JP4250125B2 - Wireless transmission device - Google Patents

Description

This invention relates to a wireless transmission device, as an example, particularly relates to a microwave band radio transmission equipment that wirelessly transmits broadcast waves in the microwave band.

  2. Description of the Related Art Conventionally, as a microwave band wireless communication system, as shown in FIG. 5, there is one provided with a high frequency wireless transmission device 100 and a high frequency wireless reception device 201 (see, for example, Japanese Patent Application Laid-Open No. 2003-258655). Here, the microwave band refers to a frequency band including a microwave band and a millimeter wave band.

  First, the high-frequency wireless transmission device 100 shown in FIG. 5 will be described. The high-frequency radio transmitter 100 includes a first up-converter (intermediate frequency modulator) and a second up-converter (microwave band modulator).

  The first up-converter includes a local oscillator 400, a mixer 130, a filter 150, an amplifier 160, a power distributor 260, an attenuator 270 (level adjuster), and a power combiner 180. .

  A first IF signal IF1 that is a modulated wave signal is input to the high-frequency wireless transmission device 100. The first IF signal IF1 is a signal modulated by, for example, an orthogonal multicarrier modulation scheme (OFDM modulation scheme). The mixer 130 multiplies the input first IF signal IF1 and the first LO signal (local oscillation signal) fLO1 output from the local oscillator 400, which is a reference signal source, and outputs a second IF signal. The signal IF2 is output.

  Furthermore, the filter 150 provided immediately after the mixer 130 mainly extracts only the component of the second IF signal IF2. Further, the power distributor 260 distributes a part of the first LO signal fLO1 output from the local oscillator 400 to the attenuator 270. The attenuator 270 adjusts the level of the distributed first LO signal fLO1, and then the power combiner 180 merges the first LO signal fLO1 and the second IF signal IF2.

  As described above, a multi-wave signal, that is, an intermediate frequency multiplexed signal, of the second IF signal IF2 (high-frequency signal fRF1) and the first LO signal fLO1 that is the reference signal is generated. This multiwave signal is amplified by the amplifier 160, and the amplified multiwave signal is input to the second up-converter.

  Next, the second up converter will be described. The second up-converter includes a second local oscillator 800, a mixer 170, a filter 900, and an amplifier 1000.

  The mixer 170 multiplies the multi-wave signal of the high-frequency signal fRF1 and the first LO signal fLO1 and the second LO signal (local oscillation signal) fLO2 output from the second local oscillator 800 to generate a radio signal. Up-conversion. Further, the filter 900 passes only the signal of the desired frequency of the radio signal that has been up-converted, and the amplifier 1000 amplifies the signal of the desired frequency of the radio signal. The signal amplified by the amplifier 1000 is a radio modulation signal component (high frequency signal fRF1 + second LO signal fLO2) and a local oscillation signal component (first LO signal fLO1 + second LO signal fLO2). Multiple signals.

  The transmission antenna 1100 transmits a radio modulation signal component (high frequency signal fRF1 + second LO signal fLO2) and a local oscillation signal component (first LO signal fLO1 + second LO signal fLO2). .

  Next, the high frequency radio receiving apparatus 201 of FIG. 5 will be described. The high frequency radio receiving apparatus 201 includes an antenna 1200, a filter 200, an amplifier 210, a mixer 220, a local oscillator 230, an amplifier 240, a power distributor 250, a filter 260, a filter 270, a mixer 310, and an amplifier. 320.

  The high-frequency wireless reception device 201 receives a signal 72 transmitted from the high-frequency wireless transmission device 100. As described above, the signal 72 transmitted by the high-frequency radio transmitter 100 is a local oscillation signal component (first LO signal fLO1 + second LO signal fLO2) and a radio modulation signal component (high-frequency signal fRF1 + second LO signal). fLO2). The high-frequency radio receiver 201 down-converts the received signal to a first IF signal IF1 that is an original modulated wave signal. The procedure will be described below.

