JP2018148322A - Transmitting and receiving system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transmit a communication signal in the upstream direction without complicating a configuration of a device.SOLUTION: One of transmitting and receiving apparatuses includes first converting means that converts a video signal into a predetermined frequency band, first transmitting means that transmits a video signal converted into the predetermined frequency band to the other transmitting and receiving apparatus, first receiving means that receives a communication signal transmitted from a subscriber side, and second conversion means that converts the communication signal into a frequency band lower than the predetermined frequency band, and the other transmitting and receiving apparatus includes second receiving means that receives a video signal, third conversion means that converts the video signal into a frequency band lower than the predetermined frequency band, fourth conversion means that converts the communication signal into the predetermined frequency band, and second transmitting means that transmits the communication signal to the one transmitting and receiving apparatus, and at least one of spurious signals generated by the fourth converting means is included in the predetermined frequency band.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transmission / reception system.

  In recent years, there has been a demand for a system that wirelessly relays a CATV signal, a terrestrial digital broadcast signal, and the like for the purpose of distributing a signal to a difficult viewing area such as CATV (Community Antenna Television) or terrestrial digital broadcasting, or for a temporary distribution in a disaster. It is growing.

  In the technique disclosed in Patent Document 1, a transmission device up-converts a transmission signal (BS / CS-IF) and a pilot signal to a millimeter wave band and wirelessly transmits them, and a reception device down-converts a reception signal. The received transmission signal and the received pilot signal are separated. Further, the receiving device generates a correction reference signal (SBASE) having the same frequency as the pilot signal generated on the transmitting device side, and generates a correction signal having a frequency difference between the frequency of this signal and the received pilot signal. The original transmission signal is restored by correcting the frequency of the reception transmission signal using this correction signal.

JP 2005-323341 A

  By the way, in recent years, for example, there is an increasing demand for transmitting communication signals in the upstream direction (from the subscriber side to the center side device) such as the Internet by wireless communication. However, the conventional technique disclosed in Patent Document 1 has a problem that transmission in the uplink direction cannot be realized.

  In addition, when an upstream communication signal is transmitted, there is a problem that the configuration of the apparatus becomes complicated due to the frequency characteristics of the communication signal.

  The present invention has been made in view of the above points, and an object thereof is to provide a transmission / reception system capable of transmitting an upstream communication signal without complicating the configuration of the apparatus.

In order to solve the above-described problem, the present invention provides a transmission / reception system that wirelessly transmits and receives information between one transmission / reception device and the other transmission / reception device using a predetermined frequency band. First conversion means for converting a signal into the predetermined frequency band; and first transmission means for transmitting the video signal converted into the predetermined frequency band by the first conversion means to the other transmission / reception device; A first receiving means for receiving a communication signal transmitted from the other transmitting / receiving apparatus; and a first receiving means for converting the frequency of the communication signal received by the first receiving means into a frequency band lower than the predetermined frequency band. And the second transmission / reception device receives the video signal transmitted by the first transmission unit and receives the video signal by the second reception unit. Third conversion means for converting the frequency of the video signal to the frequency band lower than the predetermined frequency band, fourth conversion means for converting the communication signal to the predetermined frequency band, and the fourth conversion Second transmission means for transmitting the communication signal converted into the predetermined frequency band by the means to the one transmission / reception device, and at least one of the spurious signals generated by the fourth conversion means is The transmission / reception system is included in the predetermined frequency band.
According to such a configuration, it is possible to transmit an upstream communication signal without complicating the configuration of the apparatus.

Further, the present invention is characterized in that the one transmission / reception apparatus has an increase / decrease means for increasing / decreasing a signal level of the communication signal based on the spurious signal included in the predetermined frequency band.
According to such a configuration, the signal level of the communication signal can be kept constant with a simple configuration.

Further, according to the present invention, the one transmission / reception device has an adding means for adding a pilot signal to the video signal, and the other transmission / reception device has the third conversion means based on the pilot signal. 2. The signal is converted into the frequency band lower than the predetermined frequency band, and the fourth conversion unit converts the communication signal into the predetermined frequency band based on the pilot signal. Or the transmission / reception system of 2.
According to such a configuration, the frequency conversion is performed based on the pilot signal, thereby achieving synchronization with the center side device and reducing the number of oscillators, thereby simplifying the configuration.

