processing target is a camera control signal (high priority is set in the control information). Is determined (step S906).

  When the OFDM signal generation unit 222 determines in step S906 that the processing target is a camera control signal (step S906: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the camera control signal by error correction coding or the like, Multi-level modulation is performed with BPSK having a low required CNR (step S907). Then, the multi-level modulated camera control signal is arranged on the AC carrier of the OFDM frame as shown in the first or second embodiment. On the other hand, if the OFDM signal generation unit 222 determines in step S906 that the processing target is not a camera control signal (N in step S906), the processing target is an income signal in the control information (an income with a low priority). Signal) is determined (step S908). If the OFDM signal generation unit 222 determines in step S908 that the processing target is an income signal (step S908: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the income signal by error correction coding or the like. Multi-level modulation is performed by QPSK or 16QAM, which requires a higher CNR than a camera control signal having a high value (step S909). Then, the multi-level modulated income signal is arranged on the AC carrier of the OFDM frame as shown in the first or second embodiment.

  If the OFDM signal generation unit 222 determines that the processing target is not an income signal after step S905, step S907, or step S909 or in step S908 (step S908: N), the process ends and the process proceeds to step S901. To do. Then, the OFDM signal generation unit 222 generates an OFDM signal, separates the OFDM signal for each system of two transmission antennas, and outputs the two systems of OFDM signals to the transmission unit 23-1.

  10 is a diagram showing the characteristics of BER and CNR for each modulation method (excerpt from “Supervised by Hatori,“ 1 Seg Broadcast Textbook ”, page 31, Impress R & D). 10, the horizontal axis is the CNR, as shown in Fig. 10. When the received data amount is large, the CNR increases, so it can be seen that the BER is small, that is, when the modulation method is BPSK, from QPSK and 16QAM The required CNR is low, the transmission rate is low, and transmission with high line reliability is possible, and when the modulation method is QPSK, the required CNR is lower than 16QAM, the transmission rate is low, and the line reliability is high. High transmission is possible.

  Therefore, in step S907 of the flowchart shown in FIG. 9, the OFDM signal generation unit 222 performs multi-level modulation on the camera control signal having a high priority with BPSK having a lower required CNR than QPSK and 16QAM. Enables highly reliable transmission. On the other hand, the OFDM signal generation unit 222 performs multi-level modulation on an income signal having a low priority with QPSK or 16QAM having a required CNR higher than that of BPSK.

  Note that the processing of the sending back system on the terminal side is the same as that in the first embodiment, and thus the description thereof is omitted. Further, since the processing on the base station side is the same as that in the first embodiment, the description thereof is omitted. In this case, the demodulation units 33-1 to 33-N perform demodulation corresponding to the modulation schemes of the main line / send-back transmission units 22-1 to 22-N on the terminal side.

  As described above, according to the video signal transmission system 1 of the third embodiment, in the main line system, the main line / send-back transmission units 22-1 to 22-N of the terminal devices 2-1 to 2-N are the types of control information. Priority is set according to the control information (in this example, camera control signal), multi-level modulation is performed on the control information (in this example, a camera control signal) by BPSK or the like having a low required CNR, and control information (in this example, low priority) , Income signal) is subjected to multi-level modulation by QPSK or 16QAM having a higher required CNR than BPSK or the like. Thereby, in addition to the same effects as those of the first embodiment, the camera control signal which is the control information with high priority can be reliably transmitted with high reliability. This is because the transmission rate can be lowered and high line reliability can be realized by a modulation method such as BPSK for the camera control signal.

  In the third embodiment, a control signal with a low priority (in this example, before performing multi-level modulation with BPSK or the like having a low required CNR on control information with a high priority (camera control signal in this example). Error correction coding with a coding rate lower than that of the income signal), and multilevel modulation with QPSK or 16QAM having a higher required CNR than control information with a higher priority for control information with a lower priority. Before performing, error correction coding with a higher coding rate than control information with higher priority may be performed. Thereby, for the camera control signal that is high-priority control information, error correction coding with a low coding rate is performed, and a larger amount of parity is generated than the income signal that is low-priority control information, Since the error correction capability is high, it can be reliably transmitted with high reliability.

Example 4
Next, Example 4 will be described. In the fourth embodiment, as described above, in the main line system of the first embodiment, when the control information is multi-level modulated by BPSK or the like having a low required CNR, and transmitted by an OFDM signal using an AC carrier, Set the priority according to the type of control information, secure the minimum setting amount that can be transmitted for control information with high priority (camera control signal in this example), and control information with low priority (in this example, The transmission amount of control information (camera control signal in this example) with high priority is controlled in a range equal to or greater than the minimum set amount according to the transmission amount of the incoming signal.