  The antenna 1200 receives the signal 72 transmitted from the high frequency wireless transmission device 100. The filter 200 removes unnecessary waves (for example, out-of-band interference) of the received signal. The amplifier 210 amplifies the signal that has passed through the filter 200. The mixer 220 multiplies the amplified signal and the second LO signal (local oscillation signal) fLO2 output from the local oscillator 230. As a result, the LO signal component (fLO1 + fLO2) and the radio modulation signal component (fRF1 + fLO2) are down-converted into the intermediate frequency multiplexed signal IFM2. That is, the intermediate frequency multiplexed signal IFM2 = (first LO signal fLO1 + high frequency signal fRF1). The harmonic signal fRF1 is (first IF signal IF1 + first LO signal fLO1).

  Next, the amplifier 240 amplifies the intermediate frequency multiplexed signal IFM2. The high frequency signal fRF1 of the intermediate frequency multiplexed signal IFM2 is input to the mixer 310 via the filter 260 through which only the high frequency signal fRF1 can pass. On the other hand, the first LO signal fLO1 is amplified by the amplifier 320 via the filter 270 through which only the first LO signal fLO1 can pass, and then input to the mixer 310. The mixer 310 multiplies the high-frequency signal fRF1 and the first LO signal fLO1. Thereby, the high-frequency signal fRF1 is down-converted and demodulated into the first IF signal IF1.

  Incidentally, the wireless transmission device 100 in the conventional wireless communication system has the following problems.

  That is, the conventional wireless transmission device 100 amplifies the intermediate frequency multiplexed signal generated by combining the high frequency signal fRF1 (second IF signal IF2) and the first LO signal fLO1 by the power combiner 180 by the amplifier 160. It is the composition to do. For this reason, the amplifier 160 cannot amplify the high-frequency signal fRF1 and the first LO signal fLO1 independently. Therefore, the level of the first LO signal fLO1 is always higher than the level of the high-frequency signal fRF1, and the operation of the amplifier 160 becomes a non-linear operation. For this reason, the signal components of the high-frequency signal fRF1 (second IF signal IF2) and the first LO signal fLO1 include an unnecessary wave component and a large distortion component, and a backflow to the mixer 130 also occurs. As described above, it is difficult for the conventional wireless transmission device to obtain a normal first up-conversion characteristic.

  Here, FIG. 6 shows an input side spectrum and an output side spectrum before and after the amplifier 160. FIG. 6A shows the input side spectrum. The output level of the first LO signal fLO1 that is the reference signal is equal to or higher than the total power of the high-frequency signal fRF1 that is the second IF signal IF2. In FIG. 6A, the level ratio between the first LO signal fLO1 and the high-frequency signal fRF1 is conceptually indicated by ΔP.

  On the other hand, FIG. 6B shows a spectrum on the output side of the amplifier 160. When the first LO signal fLO1 and the high-frequency signal fRF1 (second IF signal IF2) are input to the amplifier 160 (the gain is G), the amplifier 160 performs a distortion nonlinear operation by the first LO signal fLO1. Cause (compression of gain is indicated by g). By this non-linear operation, the signal level of the first LO signal fLO1 becomes ΔP + (G−g), and the high-frequency signal fRF1 (second IF signal IF2) cannot sufficiently increase the level, and the spectrum is also high. Re-growth occurs and spreads. In particular, in the case of a modulation scheme in which the high-frequency signal fRF1 is weak against distortion (OFDM (orthogonal multicarrier) modulation scheme, multilevel modulation scheme such as 64QAM (orthogonal amplitude modulation)), the influence of distortion of the amplifier 160 becomes extremely large.