In the present invention, the video signal includes the video signal in a second frequency band having a first frequency band and a band higher than the first frequency band, and the first transmission means includes the first frequency band And the video signal in the second frequency band is transmitted by polarization multiplexing.
According to such a configuration, it is possible to transmit video signals in the first frequency band and the second frequency band using a limited frequency band.

Further, the present invention is characterized in that the predetermined frequency band is a 23 GHz band.
According to such a configuration, it is possible to transmit not only a video signal but also a communication signal using a specified frequency band.

  According to the present invention, it is possible to provide a transmission / reception system capable of transmitting an upstream communication signal without complicating the configuration of the apparatus.

It is a figure which shows the structural example of the transmission / reception system which concerns on embodiment of this invention. It is a figure which shows the structural example of the center side apparatus and subscriber side apparatus which are shown in FIG. It is a figure which shows the detailed structural example of the UHF transmission part shown in FIG. It is a figure which shows the detailed structural example of the VHF transmission part shown in FIG. It is a figure which shows the detailed structural example of the UHF receiving part shown in FIG. FIG. 3 is a diagram illustrating a detailed configuration example of a VHF receiving unit illustrated in FIG. 2. It is a figure which shows the detailed structural example of the communication signal transmission part shown in FIG. It is a figure which shows the detailed structural example of the communication signal receiving part shown in FIG. It is a figure for demonstrating operation | movement of embodiment shown in FIG. It is a figure for demonstrating operation | movement of embodiment shown in FIG.

  Next, an embodiment of the present invention will be described.

(A) Description of Configuration of Embodiment of the Present Invention FIG. 1 is a diagram illustrating a configuration example of a transmission / reception system according to an embodiment of the present invention. As shown in FIG. 1, the transmission / reception system according to the embodiment of the present invention includes a center side device 10, antennas 20 and 30, and a subscriber side device 40 as main components. The transmission / reception system is a system that is installed for the purpose of providing video distribution and communication services to, for example, difficult viewing areas such as remote islands, and areas where infrastructure has been damaged by an earthquake disaster or the like.

  Here, the center side device 10 converts the video signal in the 90 to 770 MHz band into a radio wave in the 23 GHz band (23.2 to 23.6 GHz), transmits the radio signal via the antenna 20, and the subscriber side device 40. The communication signal of 23 GHz band transmitted from is received and transmitted to a network (for example, the Internet). In the following, for convenience, among the video signals in the 90 to 770 MHz band, the frequency band having a relatively low frequency (for example, 90 MHz to 402 MHz) is the VHF band, and the frequency band having a relatively high frequency (for example, 402 MHz to 770 MHz). Is called the UHF band.

  The antenna 20 is configured by, for example, a parabolic antenna, and transmits a signal supplied from the center side device 10 as a radio wave toward the antenna 30 and receives a radio wave transmitted from the antenna 30 to the center side device 10. Supply.

  The antenna 30 is configured by a parabolic antenna, for example, and transmits a signal supplied from the subscriber side device 40 as a radio wave toward the antenna 20 and receives a radio wave transmitted from the antenna 20 to receive the subscriber side device. 40.

  The subscriber-side device 40 is, for example, disposed at the subscriber's home and demodulates the signal received by the antenna 30 and supplies the communication signal supplied from the personal computer to the television receiver and the personal computer, for example. The signal is converted into a signal and supplied to the antenna 30.

  FIG. 2 is a diagram showing a detailed configuration example of the center side device 10 and the subscriber side device 40 shown in FIG. As illustrated in FIG. 2, the center side device 10 includes a UHF transmission unit 11, a VHF transmission unit 12, and a communication signal reception unit 13 as main components.

  Here, the UHF transmitter 11 converts the video signal in the UHF band into a 23 GHz band, and transmits it from the antenna 20 as a horizontally polarized radio wave. The VHF transmission unit 12 converts a video signal in the VHF band into a 23 GHz band and transmits it from the antenna 20 as a vertically polarized radio wave. The communication signal receiving unit 13 converts the communication signal received by the antenna 20 into the original frequency, and outputs it to a network such as the Internet, for example.

  The subscriber-side device 40 includes a UHF receiver 41, a VHF receiver 42, and a communication signal transmitter 43 as main components.

