JP2005192039A - Wireless transmission device, wireless transmission / reception system, wireless transmission method, wireless transmission program, and recording medium recording this program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless transmission device capable of stably transmitting a signal without erroneous determination of a radio wave condition.
A radio unit for transmitting and receiving a radio frequency signal, an electric field intensity detecting unit for detecting an electric field intensity of the radio frequency signal received by the radio unit, and a main control unit for controlling these units. Is provided. The main control unit 101 compares the detection result of the electric field strength detection unit 108 with a predetermined value of a plurality of electric field strengths registered in advance, and determines the electric field strength level of the received high frequency signal. Since the frequency channel of the high-frequency signal to be transmitted is switched to another frequency channel when the electric field strength level is equal to or higher than a predetermined value, the high-frequency signal can be transmitted using the frequency channel with less radio wave interference. .
[Selection] Figure 1

Description

  The present invention relates to a wireless transmission device and a wireless transmission / reception system for transmitting signals wirelessly, and more particularly to a wireless transmission device, a wireless transmission / reception system, and a wireless transmission method for wirelessly transmitting and receiving video.

  A general wireless transmission / reception system (here, a wireless video transmission / reception system assuming transmission / reception of a video signal (including audio)) is, for example, a wireless video transmission device 300 shown in FIG. 7 and a wireless video shown in FIG. It is comprised with the receiver 400.

  FIG. 7 is a block circuit diagram of a wireless video transmission device of a conventional wireless video system, and FIG. 8 is a block circuit diagram of a wireless video reception device 400 of the conventional wireless video system.

  For example, a video tape recorder (VTR) or the like is connected to the input side of the wireless video transmission apparatus 300 shown in FIG. 7, and an AV (video, audio) signal is input. In addition, for example, a television (TV) is connected to the output side of the wireless video reception device 400 shown in FIG. 8, and an AV (video, audio) signal is output.

  Next, the operation of the conventional wireless video system including the wireless video transmission device 300 of FIG. 7 and the wireless video reception device 400 of FIG. 8 will be described below with reference to the flowcharts shown in FIGS.

  First, the wireless video transmission device 300 of FIG. 7 is activated (step S101).

  When the wireless video transmission apparatus 300 is activated, one frequency channel is selected from the three frequency channels registered in advance in the main control unit 301 (step S102), and the main frequency channel is communicated so that communication can be performed on the selected frequency channel. The control unit 301 sets a PLL circuit in the wireless unit 306 (step S103).

  Next, the wireless unit 306 is set in a reception state (step S104), the high-frequency signal received from the antenna 307 is converted into an analog in-phase / quadrature signal, and the baseband processing circuit unit 305 converts it into a baseband signal.

  Next, the electric field strength is detected from the baseband signal (step S105). Here, the electric field strength of the high-frequency signal received by the electric field strength detection unit 308 is detected, and it is determined whether the detected electric field strength is larger than a predetermined value of the electric field strength set in the electric field strength detection unit 308 by the main control unit 301 in advance. . This determination result is used as the detected value of the electric field strength and transferred to the AND circuit 310.

  Subsequently, a carrier is detected from the baseband signal (step S106). Here, it is determined whether the carrier of the high frequency signal received by the carrier detection unit 309 is the same as the high frequency signal transmitted from the wireless unit 306. This determination result is used as a carrier detection value and transferred to the AND circuit 310.

  Next, the radio wave status is determined (step S107). Here, the AND circuit 310 calculates the logical product of the determination results of the electric field strength detection unit 308 and the carrier detection unit 309, and inputs the result to the main control unit 301. If the output of the AND circuit 310 is “1”, the main control unit 301 determines that it receives radio wave interference on the set frequency channel, and among the three frequency channels registered in advance, different frequency channels. The main control unit 301 again sets the PLL circuit in the wireless unit 306 so that communication can be performed, and thereafter performs the same operation as described above to check the radio wave condition.

  If the output of the AND circuit 310 is “0”, it is determined that there is no radio wave interference in the set frequency channel, and transmission of a high-frequency signal from the wireless unit 306 is started. Then, data for establishing communication is transmitted (step S108).

  Next, it is determined whether or not there is a response from the receiving device (step S109). Here, if it is determined that there is a response from the receiving device, video transmission is started (step S110).

  As specific processing of video transmission, in the wireless video transmission device 300, the radio unit 306 converts the high-frequency signal received from the antenna 307 into an analog in-phase / quadrature signal, and the baseband processing circuit unit 305 converts the baseband signal. Convert to

  Next, the wireless control unit 304 converts the data into arbitrary data to the main control unit 301, and the main control unit 301 determines that this data is a notification that the wireless video reception device 400 can receive video. At this time, the analog signal input unit 302 and the digital signal compression unit 303 are put into an operation state.

  Thus, the analog signal from the video tape recorder (VTR) input to the analog signal input unit 302 is converted into a digital signal, and the digital signal is converted into video digital data compressed by the digital signal compression unit 303. The compressed video digital data is converted into a baseband signal of a wireless packet by the wireless control unit 304, the baseband signal is converted into an analog in-phase / quadrature signal by the baseband processing circuit unit 305, and the analog in-phase / quadrature signal is converted. The signal is converted into a high frequency signal by the wireless unit 306, and this high frequency signal is transmitted to the wireless video reception device 400 by the antenna 307.