Further, when the mixer 130 multiplies the first IF signal IF1 and the first LO signal fLO1, the conventional radio transmission apparatus uses the first IF signal IF1 or the mixer 130 to multiply the first IF signal IF1 and the first LO signal fLO1. 1 is not configured to adjust the level of the LO signal fLO1. For this reason, when the level of the first IF signal IF1 is too large, there arises a problem that demodulation cannot be performed on the receiving device side. Conversely, when the level of the first IF signal IF1 is too small, there is a problem that the wireless transmission distance is shortened.
JP 2001-053640 A JP 2003-258655 A

An object of the present invention is on which it is possible to obtain a good up-conversion characteristics, and can enlarge the radio transmission band is to provide a wireless transmission equipment capable of accommodating a plurality of modulation wave signal.

In order to solve the above problems, a wireless transmission device of the present invention includes an input terminal,
A first up-converter that up-converts the input signal input to the input terminal,
The first up-converter is
A local oscillator that oscillates a reference signal;
A mixer that multiplies the input signal and the reference signal to generate a modulation frequency signal;
A filter that passes only the modulation frequency signal generated by the mixer;
An input signal level adjuster configured of a T-type attenuator or a π-type attenuator configured by a resistor and an amplifier and adjusting the level of the input signal or the modulation frequency signal;
A distributor for distributing the reference signal;
A reference signal level adjuster for adjusting the level of the reference signal distributed by the distributor;
A synthesizer that synthesizes the reference signal output from the reference signal level adjuster and the modulation frequency signal;
The filter is disposed between the mixer and the combiner;
The input signal level adjuster is disposed between the input terminal and the combiner ,
The signal level of the modulation frequency signal and the signal level of the reference signal are adjusted by the input signal level adjuster and the reference signal level adjuster, and the power S of the modulation frequency signal and the power T of the reference signal are The power ratio S / T is 1 or less .

  In the wireless transmission device of the present invention, the input signal level adjuster is disposed between the input terminal and the combiner. Therefore, when up-converting the input signal, before the signal is synthesized by the synthesizer, the level of the input signal or modulation frequency signal and the level of the reference signal are separated by the input signal level adjuster and the reference signal level adjuster. Can be adjusted independently. For this reason, the sum of the level of the modulation frequency signal and the level of the reference signal can be made constant, and the level ratio between the modulation frequency signal and the reference signal can be made constant.

  Further, in the wireless transmission device according to an embodiment, the input signal level adjuster is arranged at the subsequent stage of the mixer.

  In this wireless transmission device, since the input signal level adjuster is arranged after the mixer, the level of the modulation frequency signal generated by the mixer by the input signal level adjuster and the reference signal level adjuster, and the reference signal by the local oscillator Can be adjusted separately before combining with the combiner. Therefore, the level of the modulation frequency signal can be adjusted with high accuracy, and distortion of the level adjuster itself composed of an amplifier and an attenuator can be prevented. Therefore, level adjustment with better linearity is possible, and a transmission wave with excellent signal quality can be generated.

  In the wireless transmission device according to an embodiment, the input signal level adjuster is arranged in front of the mixer.

  In the wireless transmission device of this embodiment, the input signal level adjuster is arranged in the preceding stage of the mixer, so that the level of the input signal can be adjusted before the input signal is modulated. This input signal is an externally input signal, and the level can be directly measured with a spectrum analyzer, a power meter, or the like. Therefore, the input level can be adjusted according to the measurement level value. Since the input signal before modulation has a low frequency, level adjustment by an automatic gain control amplifier (AGC) or the like can be easily performed. In addition, since the modulation depth can be adjusted, the modulated radio signal is more resistant to loss in the radio section and the like, the signal quality is improved, and the radio transmission distance can be increased.

  In the wireless transmission device according to an embodiment, the input signal level adjuster is arranged in both the front stage and the rear stage of the mixer.

  In the wireless transmission device of this embodiment, the level of the input signal can be adjusted before the input signal is modulated. Further, the level of the modulation frequency signal and the level of the reference signal can be adjusted separately before synthesis by the input signal level adjuster and the reference signal level adjuster. Therefore, the input signal level adjuster at the subsequent stage can optimize the ratio and absolute power of only the level of the input signal with respect to the reference signal to be added. Furthermore, since the input signal level adjuster in the previous stage can adjust the level of the input signal before applying the modulation, the modulation depth can be optimized with respect to the reference signal. As a result, the SN (signal-to-noise) ratio, which is the demodulation quality at the time of demodulation on the receiving side, can be further increased.