  The UHF receiving unit 41 receives the 23 GHz band video signal transmitted from the UHF transmitting unit 11, converts it to the original frequency, and outputs it. The VHF receiver 42 receives the 23 GHz band video signal transmitted from the VHF transmitter 12, converts it to the original frequency, and outputs it. The communication signal transmission unit 43 converts a communication signal supplied from a subscriber's personal computer or the like into a 23 GHz band signal, and then transmits the signal through the antenna 30.

  FIG. 3 is a diagram illustrating a detailed configuration example of the UHF transmission unit 11 illustrated in FIG. 2. As shown in FIG. 3, the UHF transmitter 11 includes a synthesizer 111, a frequency converter 112, an oscillator 113, a multiplier 114, an oscillator 115, a filter 116, an oscillator 117, a frequency converter 118, and a filter 119. As a component.

  Here, the synthesizer 111 uses the 465 MHz signal supplied from the multiplier 114 as a pilot signal used for gain control and the like by detecting the synchronization between the center side device and the subscriber side device and the level of the signal. It is synthesized with the UHF input signal and output. The frequency converter 112 performs frequency conversion (up-conversion) on the signal supplied from the synthesizer 111 based on the 1stLo signal (local signal) supplied from the oscillator 115 and outputs the result. The oscillator 113 generates and outputs a 155 MHz signal.

  The multiplier 114 has a function of multiplying and generating a 155 MHz signal supplied from the oscillator 113. Here, a configuration of multiplication by three is shown. The 155 MHz signal supplied from the oscillator 113 is multiplied by 3 to generate a 465 MHz signal, which is supplied to the combiner 111. The oscillator 115 multiplies the signal of 155 MHz supplied from the oscillator 113 (10 times here) to generate a signal of 1550 MHz, and supplies it to the frequency converter 112 as a 1stLo signal.

  The filter 116 attenuates and outputs the 1550 MHz 1stLo signal included in the signal output from the frequency converter 112. As the filter 116, for example, a band removal filter that attenuates only a narrow band around 1550 MHz may be used. The oscillator 117 multiplies the 155 MHz signal supplied from the oscillator 113 to generate a 21250 MHz signal, and supplies the signal to the frequency converter 118 as a 2ndLo signal (local signal).

  The frequency converter 118 frequency-converts (up-converts) the signal output from the filter 116 using a 21250 MHz 2ndLo signal supplied from the oscillator 117, and supplies the converted signal to the filter 119. The filter 119 attenuates and outputs a 21250 MHz 2ndLo signal included in the signal supplied from the frequency converter 118. As the filter 119, for example, a band removal filter that attenuates only a narrow band around 21250 MHz may be used.

  FIG. 4 is a diagram illustrating a detailed configuration example of the VHF transmission unit 12 illustrated in FIG. 2. As shown in FIG. 4, the VHF transmission unit 12 includes a synthesizer 121, a frequency converter 122, an oscillator 123, an oscillator 125, a filter 126, an oscillator 127, a frequency converter 128, and a filter 129 as main components. .

  Here, the synthesizer 121 synthesizes and outputs a 155 MHz signal supplied from the oscillator 123 as a pilot signal to a VHF input signal. The frequency converter 122 performs frequency conversion (up-conversion) on the signal supplied from the synthesizer 121 based on the 1stLo signal supplied from the oscillator 125 and outputs the result. The oscillator 123 generates and outputs a 155 MHz signal.

  The oscillator 125 multiplies the 155 MHz signal supplied from the oscillator 123 to generate a 1922 MHz signal, and supplies the signal to the frequency converter 122 as a 1stLo signal.

  The filter 126 attenuates and outputs the 1922 MHz 1stLo signal included in the signal output from the frequency converter 122. As the filter 126, for example, a band removal filter that attenuates only a narrow band around 1922 MHz may be used. The oscillator 127 multiplies the 155 MHz signal supplied from the oscillator 123 to generate a 21250 MHz signal, and supplies the signal to the frequency converter 128 as a 2ndLo signal.

  The frequency converter 128 frequency-converts (up-converts) the signal output from the filter 126 using the 21250 MHz 2ndLo signal supplied from the oscillator 127 and supplies the signal to the filter 129. The filter 129 attenuates the 21250 MHz 2ndLo signal included in the signal supplied from the frequency converter 128 and outputs the attenuated signal. As the filter 129, for example, a band elimination filter that attenuates only a narrow band around 21250 MHz may be used.