  On the other hand, the wireless video receiving apparatus 400 shown in FIG. 8 operates as shown in the flowchart of FIG.

  First, the wireless video reception device 400 is activated (step S201).

  When the wireless video receiver 400 is activated, one frequency channel is selected from the three frequency channels registered in advance in the main control unit 401 (step S202), and the main frequency channel is communicated so that communication can be performed on the selected frequency channel. The control unit 401 sets a PLL circuit in the wireless unit 406 (step S203).

  Next, the wireless unit 406 is set in a reception state (step S204), and the presence / absence of a radio wave from the transmission device is determined (step S205).

  Specifically, the high-frequency signal received from the antenna 407 is converted into an analog in-phase / quadrature signal and converted into a baseband signal by the baseband processing circuit unit 405.

  Next, the wireless control unit 404 converts the data into arbitrary data to the main control unit 401, and the main control unit 401 receives the arbitrary data. When the main control unit 401 determines that this data is from the wireless video transmission device 300, the main control unit 401 inputs arbitrary data to the wireless control unit 404, and the baseband processing circuit unit 405, the wireless unit 406, and the antenna 407 perform high frequency. By transmitting the signal, the wireless video transmitting apparatus 300 is notified that the wireless video receiving apparatus 400 can receive the video (step S206), and the digital signal decompressing unit 403 and the analog signal output unit 402 are set in the operating state. (Step S207).

Subsequently, the wireless video reception device 400 receives the high-frequency signal from the wireless video transmission device 300 by the antenna 407, converts it to an analog in-phase / quadrature signal by the wireless unit 406, and converts the analog in-phase / quadrature signal to baseband. The processing circuit unit 405 converts it into a baseband signal, converts this baseband signal into video digital data compressed by the wireless control unit 404, and converts this compressed video digital data into a digital signal by the digital signal decompression unit 403 Then, the digital signal is output as an analog signal by the analog signal output unit 402, and an image is displayed on the connected television.
JP2003-309594 (released on October 31, 2003)

  By the way, in the conventional wireless video transmission apparatus, the electric field strength of the high-frequency signal received by the electric field strength detection unit is compared with a preset threshold value. The threshold value is set to the lower limit value of the electric field intensity that can be received by the wireless video transmission apparatus. For this reason, even a high-frequency signal with a weak electric wave and a low electric field intensity is detected, so there is a risk of misjudging that the radio wave condition is good although the radio wave condition is good. .

  Further, in the conventional wireless video transmission apparatus, when the radio wave condition is confirmed, the detection results of the electric field intensity detection unit and the carrier detection unit are determined by an AND circuit. That is, it is determined that radio wave interference is received only when the electric field strength is high and the carriers are the same. For this reason, the electric field strength of a high-frequency signal from a wireless device (for example, a microwave oven or a medical device in the 2.4 GHz band) that uses the same frequency channel but does not use the same carrier is large, so that the radio wave condition is deteriorated. Even in such a case, there is a risk of misjudging that radio wave interference is not received.

  From the above, in the conventional video wireless transmission device, there is a high possibility that the radio wave condition is erroneously determined, and thus there is a problem that the video cannot be transmitted stably.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless transmission device, a wireless transmission / reception system, and a wireless transmission method that can eliminate erroneous determination of radio wave conditions and can stably transmit video. is there.

  In order to solve the above problems, a wireless transmission device according to the present invention includes a wireless unit that transmits and receives a high-frequency signal, an electric field strength detection unit that detects an electric field strength of the high-frequency signal received by the wireless unit, A frequency channel switching unit that switches a frequency channel of a high-frequency signal to be transmitted from the radio unit to any one of a plurality of pre-registered frequency channels based on a detection result of the electric field intensity detection unit, and the frequency channel switching unit Compares the electric field intensity detected by the electric field intensity detector with a predetermined value of a plurality of different electric field strengths registered in advance, determines the electric field intensity level of the received high-frequency signal, and determines the electric field The frequency channel is switched when the intensity level is equal to or higher than a predetermined value.

  According to the above configuration, the detection result of the electric field strength detection unit is compared with the predetermined values of a plurality of different electric field strengths registered in advance in the high frequency signal, and the electric field strength level of the received high frequency signal is determined. The electric field strength level of the received high-frequency signal can be finely determined.

  As a result, it is possible to reliably detect a high-frequency signal having a low electric field intensity and a low electric field strength, so that the received high-frequency signal does not interfere with the high-frequency signal to be transmitted. In this case, there is no possibility of erroneous determination if the radio wave condition is not good.

  In addition, when the determined electric field strength level is equal to or higher than a predetermined value, that is, higher than a level that interferes with a high-frequency signal to be transmitted and affects transmission, the frequency channel of the high-frequency signal to be transmitted is switched to another frequency channel. Therefore, it is possible to transmit a high frequency signal with a frequency channel with less interference.

  Therefore, there is an effect of eliminating the erroneous determination of the radio wave condition such as determining that the radio wave condition is good even when the radio wave condition is good as in the prior art, and enabling stable transmission of the high-frequency signal.