The radio transmission apparatus of the present invention adjusts the signal level of the modulation frequency signal and the signal level of the reference signal by the input signal level adjuster and the reference signal level adjuster, and The power ratio S / T between the power S and the power T of the reference signal is set to 1 or less.

In the wireless transmission device of the present invention , since the power ratio S / T between the power S of the modulation frequency signal and the power T of the reference signal is 1 or less, the power of the reference signal is higher than the power S of the modulation frequency signal. T always increases. As a result, the intermediate frequency multiplexed signal can be input as an example to the transmission frequency converter at the next stage up to near the saturation point of the transmission frequency conversion means.

  That is, the modulation frequency signal is a modulation signal of a series of wideband signals ranging from several hundred MHz to 2 GHz as an example, that is, a wideband modulation signal spread in the frequency axis direction, and the peak level itself is small compared to the reference signal. . On the other hand, since the reference signal is a signal (sine wave signal) that spreads in the power level direction at only one frequency, if the levels of the reference signal and the modulation frequency signal are compared, The peak level is large.

  Therefore, when the input level of the intermediate frequency multiplexed signal obtained by synthesizing the modulation frequency signal and the reference signal is increased, the transmission frequency converter at the next stage is first distorted by the reference signal. Accordingly, when a multi-level phase modulation signal such as 64QAM (Quadrature Amplitude Modulation) or an OFDM modulation signal is used as the modulation frequency signal, the transmission frequency conversion unit may be directly distorted due to an increase in the modulation frequency signal. In addition, the regrowth of spectrum and the occurrence of spurious can be reduced as much as possible. Therefore, according to this embodiment, since the signal is first distorted by the reference signal (sine wave signal), the intermediate frequency multiplexed signal is moved to the vicinity of the saturation point of the transmission frequency conversion unit in the next stage without taking a large back-off. It is possible to increase the power efficiency of the transmission frequency converter.

  The radio transmission apparatus according to an embodiment further includes a second up-converter that further up-converts the signal up-converted by the first up-converter, and the signal up-converted by the second up-converter Wireless transmission.

  In the wireless transmission device of this embodiment, the first up-converter temporarily frequency-converts the input signal to the intermediate frequency band to generate an intermediate frequency multiplexed signal. In the first up-converter, as an example, when the input signal is modulated by the mixer constituting the microwave band modulator, a reference signal (local oscillation signal) as a carrier to be modulated and the modulated input signal are modulated. A double sideband signal having a large frequency interval is generated. Further, as an example, after selecting one of the sideband signals of the double sideband signals, the generated intermediate frequency multiplexed signal is further frequency upconverted by the second upconverter. Thereby, no matter how much the frequency is increased by frequency up-conversion, for example, a single-sideband signal can be generated by easily filtering one-sideband using a microwave / millimeter-wave transmission filter. Thus, by transmitting only the desired wave, it is possible to generate a high-quality radio signal with less unnecessary wave components and excellent transmission efficiency.

  In the wireless transmission device according to an embodiment, a filter that allows only a signal in a predetermined frequency band to pass is provided between the mixer and the combiner.

  In the wireless transmission device of this embodiment, only the component of the modulation frequency signal can be passed with the filter, and the lower sideband or the upper side signal waveband can be selected with this filter. Moreover, this filter can suppress the leakage component of the reference signal having a high signal level. In addition, the filter can determine the occupied frequency bandwidth of the transmission wave at the intermediate frequency stage. As a result, the bandwidth of the filter (the ratio of the pass band to the center frequency) can be reduced compared to the case where the band is limited on the lower frequency side, and the filter can be designed and manufactured easily and compactly. Further, the Q value (quality factor) of the resonator of the filter can be increased as compared with the case where the band is limited in a radio frequency band (microwave or millimeter wave band) having a higher frequency. Therefore, the degree of suppression in the attenuation band can be increased, the band can be sharply limited, the occupied frequency bandwidth can be clearly defined, and a high-quality radio transmission signal can be generated.

