JP4695955B2 - Transmission / reception system and reception apparatus - Google Patents

Description

  The present invention up-converts a transmission signal to be transmitted to a receiving device and transmits it wirelessly. The receiving device receives the transmitted radio wave and restores the original transmission signal by down-converting the received signal. The present invention relates to a transmission / reception system and a receiving apparatus suitable for constructing this system.

  Conventionally, in order to wirelessly transmit a wideband signal with high quality, the transmission apparatus side uses a local oscillation signal generated by a local oscillator as a transmission signal to be transmitted to the reception apparatus side, using SHF (centimeter wave), EHF Upconverted to a microwave band such as (millimeter wave), radiates the upconverted signal from the transmission antenna, and on the receiving device side, receives the transmission radio wave from the transmission antenna at the reception antenna, and receives the received signal, There is known a transmission / reception system configured to restore an original transmission signal by performing frequency conversion using a local oscillation signal having the same frequency as that of a transmission apparatus.

In this type of transmission / reception system, a transmission signal and a pilot signal having a constant frequency are transmitted from the transmission device side to the reception device side, and the reception device side uses the received pilot signal to transmit a reception signal (transmission). It has been proposed to restore the original transmission signal accurately and stably by controlling the frequency and the signal level of the signal (see, for example, Patent Document 1).
JP 2004-235758 A

  By the way, the pilot signal transmitted from the transmission device differs from other transmission signals due to a change (for example, fading) of radio wave propagation in the space between the transmission antenna on the transmission device side and the reception antenna on the reception device side. The level may vary depending on the amount of variation.

  For this reason, in the proposed transmission / reception system, when the pilot signal transmitted from the transmission device fluctuates in the same level as other transmission signals, the signal level of the reception signal (transmission signal) is set appropriately on the reception device side. However, if the level fluctuation amount of the pilot signal in the radio transmission path becomes different from other transmission signals due to fading, etc., the reception signal (transmission signal) is controlled to an appropriate level on the receiving device side. This causes a problem that the original transmission signal cannot be accurately restored.

  The pilot signal is also used to cancel the frequency fluctuation of the received signal (transmission signal) using the frequency fluctuation of the pilot signal itself, but the pilot signal signal level fluctuates due to fading or the like, and the pilot signal If the signal cannot be controlled to an appropriate level, there also arises a problem that the frequency of the received signal (transmission signal) cannot be corrected accurately.

  The present invention has been made in view of these problems, and the transmission device transmits the transmission signal and the pilot signal by up-conversion, and the reception device corrects the frequency of the reception signal after the down-conversion using the pilot signal. An object of the present invention is to make it possible to accurately restore the original transmission signal on the receiving device side without being affected by the fluctuation of the level of the pilot signal in the transmission / reception system for restoring the original transmission signal.

The invention according to claim 1 , which has been made to achieve the object ,
A transmission signal to be transmitted is up-converted using a signal transmitted from the transmission side station, a transmission device that radiates the signal after the up-conversion from the transmission antenna, and a transmission radio wave from the transmission antenna is received by the reception antenna. A transmission / reception system including a receiving device that restores the transmission signal by down-converting a reception signal using a reception-side local oscillation signal,
The transmitting device generates a pilot signal having a constant frequency that falls within a transmission band of a transmission signal by the up-conversion, and up-converts the pilot signal and the transmission signal by using the signal originating from the transmitting side. , Transmitting the transmission signal and the pilot signal simultaneously,
The reception device separates a signal obtained by down-converting the reception signal into a reception transmission signal corresponding to the transmission signal and a reception pilot signal corresponding to the pilot signal, and at the transmission device side A correction reference signal having a fixed frequency relationship with the generated pilot signal is generated, and a correction signal is generated by mixing the correction reference signal and the reception pilot signal, and the correction signal and the reception signal are further generated. The received transmission signal is frequency-converted by mixing with a transmission signal, and the original transmission signal transmitted from the transmission device is extracted from the frequency-converted signal,
Moreover, in the receiving apparatus, the received pilot signal or the signal of the correction signal is on a signal path through which the received pilot signal separated from the received transmission signal or the correction signal generated based on the received pilot signal passes. A second signal level control circuit for amplifying or attenuating the received pilot signal or the correction signal is provided so that the level becomes a target level.