  And a carrier detection unit for detecting a carrier of the high-frequency signal received by the radio unit, wherein the frequency channel switching unit includes a plurality of different high-frequency signals registered in advance from the electric field strength detected by the electric field strength detection unit. The field strength level of the received high-frequency signal is determined and the carrier detected by the carrier detection unit is the same as the carrier of the high-frequency signal to be transmitted from the radio unit. If the determined electric field strength level is smaller than a predetermined value and it is determined that the carriers are the same, the frequency channel may be switched.

  In this case, when it is determined that the determined electric field strength level is smaller than the predetermined value and the carrier is the same, the electric field strength level of the received high-frequency signal is set to the predetermined value described above by switching the frequency channel. In the case of smaller than that, that is, radio wave interference caused by the same carrier can be eliminated.

  In addition, since it is possible to detect a wireless device that does not use the same carrier (for example, in the 2.4 GHz band, a microwave oven or a medical device), it is possible to reliably switch to a frequency channel that is not subject to radio wave interference.

  From the above, it is possible to accurately grasp the radio wave condition, and there is an effect that stable transmission of a high-frequency signal can be ensured.

  The frequency channel switching unit prepares a plurality of groups composed of a plurality of adjacent frequency channels capable of simultaneous communication, and determines that a frequency channel in the same group cannot be used. It is preferable to determine whether or not can be used.

  In this case, it is possible to reliably select a frequency channel with less radio wave interference.

  In the wireless unit, a transmission unit for transmitting a high-frequency signal and a reception unit for receiving a high-frequency signal may be different systems.

  In this case, the reception unit is used to determine the radio wave condition, and the transmission unit is used to transmit the high frequency signal, so that the radio wave condition (electric field strength, carrier, etc.) can be obtained even during transmission of the high frequency signal. Judgment can be made in real time. That is, it becomes possible to grasp the radio wave situation in real time, which was impossible when the transmission unit and the reception unit are of the same system.

  In order to solve the above-described problem, a wireless transmission / reception system according to the present invention includes the above-described wireless transmission device and a reception device that receives a high-frequency signal transmitted from the wireless transmission device. .

  According to said structure, the system which can transmit / receive the stable signal can be provided.

  In order to solve the above-described problem, the wireless transmission method according to the present invention detects the electric field strength of the received high-frequency signal, and the detected electric field strength and a predetermined value of a plurality of different electric field strengths of the pre-registered high-frequency signal. Are compared, and the field strength level of the received high-frequency signal is determined. If the determined field strength level is equal to or higher than a predetermined value, the frequency channel of the high-frequency signal to be transmitted is switched to one of a plurality of pre-registered frequency channels. It is characterized by that.

  According to the above configuration, it is possible to transmit a signal using a frequency channel with good radio wave conditions. There is an effect of eliminating the determination and enabling stable transmission of the high-frequency signal.

  In the wireless transmission device according to the present invention, as described above, the frequency channel switching unit compares the electric field strength detected by the electric field strength detection unit with the prescribed values of a plurality of different electric field strengths of pre-registered high-frequency signals. When the field strength level of the received high-frequency signal is determined and the determined field strength level is equal to or higher than the predetermined value, the frequency channel is switched, so that erroneous determination of radio wave conditions is eliminated and stable transmission of the high-frequency signal is achieved. It has the effect of making it possible.

  An embodiment of the present invention will be described as follows. In this embodiment, a wireless video system that transmits and receives video signals will be described as a wireless transmission / reception system.

  The wireless video system according to the present embodiment includes a wireless video transmission device 100 shown in FIG. 1 and a wireless video reception device 200 shown in FIG. In this embodiment, the frequency band of a signal to be transmitted / received is described as a 2.4 GHz band, but the present invention is not limited to this. FIG. 1 shows a schematic configuration of a wireless video transmitting apparatus 100 according to the present embodiment, and FIG. 2 shows a schematic configuration of a wireless video receiving apparatus 200 according to the present embodiment.

  First, the wireless video transmission apparatus 100 will be described below.

  As shown in FIG. 1, the wireless video transmission apparatus 100 includes a main control unit 101, an analog signal input unit 102, a digital signal compression unit 103, a wireless control unit 104, a baseband processing circuit unit 105, a wireless unit 106, an antenna 107, An electric field intensity detector 108 and a carrier detector 109 are included.

  That is, in the wireless video transmission apparatus 100, the output side of the analog signal input unit 102 is connected to the input side of the digital signal compression unit 103, and the output side of the digital signal compression unit 103 is connected to the input side of the wireless control unit 104. The radio control unit 104 and the baseband processing circuit unit 105 are connected bidirectionally, and the output side of the baseband processing circuit unit 105 is connected to the input side of each of the electric field strength detection unit 108 and the carrier detection unit 109, The baseband processing circuit unit 105 and the radio unit 106 are connected bidirectionally, and an antenna 107 is connected to the radio unit 106.

  The main control unit 101 includes an analog signal input unit 102, a digital signal compression unit 103, a radio control unit 104, a baseband processing circuit unit 105, a radio unit 106, an antenna 107, an electric field strength detection unit 108, and a carrier detection unit 109. Are connected to each other to control each part.

  The analog signal input unit 102 receives an analog AV signal (video signal and audio signal) from a video device (not shown) such as a video tape recorder on the signal input side, and converts the analog AV signal into a digital AV signal. Then, the digital AV signal is transferred to the digital signal compression unit 103.

