JP4681332B2 - Transmission / reception system and reception apparatus - Google Patents

Description

  In the present invention, the transmission signal to be transmitted to the receiving device is frequency-converted on the transmitting device side and transmitted wirelessly. The receiving device receives the transmission radio wave and restores the original transmission signal by frequency-converting the received signal. The present invention relates to a transmission / reception system, and a transmission device and a reception device suitable for constructing the system.

  Conventionally, in order to wirelessly transmit a broadband signal with high quality, the transmission device side up-converts the transmission signal to be transmitted to the reception device side into a millimeter wave band using a local signal generated by a local oscillator. The up-converted signal is radiated from the transmission antenna, and the reception device side receives the transmission radio wave from the transmission antenna at the reception antenna, and the reception signal is transmitted using a local oscillation signal having the same frequency as that of the transmission device side. A transmission / reception system configured to restore an original transmission signal by performing frequency conversion is known.

  By the way, in this type of transmission / reception system, the frequency of the local oscillation signal used for frequency conversion on the transmitting device side and the receiving device side is a millimeter wave band of several tens of GHz, so the frequency is not stable, and the receiving device side There is a problem that it is difficult to accurately restore the transmission signal.

In other words, due to the frequency difference between the local oscillator signals on the transmitting device side and the receiving device side, the transmission signal frequency-converted on the receiving device side also causes a frequency shift, and the transmission quality deteriorates.
Therefore, conventionally, in order to solve such problems, from the transmission device side, the transmission signal after frequency conversion and the local signal used for frequency conversion of the transmission signal are simultaneously transmitted, and on the reception device side, A so-called self-heterodyne transmission / reception system has been proposed in which a transmission signal is restored by down-converting a reception signal using a local oscillation signal transmitted from the transmission device side (see, for example, Patent Document 1).
JP 2001-53640 A

  However, in the proposed technique, since the frequency of the local oscillation signal can be matched between the transmitting device side and the receiving device side, the original transmission signal can be accurately restored on the receiving device side. On the other hand, since it is necessary to extract a local signal from the received signal, there is a problem that it is difficult to put it to practical use with the current technology.

  That is, since the local oscillation signal used for frequency conversion on the transmission device side and the reception device side is the same millimeter wave band as the transmission signal, the reception device side extracts the transmission side local oscillation signal from the reception signal. However, a millimeter-band narrowband filter with stable frequency characteristics is required, but it is extremely difficult to manufacture such a filter, and even if it can be manufactured, it is extremely expensive. It is difficult to actually build.

  Further, in order to restore the original transmission signal on the receiving device side, it is necessary to sufficiently increase the signal level of the local oscillation signal extracted from the reception signal, and for that purpose, an amplification circuit dedicated to the local oscillation signal is required. However, since this amplifier circuit must use an expensive amplifier circuit capable of amplifying millimeter-wave band signals, there is a problem that the cost of the receiving apparatus is increased.

  The present invention has been made in view of these problems. The transmitting apparatus transmits a signal obtained by frequency-converting a transmission signal, and the receiving apparatus transmits and receives the original transmission signal by frequency-converting the received signal. It is an object of the system to enable an original transmission signal to be accurately restored on the receiving device side without transmitting a local signal for frequency conversion from the transmitting device side to the receiving device side.

In the transmission / reception system according to claim 1, which has been made to achieve the above object, the transmission device differs from the generation source of the transmission-side local oscillation signal by transmitting a constant frequency pilot signal that falls within the transmission band by frequency conversion. One wave is generated using a crystal oscillator, and the generated pilot signal and transmission signal are frequency-converted using a transmission side local oscillation signal, whereby the transmission signal and the pilot signal are simultaneously wirelessly transmitted.

  On the other hand, on the receiving device side, first, the received signal is frequency-converted using the receiving-side local oscillation signal, and the resulting signal is converted into a received transmission signal corresponding to the transmission signal and a received pilot signal corresponding to the pilot signal. To separate.

In addition, the receiving device generates a correction reference signal having the same frequency as the pilot signal generated on the transmitting device side, using a crystal oscillator different from the generation source of the receiving side local oscillation signal, and the generated correction reference signal By mixing the signal and the received pilot signal, a correction signal having a frequency that is the difference between the frequencies of these two signals is generated.

