JP2012244443A - Radio transmission system, and video signal receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for transmitting high capacity data such as a video signal between a transceiver and a receiver by radio, and a video signal receiver.SOLUTION: A radio transmission system comprises: transmission means for transmitting a video signal and a control signal by radio; detection means for detecting a reception signal level of an existing signal in a usable channel; estimation means for estimating a channel generating possibility of being usable for new transmission between a transceiver and a receiver, by using the reception signal level detected by the detection means; and determination means for respectively acquiring a transmission level and a reception level from the transceiver and the receiver using the channel estimated by the estimation means, and, by using the levels, determining whether or not the estimated channel is usable for the new transmission between the transceiver and the receiver. The radio transmission system reduces the transmission level of the transceiver using the channel determined by the determination means, and starts the new transmission between the transceiver and receiver.

Description

  The present invention relates to a system for wirelessly transmitting a large amount of data such as a video signal between a transmission device and a reception device.

  In recent years, with the development of wireless communication technology, many wireless communication systems have been proposed. As an example, a system for wirelessly transmitting a high-definition video signal, which has been difficult in the past, has been developed by greatly improving the transmission speed or devising a video signal compression method. Patent Document 1 and Non-Patent Document 1 disclose a technique for wirelessly transmitting a so-called high-definition television (HDTV) video signal.

Special table 2007-507147 gazette

“Enabling wireless uncompressed HDTV connectivity with a unique video-modem approach: A technical overview”, AMIMON Ltd.

  In the techniques of Patent Document 1 and Non-Patent Document 1, in order to transmit uncompressed data exceeding 1.5 Gbps of HDTV, it is necessary to secure a channel that can be used exclusively for transmission.

  The use of bands that do not require a license is essential for use at home, but the number of bands and channels that can be used without a license are limited, and with the spread of wireless LAN and video wireless transmission systems, the use of channels It is expected that the rate will increase and it will be difficult to find a dedicated channel. In view of the above problems, an object of the present invention is to secure a channel for a wireless transmission system that requires a dedicated channel.

  In order to achieve the above object, for example, the configuration described in the claims is adopted.

  According to the present invention, a channel can be suitably secured in a transmission system that requires a dedicated channel.

It is a block diagram which shows an example of the wireless transmission system of a present Example. It is a figure which shows an example of arrangement | positioning of the wireless transmission system of a present Example. It is a figure which shows an example of the signal level in the radio | wireless transmission system of a present Example. It is a flowchart which shows an example of the process in the wireless transmission system of a present Example. It is a flowchart which shows an example of the process in the wireless transmission system of a present Example. It is explanatory drawing about the fluctuation | variation of a transmission signal.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same portions are denoted by the same reference numerals.

  FIG. 1 shows a configuration example of an apparatus according to the present embodiment. Reference numeral 11 denotes a transmission apparatus, which includes a video signal source 111, a video signal processing unit 112, a transmission signal processing unit 113, a modulation / demodulation channel selection unit 114, and a reception amplification unit 115. , A transmission amplifying unit 116, an antenna 117, a control unit 118, and a network interface unit 119.

  On the other hand, 12 is a receiving device, 121 video display unit, 122 video signal processing unit, 123 transmission signal processing unit, 124 modulation / demodulation channel selection unit, 125 reception amplification unit, 126 transmission amplification unit, 127 antennas, 128 control units, and 129 network interface units.

  First, the operation of the transmission device 11 will be described.

  The video signal source 111 in the transmission device 11 is, for example, a broadcast tuner or a video signal recording medium, and is a means for outputting some video signal. The video signal output from the video signal source 111 is input to the video processing unit 112, and the format of the video signal is changed, the image quality is adjusted, and some OSD (On Screen Display) display is added to the video. Processing is performed. The video signal output from the video processing unit 112 is input to the transmission signal processing unit 113, and so-called MAC (Media Access Control) and BB (Baseband) layer signal processing is performed in order to wirelessly transmit the video signal.