  The digital signal compression unit 103 compresses the digital AV signal transferred from the analog signal input unit 102 by a predetermined compression method, and then transfers the compressed signal to the wireless control unit 104.

  The radio control unit 104 converts the compressed signal transferred from the digital signal compression unit 103 into a baseband signal, and then transfers the baseband signal to the baseband processing circuit unit 105.

  The baseband processing circuit unit 105 modulates the baseband signal transferred from the radio control unit 104, generates an analog in-phase / quadrature signal, and transfers the analog in-phase / quadrature signal to the radio unit 106. It has become.

  The radio unit 106 converts the analog in-phase / quadrature signal transferred from the baseband processing circuit unit 105 into a high-frequency signal and transfers the signal to the antenna 107.

  The antenna 107 sends out the transferred high-frequency signal to the outside.

  The wireless unit 106 not only transfers a high frequency signal to the antenna 107 but also receives a high frequency signal transferred from the antenna 107. The received high frequency signal is transferred from the wireless unit 106 to the baseband processing circuit unit 105.

  In the baseband processing circuit unit 105, the high-frequency signal transferred from the radio unit 106 is transferred to the electric field intensity detection unit 108 and also transferred to the carrier detection unit 109.

  The electric field strength detection unit 108 detects the electric field strength of the transferred high-frequency signal, and transfers the electric field strength detection result to the main control unit 101.

  The carrier detection unit 109 detects the carrier of the transferred high-frequency signal, and transfers the carrier detection result to the main control unit 101 (frequency channel switching unit).

  The main control unit 101 compares and determines the magnitudes of the predetermined values of different electric field strengths of the high-frequency signals registered in advance and the electric field strengths of the high-frequency signals transferred from the electric field strength detection unit 108, and is transferred. The electric field strength of high frequency signals is classified in stages. That is, the main control unit 101 determines the level of the electric field strength of the received high frequency signal. When the determined electric field intensity level is a predetermined value or more, the frequency channel is switched.

  Here, the predetermined value indicates an electric field intensity level that gives radio wave interference to a high frequency signal to be transmitted. If the electric field intensity level is higher than the predetermined value, the high frequency signal cannot be transmitted due to radio wave interference. Occurs.

  The main control unit 101 determines whether or not the carrier of the high frequency signal transferred from the carrier detection unit 109 is the same as the carrier to be transmitted from the radio unit 106.

  In this case, the main control unit 101 switches the frequency channel when it is determined that the determined electric field intensity level is smaller than a predetermined value and the carrier is the same, so that the electric field of the received high-frequency signal is changed. Problems caused when the intensity level is smaller than the predetermined value described above, that is, radio wave interference caused by the same carrier can be eliminated.

  In addition, since it is possible to detect a wireless device that does not use the same carrier (for example, in the 2.4 GHz band, a microwave oven or a medical device), it is possible to reliably switch to a frequency channel that is not subject to radio wave interference.

  From the above, it is possible to accurately grasp the radio wave condition, and there is an effect that stable transmission of a high-frequency signal can be ensured.

  Therefore, the main control unit 101 detects a frequency channel that is not subjected to radio wave interference generated by an external device or the like based on these two determination results, that is, the electric field intensity level and the carrier identity. The wireless video transmission apparatus 100 is controlled to transmit the AV signal by the detected frequency channel.

  The main control unit 101 prepares a plurality of groups composed of a plurality of adjacent frequency channels that can simultaneously communicate, and determines that all frequency channels in the same group cannot be used. The frequency channels are sequentially switched.

  Specifically, as a group composed of a plurality of adjacent frequency channels capable of simultaneous communication, A group frequency channels (2412 MHz, 2442 MHz, 2472 MHz) and B group frequency channels (2427 MHz, 2457 MHz, 2484 MHz). ) Are registered in advance, and the PLL circuit in the wireless unit 106 is set so that communication can be performed using the frequency channel detected by the above-described detection operation.

  Next, the wireless video receiving apparatus 200 will be described below.

  As shown in FIG. 2, the wireless video receiving apparatus 200 includes a main control unit 201, an analog signal output unit 202, a digital signal expansion unit 203, a wireless control unit 204, a baseband processing circuit unit 205, a wireless unit 206, and an antenna 207. Thus, the configuration is the same as that of the wireless video receiver of the conventional wireless video system.

  That is, in the wireless video receiving apparatus 200, the wireless unit 206 is connected to the antenna 207, the wireless unit 206 and the baseband processing circuit unit 205 are connected bidirectionally, and the output side of the wireless control unit 204 is a digital signal. Connected to the input side of the expansion unit 203, the output side of the digital signal expansion unit 203 is connected to the input side of the analog signal output unit 202.

  The main control unit 201 is bi-directionally connected to the analog signal output unit 202, the digital signal decompression unit 203, the radio control unit 204, the baseband processing circuit unit 205, and the radio unit 206, and controls each unit. It has become.

  The radio unit 206 converts a high-frequency signal received from the antenna 207 into an analog in-phase / quadrature signal and transfers the analog in-phase / quadrature signal to the baseband processing circuit unit 205.

  The baseband processing circuit unit 205 converts the transferred analog in-phase / quadrature signal into a baseband signal, and transfers the baseband signal to the radio control unit 204.