  Then, the receiving device mixes the generated correction signal and the received transmission signal to further frequency-convert the received transmission signal, and extracts the original transmission signal transmitted from the transmitting device from the frequency-converted signal. To do.

  That is, in the case of up-conversion on the transmission side and down-conversion on the reception side, for example, the frequency of the transmission-side local oscillation signal is ft, the fluctuation component is Δft, and the frequency of the reception-side local oscillation signal is fr. Assuming that the fluctuation component is Δfr, the received transmission signal obtained by frequency-converting the received signal on the receiving device side is expressed as follows with respect to the frequency of the original transmission signal generated on the transmitting device side. The frequency shifts by (ft−fr) + Δft + Δfr ”. This frequency shift (hereinafter referred to as frequency error) is also caused in the received pilot signal obtained by frequency conversion on the receiving apparatus side. Will occur.

  Therefore, in the present invention, the receiving apparatus generates a correction reference signal having the same frequency as the pilot signal generated by the transmitting apparatus, and mixes the generated correction reference signal and the received pilot signal, thereby obtaining both of these signals. A correction signal having a frequency difference frequency (that is, a frequency corresponding to a frequency error) is generated, and the frequency of the received transmission signal is corrected with the correction signal, thereby restoring the original transmission signal. It is.

Therefore, according to the present invention, it is possible to accurately restore the original transmission signal transmitted from the transmission device on the reception device side without transmitting the transmission-side local signal from the transmission device to the reception device.
In the present invention, a pilot signal is transmitted from the transmission device side to the reception device side so that the transmission signal can be accurately restored on the reception device side. Since this pilot signal is a single wave, transmission is performed. Compared with the case where a plurality of pilot signals are transmitted from the apparatus side to the receiving apparatus side, it is possible to suppress radio wave interference generated with other communication devices and improve communication quality.

  That is, as in the present invention, in order to accurately restore the original transmission signal on the receiving device side, a plurality of pilot signals are transmitted from the transmitting device side, and on the receiving device side, the plurality of pilot signals are transmitted. It is also conceivable to restore the original transmission signal by using the difference in frequency as a reference frequency. However, the pilot signal is an unnecessary signal that is different from the transmission signal that should originally be transmitted. When the number of such unnecessary signals increases, radio signals interfere with each other with radio signals transmitted and received by other communication devices. It becomes easy. Therefore, in the present invention, the pilot signal transmitted from the transmission device is set to one wave to suppress radio wave interference with other communication devices, and affect the communication of other communication devices and their own transmission / reception system. It is trying to prevent this.

As described above, in the present invention, in order to accurately restore the transmission signal on the receiving device side, one wave of the pilot signal is used, and the frequency of this pilot signal is in the same frequency band as the transmission signal before frequency conversion. You only have to set it.
If the frequency of the pilot signal generated on the transmitting device side and the correction reference signal generated on the receiving device side are shifted, the frequency shift appears as a frequency error of the transmission signal restored on the receiving device side. become.
However, the pilot signal and the reference signal for correction are extremely low in frequency compared to the local signal for up / down conversion, and even if a deviation occurs in the frequency of the pilot signal and the reference signal for correction, it is caused by the deviation. Since the frequency error of the transmission signal is extremely small compared to the frequency error caused by the frequency fluctuation of the local signal, the receiving terminal that uses the transmission signal output from the receiving device can operate without any problem.
In particular, in the present invention, a crystal signal having a stable oscillation frequency is used to generate the pilot signal and the correction reference signal in the transmission device and the reception device, respectively. Thus, it is possible to suppress the occurrence of a frequency shift and to accurately restore the transmission signal on the receiving device side.

  When the present invention is applied to the above-described millimeter wave transmission / reception system, the frequency of the pilot signal should be sufficiently lower than the local wave signal of the millimeter wave band used for up / down conversion of the transmission signal. Therefore, the configuration of each device (especially the receiving device) can be compared to the conventional case where the local signal is transmitted from the transmitting device to the receiving device and the local signal is shared between the devices. In this way, the cost of the transmission / reception system can be reduced.

  These effects are not limited to a transmission / reception system that transmits and receives transmission signals using millimeter-wave band (frequency: 30 GHz to 300 GHz), and transmission is performed using microwave band (frequency: 3 GHz to 30 GHz). Since even a transmission / reception system for transmitting / receiving signals can be obtained in the same manner, the present invention particularly in the microwave band or millimeter wave band between the transmission apparatus and the reception apparatus as described in claim 2. It may be applied to a transmission / reception system for transmitting / receiving radio waves.