  In the wireless transmission device according to an embodiment, the filter passes a signal in a lower sideband than the frequency of the reference signal.

  In the wireless transmission device of this embodiment, the frequency characteristic of the modulated frequency signal (first intermediate frequency signal) after frequency conversion by the mixer is inverted between the low frequency side and the high frequency side with respect to the frequency of the input signal. By this inversion, the modulation frequency signal (first intermediate frequency signal), which is a wideband signal, is converted into an amplifier having a level control function, up-conversion (transmitter side) and down-conversion (receiver side) to the millimeter wave band after the next stage. The frequency characteristics (frequency flatness) of frequency conversion and amplification characteristics can be improved. This is due to the following reason.

  In general, at high frequencies above the quasi-microwave band (UHF band), the loss is smaller on the low frequency side than on the high frequency side of the signal in the frequency conversion process and amplification process (the gain is higher in the case of amplification). (Large), loss on the high band side is larger (gain is smaller in the case of amplification), and when the signal level is the horizontal axis frequency and the vertical axis signal strength level, the flat frequency characteristics are ideal characteristics On the other hand, the frequency characteristic has a downward slope. As an example, the input signal itself that is input to this wireless transmission device is a (super) wideband signal of a composite signal of a series of multi-channel video signals, so that there is a level difference between the high frequency side and the low frequency side. The modulation signal has a high-frequency side lowered. In addition to such characteristics, in the first frequency conversion (first up-conversion) on the wireless transmission device side, a loss is caused on the high frequency side of the signal subjected to the frequency conversion in the same manner as the above-mentioned one series of input signals. The characteristic that the loss is large and the loss is small on the low frequency side is further added. In order to improve such frequency characteristics and make them flat, by using the lower sideband by the first frequency conversion on the transmission side (specifically, the lower sideband is selected by a filter) The frequency characteristics to be converted can be inverted between the high frequency side and the low frequency side. That is, in the process after the first frequency conversion, the loss is large on the high frequency side of the signal (small gain) and small on the low frequency side with respect to the signal inverted on the low frequency side and the high frequency side. Since the characteristic that the gain is large is added, the frequency characteristic is compensated and the characteristic becomes flatter.

  A wireless communication system according to an embodiment includes the wireless transmission device and a reception device that receives a signal transmitted from the wireless transmission device.

  In the wireless communication system of this embodiment, the signal up-converted by the wireless transmission device is down-converted on the receiving device side, so that the reception demodulation quality can be improved and a good communication system can be configured.

  According to the wireless transmission device of the present invention, the input signal level adjuster is disposed between the input terminal and the combiner. Therefore, when up-converting the input signal, before the signal is synthesized by the synthesizer, the level of the input signal or modulation frequency signal and the level of the reference signal are separated by the input signal level adjuster and the reference signal level adjuster. Can be adjusted independently. For this reason, the sum of the level of the modulation frequency signal and the level of the reference signal can be made constant, and the level ratio between the modulation frequency signal and the reference signal can be made constant.

  Further, since the input signal level adjuster adjusts the level of the input signal or the modulation frequency signal at the front stage of the combiner, the amplifier in the first up-converter is difficult to distort.

  Therefore, according to the present invention, a good upconversion characteristic can be obtained, and the radio transmission band can be expanded to cope with a plurality of modulated wave signals.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 shows a schematic configuration of a microwave band radio communication system as an embodiment of the present invention. The microwave radio communication system includes a millimeter wave radio transmitter 9 and a millimeter wave radio receiver 10. Here, the microwave band refers to a frequency band including a microwave band and a millimeter wave band. Further, this microwave band wireless communication system includes a frequency arrayer 5 connected to the input terminal IP of the millimeter wave band wireless transmission apparatus 9 and a duplexer 190 connected to the output terminal 500 of the millimeter wave band wireless reception apparatus 10. Is provided. A plurality of TV receivers 31 are connected to the duplexer 190. The duplexer 190 is connected to a terrestrial broadcast antenna 1a and a satellite broadcast antenna 1b.