  The wireless control unit 204 converts the transferred baseband signal into compressed digital AV data and arbitrary transmission / reception data for control, and transfers the compressed digital AV data to the digital signal decompressing unit 203. At the same time, arbitrary transmission / reception data for control is transferred to the main control unit 201.

  The digital signal decompression unit 203 decompresses the transferred compressed digital AV data by a method corresponding to the data compression method, and transfers the decompressed digital AV data to the analog signal output unit 202.

  The analog signal output unit 202 converts the transferred digital AV data into analog AV data, and transfers the analog AV data as an AV signal to a display device such as a TV.

  Further, the main control unit 201 is similar to the main control unit 101 of the wireless video transmission apparatus 100 described above, and the A group frequency channels (2412 MHz, 2442 MHz, 2472 MHz) and the B group frequency channels (2427 MHz, 2457 MHz). , 2484 MHz) is registered in advance, and a PLL circuit in the wireless unit 206 is set so that communication can be performed using the frequency channel detected by the above-described detection operation.

  Here, the operation flow of the wireless video system having the above-described configuration will be described below.

  First, the transmission operation of the wireless video transmission apparatus 100 will be described below with reference to the block diagram shown in FIG. 1 and the flowchart shown in FIG.

  The wireless video transmission device 100 is activated (step S1).

  When starting up the wireless video transmission apparatus 100, a group of frequency channels registered in advance in the main control unit 101 is selected (step S2), and further, a frequency channel is selected from the selected group (step S3). The frequency channel which can be communicated by the part 106 is set (step S4).

  Specifically, the main control unit 101 first selects the A group frequency channel (2412 MHz, 2442 MHz, 2472 MHz) and the B group frequency channel (2427 MHz, 2457 MHz, 2484 MHz) registered in advance. One frequency channel (for example, 2412 MHz) of the group is selected, and the PLL circuit in the wireless unit 106 is set so that communication can be performed on the selected frequency channel.

  Next, the wireless unit 106 is set to the reception state (step S5). As a result, it is possible to receive a high-frequency signal emitted from a device existing around the wireless video transmission device 100.

  Specifically, the radio unit 106 is set in a receiving state, the radio unit 106 converts a high-frequency signal received from the antenna 107 into an analog in-phase / quadrature signal, and the baseband processing circuit unit 105 converts it into a baseband signal.

  Subsequently, the electric field strength of the received high frequency signal is detected (step S6). Here, the main control unit 101 sets a plurality of different (for example, three types) prescribed values of electric field strength in the electric field strength detection unit 108, and determines whether the detected electric field strength is larger than the prescribed value. The electric field strength of the signal is divided into stages.

  And based on the detected electric field strength, a radio wave condition is judged (step S7). Here, if the detected electric field strength is larger than a specified value (for example, a preset electric field strength), it is determined that the high-frequency signal of the frequency channel set in step S4 has already been used, and the process proceeds to step S13. On the other hand, if the detected electric field strength is equal to or less than the above specified value, the process proceeds to step S8.

  In step S8, the carrier detection unit 109 detects the carrier of the received high frequency signal.

  Subsequently, the radio wave status is determined based on the detected carrier (step S9). Here, it is determined whether the detected carrier is the same carrier as the high-frequency signal transmitted from the wireless unit 106.

  If it is determined in step S9 that the detected carrier is the same carrier as the high-frequency signal transmitted from the radio unit 106, it is determined that the high-frequency signal of the frequency channel set in step S4 is already used, and step S13. Migrate to This is because even if the electric field strength is less than the specified value, there is a possibility of interfering with the high frequency signal to be transmitted.

  If it is determined in step S9 that the detected carrier is not the same carrier as the high-frequency signal transmitted from the radio unit 106, it is determined that the high-frequency signal of the frequency channel set in step S4 is not used. A high frequency signal is transmitted from the wireless unit 106 through the frequency channel.

  Here, when it is determined in steps S7 and S9 that the radio wave condition is bad, the process proceeds to step S13 and the following processing is performed.

  The main control unit 101 determines whether there is a possibility of radio wave interference in the set frequency channel based on the determination results of the electric field intensity detection unit 108 and the carrier detection unit 109, and may cause radio wave interference. If it is determined that there is, it is determined in step S13 whether or not the setting of all the frequency channels in the current frequency channel group has been completed.

  If it is determined in step S13 that all frequency channels in the current frequency channel group have not been set, the process proceeds to step S3, and other frequency channels in the same group are selected and the same as described above. Process. That is, the main control unit 101 sets the PLL circuit in the radio unit 106 again so that communication can be performed on another frequency channel (for example, 2442 MHz) of the A group, and thereafter, the same operation as described above is performed, and the radio wave condition is changed. Check.

  In step S13, if the setting of all the frequency channels in the current frequency channel group is completed, the process proceeds to step S2, the frequency channel of another group is selected, and the same as described above. Process. That is, when it is determined that there is a possibility of receiving radio wave interference in all frequency channels of the A group, one frequency channel (for example, 2427 MHz) out of the B group frequency channels (2427 MHz, 2457 MHz, 2484 MHz). The main control unit 101 sets the PLL circuit in the wireless unit 106 again so that communication can be performed on the selected frequency channel. Thereafter, the same operation as described above is performed to check the radio wave condition.