  FIG. 5 is a diagram illustrating a detailed configuration example of the UHF receiving unit 41 illustrated in FIG. 2. As shown in FIG. 5, the UHF receiver 41 includes a filter 411, a frequency converter 412, a filter 413, a frequency converter 414, oscillators 415 to 417, a separator 418, and a frequency converter 419 as main components. Yes.

  Here, the filter 411 passes the video signal in the UHF band from the signal supplied from the antenna 30, attenuates the other video signal, and supplies it to the frequency converter 412. As the filter 411, for example, a band pass filter that passes only the UHF band may be used. The frequency converter 412 frequency-converts (down-converts) the UHF band video signal using a 21250 MHz 2ndLo signal supplied from the oscillator 416 and outputs the signal. The filter 413 attenuates the 2ndLo signal of 21250 MHz from the signal output from the frequency converter 412 and outputs the attenuated signal. As the filter 413, for example, a band removal filter that attenuates only a narrow band around 21250 MHz may be used.

  The frequency converter 414 frequency-converts (down-converts) the signal supplied from the filter 413 using the 1550 MHz 1stLo signal supplied from the oscillator 417 and outputs the signal. The oscillator 415 generates a 155 MHz signal based on the signal supplied from the frequency converter 419 and supplies the signal to the oscillator 416 and a communication signal transmission unit 43 described later with reference to FIG. The oscillator 416 multiplies the 155 MHz signal supplied from the oscillator 415 to generate and output a 21250 MHz signal. The oscillator 417 multiplies the 155 MHz signal supplied from the oscillator 415 to generate and output a 1550 MHz signal. The separator 418 separates the 465 MHz pilot signal included in the signal output from the frequency converter 414 and supplies it to the frequency converter 419. The frequency converter 419 converts the frequency of the 465 MHz pilot signal supplied from the separator 418 and supplies the converted signal to the oscillator 415.

  FIG. 6 is a diagram illustrating a detailed configuration example of the VHF receiving unit 42 illustrated in FIG. 2. As shown in FIG. 6, the VHF receiver 42 includes a filter 421, a frequency converter 422, a filter 423, a frequency converter 424, an oscillator 425 to 427, a separator 428, and a frequency converter 429 as main components. Yes.

  Here, the filter 421 passes the video signal in the VHF band from the signal supplied from the antenna 30, attenuates the other band, and supplies it to the frequency converter 422. As the filter 421, for example, a band pass filter that passes only the VHF band may be used. The frequency converter 422 performs frequency conversion (down-conversion) on the VHF band video signal using a 21250 MHz 2ndLo signal supplied from the oscillator 426 and outputs the result. The filter 423 attenuates and outputs a 2ndLo signal of 21250 MHz from the signal output from the frequency converter 422. As the filter 423, for example, a band removal filter that attenuates only a narrow band around 21250 MHz may be used.

  The frequency converter 424 frequency-converts (down-converts) the signal supplied from the filter 423 using the 1922 MHz 1stLo signal supplied from the oscillator 427 and outputs the signal. The oscillator 425 generates a 155 MHz signal based on the signal supplied from the frequency converter 429 and supplies the signal to the oscillator 426. The oscillator 426 multiplies the 155 MHz signal supplied from the oscillator 425 to generate and output a 21250 MHz signal. The oscillator 427 multiplies the 155 MHz signal supplied from the oscillator 425 to generate and output a 1922 MHz signal. The separator 428 separates the 155 MHz pilot signal included in the signal output from the frequency converter 424 and supplies it to the frequency converter 429. The frequency converter 429 converts the frequency of the 155 MHz pilot signal supplied from the separator 428 and supplies the converted signal to the oscillator 425.

  FIG. 7 is a diagram illustrating a detailed configuration example of the communication signal transmission unit 43 illustrated in FIG. 2. As illustrated in FIG. 7, the communication signal transmission unit 43 includes a frequency converter 431, a frequency converter 432, an oscillator 433, an oscillator 434, and a filter 435 as main components.

  Here, the frequency converter 431 frequency-converts (up-converts) the communication input signal based on the 1953 MHz 1stLo signal supplied from the oscillator 433 and outputs the signal.