Next, the invention according to claim 2 is the transmission / reception system according to claim 1,
In addition to the second signal level control circuit, the receiving device includes:
A first signal for detecting an average power of the entire reception signal including the reception transmission signal and the reception pilot signal obtained by the down-conversion, and amplifying or attenuating the reception signal so that the average power becomes a target level. Level control circuit,
Is provided.

The invention according to claim 3 is the transmission / reception system according to claim 1 or 2 , wherein the transmission device is configured to transmit the transmission signal and the pilot signal at the same level. It is characterized by.

On the other hand, the invention described in claim 4 up-converts a transmission signal to be transmitted and a pilot signal having a constant frequency using a signal originating from the transmitting side, and transmits the up-converted signal wirelessly from a transmitting antenna. A receiving device that receives a transmission radio wave from a transmitting device that is received by a receiving antenna and restores the transmission signal by down-converting the received signal using a receiving side local oscillation signal;
A reception side local oscillation signal generating means for generating the reception side local oscillation signal;
Frequency converting means for down-converting the received signal from the receiving antenna using the receiving side local signal generated by the receiving side local signal generating means;
Signal separating means for separating the signal down-converted by the frequency converting means into a received transmission signal corresponding to the transmission signal and a received pilot signal corresponding to the pilot signal;
A reference signal generating means for generating a reference signal for correction having a constant frequency relationship with the pilot signal generated on the transmitter side;
A correction signal for restoring the original transmission signal from the reception transmission signal by mixing the correction reference signal generated by the reference signal generation means and the reception pilot signal separated by the signal separation means Correction signal generating means for generating
The received transmission signal is frequency-converted by mixing the correction signal generated by the correction signal generating means and the received transmission signal separated by the signal separating means, and the transmission is performed from the frequency-converted signal. Signal extraction means for extracting the original transmission signal transmitted by the apparatus;
On the signal path through which the reception pilot signal separated by the signal separation means passes or on the signal path through which the correction signal generated by the correction signal generation means passes. A second signal level control circuit for amplifying or attenuating the received pilot signal or the correction signal is provided so that the signal level of the signal becomes a target level.

The invention according to claim 5 is the receiving apparatus according to claim 4,
On the signal path of the received signal from the frequency converting means to the signal separating means, an average power of the entire received signal including the received transmission signal and the received pilot signal obtained by the down-conversion is detected, and the average A first signal level control circuit for amplifying or attenuating the received signal so that the power reaches a target level is provided .

  The transmission / reception system according to claim 1, wherein the transmission apparatus up-converts the transmission signal and the pilot signal by using the signal transmitted from the transmission side station, thereby simultaneously transmitting the transmission signal and the pilot signal wirelessly, and receiving apparatus. On the side, the received signal is down-converted using the signal originating from the receiving side, and the down-converted signal is separated into a received transmission signal and a received pilot signal, and the separated received pilot signal and correction reference signal are separated. To generate a correction signal. By mixing the correction signal and the received transmission signal, the received transmission signal is frequency-converted to extract the original transmission signal.

  In particular, in the receiving apparatus of the present invention, the second signal is transmitted on the signal path through which the received pilot signal separated from the received transmission signal passes or on the signal path through which the correction signal generated based on the received pilot signal passes. The second signal level control circuit amplifies or attenuates the received pilot signal or the correction signal so that the signal level of the received pilot signal or the correction signal becomes the target level.