  Next, in the receiving apparatus according to claim 3, the reception side local oscillation signal generation means generates the reception side local oscillation signal, and the first frequency conversion means receives the reception side local oscillation signal using the reception side local oscillation signal. The frequency of the received signal from the antenna is converted, and the signal separating means corresponds to the received transmission signal corresponding to the transmission signal on the transmitting apparatus side and the pilot signal on the transmitting apparatus side, after the frequency conversion by the first frequency converting means. The received pilot signal is separated.

In addition, the receiving apparatus includes a correction reference signal generating unit that generates a correction reference signal having the same frequency as the pilot signal generated on the transmission apparatus side . The correction reference signal generation means is composed of a crystal oscillator different from the reception side local oscillation signal generation means, and generates the correction reference signal independently of the reception side local oscillation signal.
Then, the correction signal generation means mixes the correction reference signal generated by the correction reference signal generation means and the received pilot signal separated by the signal separation means, so that the difference in frequency between these two signals is obtained. A correction signal having a frequency of is generated .
Then, the second frequency converting means mixes the correction signal generated by the correction signal generating means and the received transmission signal, thereby frequency-converting the received transmission signal, and the signal extracting means converts the frequency-converted signal. The original transmission signal transmitted from the transmission device is extracted from.

Therefore, according to this receiving apparatus, the transmission / reception system of the present invention can be constructed.
According to a fourth aspect of the present invention, in the receiving device according to the third aspect, the transmission radio wave from the transmission device received by the reception antenna is in a microwave band or a millimeter wave band. Therefore, according to the receiving apparatus according to the fourth aspect, the transmission / reception system according to the second aspect can be constructed.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram showing the overall configuration of a transmission / reception system to which the present invention is applied.
As shown in FIG. 1, the transmission / reception system of the present embodiment wirelessly distributes the output from the BS / CS antenna 2 installed on the rooftop of an apartment house to each dwelling unit in the apartment house, A transmission device 30 provided near the roof where the BS / CS antenna 2 is installed, and a plurality of reception devices 50 installed at positions (for example, a veranda) overlooking the transmission device 30 in each dwelling unit.

  Here, the BS / CS antenna 2 is a satellite broadcast receiving antenna that receives a satellite broadcast distributed via a broadcast satellite (BS) or a communication satellite (CS), and is reflected via a reflecting mirror 2a and a support arm. The receiving unit 2b is disposed at the focal position of the mirror 2a.

  And this receiving unit 2b receives the transmission radio wave from a broadcast / communication satellite (BS / CS), and the received signal (frequency: for example, 11.7 GHz to 12.75 GHz) is a predetermined lower frequency than the original frequency. Down-converted to an intermediate frequency signal (BS / CS-IF) in a frequency band (for example, 1032 to 2071 MHz) and outputs.

  Next, the intermediate frequency signal output from the reception unit 2b of the BS / CS antenna 2 is input to the transmission device 30 via the transmission line L1 formed of a coaxial cable. Then, the transmission device 30 takes in the intermediate frequency signal as a transmission signal to be transmitted to the reception device 50 side, up-converts it to the millimeter wave band (60 GHz band in the present embodiment), and transmits it from the millimeter wave transmission antenna 40. Radiate.

  On the transmission line L1 connecting the receiving unit 2b of the BS / CS antenna 2 and the transmitting device 30, a power insertion device 12 for supplying power to the receiving unit 2b and the transmitting device 30 is provided. The reception unit 2b and the transmission device 30 operate by receiving a direct-current power supply voltage (for example, DC15V) supplied from the power supply device 14 via the power supply inserter 12 and the transmission line L1.

  On the other hand, the reception device 50 receives the transmission radio wave (millimeter wave) from the millimeter wave transmission antenna 40 by the millimeter wave reception antenna 51 and down-converts the reception signal, thereby receiving the reception unit 2b of the BS / CS antenna 2. The intermediate frequency signal (BS / CS-IF) output from the BS / CS receiver is restored to the BS / CS receiving terminal such as the BS / CS tuner 18 installed in the corresponding dwelling unit via the transmission line L2 made of a coaxial cable. Output.