  The frequency converter 432 converts the frequency of the signal supplied from the frequency converter 431 based on the 21250 MHz 2ndLo signal supplied from the oscillator 434 and outputs the converted signal.

  The oscillator 433 multiplies the 155 MHz signal supplied from the UHF receiver 41 to generate and output a 1953 MHz 1stLo signal. The oscillator 434 multiplies the 155 MHz signal supplied from the UHF receiver 41 to generate and output a 21250 MHz 2ndLo signal.

  The filter 435 attenuates and outputs a 21250 MHz signal included in the signal output from the frequency converter 432. As the filter 435, for example, a band removal filter that attenuates only a narrow band around 21250 MHz may be used.

  FIG. 8 is a diagram illustrating a detailed configuration example of the communication signal receiving unit 13 illustrated in FIG. 2. As shown in FIG. 8, the communication signal receiving unit 13 includes an AGC (Auto Gain Control) circuit 131, a filter 132, a frequency converter 133, oscillators 134 to 136, a filter 137, a frequency converter 138, and a detection unit 139. Is the main component.

  Here, the AGC circuit 131 adjusts the gain of the signal supplied from the antenna 20 so that the signal detected by the detection unit 139 becomes a predetermined level. The filter 132 passes the communication signal from the signal output from the AGC circuit 131 and attenuates and outputs the other signals. As the filter 132, for example, a band pass filter that passes only the communication signal band may be used.

  The frequency converter 133 frequency-converts (down-converts) the signal output from the filter 132 using a 21250 MHz 2ndLo signal supplied from the oscillator 135 and outputs the signal.

  The oscillator 134 generates and outputs a 155 MHz signal. The oscillator 135 multiplies the 155 MHz signal supplied from the oscillator 134 and outputs the signal as a 21250 MHz signal. The oscillator 136 multiplies the 155 MHz signal supplied from the oscillator 134 and outputs it as a 1953 MHz signal.

  The filter 137 attenuates and outputs a 21250 MHz signal from the signal output from the frequency converter 133. As the filter 137, for example, a band removal filter that attenuates only a narrow band around 21250 MHz may be used. The frequency converter 138 frequency-converts (down-converts) the signal output from the filter 137 using a 1953 MHz 1stLo signal supplied from the oscillator 136 and outputs the signal.

  The detection unit 139 detects the level of a DC signal (pilot signal) included in the signal output from the frequency converter 138 and supplies the detected level to the AGC circuit 131.

(B) Description of Operation of the Embodiment of the Present Invention Next, the operation of the embodiment of the present invention will be described. The IF video signal (see FIG. 9) of 402 to 770 MHz UHF band input to the UHF transmitter 11 shown in FIG. 3 is added with a 465 MHz pilot signal by the synthesizer 111 and supplied to the frequency converter 112 . The frequency converter 112 up-converts the signal supplied from the synthesizer 111 using the 1st MHz signal of 1550 MHz supplied from the oscillator 115 and outputs the converted signal as an RFIF signal of 1952 to 2320 MHz. The filter 116 attenuates and outputs the 1550 MHz 1stLo signal included in the signal output from the frequency converter 112. The frequency converter 118 up-converts the signal supplied from the filter 116 into a signal of 23202 to 23570 MHz by a 21250 MHz 2ndLo signal supplied from the oscillator 117 and outputs the signal. The filter 119 attenuates and outputs the 21250 MHz 2ndLo signal included in the signal output from the frequency converter 118. A signal output from the filter 119 is transmitted through the antenna 20 as, for example, a horizontally polarized radio wave.

  The IF video signal of 90 to 402 MHz VHF band (see FIG. 9) input to the VHF transmitter 12 shown in FIG. 4 is added with a 155 MHz pilot signal by the synthesizer 121 and supplied to the frequency converter 122. . The frequency converter 122 up-converts the signal supplied from the synthesizer 121 by the 1922 MHz 1stLo signal supplied from the oscillator 125 and outputs the converted signal as a 2012 to 2324 MHz RFIF signal. The filter 126 attenuates and outputs the 1922 MHz 1stLo signal included in the signal output from the frequency converter 122. The frequency converter 128 up-converts the signal supplied from the filter 126 into a signal of 23262 to 23574 MHz by a 21250 MHz 2ndLo signal supplied from the oscillator 127 and outputs the signal. The filter 129 attenuates and outputs a 21250 MHz 2ndLo signal included in the signal output from the frequency converter 128. The signal output from the filter 129 is transmitted as, for example, a vertically polarized radio wave via the antenna 20.