  Therefore, according to the transmission / reception system of the present invention, even if the level of the pilot signal transmitted from the transmission device fluctuates due to fading in the wireless transmission path, the reception device uses the reception pilot signal or the reception pilot signal. The received transmission signal can be frequency-converted by controlling the signal level of the generated correction signal to an appropriate level. Therefore, according to the present invention, the original transmission signal can be accurately restored on the receiving device side.

Next, in the transmission / reception system according to the second aspect , the receiving apparatus is provided with a first signal level control circuit. The first signal level control circuit detects the average power of the entire received signal including the received transmission signal and the received pilot signal obtained by down-conversion, and the received signal so that the average power becomes the target level. Is amplified or attenuated.

Therefore, according to the transmission and reception system according to claim 2, in the receiving apparatus, by the first signal level control circuitry and a second signal level control circuit, and the signal level of the received signal after down-conversion, a received pilot signal Alternatively, the signal level of the correction signal is controlled to a predetermined target level .

Therefore, according to the transmission / reception system according to claim 2, even if the pilot signal transmitted from the transmission apparatus changes in level by a variation amount different from that of other transmission signals due to fading in the wireless transmission path, etc. It is possible to restore the original transmission signal from the received transmission signal by controlling the transmission signal and the received pilot signal or the correction signal to appropriate levels, respectively, and to restore the transmission signal more accurately. .

Next, in the transmission / reception system according to claim 3 , in the transmission / reception system according to claim 1 or 2 , the transmission device is configured to transmit the transmission signal and the pilot signal at the same level. The level difference between the received transmission signal and the received pilot signal obtained on the receiving device side can be suppressed, the transmission signal restoration operation caused by the increase in the level difference can be suppressed, and the transmission signal restoration accuracy can be improved.

In the transmission / reception system according to claim 3 , the transmission levels of the transmission signal from the transmission apparatus and the pilot signal do not necessarily coincide completely, and in practical operation, the level difference is 5 dB or less. do it.

Next, in the receiving device according to claim 4 , the frequency converting means down-converts the received signal from the receiving antenna using the receiving side local signal generated by the receiving side local signal generating means, and performs signal separation. Means separates the down-converted signal into a received transmission signal and a received pilot signal, and a correction signal generating means generates the received received pilot signal and the reference signal for correction generated by the reference signal generating means; The signal extraction means mixes the generated correction signal and the received transmission signal separated by the signal separation means to frequency-convert the received transmission signal, and The original transmission signal transmitted by the transmission apparatus is extracted from the frequency-converted signal.

Then, on signal path correction signal received pilot signals demultiplexed by the signal separating means is generated by the signal path or on the correction signal generating means for passing through, the signal level of the received pilot signal or the correction signal A second signal level control circuit for amplifying or attenuating the received pilot signal or the correction signal is provided so as to achieve the target level.

Therefore, if this receiving apparatus is used, the transmission / reception system according to claim 1 can be constructed.
Further, in the receiving apparatus according to claim 5 , the average of all received signals including the received transmission signal and the received pilot signal obtained by down-conversion on the signal path of the received signal from the frequency converting means to the signal separating means. by detecting the power, first signal level control circuit which amplifies or attenuates the received signal to the average power becomes a target level is al provided.

Therefore, if this receiving apparatus is used, the transmission / reception system according to claim 2 can be constructed.

An embodiment of the present invention will be described below with reference to the drawings.
[ Reference example ]
First, FIG. 1 is a block diagram showing a configuration of an entire transmission / reception system as a reference example of the present invention .

As shown in FIG. 1, the transmission / reception system of this reference example transmits an intermediate frequency signal (terrestrial digital IF signal: center frequency 37.15 MHz) of a terrestrial digital broadcast television broadcast signal between transmission stations of a television broadcast station. The transmitter 30 is used for transmission / reception, and transmits the terrestrial digital IF signal by up-converting the terrestrial digital IF signal to the microwave band, and by receiving and down-converting the transmission radio wave from the transmitter 30. And a receiving device 50 for restoring the terrestrial digital IF signal.