  The microwave band radio communication system includes the electronic apparatus of the present invention including the millimeter wave band radio receiver 10, the duplexer 190, and the satellite / terrestrial broadcast tuner 30.

  As shown in FIG. 1, the millimeter-wave band wireless transmission device 9 on the transmission side included in the microwave wireless communication system of this embodiment includes a frequency array 5 and a reference signal addition / power connected to the frequency array 5. A level control circuit 2, a frequency conversion / transmission circuit 3, a local oscillator 7, and a transmission antenna 4 are provided. The reference signal addition / power level control circuit 2 constitutes a first up-converter, and the frequency conversion / transmission circuit 3 constitutes a second up-converter.

  First, a schematic configuration and a schematic operation of the frequency array device 5 on the transmission side and the millimeter wave band wireless transmission device 9 will be described with reference to FIG. On the transmitting side, first, as a first step, as shown in FIG. 3A, for example, from the input modulated wave signal 5a from the terrestrial broadcasting antenna 1a and the satellite broadcasting antenna 1b. The input modulated wave signal 5b is adjusted by the amplifiers 51 and 52 so that the power levels of the respective input modulated signals 5a and 5b are substantially equal, frequency-aligned by the mixer 53, and a series of input signals 5e. (Frequency fIF1e) is generated.

  As the next step, in the millimeter waveband radio transmission apparatus 9, the input signal 5e is input to the reference signal addition / power level control circuit 2 and arranged on the frequency axis as shown in FIG. A series of input modulated wave signals 5e (frequency fIF1e) undergoes a first frequency conversion. In the reference signal addition / power level control circuit 2, the first IF signal 71a subjected to the first frequency conversion is subjected to level control, and at the same time, an appropriate level reference signal 71c is added to the intermediate frequency multiplexed signal ( A first IF multiplexed signal 71d which is a frequency array signal) is generated. The first IF signal 71a is a modulation frequency signal.

  As the next step, the first IF multiplexed signal 71 d output from the reference signal addition / power level control circuit 2 is input to the frequency conversion / transmission circuit 3. In the frequency conversion / transmission circuit 3, the first IF multiplexed signal 71 d is frequency-converted to the millimeter wave band and amplified by the local oscillation signal output from the local oscillator 7.

  As shown in FIG. 3C, the radio multiplexed signal 72 generated by the frequency conversion and amplification is transmitted as a radio signal by the transmission antenna 4. In FIGS. 3A to 3C, white arrow symbols indicate signal arrangement directions.

  Next, a schematic configuration and a schematic operation of the millimeter wave band radio receiving apparatus 10 will be described with reference to FIG. The millimeter-wave band radio receiving apparatus 10 receives a radio multiplex signal from the transmission side, and receives a radio multiplex signal 73 from the reception antenna 14 to perform first frequency down-conversion / frequency conversion / reception. The circuit 11 includes a local oscillator 8 that supplies a local oscillation signal, and a reference signal reproduction / frequency conversion circuit 12 that performs second frequency down-conversion on the receiving side. The frequency conversion / reception circuit 11 serves as a first down converter, and the reference signal reproduction / frequency conversion circuit 12 serves as a second down converter.

  As shown in FIG. 4A, the millimeter wave band radio receiving apparatus 10 receives the radio multiplexed signal 72 from the transmission side by the receiving antenna 14 as the first step. The frequency conversion / reception circuit 11 receives the radio multiplexed signal 73 from the antenna 14 and performs first frequency down-conversion. That is, in the frequency conversion / reception circuit 11, the radio multiplexed signal 73 is converted into the second intermediate frequency band by the local oscillation signal supplied from the local oscillator 8, and the intermediate frequency multiplexed signal as shown in FIG. The second IF multiplexed signal 74 is generated. In FIGS. 4A to 4C, white arrow symbols indicate signal arrangement directions.