  Also, the modulation / demodulation channel selection unit 114 performs modulation processing for radio transmission on the transmission signal processed by the transmission signal processing unit 113, and further performs frequency conversion on the frequency band of the channel used for transmission to generate the modulation signal. Generate. The generated modulated signal is amplified to a predetermined signal level by transmission amplifier 116 and transmitted from antenna 117 to receiving device 12. At this time, the level of the modulation signal to be transmitted changes when the control unit 118 controls the transmission amplification unit 116. Further, not only the modulated video signal but also the control signal for the receiver 12 is transmitted from the control unit 118 via the transmission signal processing unit 113, the modulation / demodulation channel selection unit 114, the transmission amplification unit 116, and the antenna 117. be able to. The channel for transmitting the control signal is the same as the channel for modulating and transmitting the video signal, and is transmitted time-divisionally or superimposed on the video signal.

  On the other hand, the antenna 117 also serves as a reception antenna. The antenna 117 receives the modulated signal transmitted from the receiving device 12, amplifies it by the receiving amplification unit 115, and inputs it to the modulation / demodulation channel selection unit 114. The modulation / demodulation tuning unit 114 demodulates the transmission signal transmitted from the receiving device 12 by selecting a channel through which the modulated signal is transmitted and performing demodulation processing. Further, the transmission signal processing unit 113 performs signal processing on the demodulated signal, thereby extracting the control signal transmitted by the receiving device 12 and inputting the control signal to the control unit 118.

  The control unit 118 acquires the control signal transmitted by the receiving device 12 from the transmission signal processing unit 113, and the video signal source 111, the video signal processing unit 112, the transmission signal processing unit 113, the modulation / demodulation channel selection unit 114, and the reception amplification unit 115. The transmission amplification unit 116 is controlled. When starting the transmission of the video signal, the transmission signal processing unit 113 and the modulation / demodulation channel selection unit 114 are controlled to detect the state of each channel and to check whether a connection request has arrived from the receiving device 11. If a connection request has arrived, that channel is used for video signal transmission.

  Furthermore, the control unit 118 can communicate control signals with other transmission devices and reception devices through the network interface unit 119.

  As described above, the transmission device 11 has a function of processing a video signal and wirelessly transmitting the video signal using a predetermined channel, and receiving a control signal wirelessly transmitted from the reception device 12. In the present invention, in order to transmit high-quality video, the transmission signal is required to occupy a channel.

  Next, the operation of the receiving device 12 will be described.

  The antenna 127 receives the modulated signal transmitted from the transmission apparatus 11, amplifies the signal by the reception amplification unit 125, and inputs the amplified signal to the modulation / demodulation channel selection unit 124. The modulation / demodulation channel selection unit 124 performs frequency conversion from the frequency of the channel used for transmission to a frequency for demodulation processing, performs demodulation processing, and inputs the result to the transmission signal processing unit 123. Subsequently, the transmission signal processing unit 123 performs signal processing of MAC (Media Access Control) and BB (Baseband) layers, and inputs the generated video signal to the video processing unit 122. The video processing unit 122 performs processing such as changing the format of the video signal, adjusting the image quality, and adding some OSD (On Screen Display) display to the video. The display unit 121 displays the video signal processed by the video processing unit 122.

  The receiving device 12 receives not only the modulated video signal but also the control signal transmitted from the transmitting device 11 via the antenna 127, the receiving amplification unit 125, the modulation / demodulation channel selection unit 124, and the transmission signal processing unit 123. Thus, the control unit 128 can acquire the information.

  In addition to receiving the modulated video signal, a control signal for the transmission device 11 is also input from the control unit 128 to the transmission signal processing unit 123 to perform transmission signal processing, and the modulation / demodulation unit 124 performs modulation and channel frequency conversion. Frequency conversion is performed, and the signal is amplified to a predetermined signal level by the transmission amplifier 126 and transmitted from the antenna 127.