  The filter 411 of the UHF receiver 41 shown in FIG. 5 passes the UHF band signal (signal of 23202 to 23570 MHz) up-converted from the signal supplied from the antenna 30, and attenuates and outputs the other band. To do. The frequency converter 412 down-converts the signal supplied from the filter 411 with the 2ndLo signal of 21250 MHz supplied from the oscillator 416 and outputs the signal as a signal of 1952 to 2320 MHz. The filter 413 attenuates the 21250 MHz 2ndLo signal included in the signal output from the frequency converter 412 and outputs the attenuated signal. The frequency converter 414 down-converts the signal supplied from the filter 413 using the 1550 MHz 1stLo signal supplied from the oscillator 417, and outputs the signal as a 402 to 770 MHz signal (original UHF band signal). The separator 418 separates the 465 MHz pilot signal included in the signal output from the frequency converter 414 and supplies it to the frequency converter 419. The frequency converter 419 down-converts the pilot signal supplied from the separator 418 and outputs it as a signal having a predetermined frequency (for example, 6 MHz). The oscillator 415 generates and outputs a 155 MHz signal based on the signal supplied from the frequency converter 419.

  The filter 421 of the VHF receiving unit 42 shown in FIG. 6 passes the VHF band signal (23262 to 23574 MHz signal) up-converted from the signal supplied from the antenna 30, and attenuates and outputs the other band. To do. The frequency converter 422 down-converts the signal supplied from the filter 421 by the 21250 MHz 2ndLo signal supplied from the oscillator 426 and outputs the signal as a 2012 to 2324 MHz signal. The filter 423 attenuates and outputs the 21250 MHz 2ndLo signal included in the signal output from the frequency converter 422. The frequency converter 424 down-converts the signal supplied from the filter 423 with the 1922 MHz 1stLo signal supplied from the oscillator 427, and outputs the signal as a 90 to 402 MHz signal (original VHF band signal). The separator 428 separates the 155 MHz pilot signal included in the signal output from the frequency converter 424 and supplies it to the frequency converter 429. The frequency converter 429 down-converts the pilot signal supplied from the separator 428 and outputs it as a signal having a predetermined frequency (for example, 6 MHz). The oscillator 425 generates and outputs a 155 MHz signal based on the signal supplied from the frequency converter 429.

  The frequency converter 431 of the communication signal transmission unit 43 shown in FIG. 7 converts a communication signal of 15 to 65 MHz supplied from a personal computer (not shown) to 1968 to 2018 MHz by a 1st Lo signal of 1953 MHz supplied from the oscillator 433, for example. Up-convert and output. The frequency converter 432 up-converts the signal output from the frequency converter 431 by the 21250 MHz signal supplied from the oscillator 434 and outputs the signal as a signal of 23218 to 23268 MHz. The filter 435 attenuates the 21250 MHz 2ndLo signal included in the signal output from the frequency converter 432 and outputs the attenuated signal.

  Here, in the UHF transmission unit 11, as shown in FIG. 9, the 1stLo signal of 1550 MHz is up-converted by the 2ndLo signal of 21250 MHz to be converted to a frequency of 22800 MHz, and is a spurious signal that is an unnecessary signal in wireless communication. Occurs. Since this 22800 MHz spurious signal is located outside the 23200 to 23600 MHz band (23 GHz communication band) assigned to the transmission / reception system, it may affect other wireless devices unless it is properly attenuated. There is a need. For this reason, the filters 116 and 119 attenuate such spurious signals, thereby suppressing 22800 MHz spurious signals outside the band.

  Similarly, in the VHF transmission unit 12, as shown in FIG. 9, the 1stLo signal of 1922 MHz is up-converted by the 2ndLo signal of 21250 MHz to be converted to a frequency of 23172 MHz, which is a spurious signal that is an unnecessary signal in wireless communication. Occurs. Since the 23172 MHz spurious signal is located outside the 23200 to 23600 MHz band (23 GHz communication band) assigned to the transmission / reception system, it may affect other wireless devices unless it is appropriately attenuated. There is a need. For this reason, the filters 126 and 129 attenuate such spurious signals, thereby suppressing 23172 MHz spurious signals outside the band.