  In addition, a BS / CS receiving terminal such as the BS / CS tuner 18 ordinarily receives a received signal to which the transmission line L2 is connected so that power can be directly supplied to the BS / CS antenna via a coaxial cable. Since the power supply voltage (for example, DC15V) can be output from the input terminal, the receiving device 50 of the present embodiment is powered from the BS / CS receiving terminal such as the BS / CS tuner 18 via the transmission line L2. It is configured to operate upon supply.

Next, FIG. 2 is a block diagram illustrating configurations of the transmission device 30 and the reception device 50.
As shown in FIG. 2, the transmission device 30 receives the intermediate frequency signal (BS / CS-IF) output from the reception unit 2b and the power supply voltage (DC15V) supplied from the power supply device 14 via the transmission line L1. An input terminal T1 for input, a power supply separation filter 31 that extracts a DC signal component (that is, power supply voltage: DC15V) from the signal input to the input terminal T1 and supplies it to an internal circuit, and a power supply separation filter 31 An equalizer (EQ) 32 that adjusts the other transmission signals that have passed (that is, the intermediate frequency signal: BS / CS-IF) so that the signal level becomes higher toward the high frequency side (in other words, so-called tilt characteristics). And an amplifier circuit 33 for amplifying the intermediate frequency signal (BS / CS-IF) whose level is adjusted by the EQ 32.

  Further, the transmission device 30 includes a local oscillator that generates a pilot signal (PILOT) having a constant frequency fp (for example, 900 MHz) in substantially the same frequency band as the intermediate frequency signal (BS / CS-IF) output from the reception unit 2b. 34 and a transmission side local oscillation signal of a predetermined frequency ft (for example, 59.0 GHz) necessary for up-converting the intermediate frequency signal (BS / CS-IF) and the pilot signal (PILOT) to the millimeter wave band. A local oscillator 35 is provided.

  The pilot signal (PILOT) generated by the local oscillator 34 is superimposed on the intermediate frequency signal (BS / CS-IF) amplified by the amplifier circuit 33 via the directional coupler 36. The transmission signal (“BS / CS-IF” + PILOT) in which the pilot signal (PILOT) is superimposed on the intermediate frequency signal (BS / CS-IF) in this way is input to the mixer 37, By being mixed with the transmission side local oscillation signal generated by the local oscillator 35, it is up-converted into a millimeter wave band transmission signal.

  In addition, a band pass filter (BPF) 38 is provided on the output side of the mixer 37, and in this BPF 38, the frequency band (60 GHz band) having a higher frequency than the transmission side local oscillation signal among the outputs from the mixer 37. Only the transmission signal ("BS / CS-IF" + PILOT) is selectively extracted.

  That is, the output signal from the mixer 37 includes two transmission signals that are frequency-converted to the higher frequency side than the transmission-side local oscillation signal and transmission signals that are frequency-converted to the lower frequency side than the transmission-side local oscillation signal. In this embodiment, only a 60 GHz band transmission signal (“BS / CS-IF” + PILOT) having a frequency higher than that of the signal transmitted from the transmission side station is received via the BPF 38 in this embodiment. 50 is selectively extracted as a transmission signal to be transmitted to 50.

  The transmission signal ("BS / CS-IF" + PILOT) that has passed through the BPF 38 is input to the millimeter-wave amplifier circuit 39, amplified to a predetermined level by the amplifier circuit 39, and then transmitted to the millimeter-wave transmission antenna 40. To the receiving device 50.

  On the other hand, the receiving device 50 includes an amplifying circuit 52 for millimeter waves that amplifies the received signal from the millimeter wave receiving antenna 51, and a predetermined frequency required for down-converting the received signal amplified by the amplifying circuit 52. A local oscillator 53 for generating a reception side local oscillation signal of fr, and a reception side local oscillation signal generated by the local oscillator 53 and the reception signal amplified by the amplification circuit 52 are mixed to downconvert the reception signal. And a local oscillator 57 that generates a correction reference signal (SBASE) having the same fixed frequency fp (for example, 900 MHz) as the local oscillator 34 on the transmission device 30 side.