[Terminal side]
Referring to FIG. 1, when Example 1 and Example 4 are compared, Examples 1 and 4 are the same in that they include the same terminal devices 2-1 to 2-N. Terminal apparatuses 2-1 to 2-N are different in that they include main line / send-back transmission units 22-1 to 22-N different from the first embodiment. Specifically, referring to FIG. 3, the main line / send-back transmission unit 22-1 of the fourth embodiment includes an OFDM signal generation unit 222 different from that of the first embodiment. Hereinafter, the terminal device 2-1 will be described. The configuration of the terminal devices 2-2 to 2-N is the same as that of the terminal device 2-1.

  The camera 20-1, the intercom 21-1, the transmitting unit 23-1, the receiving unit 24-1, and the demultiplexing unit 221 and the sending back demodulating unit 223 in the main line / sending transmission unit 22-1 have the same functions as those in the first embodiment. Since it has already been described, it is omitted here.

(Terminal side: Processing by the OFDM signal generator of the main line / send-back transmission unit (main line processing))
Of the main line processing on the terminal side, the OFDM signal generation unit 222 of the main line / send-back transmission unit 22-1 will be described in detail. FIG. 11 is a flowchart illustrating a part of the processing performed by the OFDM signal generation unit 222 in the terminal device 2-1 according to the fourth embodiment. Steps S1101 to S1105 are the same as steps S601 to S605 shown in FIG.

  The OFDM signal generation unit 222 proceeds from step S1104 to determine whether or not the processing target is a camera control signal (camera control signal set with a high priority) in the control information (step S1106).

  If the OFDM signal generation unit 222 determines in step S1106 that the processing target is a camera control signal (step S1106: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the camera control signal by error correction coding or the like, Multi-level modulation with BPSK with low required CNR, and near the center of the carrier axis in the OFDM frame so that the transmission amount exceeds a predetermined minimum setting amount according to the transmission amount of the income signal set with low priority Are arranged on AC carriers within a predetermined range (step S1107). On the other hand, if the OFDM signal generation unit 222 determines in step S1106 that the processing target is not a camera control signal (step S1106: N), the processing target is an income signal in the control information (an income with a low priority). Signal) (step S1108). When the OFDM signal generation unit 222 determines in step S1108 that the processing target is an income signal (step S1108: Y), the OFDM signal generation unit 222 performs signal processing such as compression on the income signal by error correction coding or the like, and obtains the required CNR. Multi-level modulation is performed by BPSK having a low A or a QPSK or 16QAM having a higher required CNR than a camera control signal having a high priority, and arranged in a predetermined range of AC carriers near the end of the carrier axis in the OFDM frame (step S1109).

  If the OFDM signal generation unit 222 determines that the processing target is not an income signal after step S1105, step S1107, or step S1109 or in step S1108 (step S1108: N), the process ends and the process proceeds to step S1101. To do. Then, the OFDM signal generation unit 222 generates an OFDM signal, separates the OFDM signal for each system of two transmission antennas, and outputs the two systems of OFDM signals to the transmission unit 23-1.

  FIG. 12 is a diagram illustrating an arrangement example of camera control signals and income signals allocated to the AC carrier of the OFDM frame according to the fourth embodiment. FIG. 12 (1) corresponds to FIG. 7, and the AC carrier arrangement area is divided into two sections: a predetermined range α near the center of the carrier axis in the OFDM frame, and predetermined ranges β1 and β2 near the ends. It is divided. Within the predetermined range α, a minimum setting range A that is a fixed range is set in advance. This is to ensure a minimum response speed of the camera control signal so that the transmission rate of the camera control signal decreases due to an increase in information such as an income signal and the response is not slowed when controlling the camera. Note that the predetermined ranges α, β1, and β2 of the second embodiment shown in FIG. 7 are fixed, whereas the predetermined ranges α, β1, and β2 shown in FIG. 12 are not fixed, depending on the transmission amount of the income signal. fluctuate.

  In this case, in step S1107 of the flowchart shown in FIG. 11, the OFDM signal generation unit 222 transmits the camera control signal as a transmission amount equal to or larger than the minimum setting amount indicated by the predetermined minimum setting range A according to the transmission amount of the income signal. In such a manner, they are arranged on AC carriers in a predetermined range (α region shown in FIG. 12 (1)) near the center of the carrier axis in the OFDM frame. In step S1109, the OFDM signal generation unit 222 arranges the income signal on the AC carrier in a predetermined range (β1 region and β2 region shown in FIG. 12A) near the end of the carrier axis in the OFDM frame. .