  As the next step, the second IF multiplexed signal 74 is subjected to the second reception side frequency down-conversion by the reference signal reproduction / frequency conversion circuit 12, and then the reference signal reproduction / frequency conversion circuit 12 performs FIG. As shown in (C), a series of output signals 76 (frequency fIF1e) corresponding to the original series of input signals 5e (frequency fIF1e) is reproduced.

  That is, the reference signal reproduction / frequency conversion circuit 12 extracts and amplifies the reference signal 74c from the second IF multiplexed signal 74 shown in FIG. 4B with a filter described later, and this reference signal 74c. Accordingly, the second IF multiplexed signal 74, which is an intermediate frequency multiplexed signal, is frequency-converted. As a result, the reference signal reproduction / frequency conversion circuit 12 converts a series of input signals 5e (frequency fIF1e) input on the transmission side into a series of output signals 76 (frequency fIF1e) as shown in FIG. ).

  Next, the output signal 76 output from the output terminal 500 of the radio reception apparatus 10 is input to the frequency reverse arrangement / separation unit 190 as the final step on the reception side. In the frequency reverse arrangement / separation unit 190, a signal 76a corresponding to the signal 5a for terrestrial broadcasting from one series of serial output signals 76 (frequency fIF1e) corresponding to the input signal 5e reproduced on the receiving side. The signal 76b corresponding to the satellite broadcast signal 5b is reproduced. The demultiplexed signals 76 a and 76 b are input to a plurality of satellite / terrestrial broadcast tuners 30 in the plurality of TV receivers 31.

  Next, a detailed configuration of the microwave band radio communication system according to the first embodiment will be described with reference to FIG.

  As shown in FIG. 2, the millimeter band radio transmission apparatus 9 as an example of the microwave band radio transmission apparatus includes a first frequency conversion circuit 2 a that is an intermediate frequency conversion section connected to the frequency arrangement section 5, and a local oscillator. A reference signal source 2c, a reference signal addition circuit 2d as an example of a multiplexed signal generation unit, and a millimeter wave frequency conversion circuit 3a as a transmission side frequency conversion unit.

  The first frequency conversion circuit 2a, the reference signal source 2c, and the reference signal addition circuit 2d constitute the reference signal addition / power level control circuit 2 as a first up-converter. The millimeter wave frequency conversion circuit 3a constitutes the frequency conversion / transmission circuit 3 as the second up-converter and the local oscillator 7.

  The reference signal addition / power level control circuit 2 includes a first frequency conversion circuit 2a connected to the input terminal IP, a reference signal addition circuit 2d connected to the first frequency conversion circuit 2a, and the reference signal. And a reference signal source 2c connected to the additional circuit 2d.

  The first frequency conversion circuit 2a includes an amplifier 203a whose input side is connected to the input terminal IP, and a frequency mixer 201 whose input port is connected to the output side of the amplifier 203a. The other power supply port 204b of the reference signal adding circuit 2d is connected to another input port of the frequency mixer 201. A reference signal source 2c is connected to the power distributor 204b.

  The reference signal adding circuit 2d includes a level controller 95, which is a reference signal level adjuster having an input side connected to the power distributor 204b, and power having an input port connected to the output side of the level controller 95. It has a synthesizer 204a. Another input port of the power combiner 204a is connected to the output side of the amplifier 203b included in the first frequency conversion circuit 2a. The first frequency conversion circuit 2a includes a filter 202a connected between the output terminal of the frequency converter 201 and the input side of the amplifier 203b. The amplifiers 203a and 203b constitute an input signal level adjuster and include a level controller. In addition, the transmitter 9 includes both the amplifiers 203a and 203b, but may include only one of them.