  Note that the oscillation frequency fr of the local oscillator 53 is lower than the oscillation frequency ft of the local oscillator 35 on the transmission device 30 side by a predetermined frequency Δf0 (1.5 GHz in this embodiment) (that is, fr = ft− Δf0, for example, 57.5 GHz). Therefore, the output signal of the mixer 54 has a frequency that is higher by Δf 0 than the frequency of the original transmission signal (“BS / CS-IF”) on the transmission side.

  Further, the output side of the mixer 54 includes a reception transmission signal corresponding to the intermediate frequency signal before being up-converted on the transmission device 30 side among the output signals from the mixer 54 (that is, the intermediate signal output from the reception unit 2b). A band-pass filter (BPF) 55 that selectively passes only a signal obtained by shifting the frequency signal to the high-frequency side by a predetermined frequency Δf0 (BS / CS-IF ′) and before being up-converted on the transmission device 30 side. A band that selectively passes only a signal corresponding to the pilot signal (that is, a received pilot signal: PILOT ′ obtained by shifting the pilot signal generated by the local oscillator 34 on the transmitting device 30 side to the high frequency side by a predetermined frequency Δf0). Two BPFs with a pass filter (BPF) 56 are connected.

The received pilot signal (PILOT ′) that has passed through the BPF 56 is input to the mixer 58 and mixed with the correction reference signal (SBASE) generated by the local oscillator 57.
On the output side of the mixer 58, the difference between the frequency fp ′ of the received pilot signal (PILOT ′) and the frequency fp of the correction reference signal (SBASE) among the signals obtained by mixing these two signals. A band pass filter (BPF) 59 that selectively passes only a signal having a frequency Δfx (Δfx = fp′−fp) as a correction signal is provided.

  The correction signal that has passed through the BPF 59 is amplified by the amplifier circuit 60 and then input to the mixer 61, and the received transmission signal (BS / CS-IF ′) that has passed through the BPF 55 by the mixer 61. Mixed.

  On the output side of the mixer 61, the received transmission signal (BS / CS-IF ′) among the signals obtained by mixing the received transmission signal (BS / CS-IF ′) and the correction signal having the frequency Δfx is mixed. ) Is a band-pass filter that selectively passes only a signal (in other words, an intermediate frequency signal: BS / CS-IF output from the receiving unit 2b) shifted to the low frequency side by the frequency Δfx of the correction signal. (BPF) 62 is provided.

  Then, the intermediate frequency signal (BS / CS-IF) that has passed through the BPF 62 is amplified to a predetermined level by the amplifier circuit 63, and further, the level is adjusted by the equalizer (EQ) 64 so as to obtain a desired tilt characteristic. Then, it is transmitted to the output terminal T2, and is output from the output terminal T2 to the BS / CS tuner 18 (or another BS / CS receiving terminal) in the corresponding dwelling unit.

  Since the power supply voltage (DC15V) supplied from the BS / CS tuner 18 (or another BS / CS receiving terminal) is input to the output terminal T2, a transmission path between the EQ 64 and the output terminal T2 Includes a power supply separation filter 65 that extracts the power supply voltage (DC15V) input to the output terminal T2 and supplies power to the internal circuit of the receiving device 50.

  As described above, in the transmission / reception system of the present embodiment, first, on the transmission device 30 side, the intermediate frequency signal (BS / CS-IF) output from the reception unit 2b of the BS / CS antenna 2 and this A pilot signal (PILOT) having a constant frequency in substantially the same frequency band as that of the intermediate frequency signal is simultaneously up-converted to a millimeter wave band using a signal transmitted from the transmission side at the frequency ft, and the transmission signal after the up-conversion is made wireless. To send.

  On the other hand, on the receiving device 50 side, the transmission radio wave from the transmitting device 30 is received by the millimeter wave receiving antenna 51, and the received signal is transmitted from the receiving side station whose frequency is lower than the transmitting side local signal by a predetermined frequency Δf0. Down-convert using issue. The received signal after down-conversion corresponds to the received transmission signal (BS / CS-IF ′) corresponding to the intermediate frequency signal (BS / CS-IF) output from the receiving unit 2b and the pilot signal (PILOT). And the received pilot signal (PILOT ').

  On the receiving device 50 side, a correction reference signal (SBASE) having the same frequency as the pilot signal generated by the transmission device 30 is generated, and the generated correction reference signal (SBASE) and the received pilot signal (PILOT ′) are generated. ) To generate a correction signal having a frequency difference Δfx between these two signals, and further mixing this correction signal with the received transmission signal (BS / CS-IF ′). The received transmission signal (BS / CS-IF ′) is frequency-converted, and the intermediate frequency signal (BS / CS-IF) output from the receiving unit 2b of the BS / CS antenna 2 is converted from the frequency-converted signals. To extract.