  The control unit 128 generates a control signal to be transmitted to the transmission device 11, and also includes a video display unit 121, a video signal processing unit 122, a transmission signal processing unit 123, a modulation / demodulation channel selection unit 124, a reception amplification unit 125, and a transmission amplification unit. 126 is controlled.

  In starting the transmission of the video signal, the demodulation amplifying unit 125 and the modulation / demodulation tuning unit 124 are controlled to detect the existing signal level information of each channel. The signal level of each channel is notified to the control unit 128. When there is a channel that is not used for communication, the control unit 128 selects the channel and transmits a connection request to the transmission device 11 using the channel. To control.

  Further, as will be described later, when all channels are used, the control unit 128 estimates a channel that can be newly transmitted by reducing the level of an existing signal in another device. Then, a signal level is acquired from a device that uses the estimated channel, and based on this, control is performed to determine whether or not the estimated channel can be used.

  Note that the control unit 128 can communicate control signals with other transmission devices and reception devices through the network interface unit 129.

  Next, an environment in which a plurality of transmitting devices and receiving devices are used simultaneously will be described with reference to FIG.

  FIG. 2 shows a floor plan of the building. In the rooms 21, 22, 23, 24 and 25, the transmission device 211 and the reception device 212, the transmission device 221 and the reception device 222, the transmission device 231 and the reception device 232, and the transmission device, respectively. 241 and a receiver 242, a transmitter 251 and a receiver 252 are installed. Each transmission device and each reception device are the same as the transmission device 11 and the reception device 12 described above, respectively.

  Although not shown in the figure, the network interface 119 of all transmitting apparatuses and the network interface 129 of all receiving apparatuses are connected to a network hub and can communicate control signals with each other.

  Further, it is assumed that the transmission device and the reception device can use four channels. For example, in the case of a transmitter / receiver that uses a W52 band that is not licensed in the 5 GHz band and supports 20 MHz width transmission in Japan, there are four channels 36, 40, 44, and 48 that can be used. It will be the same. Hereinafter, the control in the case where the channels 36, 40, 44, and 48 in the 5 GHz band can be used will be described.

  In FIG. 2, there are no other wireless devices using channels 36, 40, 44, and 48, and it is assumed that the transmitting device and the receiving device are activated sequentially from the room 21. Assuming that a channel is secured from a channel having a low frequency, the transmitting device 211 and the receiving device 212 in the room 21 have 36 channels, the transmitting device 221 and the receiving device 222 in the room 22 have 40 channels, and the transmitting device in the room 23. 231 and the receiving device 232 use 44 channels, and the transmitting device 241 and the receiving device 242 in the room 24 use the channel 48.

  When the transmitting device 251 and the receiving device 252 in the room 25 perform communication, since all four usable channels are already used, the same channel used by the transmitting device and the receiving device in any room is used. Need to be reused. However, depending on the conditions such as the distance between the rooms and the wall material, all the signals of the four channels being used reach the room 25, and it is possible that none of the channels can be reused.

  The situation where the above channel reuse is impossible will be described with reference to FIG.

  In FIG. 3, the horizontal axis indicates the channel, and the vertical axis indicates the signal level of the modulation signal. A signal received by the receiving device 252 from the modulated signal of the channel 36 transmitted by the transmitting device 211 is indicated by 31. Similarly, the signal received by the receiving device 252 is 32 when the modulation signal of the channel 40 transmitted by the transmitting device 221 is received, and the signal 33 and the transmitting device 241 are received by the receiving device 252 of the modulated signal of the channel 44 transmitted by the transmitting device 231. 34 is a signal received by the receiving device 252 of the transmitted modulation signal of the channel 48. Assuming that the transmission apparatuses 211, 221, 231 and 241 are transmitting at the same transmission level, the signal level of the channel 36 used by the transmission apparatus 211 is one due to the positional relationship between each transmission apparatus and the reception apparatus 252. The signal level of the channel 48 used by the transmitter 234 is the smallest and the highest.