FIG. 2 is a block diagram illustrating the configuration of the transmission device 30 and the reception device 50.
As shown in FIG. 2, the transmitter 30 selectively inputs only the terrestrial digital IF signal among the input terminal T1 for inputting the terrestrial digital IF signal and the input signal from the input terminal T1. A band-pass filter (BPF) 32 to be operated and an amplifier circuit 34 for amplifying the terrestrial digital IF signal that has passed through the BPF 32 are provided.

  The transmitter 30 also includes an oscillator 36 that generates a pilot signal (PILOT) of a constant frequency fp (for example, 33.15 MHz) in substantially the same frequency band as the terrestrial digital IF signal, and the terrestrial digital IF signal and pilot signal. An oscillator 38 for generating a transmission-side first local oscillation signal having a predetermined frequency ft1 (for example, 260 MHz) necessary for up-converting (PILOT) to the VHF band, and using this transmission-side first local oscillation signal for the VHF band Generates a transmitter-side second-station signal of a predetermined frequency ft2 (for example, 5595.35 MHz) necessary for up-converting the up-converted terrestrial digital IF signal and pilot signal (PILOT) to a microwave band for transmission. An oscillator 40 is provided.

  The pilot signal (PILOT) generated by the oscillator 36 is superimposed on the terrestrial digital IF signal amplified by the amplifier circuit 34 via the directional coupler 37. Further, the transmission signal (terrestrial digital IF signal + PILOT) in which the pilot signal (PILOT) is superimposed on the terrestrial digital IF signal in this way is input to the mixer 39, and the first generated by the oscillator 38 is generated in the mixer 39. By being mixed with the local oscillation signal, it is up-converted to a transmission signal in the VHF band. Further, the transmission signal after the up-conversion is input to the mixer 41, and is mixed with the second local oscillation signal generated by the oscillator 40 in the mixer 41, thereby up-converting the transmission signal into the microwave band. Is done.

  Further, a band pass filter (BPF) 42 is provided on the output side of the mixer 41, and in this BPF 42, a microwave band transmission signal (terrestrial digital IF signal + PILOT) up-converted in order by the mixers 39, 41. ) Only selectively. The upconverted transmission signal (terrestrial digital IF signal + PILOT) selectively extracted by the BPF 42 is input to the microwave amplification circuit 44 and amplified to a predetermined level by the amplification circuit 44. Thereafter, the signal is transmitted from the transmission antenna 46 toward the reception device 50.

  The transmission level of the transmission signal (terrestrial digital IF signal) from the transmission antenna 46 and the pilot signal (PILOT) is at least the signal level by adjusting the amplification factor of the amplifier circuit 34 and the signal output level of the oscillator 36. The difference is set to be 5 dB or less.

  On the other hand, the receiving device 50 includes a microwave amplification circuit 52 that amplifies the reception signal from the reception antenna 51, and a predetermined frequency fr1 (required for down-converting the reception signal amplified by the amplification circuit 52). For example, an oscillator 54 that generates a reception side local oscillation signal of the same frequency as the transmission side second local oscillation signal: 5595.35 MHz, and a reception side local oscillation signal generated by the oscillator 54 and an amplification circuit 52 amplify it. A mixer 56 that down-converts the reception signal by mixing the reception signal, and a transmission signal (terrestrial digital IF signal) transmitted from the transmission device 30 among the reception signals down-converted by the mixer 56, and The received transmission signal (terrestrial digital IF signal ′) and the received pilot signal (PILOT ′) respectively corresponding to the pilot signal (PILOT) And a bandpass filter (BPF) 58 that selectively passes is provided with.

  Then, the reception signal (terrestrial digital IF signal '+ PILOT') that has passed through the BPF 58 is amplified by the amplifier circuit 60, and then once attenuated by the variable attenuator (ATT) 62 for signal level adjustment. After further amplification by the amplifier circuit 64, it is separated into two systems.