  Therefore, according to the transmission / reception system of the present embodiment, 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 ( That is, the intermediate frequency signal (BS / CS-IF) output from the receiving unit 2b of the BS / CS antenna 2 can be accurately restored.

  That is, when the frequency variation of the transmission side local oscillation signal is Δft and the frequency variation of the reception side local oscillation signal is Δfr, the reception transmission signal (BS) obtained by down-converting the reception signal on the reception device 50 side. / CS-IF ′) is shifted in frequency by “Δf0 + Δft + Δfr” with respect to the intermediate frequency signal (BS / CS-IF) output from the receiving unit 2b of the BS / CS antenna 2. However, this frequency error also occurs in the received pilot signal (PILOT ′) obtained by down-converting the received signal on the receiving device 50 side.

  Therefore, in the receiving apparatus 50, the frequency of the correction signal generated by mixing the correction reference signal (SBASE) generated by the local oscillator 57 and the received pilot signal (PILOT ′) is the frequency error “Δf0 + Δ”. ft + Δfr ”.

  The receiving device 50 mixes the correction signal thus generated and the received transmission signal (BS / CS-IF ′) to convert the received transmission signal (BS / CS-IF ′) to the frequency (Δ of the correction signal). Since it is configured to extract a signal shifted to the low frequency side by f0 + Δft + Δfr), the intermediate frequency signal obtained thereby is a frequency error from the received transmission signal (BS / CS-IF ′). The regular intermediate frequency signal (BS / CS-IF) from which “Δf0 + Δft + Δfr” has been removed is obtained, and the receiver 50 accurately determines the intermediate frequency signal (BS / CS-IF) output from the reception unit 2b. It can be restored.

  As described above, in this embodiment, a pilot signal having a constant frequency is used in order to accurately restore the transmission signal (here, intermediate frequency signal: BS / CS-IF) on the receiving device 50 side. The frequency of the signal may be set to substantially the same frequency band as the transmission signal before up-conversion, and the frequency may be made sufficiently lower than the millimeter wave band local signal used for up-down conversion of the transmission signal. As a result, the apparatus configuration (particularly the reception) can be compared with the conventional case where the local signal for frequency conversion is transmitted from the transmitting device 30 to the receiving device 50 and the local signals are shared between the devices. The configuration of the apparatus can be simplified, and the cost of the transmission / reception system can be reduced.

  In the present embodiment, since only one wave of the pilot signal is transmitted from the transmission device 30 to the reception device 50, compared to a case where a plurality of pilot signals are transmitted from the transmission device 30 to the reception device 50, It is possible to suppress the pilot signal from interfering with a radio signal transmitted / received by another communication device and affecting the wireless communication of the other communication device or its own transmission / reception system.

  Furthermore, in the present embodiment, the receiving device 50 extracts the received transmission signal (BS / CS-IF ′) and the received pilot signal (PILOT ′) from the output signal from the mixer 54. Instead of using a low-pass filter, band-pass filters (BPF 55, BPF 56) that selectively pass only these signals are used, so that spurious (unnecessary signals) generated in the mixer 54 can be more reliably removed. In addition, spurious (unnecessary signal) generated in the mixer 58 can be prevented from entering the mixer 61.

  Further, in the present embodiment, in the receiving device 50, only the correction signal is selectively passed instead of using a high-pass filter or a low-pass filter to extract the correction signal from the output signal from the mixer 58. A band pass filter (BPF 59) is used. As a result, spurious (unnecessary signal) generated in the mixer 58 can be more reliably suppressed.

  In particular, when the correction signal is a signal having substantially the same frequency band as the transmission signal (BS / CS-IF), the role of the BPF 59 is important in ensuring the reception quality of the transmission signal. That is, the spurious applied to the input terminal of the mixer 61 together with the correction signal is attenuated by the value of the isolation between the terminals of the mixer 61 when the frequency is substantially the same as the transmission signal. It will occur as an interference signal within the transmission signal band. Since this interference signal is within the band of the transmission signal, it cannot be removed by the main band band-pass filter (BPF 62).