  In order to transmit the modulated signal, the level of the existing signal existing in the channel must be equal to or lower than a certain value. When the signal level threshold is 300, all of the signals 31, 32, 33, and 34 are the same. Above the level. Therefore, in such a situation, there is no channel that can be used by the transmission device 251 and the reception device 252 in the room 25, and transmission cannot be started.

  In such a situation, an operation performed by the transmission device and the reception device to secure a channel that can be transmitted by the transmission device 251 and the reception device 252 will be described. Hereinafter, control of the reception device 251 and the transmission device 252 in the situation shown in FIGS. 2 and 3 will be described with reference to the flowchart shown in FIG.

  First, in step 401, the reception level of the existing modulated signal of each channel in the receiving device 252 is acquired. As described above, the signal level of each channel can be acquired from the demodulation amplifying unit 125 and the modulation / demodulation channel selection unit 124.

  Next, in step 402, it is determined whether there is a newly available channel. If the level of the existing signal is equal to or lower than the signal level threshold 300 in FIG. 3, it is regarded as a usable channel, and if there is a usable channel, the process proceeds to step 403. If all the channels are higher than the signal level 300, that is, if it is in the state shown in FIG.

  If the process proceeds to step 403, the channel used for transmission is determined. If there are a plurality of usable channels, an arbitrary channel may be selected from them. Subsequently, in step 404, the receiving device 252 transmits a connection request as a control signal to the transmitting device 251 using the determined channel, and the transmitting device 251 uses the same channel to perform transmission processing and processing on the video signal. Modulation processing is performed, and transmission to the receiving device 252 is started as a modulated signal.

  In the case of proceeding to step 405, if the level of the existing signal of each channel is lowered, a channel that can be used for new transmission is estimated. For the estimation, the reception level of the existing signal, the transmission output control range information in the transmission device, and the reception signal level information that can be received by the reception device are used.

  As already described, the level of the modulation signal transmitted by the transmission apparatus can be changed by the transmission amplification unit 116. Therefore, it is estimated whether or not the reception level in the receiving apparatus 252 can be lowered to the threshold value 300 by lowering the transmission level of another transmitting apparatus. In FIG. 3, 37 is a transmission signal of the transmission device 211, and the signal level is 330. If the maximum transmission level reduction width by controlling the transmission amplifier 116 is 331, the transmission signal after the transmission level reduction is 38, and the transmission level is reduced to level 340. On the other hand, when the receiving state of the receiving device 252 is considered, the signal 31 is transmitted when the transmitting device 211 is transmitting the signal 37, the signal level is 310, and the signal 36 is transmitted when the signal 38 is transmitted. The level is 320. Assuming that the reception level of the reception device 252 is proportional to the transmission level of the transmission device 211, the level decrease 330 in the reception device is equivalent to 331. At this time, since the signal level 320 is lower than the threshold 300, it can be estimated that a new transmission can be started using the channel 36.

  To summarize the above, a value obtained by subtracting the maximum transmission level decrease value 331 from the reception level of the receiving device 252 is calculated. If there is a channel whose calculated value is smaller than the threshold 300, the process proceeds to step 406, and there is no such channel. If not, the process proceeds to step 416.

  If the process proceeds to step 406, the channel with the lowest signal level of the existing signal is determined. In FIG. 3, the channel 36 corresponds.

  Next, in step 407, each transmission apparatus and reception apparatus are inquired via the network interfaces 119 and 129 as to whether or not the minimum signal level channel determined in step 406 is used. In the example of FIGS. 2 and 3, the channel with the lowest signal level is 36, and the transmission devices 211, 221, 223, and 241 and the reception devices 212, 222, 232, and 242 are inquired whether the channel is used. Do.