  A branch circuit 66 for branching a part of the received signal (terrestrial digital IF signal '+ PILOT') is provided on the path from the amplifier circuit 64 to the signal separation point. The received signal (terrestrial digital IF signal '+ PILOT') is converted into a voltage signal representing the average power by the detection circuit 68, and used to adjust the attenuation of the variable attenuator (ATT) 62. The

  That is, the variable attenuator 62, the amplifier circuit 64, the branch circuit 66, and the detection circuit 68 adjust the gain so that the signal level of the received signal (terrestrial digital IF signal '+ PILOT') becomes a preset target level. Is configured as an AGC circuit that functions as a first signal level control circuit of the present invention.

  Next, one of the signal paths of the received signal that has passed through the branch circuit 66 and separated into two systems is a received transmission signal (terrestrial digital IF ′, center) corresponding to the terrestrial digital IF signal. A band-pass filter (BPF) 70 that selectively passes only the frequency (297.15 MHz) is provided, and only the received pilot signal (PILOT ': 293.15 MHz) corresponding to the pilot signal is provided on the other signal path. A band-pass filter (BPF) 72 that selectively passes is provided.

The received transmission signal (terrestrial digital IF ′) that has passed through the BPF 70 is amplified by the amplifier circuit 74 and then input to the mixer 76.
On the other hand, the received pilot signal (PILOT ′) that has passed through the BPF 72 is mixed by the mixer 78 with the correction reference signal (SBASE) having the constant frequency fr 2 generated by the oscillator 80.
In this reference example , the frequency fr2 of the correction reference signal (SBASE) is set to the same frequency fp (33.15 MHz) as the pilot signal (PILOT) before being up-converted on the transmission device 30 side. .

  In addition, the signal mixed in the mixer 78 in this way is a bandpass filter that passes only a signal component having a frequency fh that is a difference in frequency between the received pilot signal (PILOT ′) and the correction reference signal (SBASE) ( By being input to (BPF) 82, it is converted into a correction signal having substantially the same frequency ft1 (260 MHz) as the first local oscillation signal on the transmission device 30 side.

  The correction signal is input to the mixer 76, and is mixed with the received transmission signal (terrestrial digital IF signal ′) extracted by the BPF 70. As a result, the mixer 76 converts the received transmission signal (terrestrial digital IF signal ′) into the original terrestrial digital IF signal (center frequency: 37.15 MHz) before being up-converted on the transmitting device 30 side ( Downconverted).

  The terrestrial digital IF signal thus frequency-converted (down-converted) by the mixer 76 is input to the amplifier circuit 86 via the band-pass filter (BPF) 84, and is amplified to a predetermined level by the amplifier circuit 86. Then, the data is output to a predetermined broadcasting device via a band pass filter (BPF) 88 and an output terminal T2.

As described above, in the transmission / reception system of the present reference example , first, on the transmission device 30 side, a terrestrial digital IF signal and a pilot signal having a constant frequency fp in substantially the same frequency band as the terrestrial digital IF signal ( PILOT) is up-converted to the microwave band using the transmission-side first local signal at frequency ft1 and the transmission-side second local signal at frequency ft2, and the transmission signal after the up-conversion is transmitted wirelessly. To do.

  On the other hand, on the receiving device 50 side, the transmission radio wave from the transmitting device 30 is received by the receiving antenna 51, and the received signal is received at the receiving side local oscillation signal having the same frequency fr1 (= ft2) as the transmitting side second local oscillation signal. And down-convert the received signal into a received transmission signal (terrestrial digital IF signal ′) corresponding to the terrestrial digital IF signal and a received pilot signal (PILOT ′) corresponding to the pilot signal (PILOT). And the received pilot signal (PILOT ′) is frequency-converted by using the correction reference signal (SBASE) having the same frequency fr2 (= fp) as the original pilot signal, so that the first station on the transmission side A correction signal having the same frequency fh (= ft1) as that of the emitted signal is generated, and this correction signal is mixed with the received transmission signal (terrestrial digital IF signal '). By the received transmission signal (digital terrestrial IF ') frequency conversion, from among the signals after the frequency conversion, and extracts the original terrestrial digital IF signal before transmitting apparatus 30 upconverts.