  FIG. 12 (2) shows a case where the amount of income signal transmission is small (for example, a case where there is little audio information from the cameraman to the demodulating operator). The arrangement region of the AC carrier includes a predetermined range α near the center of the carrier axis in the OFDM frame (a range wider than α in FIG. 12 (1)) and predetermined ranges β1 and β2 near the end (of FIG. 12 (1)). The range is narrower than β1 and β2. Within the predetermined range α, a minimum setting range A that is a fixed range is set in advance.

  Also in this case, the OFDM signal generator 222 sends the camera control signal to the predetermined range near the center of the carrier axis in the OFDM frame (the α region shown in FIG. 12 (2)) in step S1107 of the flowchart shown in FIG. ) On the AC carrier. In step S1109, the OFDM signal generation unit 222 arranges the incoming signal on the AC carrier in a predetermined range (β1 region and β2 region shown in FIG. 12 (2)) near the end of the carrier axis in the OFDM frame. . The α region where the camera control signal is arranged is wider than FIG. 12 (1) because the amount of income signal transmission is small, and the β1 region and β2 region where the income signal is arranged are larger than those shown in FIG. 12 (1). Narrow. Accordingly, since a large amount of camera control signals can be transmitted at a time, the camera can be controlled smoothly.

  FIG. 12 (3) shows a case where the amount of income signal transmission is large (for example, when there is a lot of audio information from the cameraman to the demodulating operator). The arrangement region of the AC carrier includes a minimum setting range A (a range narrower than α in FIG. 12 (1)) that is a predetermined range α near the center of the carrier axis in the OFDM frame, and predetermined ranges β1 and β2 ( It is divided into two sections, a range wider than β1 and β2 in FIG. The predetermined range α and the minimum setting range A are the same.

  In this case, in step S1107 of the flowchart shown in FIG. 11, the OFDM signal generation unit 222 sends the camera control signal to a predetermined range near the center of the carrier axis in the OFDM frame (the minimum setting range shown in FIG. 12 (3)). A) is placed on the AC carrier. In step S1109, the OFDM signal generation unit 222 arranges the income signal on the AC carrier in a predetermined range (β1 region and β2 region shown in FIG. 12 (3)) near the end of the carrier axis in the OFDM frame. . The α region in which the camera control signal is arranged has a larger amount of intercom signal transmission. Therefore, the α region is narrower than that in FIG. 12 (1) and is at least the minimum set range A or more, and β1 in which the intercom signal is arranged. The region and the β2 region are wider than those in FIG. In this way, the predetermined range α in which the camera control signal is transmitted does not fall below the minimum setting range A. When there is a large amount of data to be sent at a time with an income signal, the modulation method is changed (for example, changed from QPSK to 16QAM) so that the multi-value number of multi-value modulation applied to the income signal is increased, It is also possible to intentionally delay the transmission of the income signal by storing the income signal in the memory and gradually transmitting it.

  Note that the processing of the sending back system on the terminal side is the same as that in the first embodiment, and thus the description thereof is omitted. Further, since the processing on the base station side is the same as that in the first embodiment, the description thereof is omitted. In this case, when extracting the control information from the AC carrier, the demodulation units 33-1 to 33-N extract the camera control signal from the region α shown in FIG. 12 and extract the income signal from the region β1 and the region β2. To do. Predetermined ranges α, β1, and β2 that change according to the amount of income signal transmitted are also transmitted as part of the control information.

  As described above, according to the video signal transmission system 1 of the fourth embodiment, in the main line system, the main line / send-back transmission units 22-1 to 22-N of the terminal devices 2-1 to 2-N are the types of control information. The priority according to the control information is set, the control information with high priority (in this example, the camera control signal) is changed to a predetermined minimum according to the transmission amount of the control information with low priority (in this example, the incoming signal). Control information with low priority (this example) is transmitted as an OFDM signal using an AC carrier in a predetermined range near the center of the carrier axis in the OFDM frame so that the transmission amount is equal to or greater than the minimum setting amount indicated by the setting range A. In this case, the income signal is transmitted as an OFDM signal using the remaining AC carrier arranged in a predetermined range near the end of the carrier axis in the OFDM frame. As a result, in addition to the same effects as in the first embodiment, the camera control signal, which is the control information with high priority, can be increased in transmission rate when the transmission amount of the income signal is small and high. It can be reliably transmitted under reliability. This is because when the amount of incoming income signal is small, the camera control signal can be transmitted using more AC carriers.