  Next, in step 408, the transmitting device and the receiving device that use the inquired (estimated) channel are determined. That is, it can be determined that the transmission device 211 and the reception device 221 are using the channel 36 based on the responses from the transmission devices 211, 221, 223, and 241 and the reception devices 212, 222, 232, and 242.

  In step 407, it is also possible to uniquely determine the transmission device and the reception device by performing modulation and transmission signal processing of the modulation signal of the minimum signal level channel and obtaining the IDs of the transmission device and the reception device. In that case, step 408 may be skipped.

  Next, in step 409, the transmission level value in the transmission device and the reception level value in the reception device are acquired. That is, the transmission device 211 is inquired about the transmission level, and the transmission device 211 replies with the transmission level set by the transmission amplification unit 116. That is, the transmission device 211 answers level 330 in FIG. Similarly, the reception device 212 is inquired about the reception level, and the reception device 212 replies with the reception level detected by the transmission amplifying unit 125 and the channel selection and modulation / demodulation unit. In FIG. 3, when the reception signal of the reception device 212 is 39, the reception device 212 replies with a signal level 350.

  Subsequently, in step 410, it is determined whether or not the transmission device 211 can actually reduce the transmission level and use the inquired (estimated) channel. For the determination, the reception level of the existing signal, the transmission output control range information in the transmission device, the reception signal level information that can be received by the reception device, the transmission level of the transmission device, and the reception level of the reception device are used.

For example, when the transmission apparatus 211 has already controlled to lower the transmission level to some extent, the transmission level cannot be lowered by the magnitude of the transmission level reduction maximum value 331. Therefore, using the signal level acquired in step 409, it is determined whether or not the reduction level of the transmission level is sufficient. The maximum transmission level of the transmission device is Pmax, the transmission level of the actual transmission device corresponding to the signal 37 is Pt, the reception level of the reception device corresponding to the signal 31 is Rr, the value of the maximum transmission level decrease 331 is Pd, and the threshold value 300 If the value of is Pth, the judgment formula can be expressed by Formula 1.
Pr-Pd + (Pmax-Pt) <Pth ... Formula 1
Further, as a result of reducing the transmission level, if the reception level of the reception device 212 becomes equal to or less than the threshold value, the reception device 212 cannot receive. Therefore, the reception level of the reception device corresponding to the signal 39 is Rr2, and it is determined whether the reception level of the reception device 212 is sufficient by using the equation (2).
Pr2-Pd + (Pmax-Pt)> Pth ... Formula 2
If Expression 1 and Expression 2 are satisfied, the transmission level can be lowered, and the process proceeds to Step 411. If either Equation 1 or Equation 2 is not established, it is determined that the transmission level cannot be lowered, and the process proceeds to Step 416.

  Next, in step 411, the control unit 128 performs control via the network interface 129 so as to lower the transmission level of the transmission device 211.

  Subsequently, in step 412, transmission is started in the same manner as in step 404.

  Next, in step 413, the reception state of the reception device 212 that receives the modulation signal of the transmission device 211 whose transmission level has been lowered is confirmed. The reception level of the reception device 212, ie, 360 or SN (Signal to Noise) ratio is acquired via the network interface 129. If the reception level or SN ratio is worse than a predetermined value, the transmission device 251 that newly started transmission is sent. Assuming that the modulated signal is disturbing, the process proceeds to step 415 and the transmission of the transmission device 251 is stopped.

  On the other hand, if there is no problem with the reception level and the SN ratio in step 413, the control according to this embodiment is completed. In this case, it goes without saying that all the existing transmission devices and reception devices can perform video transmission.