  By repeating the above operation, a frequency channel that is not subject to radio wave interference is detected, and a high-frequency signal is transmitted through this frequency channel.

  Next, the wireless video transmission apparatus 100 transmits data for establishing communication on a frequency channel that is not subject to radio wave interference (step S10).

  Subsequently, it is determined whether or not there is a response from the receiving device (step S11). Here, whether or not there is a response to the result of transmitting the data for establishing communication from the wireless video transmission device 100 to the wireless video reception device 200 that is the transmission partner, that is, whether or not the wireless video reception device 200 is enabled to receive video. Judging.

  In step S11, if there is a response from the receiving device, the process proceeds to step S12 and video transmission is started.

  On the other hand, if there is no response from the receiving device in step S11, the process proceeds to step S13, and the same processing is performed on other frequency channels.

  Specifically, the high-frequency signal received from the antenna 107 is converted into an analog in-phase / quadrature signal by the wireless unit 106, and converted to a baseband signal by the baseband processing circuit unit 105. Next, the wireless control unit 104 converts the data into arbitrary data to the main control unit 101, and the main control unit 101 determines that this data is a notification that the wireless video reception device 200 can receive video. At this time, the analog signal input unit 102 and the digital signal compression unit 103 are set in an operating state.

  Thus, the analog signal from the video tape recorder (VTR) input to the analog signal input unit 102 is converted into a digital signal, and the digital signal is converted into video digital data compressed by the digital signal compression unit 103. The compressed video digital data is converted into a baseband signal of a wireless packet by the wireless control unit 104, the baseband signal is converted into an analog in-phase / quadrature signal by the baseband processing circuit unit 105, and the analog in-phase / quadrature signal is converted. The signal is converted into a high-frequency signal by the wireless unit 106, and this high-frequency signal is transmitted to the wireless video reception device 200 by the antenna 107.

  Next, the receiving operation in the wireless video receiving apparatus 200 will be described below with reference to the block diagram shown in FIG. 2 and the flowchart shown in FIG.

  The wireless video reception device 200 is activated (step S21).

  When the wireless video reception device 200 is activated, a frequency channel registered in advance in the main control unit 201 is selected (step S22), and a frequency channel that can be communicated by the wireless unit 206 is set (step S23).

  Specifically, from the A group frequency channels (2412 MHz, 2442 MHz, 2472 MHz) and the B group frequency channels (2427 MHz, 2457 MHz, 2484 MHz) pre-registered in the main control unit 201 at the start, The main control unit 201 sets a PLL circuit in the radio unit 206 so that one frequency channel (for example, 2412 MHz) of the A group is selected and communication can be performed on the selected frequency channel.

  Next, the wireless unit 206 is set to the reception state (step S24), and the presence / absence of radio waves from the transmission device is determined (step S25).

  Specifically, the radio unit 206 converts the high-frequency signal received from the antenna 207 into an analog in-phase / quadrature signal, and the baseband processing circuit unit 205 converts it into a baseband signal. Next, the wireless control unit 204 converts the data into arbitrary data to the main control unit 201, and the main control unit 201 receives the arbitrary data.

  Here, if the main control unit 201 determines that the received arbitrary data is from the wireless video transmission device 100, the main control unit 201 transmits data for establishing communication (step S26).

  Specifically, when the main control unit 201 determines that the received data is from the wireless video transmission device 100, the main control unit 201 inputs arbitrary data to the wireless control unit 204, and the baseband processing circuit unit 205, The high-frequency signal is transmitted from the unit 206 and the antenna 207 to notify the wireless video transmission device 100 that the wireless video reception device 200 can receive video, and the digital signal expansion unit 203 and the analog signal output unit 202 operate. Put it in a state.

  On the other hand, if the main control unit 201 determines that the received arbitrary data is not from the wireless video transmission device 100, the main control unit 201 proceeds to step S22 to select and set another frequency channel.

  Further, after establishing communication, the wireless video reception device 200 starts video reception (step S27).

  Specifically, the wireless video reception device 200 receives the high-frequency signal from the wireless video transmission device 100 by the antenna 207, converts it to an analog in-phase / quadrature signal by the wireless unit 206, and converts this analog in-phase / quadrature signal to The baseband processing circuit unit 205 converts the baseband signal into a baseband signal, converts the baseband signal into video digital data compressed by the wireless control unit 204, and converts the compressed video digital data into a digital signal by the digital signal decompression unit 203. The digital signal is output as an analog AV signal by the analog signal output unit 202, and the video is displayed on the television connected to the wireless video receiver 200.

  As described above, in the wireless video transmission device 100, based on the electric field strength and carrier of the high-frequency signal received by the wireless video transmission device 100, a frequency channel that is not subject to radio wave interference is found, and the high-frequency signal is detected by the frequency channel. That is, since the AV signal is transmitted, the wireless video receiving apparatus 200 can reliably receive the AV signal.

  As a result, it is possible to eliminate problems such as image disturbance due to the disconnection of radio, so that it is possible to view a video with high display quality.

  In wireless video transmission apparatus 100, as shown in step S12 of the flowchart shown in FIG. 3, after starting video transmission, the communication status is determined, and processing such as changing the frequency channel according to the communication status is performed. May be.