  On the other hand, as shown in FIG. 9, the communication signal transmission unit 43 converts the 1953 MHz 1stLo signal into a frequency of 23203 MHz by up-conversion with a 21250 MHz 2ndLo signal, and is a spurious signal that is an unnecessary signal in wireless communication. Occurs. As shown in FIG. 10, the 23203 MHz spurious signal is located within “inside” a band of 23200 to 23600 MHz (band indicated by a broken line in FIG. 10) allocated to the transmission / reception system. For this reason, since it is not necessary to attenuate the 23203 MHz spurious signal, the communication signal transmitting unit 43 should be disposed between the frequency converter 431 and the frequency converter 432 and a filter for attenuating the 1stLo signal of 1953 MHz. Can be omitted. The filter for attenuating the 1953 MHz 1stLo signal needs to have 1968 MHz as the passband and 1953 MHz as the attenuation band, so the bandwidth allocated to the cutoff band is only 15 MHz and has very steep characteristics. I need it. A filter having such a steep characteristic is expensive, and the characteristic may change depending on temperature and aging. However, by using the circuit configuration described above, such a steep filter can be omitted. In addition, it is preferable to use the above-described frequency arrangement because a filter having such a steep characteristic can be omitted with a simple configuration.

  In addition, the communication signal transmission unit 43 illustrated in FIG. 7 uses the 155 MHz signal supplied from the UHF reception unit 41 to generate the 1stLo signal and the 2ndLo signal using the oscillators 433 and 434. Since the 155 MHz signal used as the reference of the video signal is very accurate, stable communication can be performed by using such a highly accurate signal. Further, by using the 155 MHz signal supplied from the UHF receiver 41, the 155 MHz oscillator can be omitted.

  A radio wave transmitted from the communication signal transmission unit 43 via the antenna 30 is received by the antenna 20 and supplied to the communication signal reception unit 13. In the communication signal receiving unit 13, as shown in FIG. 8, the AGC circuit 131 adjusts and outputs the signal supplied from the antenna 20 by adjusting the signal level. The filter 132 passes a signal of 23218 to 23268 MHz from the signal output from the AGC circuit 131 and attenuates and outputs the other signals. The frequency converter 133 down-converts the signal of 23218 to 23268 MHz supplied from the filter 132 to the signal of 1968 to 2018 MHz by the 2ndLo signal of 21250 MHz supplied from the oscillator 135 and outputs the signal. The filter 137 attenuates and outputs the 21250 MHz 2ndLo signal included in the signal supplied from the frequency converter 133. The frequency converter 138 down-converts the signal supplied from the filter 137 to the original communication signal of 15 to 65 MHz by the 1st Lo signal of 1953 MHz supplied from the oscillator 136 and outputs the signal.

  Here, the 23200 to 23600 MHz signal passing through the filter 132 includes a spurious signal of 23203 MHz as shown in FIG. Such a spurious signal is down-converted by a 21250 MHz signal in the frequency converter 133, down-converted by a 1953 MHz signal in the frequency converter 138, and output as an analog signal. The detection unit 139 detects the signal level of such an analog signal output from the frequency converter 138, and controls the AGC circuit 131 so that the signal level becomes a desired value. Since the communication signal transmission unit 43 controls the spurious signal level to be constant, the communication signal output from the frequency converter 138 is controlled so that the signal level is always constant.

  As described above, according to the embodiment of the present invention, the frequency of each unit is set so that the spurious signal generated in the communication signal transmission unit 43 is arranged in the allowed 23 GHz band (23218 to 23268 MHz). Therefore, the configuration for attenuating the spurious signal can be omitted.

  In the embodiment of the present invention, the signal level of the spurious signal down-converted by the frequency converters 133 and 138 is detected by the detection unit 139, and the signal level is adjusted by the AGC circuit 131. Regardless of the influence of the environment or the like, the signal level of the output communication signal can be kept constant.

  Further, in the embodiment of the present invention, the up-converted UHF band video signal and VHF band video signal are transmitted by polarization multiplexing, and therefore, using a 400 MHz band of 23200 to 23600 MHz, A single antenna can transmit and receive a 770 MHz UHF band video signal and a 90 to 402 MHz VHF band video signal.