[Modification]
Next, modified examples of the first to fourth embodiments will be described. In this modification, in the main line system of the video signal transmission system 1 shown in FIG. 1, a video signal and control information of the main line video are multiplexed to generate a TS signal, and the TS signal is transmitted in an arbitrary signal format. It is characterized by. In the sending back system, the video signal of the sending back video and the control information are multiplexed to generate a TS signal, and the TS signal is transmitted in an arbitrary signal format.

  Comparing the first to fourth embodiments with this modification, the first to fourth embodiments and the modification are the same as the video signal transmission system 1 shown in FIG. The main line / send-back transmission units 22-1 to 22-N and the send-back transmission processing unit 35 are different in that they perform processing different from those of the first to fourth embodiments. As shown in FIG. 1, in this modification, the main line video signal and control in N cameras 20-1 to 20-N (or terminal apparatuses 2-1 to 2-N) which are main line transmissions. A TS signal is generated by multiplexing information, and a video signal and control of a return video to N cameras 20-1 to 20-N (or terminal devices 2-1 to 2-N) which are transmissions of a return system In this example, information is multiplexed and a TS signal is generated and transmitted in a signal of any signal format.

[Terminal side: Main line processing of main line / return transmission unit]
The main line / send-back transmission unit 22-1 in the terminal device 2-1 on the terminal side will be described in detail. FIG. 13 is a block diagram illustrating a configuration of the main line / send-back transmission unit 22-1 in the terminal device 2-1. The main line / send-back transmission unit 22-1 of this modification includes a demultiplexing unit 221, a send-back demodulation unit 223, a multiplexing unit 226, and a modulation unit 227. Comparing the main line / send-back transmission unit 22-1 of the first to fourth embodiments shown in FIG. 3 and the main line / send-back transmission unit 22-1 of the modification shown in FIG. The main line / send-back transmission unit 22-1 in the modification is the same as that in the first to fourth embodiments except that the demultiplexing unit 221 and the return-back demodulation unit 223 are provided. It is different in that a unit 226 and a modulation unit 227 are provided. The description of the demultiplexing unit 221 and the sending back demodulation unit 223 is omitted.

  The multiplexing unit 226 included in the main line / send-back transmission unit 22-1 of the modified example inputs the video signal of the main line video from the camera 20-1, and inputs control information from the demultiplexing unit 221. The multiplexing unit 226 performs signal processing such as compression on the video signal and control information of the main line video by error correction coding, etc., multiplexes the video signal of the main line video and the control information, and modulates the multiplexed signal to the modulation unit Output to H.227. The modulation unit 227 receives the multiplexed signal from the multiplexing unit 226, performs a predetermined modulation process, generates an OFDM signal or a single carrier signal, etc., separates the signal for each system of two transmission antennas, The system signal is output to the transmitter 23-1.

  Note that the sending-back processing on the terminal side is the same as in the first to fourth embodiments, and thus the description thereof is omitted. Further, since the processing on the base station side is the same as in the first to fourth embodiments, the description thereof is omitted. In this case, in the base station device 3 on the base station side, the demodulation units 33-1 to 33-N perform demodulation corresponding to the modulation schemes of the main line / send-back transmission units 22-1 to 22-N on the terminal side. Further, the return transmission processing unit 35 performs a predetermined modulation process on the multiplexed TS signal from the demultiplexing unit 34 to generate an OFDM signal, a single carrier signal, or the like.

  As described above, according to the video signal transmission system 1 of the modified example, in the main line system, the video signal and control information of the main line video are multiplexed to generate a TS signal, and the TS signal is an arbitrary signal including an OFDM signal. Transmitted in the format. In the sending back system, the TS signal is generated by multiplexing the video signal and the control information of the sending back video, and the TS signal is transmitted in an arbitrary signal format. As a result, high line reliability can be realized and transmitted reliably for the main line control information and the video signal and control information of the return video in the return system. Further, unlike the first to fourth embodiments, since the OFDM frame AC carrier is not used, the video signal transmission system 1 applicable to any signal format can be realized.