  Such a processing flow can be shown by a flowchart shown in FIG. 5, for example.

  In the flowchart shown in FIG. 5, steps S31 to S43 correspond to steps S1 to S13 in the flowchart shown in FIG. 3, respectively, and steps S44 to S46 are newly added processes.

That is, after video transmission is started in step S42, the presence or absence of a communication error is monitored (step S44). Here, if a communication error occurs, video transmission is stopped (step S45). Then, it is determined whether or not the wireless video transmission device 100 is stopped (step S46).
In step S46, if the wireless video transmitting apparatus 100 is not stopped, the process proceeds to step S13, another frequency channel is selected, and the same processing is performed.

  Specifically, the wireless video transmission apparatus 100 periodically monitors whether a received packet has been normally received from a signal converted into a packet by the wireless control unit 104 even after the start of video transmission, and the packet that has not been received. If there is a lot of interference and it is determined that radio wave interference can occur (when a communication error occurs), search again for a frequency channel with good radio wave conditions and use another frequency channel that is prepared in advance. By doing so, interference with other wireless systems is reduced.

  In step S46, if the wireless video transmission device 100 is stopped, the process is terminated.

  As described above, for example, a wireless video transmission as shown in FIG. 6 is performed as an apparatus for determining the presence or absence of a communication error after video transmission is started and constantly transmitting a high-frequency signal through an appropriate frequency channel. A device 110 is conceivable.

  FIG. 6 shows a schematic configuration of the wireless video transmission apparatus 110.

  The wireless video transmission device 110 is obtained by adding a second baseband processing circuit unit 111, a second wireless unit 112, and a second antenna 113 to each component of the wireless video transmission device 100 shown in FIG. .

  That is, in the wireless video transmission device 100 described above, the radio wave condition is detected by the baseband processing circuit unit 105, the wireless unit 106, and the antenna 107 used for video transmission. 110 has a configuration in which a second baseband processing circuit unit 111, a second radio unit 112, and a second antenna 113 for detecting a radio wave condition are separately provided.

  The second baseband processing circuit unit 111 is connected to the baseband processing circuit unit 105, the electric field strength detection unit 108, the carrier detection unit 109, and the second radio unit 112.

  Accordingly, the high-frequency signal received by the second antenna 113 is converted into an analog in-phase / quadrature signal by the second radio unit 112 and converted to a baseband signal by the second baseband processing circuit unit 111.

  This baseband signal is transferred to the electric field strength detection unit 108 and the carrier detection unit 109, and is used for electric field strength detection and carrier detection. Based on the detected electric field strength and carrier, the radio wave condition, that is, a free frequency channel can be found.

  In the wireless video transmission device 110 illustrated in FIG. 6, while transmitting video using the baseband processing circuit unit 105, the wireless unit 106, and the antenna 107, the second baseband processing circuit unit 111 and the second wireless unit 112. Since the radio wave condition can be detected by the second antenna 113, the frequency channel can be quickly switched when the radio wave condition becomes worse and the frequency channel has to be changed.

  Therefore, in the wireless video receiving apparatus 200 shown in FIG. 2, for example, which is a communication partner of the wireless video transmitting apparatus 110, the time during which video is interrupted due to changes in radio wave conditions can be shortened. It is possible to provide a video system.

  In the present embodiment, as a frequency channel used for communication, two groups of 2.4 GHz band, that is, a frequency band of A group (2412 MHz, 2442 MHz, 2472 MHz) and a frequency channel of B group (2427 MHz, 2457 MHz). However, the present invention is not limited to this, and other frequency channels may be used.

  In addition, the present invention can be applied not only when the 2.4 GHz band is used but also when the frequency channel of the 5 GHz band is used.

  In the present embodiment, an example in which an analog video signal is converted to digital in the wireless video system has been described. However, the present invention is not limited to this, and a digital video signal may be directly handled. . For example, in FIG. 1, when the AV signal from the VTR is digital instead of analog, the digital AV signal is directly input to the transmitting device 100, or the digital AV signal is output from the receiving device 200 in FIG. The case where it inputs into digital TV can be considered. In this case, each circuit for A / D and D / A conversion can be omitted, so that the apparatus can be miniaturized. Further, since transmission with analog signals can be eliminated, high-quality video signals can be transmitted.

  In addition, in each unit and each processing step of the wireless video transmission apparatus according to the above embodiment, a calculation unit such as a CPU executes a program stored in a storage unit such as a ROM (Read Only Memory) or a RAM, and an input such as a keyboard is performed. It can be realized by controlling a means, an output means such as a display, or a communication means such as an interface circuit. Therefore, various functions and various processes of the wireless video transmission apparatus according to the present embodiment can be realized simply by a computer having these means reading the recording medium storing the program and executing the program. In addition, by recording the program on a removable recording medium, the various functions and various processes described above can be realized on an arbitrary computer.

  As this recording medium, a program medium such as a memory (not shown) such as a ROM may be used for processing by the microcomputer, or a program reader is provided as an external storage device (not shown). It may be a program medium that can be read by inserting a recording medium therein.

  In any case, the stored program is preferably configured to be accessed and executed by the microprocessor. Furthermore, it is preferable that the program is read out, and the read program is downloaded to a program storage area of the microcomputer and the program is executed. It is assumed that the download program is stored in the main device in advance.