After proceeding to step 415, the process of step 416 is performed. In step 416, since there is no new channel for starting transmission, a display such as “There is no free channel for wireless transmission” is generated by the video signal processing unit 122 and displayed on the video display unit 121.
The variation of the transmission signal when the above control is performed will be described with reference to FIG. In FIG. 6, the horizontal axis represents time, the vertical axis represents the transmission level of the modulated signal output from the transmission apparatuses 211 and 251, 601 represents the output from the transmission apparatus 211, and 602 represents the output from the transmission apparatus 251. At time t0, which is the initial state, the transmission device 211 performs transmission at the signal level 330, and the transmission device 251 is in a stopped state. Assume that at time t1, the transmission device 251 is activated and the control shown in FIG. 4 is started.
Whether there is a channel that can be used in step S402, or there is no channel that can start transmission due to a level decrease in step S405, or a case where the transmission level cannot be lowered in step S410 is determined. In this case, the signal level of the transmission device 211 is not changed, and the signal level remains 330 and does not change as in the state indicated by 610.
On the other hand, if it is determined in step 410 that the signal level is lowered, control is performed to lower the signal level of the transmission device 211 in step S411. In FIG. 6, step 411 is executed at time t <b> 2, and the signal level transmitted by the transmission apparatus 211 decreases to 340. Subsequently, at time t3, step 412 is executed, and the transmission apparatus 251 starts transmission at the signal level 600.
As described above, when a plurality of transmission apparatuses perform transmission using the same channel, the new transmission apparatus 251 starts transmission after reducing the signal level of the transmission apparatus 211 that has already performed transmission.
In FIG. 6, the signal level 600 is shown as an example, and the signal level 600 is uniquely determined by the transmission device 251. Therefore, the relative levels with the signal levels 330 and 340 are in the relationship shown in FIG. It is not limited.

  According to the embodiment described above, even when the channel is all used by other existing devices, the transmission level can be determined by determining the transmission device that can reuse the channel by lowering the transmission level. By controlling, it is possible to secure a transmission channel for a newly added transmission device and reception device, and the reception device can receive a modulation signal transmitted from the transmission device and display a video signal.

  Next, a control method different from that in the first embodiment will be described with reference to the drawings.

  In the present embodiment, the description of the same parts as those in the first embodiment is omitted.

  FIG. 5 shows control when the network interfaces 119 and 129 in FIG. 1 are not connected. In FIG. 5, the same reference numerals as those in FIG. 4 indicate the same control.

  First, Step 401, Step 402, Step 403, Step 404, Step 405, and Step 406 are the same as those in FIG. However, after step 406, the process proceeds to step 520.

  Next, in step 520, a connection request is made to the transmission device and the reception device that use the channel with the minimum reception level. That is, a connection request is transmitted as a control signal to the transmission device 211 and the reception device 212 using the channel 36.

  Next, in step 521, it is determined whether or not connection to the transmitting device and the receiving device that have requested connection has been established. If the transmitting device 211 and the receiving device 212 do not register the receiving device 252 as a connectable device, the connection is rejected. In this case, the process returns to step 405 to determine the level of another channel. If the transmission device 211 and the reception device 212 have registered the reception device 252 as a connectable device, the connection state is established, and the process proceeds to step 409.

  Next, in step 409, the values of the transmission level in the transmission device and the reception level in the reception device are acquired as in FIG. However, since it is in a wireless connection state, level acquisition is performed by wireless transmission of a control signal without passing through the network interfaces 119 and 129.

  The control in the next step 410 and step 411 is the same as in FIG.

  Next, in step 522, a connection release request is issued to the transmission device and the reception device that use the channel with the minimum reception level. That is, a connection release request is transmitted as a control signal to the transmission device 211 and the reception device 212 using the channel 36. By this control, the connection between the transmission device 211 and the reception device 212 is released, and the transmission device 251 and the reception device 252 can perform independent transmission.

  Subsequently, in step 412, transmission of a modulated signal is started in the same manner as in step 404.

  If a usable channel cannot be secured in step 405 and step 410, the same control as in FIG. 4 is performed in step 416.