Therefore, according to the transmission / reception system of this reference example , even if a frequency variation occurs in the transmission side local oscillation signal or the reception side local oscillation signal, the reception device 50 side does not receive the influence of the frequency variation and the transmission signal ( (Terrestrial digital IF signal) can be accurately restored.

In the receiving device 50, the signal level of the received transmission signal (terrestrial digital IF signal ') obtained by the down-conversion in the mixer 56 is the distance of the wireless transmission path between the transmitting device 30 and the receiving device 50, and between them. If the fluctuation amount is large and the received transmission signal and the correction signal are mixed by the mixer 76, the original transmission signal (terrestrial digital IF signal) is accurately restored. In this reference example , the received signal (terrestrial digital IF signal '+ PILOT') is converted into the received transmission signal (terrestrial digital IF signal ') and the received pilot signal (PILOT') by the BPF 70, 72. ), The received signal (terrestrial digital IF signal '+ PILOT) is set so that the average power of the entire received signal becomes a predetermined target level. ) Is adjusted, even if the received transmission signal (terrestrial digital IF signal ′) and the received pilot signal (PILOT ′) fluctuate in level, these signals greatly deviate from the target level. The original transmission signal (terrestrial digital IF signal) can be restored more accurately by the mixer 76.

Further, in this reference example , the signal level of the transmission signal from the transmission device 30 is substantially matched between the transmission signal (terrestrial digital IF signal) and the pilot signal (PILOT). The signal level of the received transmission signal (terrestrial digital IF signal ′) and the received pilot signal (PILOT ′) is prevented from greatly deviating from the target level, and the transmission signal (terrestrial digital IF signal) is restored by the receiver 50. Accuracy can be improved.

In the receiving apparatus 50 of this reference example , the oscillator 54 corresponds to the receiving side local oscillation signal generating means of the present invention, the mixer 56 corresponds to the frequency converting means of the present invention, and the BPFs 70 and 72 correspond to the present invention. The oscillator 80 corresponds to the reference signal generation means, the mixer 78 and the BPF 82 correspond to the correction signal generation means of the present invention, and the mixer 76 and the BPF 84 serve as the signal extraction means of the present invention. Equivalent to.
[Embodiment]
Next, a transmission / reception system according to an embodiment to which the present invention is applied will be described.

FIG. 3 is a block diagram showing the configuration of the receiving device 50 used in this transmission / reception system.
The transmitter used in the transmission / reception system of this embodiment is the same as that of the reference example shown in FIG. 2, and the receiver 50 is basically the same as that of the reference example shown in FIG. Since a part of the configuration is added to the reference example , in the following description, only differences from the reference example in the receiving device 50 will be described.

  As shown in FIG. 3, the receiving apparatus 50 of this embodiment includes a second signal level control circuit that controls the signal level of the received pilot signal (PILOT ′) that has passed through the bandpass filter (BPF) 72 to a target level. The received pilot signal (PILOT ′) controlled to the target level by the second signal level control circuit is input to the correction signal generating mixer 78.

  In the present embodiment, the second signal level control circuit passes through the variable attenuator (ATT) 92 that attenuates the received pilot signal (PILOT ′) that has passed through the BPF 72, and the variable attenuator (ATT) 92. An amplifying circuit 94 that amplifies the received pilot signal, a receiving pilot signal (PILOT ′) amplified by the amplifying circuit 94 is input to the mixer 78 and a part of the signal is branched, and this branch The detection circuit 98 includes a detection circuit 98 that detects a received pilot signal (PILOT ′) branched by the circuit 66 and generates a voltage signal representing the signal level. The voltage signal from the detection circuit 98 variably attenuates. The received pilot signal (PILOT ′) used to generate the correction signal by adjusting the attenuation of the detector (ATT) 92 The signal level is controlled to a target level set in advance.