  The program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a flexible disk or a hard disk, or a disk such as a CD / MO / MD / DVD. Fixed disk system, card system such as IC card (including memory card), or semiconductor memory such as mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), flash ROM, etc. In particular, there are recording media that carry programs.

  In addition, if the system configuration is capable of connecting to a communication network including the Internet, the recording medium is preferably a recording medium that fluidly carries the program so as to download the program from the communication network.

  Further, when the program is downloaded from the communication network as described above, it is preferable that the download program is stored in the main device in advance or installed from another recording medium.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. That is, embodiments obtained by combining technical means appropriately changed within the scope of the claims are also included in the technical scope of the present invention.

  The present invention is preferably used in a wireless transmission / reception system that is susceptible to radio wave interference, and in particular, can be preferably used in a system that wirelessly transmits and receives video.

1, showing an embodiment of the present invention, is a block diagram showing a wireless video transmission apparatus. FIG. 1, showing an embodiment of the present invention, is a block diagram showing a wireless video receiver. FIG. It is a flowchart which shows the flow of a process of transmission operation | movement of the radio | wireless video transmission apparatus shown in FIG. 3 is a flowchart showing a flow of processing of a reception operation of the wireless video reception device shown in FIG. 6 is a flowchart showing another process flow of the transmission operation of the wireless video transmission apparatus shown in FIG. 1. FIG. 10 is a block diagram illustrating a wireless video transmission apparatus according to another embodiment of the present invention. It is a block diagram which shows a prior art and shows a radio | wireless video transmission apparatus. It is a block diagram which shows a prior art and shows a radio | wireless video receiver. It is a flowchart which shows the flow of a process of transmission operation | movement of the radio | wireless video transmission apparatus shown in FIG. It is a flowchart which shows the flow of a process of the transmission operation | movement of the radio | wireless video receiver shown in FIG.

Explanation of symbols

100 wireless video transmission apparatus 101 main control unit (frequency channel switching unit)
102 Analog signal input unit 103 Digital signal compression unit 104 Radio control unit 105 Baseband processing circuit unit 106 Radio unit 107 Antenna 108 Electric field intensity detection unit 109 Carrier detection unit 110 Wireless video transmission device 111 Second baseband processing circuit unit 112 2 radio units 113 second antenna 200 radio video receiver 201 main control unit 202 analog signal output unit 203 digital signal decompression unit 204 radio control unit 205 baseband processing circuit unit 206 radio unit 207 antenna

Claims (8)

A radio unit for transmitting and receiving high-frequency signals;
An electric field strength detection unit for detecting the electric field strength of the high-frequency signal received by the radio unit;
A frequency channel switching unit that switches a frequency channel of a high-frequency signal to be transmitted from the radio unit to one of a plurality of pre-registered frequency channels based on a detection result of the electric field strength detection unit;
The frequency channel switching unit is
The electric field intensity detected by the electric field intensity detection unit is compared with a predetermined value of a plurality of different electric field strengths of the pre-registered high-frequency signal, the electric field intensity level of the received high-frequency signal is determined, and the determined electric field intensity level A radio transmission apparatus that switches a frequency channel when is equal to or greater than a predetermined value. Furthermore, a carrier detection unit that detects a carrier of a high-frequency signal received by the radio unit,
The frequency channel switching unit is
The carrier intensity is detected by comparing the electric field intensity detected by the electric field intensity detector with a predetermined value of a plurality of different electric field intensities registered in advance to determine the electric field intensity level of the received high-frequency signal. It is determined whether or not the carrier detected by the radio unit and the carrier of the high-frequency signal to be transmitted from the radio unit are the same, and the determined electric field strength level is smaller than a predetermined value and the carrier is the same. The radio transmission apparatus according to claim 2, wherein the frequency channel is switched in a case where the frequency channel is changed. The frequency channel switching unit is
Prepare multiple groups consisting of multiple adjacent frequency channels that can communicate simultaneously, and when it is determined that all frequency channels in the same group cannot be used, the frequency channels in other groups are switched sequentially. The wireless transmission device according to claim 1.   The radio transmission apparatus according to claim 1, wherein the radio unit includes a transmission unit for transmitting a high-frequency signal and a reception unit for receiving the high-frequency signal in different systems. The wireless transmission device according to any one of claims 1 to 4,
A wireless transmission / reception system comprising: a wireless reception device that receives a high-frequency signal transmitted from the transmission device. Detect the electric field strength of the received high-frequency signal,
Comparing the detected electric field strength with a predetermined value of a plurality of different electric field strengths of the high-frequency signal registered in advance, determining the electric field strength level of the received high-frequency signal, and when the determined electric field strength level is a predetermined value or more, A radio transmission method characterized by switching a frequency channel of a high-frequency signal to be transmitted to one of a plurality of frequency channels registered in advance. On the computer,
A procedure for comparing the field strength of the received high-frequency signal with a predetermined value of a plurality of different field strengths of the pre-registered high-frequency signal and determining the field strength level of the received high-frequency signal;
A program for executing a procedure for switching a frequency channel of a high-frequency signal to be transmitted to one of a plurality of pre-registered frequency channels when the electric field strength level determined by the above procedure is a predetermined value or more.   A computer-readable recording medium on which the program according to claim 7 is recorded.

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