  According to the embodiment described above, even when the channel is all used by other existing devices, the transmission level can be determined by determining the transmission device that can reuse the channel by lowering the transmission level. By controlling, it is possible to secure a transmission channel for a newly added transmission device and reception device, and the reception device can receive a modulation signal transmitted from the transmission device and display a video signal. Furthermore, even in an environment where the network interface unit is not connected, the above effect can be obtained by using only the wireless processing unit for video transmission.

  DESCRIPTION OF SYMBOLS 11 ... Reception apparatus, 111 ... Video signal source, 112 ... Video signal processing part, 113 ... Transmission signal processing part, 114 ... Modulation / demodulation channel selection part, 115 ... Reception amplification part, 116 ... Transmission amplification part, 117 ... Antenna, 118 ... Control unit, 119 ... Network interface unit, 12 ... Receiving device, 121 ... Video display unit, 122 ... Video signal processing unit, 123 ... Transmission signal processing unit, 124 ... Modulation / demodulation channel selection unit, 125 ... Reception amplification unit, 126 ... Transmission amplifying unit, 127... Antenna, 128... Control unit, 129.

Claims (7)

A wireless transmission system comprising a plurality of transmission devices that wirelessly transmit video signals and control signals, and a plurality of reception devices that receive and display signals transmitted from the transmission devices,
The wireless transmission system includes:
Transmission means for wirelessly transmitting video signals and control signals;
Detecting means for detecting a received signal level of an existing signal of an available channel;
Using the level of the received signal detected by the detecting means, estimating means for estimating a channel that is likely to be used for transmission between a new transmitting device and a receiving device;
Signal level acquisition means for acquiring a transmission level and a reception level, respectively, from a transmission apparatus and a reception apparatus that use the channel estimated by the estimation means;
Determination means for determining whether or not the estimated channel can be used for transmission between a new transmission device and a reception device, using the acquired transmission level and reception level;
A wireless transmission system, wherein a transmission level of a transmission device using a channel determined by the determination means is reduced, and transmission between a new transmission device and a reception device is started. The wireless transmission system according to claim 1,
The estimation means performs estimation using a reception signal level of the existing signal, information on a control range of a transmission output in a transmission device, and information on a reception signal level that can be received by the reception device. Wireless transmission system. The wireless transmission system according to claim 1,
The determination means includes: a reception signal level of the existing signal; information on a transmission output control range in the transmission device; information on a reception signal level that can be received by the reception device; a transmission level of the transmission device; A wireless transmission system that performs determination using a reception level of a receiving device. The wireless transmission system according to claim 1,
The signal level acquisition unit acquires a transmission level and a reception level from a transmission device and a reception device that use the channel estimated by the estimation unit, using communication by the transmission unit, respectively. system. The wireless transmission system according to any one of claims 1, 2, and 3,
After starting transmission between a new transmission device and a reception device, the reception level of the reception device using the channel determined by the determination means is acquired, and if the acquired signal level is equal to or lower than the threshold, a new transmission is performed. A wireless transmission system for stopping transmission between a device and a receiving device. A wireless transmission system according to any one of claims 1 to 5,
In the estimation means, when it is estimated that there is no channel that can be used for transmission between a new transmission apparatus and a reception apparatus, or in the determination means, transmission between a new transmission apparatus and a reception apparatus When it is determined that there is no channel that can be used, or after starting transmission between the new transmitter and receiver, the reception level of the receiver that uses the channel determined by the determination unit is acquired. When the acquired signal level is equal to or lower than the threshold value, the reception apparatus displays that there is no usable channel in the wireless transmission system. Receiving means for receiving a video signal from the transmitting device;
Communication means for communicating control signals with other devices;
Control means for controlling the receiving means and the communication means,
The control means includes
A signal reception level of a plurality of channels is detected, and based on the signal reception level, an available channel is estimated by lowering a signal level in the other device, and the transmission device is estimated using the estimated channel. A video signal receiving apparatus, wherein the video signal is controlled to be received from a video signal.

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