  For example, when the frequency Δf0 of the correction signal is 1.5 GHz and the frequency fp of the pilot signal and the correction reference signal is 900 MHz, the frequency fp ′ of PILOT ′ is 2.4 GHz. As the spurious of the mixer 58, the frequency of the sum or difference of integer multiples of fp ′ and fp (± n × fp ′ ± m × fp, where n and m are integers) is generated. Accordingly, it is necessary for the BPF 59 to sufficiently remove spurious (900 MHz, 1200 MHz, 1800 MHz, etc.) through only 1.5 GHz of Δf0. When a lower frequency is used as the pilot signal, spurious is generated at a frequency near the correction signal, so that spurious suppression by the BPF 59 becomes more important.

  In the above description, the local oscillators 34 and 57 provided in the transmission device 30 and the reception device 50 have been described as generating pilot signals and correction reference signals having the same frequency. , 57 oscillates and the oscillation frequencies of these local oscillators 34, 57 shift (the frequency variation of the oscillator 34 is Δpt and the frequency variation of the oscillator 57 is Δpr), the frequency shifts. The minute appears as a frequency error of a transmission signal (here, intermediate frequency signal: BS / CS-IF) restored on the receiving device 50 side.

That is, the frequency of the correction signal obtained on the output side of the mixer 58 is the frequency Δfx of the difference between the frequency fp ′ of the reception pilot signal (PILOT ′) and the frequency fs of the correction reference signal (SBASE) on the reception side. From the above, considering the frequency variation of the pilot signal and the correction reference signal,
Δfx = fp′−fs
= (Δf0 + Δft + Δfr + fp + Δpt) − (fp + Δpr)
= (Δf0 + Δft + Δfr) + (Δpt−Δpr)
It is. The first term in the above equation is canceled when the mixer 61 performs frequency conversion, but the second term in the above equation remains as a frequency error.

  However, the pilot signal and the reference signal for correction are extremely low in frequency compared to the local signal for up / down conversion, and it is assumed that the frequency of each signal is shifted between the transmitting device 30 side and the receiving device 50 side. However, since the frequency error caused by the deviation is extremely small compared with the frequency error caused by the frequency fluctuation of the local oscillation signal, the receiving terminal (BS / CS tuner 18 or the like) that uses the transmission signal output from the receiving device 50. Can work without problems.

  Since the frequency of the pilot signal on the transmission side and that on the reception side are the same, a common component can be used, so it is relatively easy to generate a pilot signal and a correction reference signal having similar characteristics. . If the use conditions (environment temperature, bias voltage, etc.) for transmission and reception are not significantly different, the frequency fluctuations Δpt and Δpr of the pilot signals on the transmission side and reception side do not differ greatly. By using the difference frequency component at 58 as a correction signal, it is possible to suppress the frequency error due to the frequency fluctuation of the pilot signal and the correction reference signal by canceling each other.

In this embodiment, the receiving terminal such as the BS / CS tuner 18 operates normally due to the frequency shift between the pilot signal generated on the transmitting device 30 side and the correction reference signal generated on the receiving device 50 side. to prevent the Sina Kunar, the local oscillator 34,57 for generating a pilot signal and the correction reference signal, the oscillation frequency is stabilized crystal oscillator or temperature compensated crystal oscillator is used.

  On the other hand, in the above embodiment, the transmission / reception system that performs radio transmission by converting the frequency of the BS / CS-IF signal to a millimeter wave has been described. However, in the present invention, the transmission signal is limited to the BS / CS-IF signal. Further, the frequency for wireless transmission of the transmission signal is not limited to millimeter waves. That is, even when an arbitrary signal is frequency-converted to an arbitrary frequency, the same effect can be obtained.

  In the above-described embodiment, the transmission / reception system in which the transmission device performs up-conversion with the transmission-side local oscillation signal of frequency ft and the reception device on the down-conversion with the reception-side local oscillation signal of frequency fr has been described. Even if the present invention is applied to a transmission / reception system that down-converts the signal from the transmitting station at frequency ft and up-converts the signal from the receiving station at frequency fr on the receiving side, the same effects as described above can be obtained. Can do.

  Furthermore, in the above-described embodiment, each of the frequency conversion with the transmission side local oscillation signal of the frequency ft and the frequency conversion with the reception side local oscillation signal of the frequency fr has been described as one frequency conversion. The same effect can be obtained even if conversion is performed.