  While the present invention has been described with reference to the embodiments and the modifications, the present invention is not limited to the embodiments and the modifications, and various modifications can be made without departing from the technical idea thereof. For example, in a situation in which the video signal transmission system 1 shown in FIG. 1 can secure a sufficient number of channels using millimeter wave charging waves, a plurality of cameras 20-1 to 20-N can be operated simultaneously. Different frequency channels are allocated and used for the cameras 20-1 to 20-N. In this case, the transmission units 23-1 to 23-N of the terminal devices 2-1 to 2-N allocate different frequency channels to the corresponding cameras 20-1 to 20-N, and use the allocated frequency channels. An OFDM signal is transmitted. In ARIB STD-B43, a maximum of 16 channels can be used. For example, the video signal transmission system 1 includes 15 cameras 20-1 to 20-15, and in the main line system, one frequency channel is allocated to one camera, and OFDM signals are transmitted through a total of 15 frequency channels. . Further, in the sending back system, the remaining one frequency channel may be allocated to the sending back video and control information, and OFDM transmission may be performed. Further, for example, a main frequency OFDM signal of one frequency channel and a return OFDM signal of one frequency channel may be assigned to one camera.

  Further, the terminal devices 2-1 to 2-N constituting the video signal transmission system 1 transmit the camera control signal and the intercom signal as the control information. Etc. may be included in the control information and transmitted to the base station side. In addition, the base station apparatus 3 is configured to transmit a genlock signal, a camera control signal, and an intercom signal as control information. However, the control information also includes electronic script, radio propagation information for performing transmission control on the terminal side, and the like. May be transmitted to the terminal side. In this case, with regard to battery information, electronic script, etc., video signal transmission is further adapted to the shooting situation and environment, etc. by setting priorities and placing them on the AC carrier in the same manner as camera control signals, income signals, etc. The system 1 can be constructed. The control information shown in the above-described first to fourth embodiments and modifications is an exemplification, and the present invention is not limited to this control information.

  Further, the base station apparatus 3 constituting the video signal transmission system 1 performs multi-level modulation on the video signal and control information of the return video in the sending back system using BPSK or the like having a low required CNR, and an OFDM signal using the data carrier. It was made to transmit with. On the other hand, for example, when the rate of the video signal of the return video is necessary, the base station apparatus 3 performs multi-value modulation on the video signal of the return video by 16QAM or the like as in the first embodiment, and the data While transmitting with an OFDM signal using a carrier, the control information may be subjected to multi-level modulation with BPSK or the like having a low required CNR, and transmitted with an OFDM signal using an AC carrier. In this case, in the terminal devices 2-1 to 2 -N, the demultiplexing unit 225 in the demultiplexing unit 221 of the main line / sending-back transmission units 22-1 to 22-N performs signal separation according to the position of the AC carrier. At this time, when transmitting / receiving information other than the camera control signal and the intercom signal, such as an electronic script, battery information, etc., a high priority is set for a signal that needs to be particularly difficult to interrupt, and the camera It is also possible to treat the control signal in the same manner as the control signal and place it on the AC carrier, and as described in the first to fourth embodiments, it is possible to devise a device that is not easily interrupted in the AC carrier and has high line reliability.

  In addition, the base station device 3 sets a priority according to the type of video signal and control information of the return video in the return system as in the second and third embodiments, and for the control information with a high priority, Multi-level modulation is performed with BPSK or the like having a low required CNR, and it is arranged on the data carrier near the center of the OFDM frame, and control information with a low priority is lower than BPSK with a low required CNR or control information with a high priority. Performs multi-level modulation using QPSK or 16QAM with a high required CNR (multi-level modulation using a modulation method with a larger number of data (multi-level number) that can be transmitted per signal point than BPSK), and near the end of the OFDM frame You may make it arrange | position to a data carrier. Further, as in the fourth embodiment, the priority is set according to the type of the video signal and control information of the return video, and the minimum setting that can be transmitted for the control information (for example, camera control signal, genlock signal) with high priority. The amount of control information having a high priority may be controlled within a range equal to or greater than the minimum set amount in accordance with the amount of control information having a low priority (for example, an income signal). In this case, in the terminal devices 2-1 to 2 -N, the demultiplexing unit 225 in the demultiplexing unit 221 of the main line / sending-back transmission units 22-1 to 22-N performs signal separation according to the position of the AC carrier.

  In the above-described modification, an OFDM signal or a single carrier signal is transmitted. However, the present invention is not limited to these signals.