  As described above, in the receiving apparatus 50 according to the present embodiment, after being down-converted by the mixer 56, the received transmission signal (terrestrial digital IF signal ′) and the received pilot signal are received by the band pass filters (BPF) 70 and 72. In addition to the signal level of the received signal (terrestrial digital IF signal '+ PILOT') before being separated into (PILOT '), it is separated by bandpass filters (BPF) 70, 72 to generate a correction signal. The signal level of the received pilot signal (PILOT ') used in the above is also controlled to a preset target level.

  For this reason, even if the pilot signal transmitted from the transmitting device 30 fluctuates in a variation amount different from that of the transmission signal due to fading in the wireless transmission path, the received pilot signal (PILOT ′) is controlled to an appropriate level. Thus, it becomes possible to generate a correction signal at an appropriate level, and it is possible to restore the transmission signal (terrestrial digital IF signal) more accurately using the generated correction signal.

Having described embodiments according to the present invention, the present invention is not intended to be limited to the above embodiment, it is possible to take various aspects within the scope not departing from the gist of the present invention.

  For example, the receiving apparatus 50 is not provided with a first signal level control circuit that controls the signal level of the entire received signal (terrestrial digital IF signal '+ PILOT'), and controls the signal level of the received pilot signal (PILOT '). Even if only the second signal level control circuit is provided, the restoration accuracy of the transmission signal (terrestrial digital IF signal) can be improved as compared with the conventional apparatus.

In the above embodiment , the received pilot signal (PILOT ′) that has passed through the band-pass filter (BPF) 72 by the variable attenuator 92, the amplifier circuit 94, the mixer 96, and the detection circuit 98 as the second signal level control circuit. The second signal level control circuit is provided on the signal path of the correction signal from the band-pass filter (BPF) 82 to the mixer 76, so that the correction signal level can be reduced. The signal level may be directly controlled to the target level.

In the above-described embodiment , the first signal level control circuit and the second signal level control circuit adjust the attenuation amount of the variable attenuators (ATT) 62 and 92 to thereby adjust the signal level of the received signal or the pilot signal. However, the gain of the amplifier circuits 64 and 94 may be directly controlled by adjusting the operating voltage of the amplifier circuits 64 and 94.

  Furthermore, in the above embodiment, a transmission / reception system has been described in which a terrestrial digital IF signal is converted into a microwave by radio transmission between transmission stations of a television broadcast. However, in the present invention, a terrestrial digital signal is used as a transmission signal. It is not limited to the IF signal, and the frequency for wireless transmission of the transmission signal is not limited to the microwave.

It is a block diagram showing the structure of the whole transmission / reception system of a reference example . It is a block diagram showing the circuit structure of the transmitter which comprises the transmission / reception system of a reference example , and a receiver. It is a block diagram showing the circuit structure of the transmitter which comprises the transmission / reception system of embodiment , and a receiver.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 30 ... Transmitter, 32 ... Band pass filter (BPF), 34, 44 ... Amplifier circuit, 36, 38, 40 ... Oscillator, 37 ... Directional coupler, 39, 41 ... Mixer, 46 ... Transmitting antenna, 50 ... Reception Device 51: Receiving antenna 52, 60, 64, 74, 86 ... Amplifier circuit 54 ... Oscillator 56, 76, 78 ... Mixer 62 ... Variable attenuator (ATT) 66 ... Branch circuit 68 ... Detector circuit , 80... Oscillator, 58, 70, 72, 82, 84, 88... Band pass filter (BPF), 92... Variable attenuator (ATT), 94.