  Further, in the above description, the frequency fluctuations of the local oscillator, the pilot signal, and the correction reference signal are Δft, Δfr, Δpt, Δpr, and according to the present invention, this frequency fluctuation is regarded as a frequency value deviation. The description has been made assuming that the frequency error can be corrected. However, if the frequency variation is the phase noise of the local oscillator, the pilot signal, and the correction reference signal, the present invention can also be described as a technique capable of correcting the deterioration of the phase noise.

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

Explanation of symbols

  2 ... BS / CS antenna, 2a ... reflecting mirror, 2b ... receiving unit, 12 ... power supply inserter, 14 ... power supply device, 18 ... BS / CS tuner, L1, L2 ... transmission line, T1 ... input terminal, 30 ... transmission Device 31... Power separation filter 32. Equalizer (EQ) 33 and 39... Amplifier circuit 34 and 35 Local oscillator 36. Directional coupler 37 37 Mixer 38 Bandpass filter (BPF) 40 ... Millimeter wave transmitting antenna, 50 ... Receiving device, 51 ... Millimeter wave receiving antenna, 52, 60, 63 ... Amplifier circuit, 53, 57 ... Local oscillator, 54, 58, 61 ... Mixer, 55, 56, 59, 62 ... Band pass filter (BPF), 64... Equalizer (EQ), 65... Power supply separation filter, T 2.

Claims (4)

A transmission device that frequency-converts a transmission signal to be transmitted using a signal transmitted from a transmission-side station, and radiates the signal after the frequency conversion from a transmission antenna;
A receiving device that receives a transmission radio wave from the transmission antenna at a reception antenna and frequency-converts the reception signal using a reception-side local oscillation signal to restore the transmission signal;
A transmission / reception system comprising:
In the transmission device, a pilot signal having a constant frequency that falls within a transmission band by the frequency conversion is generated using a crystal oscillator different from the source of the transmission side local oscillation signal , and the pilot signal and the transmission signal are generated. And transmitting the transmission signal and the pilot signal simultaneously by radio frequency conversion using the signal transmitted from the transmitting station,
The receiving apparatus separates a signal obtained by frequency-converting the received signal into a received transmission signal corresponding to the transmission signal and a received pilot signal corresponding to the pilot signal, and is generated on the transmitting apparatus side A correction reference signal having the same frequency as the pilot signal to be generated is generated using a crystal oscillator different from the generation source of the reception side local oscillation signal , and the generated correction reference signal and the reception pilot signal are mixed By generating a correction signal having a frequency difference between the two signals, and mixing the generated correction signal and the received transmission signal, the received transmission signal is frequency-converted, and after the frequency conversion A transmission / reception system that extracts an original transmission signal transmitted by the transmission device from the signal of   The transmission / reception system according to claim 1, wherein a radio wave transmitted and received between the transmission device and the reception device is in a microwave band or a millimeter wave band. Transmission from a transmitting apparatus that performs frequency conversion of a transmission signal to be transmitted and a single pilot signal having a constant frequency using a signal transmitted from a transmitting side, and transmits the frequency-converted signal wirelessly from a transmission antenna A receiving device that receives a radio wave at a receiving antenna and frequency-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;
First frequency converting means for converting the frequency of 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 frequency-converted by the first frequency converting means into a received transmission signal corresponding to the transmission signal and a received pilot signal corresponding to the pilot signal;
A correction comprising a crystal oscillator different from the reception side local oscillation signal generating means, and generating a correction reference signal having the same frequency as the pilot signal generated on the transmission device side independently of the reception side local oscillation signal Reference signal generating means,
By mixing the correction reference signal generated by the correction reference signal generation means and the reception pilot signal separated by the signal separation means, a correction signal having a frequency difference between the two signals is obtained. Correction signal generating means for generating,
A second frequency converting means for converting the frequency of the received transmission signal by mixing the correction signal generated by the correction signal generating means and the received transmission signal;
Signal extraction means for extracting the original transmission signal transmitted by the transmission device from the signal frequency-converted by the second frequency conversion means;
A receiving apparatus comprising:   4. The receiving apparatus according to claim 3, wherein a transmission radio wave from the transmitting apparatus is a microwave band or a millimeter wave band.

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