  In the embodiment of the present invention, the UHF receiver 41, the VHF receiver 42, and the communication signal transmitter 43 generate local signals for frequency conversion based on the pilot signal. In addition to achieving synchronization with the local signal, the circuit configuration can be simplified.

(E) Description of Modified Embodiment The above embodiment is an example, and it is needless to say that the present invention is not limited to the case as described above. For example, the frequency of each part in the above embodiment is an example, and the present invention is not limited to the frequency described above, and it is also possible to select a frequency other than the illustrated frequency.

  In the above embodiment, the video signal and the communication signal are transmitted and received by the same antennas 20 and 30. However, they may be transmitted and received by different antennas.

  In the above embodiment, the communication signal transmitter 43 is supplied with a 155 MHz signal from the UHF receiver 41, but may be supplied with a 155 MHz signal from the VHF receiver 42.

  In the above embodiment, the UHF transmission unit 11 and the VHF transmission unit 12 individually transmit pilot signals. However, one of the UHF transmission unit 11 and the VHF transmission unit 12 transmits a pilot signal, and the subscriber In the side device 40, the UHF transmission unit 11, the VHF transmission unit 12, and the communication signal transmission unit 43 may use this pilot signal.

  In the above embodiment, only 23203 spurious signals are arranged in the 23 GHz band, but a plurality of spurious signals may be arranged in the 23 GHz band.

DESCRIPTION OF SYMBOLS 10 Center side apparatus 11 UHF transmission part 12 VHF transmission part 13 Communication signal reception part 20, 30 Antenna 40 Subscriber side apparatus 41 UHF reception part 42 VHF reception part 43 Communication signal transmission part 111,121 Synthesizer (addition means)
112, 118, 122, 128 Frequency converter (first conversion means)
113, 115, 117, 123, 125, 127 Oscillator 114, 124 Multiplier 116, 126 Filter 119, 129 Filter (first transmission means)
131 AGC circuit (first receiving means, adjusting means)
132,137 Filter 133,138 Frequency converter (second conversion means)
134-136 Oscillator 139 Detection unit 411, 421 Filter (second receiving means)
413, 423 filter 412, 414, 422, 424 Frequency converter (third conversion means)
415 to 417, 425 to 427 Oscillator 418, 428 Separator 419, 429 Frequency converter 431, 432 Frequency converter (fourth conversion means)
433-434 oscillator 435 filter (second transmission means)

Claims (5)

In a transmission / reception system that transmits and receives information wirelessly between one transmission / reception device and the other transmission / reception device using a predetermined frequency band,
The one transmitting / receiving device is:
First conversion means for converting a video signal into the predetermined frequency band;
First transmission means for transmitting the video signal converted into the predetermined frequency band by the first conversion means to the other transmission / reception device;
First receiving means for receiving a communication signal transmitted from the other transmitting / receiving device;
Second conversion means for converting the frequency of the communication signal received by the first reception means to a frequency band lower than the predetermined frequency band;
The other transmission / reception device is:
Second receiving means for receiving the video signal transmitted by the first transmitting means;
Third conversion means for converting the frequency of the video signal received by the second reception means to the frequency band lower than the predetermined frequency band;
Fourth conversion means for converting the communication signal into the predetermined frequency band;
Second transmission means for transmitting the communication signal converted into the predetermined frequency band by the fourth conversion means to the one transmission / reception device;
The transmission / reception system, wherein at least one of spurious signals generated by the fourth conversion means is included in the predetermined frequency band. The one transmitting / receiving device is:
An increase / decrease means for increasing / decreasing the signal level of the communication signal based on the spurious signal included in the predetermined frequency band;
The transmission / reception system according to claim 1. The one transmitting / receiving device is:
Adding means for adding a pilot signal to the video signal;
The other transmission / reception device is:
The third conversion means converts the video signal to the frequency band lower than the predetermined frequency band based on the pilot signal,
The fourth conversion means converts the communication signal into the predetermined frequency band based on the pilot signal;
The transmission / reception system according to claim 1 or 2. The video signal includes the video signal in a second frequency band having a first frequency band and a band higher than the first frequency band,
The first transmission means transmits the video signal in the first and second frequency bands by polarization multiplexing.
The transmission / reception system according to any one of claims 1 to 3.   The transmission / reception system according to claim 1, wherein the predetermined frequency band is a 23 GHz band.

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