Claims (5)

A transmission device that up-converts a transmission signal to be transmitted using a signal transmitted from a transmission-side station, and radiates the signal after the up-conversion from a transmission antenna;
A receiving device that receives a transmission radio wave from the transmitting antenna at a receiving antenna, and downconverts the received signal using a reception-side local oscillation signal, thereby restoring the transmission signal;
A transmission / reception system comprising:
The transmitting device generates a pilot signal having a constant frequency that falls within a transmission band of a transmission signal by the up-conversion, and up-converts the pilot signal and the transmission signal by using the signal originating from the transmitting side. , Transmitting the transmission signal and the pilot signal simultaneously,
The reception device separates a signal obtained by down-converting the reception signal into a reception transmission signal corresponding to the transmission signal and a reception pilot signal corresponding to the pilot signal, and at the transmission device side A correction reference signal having a fixed frequency relationship with the generated pilot signal is generated, and a correction signal is generated by mixing the correction reference signal and the reception pilot signal, and the correction signal and the reception signal are further generated. The received transmission signal is frequency-converted by mixing with a transmission signal, and the original transmission signal transmitted from the transmission device is extracted from the frequency-converted signal,
Moreover, the for the receiving apparatus, the in receiving transmission signal received pilot signal is separated from or the signal path the correction signal generated based on the received pilot signal passes, the received pilot signal or the correction signal And a second signal level control circuit for amplifying or attenuating the received pilot signal or the correction signal so that the signal level becomes a target level . In addition to the second signal level control circuit, the receiving device includes:
A first signal for detecting an average power of the entire reception signal including the reception transmission signal and the reception pilot signal obtained by the down-conversion, and amplifying or attenuating the reception signal so that the average power becomes a target level. Level control circuit,
The transmission / reception system according to claim 1, further comprising: The transmission / reception system according to claim 1 or 2, wherein the transmission device is configured to transmit the transmission signal and the pilot signal at the same level . Up-converts a transmission signal to be transmitted and a pilot signal of a constant frequency using a signal originating from the transmitting side, and receives a transmission radio wave from a transmission device that transmits the up-converted signal wirelessly from a transmission antenna A receiving apparatus that receives the signal by an antenna and down-converts the received signal using a reception-side local oscillation signal to restore the transmission signal;
  A reception side local oscillation signal generating means for generating the reception side local oscillation signal;
  Frequency converting means for down-converting the received signal from the receiving antenna using the receiving side local signal generated by the receiving side local signal generating means;
  Signal separating means for separating the signal down-converted by the frequency converting means into a received transmission signal corresponding to the transmission signal and a received pilot signal corresponding to the pilot signal;
  A reference signal generating means for generating a reference signal for correction having a constant frequency relationship with the pilot signal generated on the transmitter side;
  A correction signal for restoring the original transmission signal from the reception transmission signal by mixing the correction reference signal generated by the reference signal generation means and the reception pilot signal separated by the signal separation means Correction signal generating means for generating
  The received transmission signal is frequency-converted by mixing the correction signal generated by the correction signal generating means and the received transmission signal separated by the signal separating means, and the transmission is performed from the frequency-converted signal. Signal extraction means for extracting the original transmission signal transmitted by the apparatus;
  On the signal path through which the reception pilot signal separated by the signal separation means passes or on the signal path through which the correction signal generated by the correction signal generation means passes. A receiving apparatus comprising: a second signal level control circuit for amplifying or attenuating the received pilot signal or the correction signal so that the signal level of the signal becomes a target level. On the signal path of the received signal from the frequency converting means to the signal separating means, an average power of the entire received signal including the received transmission signal and the received pilot signal obtained by the down-conversion is detected, and the average The receiving apparatus according to claim 4, further comprising a first signal level control circuit for amplifying or attenuating the received signal so that the power reaches a target level .

Images