  In addition, as a hardware configuration of the terminal devices 2-1 to 2-N and the base station device 3 constituting the video signal transmission system 1 according to the first to fourth embodiments and the modification example of the present invention, a normal computer is used. Can do. Each of the terminal devices 2-1 to 2-N and the base station device 3 is configured by a computer having a volatile storage medium such as a CPU and a RAM, a non-volatile storage medium such as a ROM, and an interface. The functions of the main line / send-back transmission units 22-1 to 22-N, transmission units 23-1 to 23-N, and reception units 24-1 to 24-N provided in the terminal devices 2-1 to 2-N are as follows. This is realized by causing the CPU to execute a program describing the above functions. Further, the main line / send-back transmission / reception units 30-1 to 30-4, the signal demultiplexing units 31 and 32, the demodulation units 33-1 to 33-N, the demultiplexing unit 34, and the return transmission processing unit 35 provided in the base station apparatus 3 are provided. These functions are also realized by causing the CPU to execute a program describing these functions. These programs can be stored and distributed in a storage medium such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), optical disk (CD-ROM, DVD, etc.), semiconductor memory, or the like.

DESCRIPTION OF SYMBOLS 1 Video signal transmission system 2 Terminal apparatus 3 Base station apparatus 20 Camera 21, 37 Intercom 22 Main line / send-back transmission part 23 Transmission part 24 Reception part 30 Main line / send-back transmission / reception part 31, 32 Signal demultiplexing part 33 Demodulation part 34, 221 Multiplexing Separator 35 Send back processor 36 Camera controller 222 OFDM signal generator 223 Send back demodulator 224, 226, 342 Multiplexer 225, 341 Separator 227 Modulator

Claims (5)

In a video signal transmission system comprising a terminal device that transmits a video signal and a base station device that receives the video signal from the terminal device,
The terminal device
Modulate the video signal and control information used in the video signal transmission system, and transmit to the base station apparatus as an OFDM signal,
The terminal side that receives and demodulates the video signal transmitted from the base station apparatus and the OFDM signal of the control information used in the video signal transmission system, and separates it into various information constituting the video signal and the control information With a transmission section,
The base station device
Receiving and demodulating the video signal and control information transmitted from the terminal device, extracting the video signal and the control information, separating the control information into various information;
A base station side transmission unit that modulates a video signal to be transmitted to the terminal device and control information used in the video signal transmission system and transmits the modulated signal to the terminal device as an OFDM signal,
The terminal-side transmission unit is
The video signal to be transmitted to the base station apparatus is multi-level modulated by a predetermined modulation method and transmitted by an OFDM signal using a data carrier, and the control information is less than the predetermined modulation method. A video signal transmission system characterized in that multi-level modulation is performed by a multi-level modulation method and transmission is performed using an AC carrier as an OFDM signal. The video signal transmission system according to claim 1,
The terminal-side transmission unit is
Priorities are set according to the types of various information constituting the control information, and the control information having a high priority is converted into an OFDM signal using an AC carrier arranged in a predetermined range near the center of the carrier axis in the OFDM frame. A video signal transmission system characterized in that control information having a low priority is transmitted as an OFDM signal using an AC carrier arranged in a predetermined range near the end of the carrier axis in the OFDM frame. . The video signal transmission system according to claim 2,
The terminal-side transmission unit is
Priorities are set according to the types of various information constituting the control information, error correction with a lower coding rate than control information with low priority is added to control information with high priority, and the video Multi-level modulation with a multi-level modulation scheme smaller than a predetermined modulation scheme for a signal, and transmitting with an OFDM signal using an AC carrier arranged in a predetermined range near the center of the carrier axis in the OFDM frame, Adds error correction with a higher coding rate than control information with high priority to control information with low priority, and uses a modulation scheme with a larger number of values than modulation schemes for control information with high priority. A video signal transmission system that performs multi-level modulation and transmits an OFDM signal using an AC carrier arranged in a predetermined range near an end of a carrier axis in an OFDM frame. In the video signal transmission system according to any one of claims 1 to 3,
The terminal-side transmission unit is
Priorities are set according to the types of various information constituting the control information, and control information with a high priority is transmitted over a predetermined minimum transmission amount, and the transmission amount of control information with a low priority is small. If the transmission amount of control information with a high priority is increased, and the transmission amount of control information with a low priority is increased, the transmission amount of control information with a high priority is set higher than the predetermined minimum transmission amount. A video signal transmission system characterized by reducing so as not to fall below. In the video signal transmission system according to any one of claims 1 to 4,
A plurality of terminal devices that respectively transmit the video signals; and a base station device that respectively receives the video signals from the plurality of terminal devices;
The base station side transmission unit,
A video signal transmission system, wherein control information addressed to each terminal device is added with identification information for distinguishing each terminal device and transmitted.

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