  The millimeter-wave frequency conversion circuit 3a is connected to a frequency mixer 301 having an input port connected to the output side of the power combiner 204a of the reference signal adding circuit 2d and another input port of the frequency mixer 301. The local oscillator 7, a band pass filter 302 whose input side is connected to the output port of the frequency mixer 301, and a millimeter wave amplifier 303 connected to the output side of the band pass filter 302.

  The transmitting antenna 4 is connected to the output side of the millimeter wave amplifier 303 of the millimeter wave frequency conversion circuit 3a.

  The operation of the millimeter waveband radio transmission apparatus 9 configured as described above will be described.

  In the frequency arrangement unit 5, the power levels of the input modulated wave signal 5a from the terrestrial broadcast antenna 1a and the input modulated wave signal 5b from the satellite broadcast antenna 1b are adjusted by the amplifier 51 and the amplifier 52, respectively. . As a result, the power levels of the input modulated wave signals 5a and 5b are adjusted to be substantially equal, and the input modulated wave signals 5a and 5b are further combined by the mixer 53 and frequency-aligned. Thereby, a series of input signals 5e (frequency fIF1e) illustrated in FIG. 6A is generated. Here, when the input modulation signal 5a and the input modulation signal 5b are in the same frequency band, since it is not possible to directly combine the power of both, the frequency of any one of the input modulation signals is converted. , Each signal is combined with power. Thus, a series of input signals 5e (frequency fIF1e) is generated. In addition, here, the power levels of the input modulation signals 5a and 5b are adjusted to be substantially equal, but the power levels of the input modulation signals 5a and 5b differ depending on the quality of the input modulation signals 5a and 5b. The power may be combined as a different level.

  Next, a series of input signals 5e (frequency fIF1e) arranged on the frequency axis is amplified to an appropriate level by the amplifier 203a and input to the frequency mixer 201 to be subjected to the first frequency conversion. The In the first IF signal 71a subjected to the first frequency conversion, only one sideband signal is filtered by the filter 202a, and adjusted to an appropriate level by the amplifier 203b. This adjustment may be performed by appropriately combining an attenuator with the amplifier 203b.

  The first IF signal 71a after the level adjustment is input to the power combiner 204a. On the other hand, the power combiner 204a is output from the reference signal source 2c and input to the power distributor 204b of the reference signal adding circuit 2d, and the reference signal 71c adjusted to an appropriate level by the level controller 95 is input. The

  In the power combiner 204a, the reference signal 71c is added to the first IF signal 71a, and the first IF as an intermediate frequency multiplexed signal (frequency array signal) as shown in FIG. A multiplexed signal 71d is generated.

  As described above, the reference signal 71c having the frequency fLO1 output from the reference signal source 2c is divided into two by the power distributor 204b, and one reference signal 71c is input to the frequency mixer 201 as a local oscillation signal. The other reference signal 71c to which power has been distributed is input to the level controller 95, and after appropriate level control described later, is input to the power combiner 204a as the reference signal 71c. Then, in the power combiner 204a, as described above, the reference signal 71c and the first IF signal 71a are combined with each other to generate the first IF multiplexed signal 71d.

  Here, the first IF signal 71a is filtered by the filter 202a connected between the frequency mixer 201 of the first frequency conversion circuit 2a and the amplifier 203b, and the amplifier 203 (or the amplifier 203 and the attenuator) is filtered. Thus, the reference signal 71c is added after amplification and level control.

  As described above, the first IF signal 71a is level-controlled by the level control means constituted by the amplifier 203b and the like, and then the reference signal 71c is added. Accordingly, the amplifier 203b can efficiently amplify only the first IF signal 71a signal having a low level without being distorted by the reference signal 71c having a level higher than that of the first IF signal 71a. .

  Further, the power level of the first IF signal 71a included in the first IF multiplexed signal 71d and the power level of the reference signal 71c are respectively determined by the amplifier 203b (or a combination with an attenuator) and the level controller 95, respectively. Can be controlled independently. Therefore, since the power level distribution ratio of both can be controlled by independently controlling the power level of the first IF signal 71a and the power level of the reference signal 71c, the frequency conversion / transmission circuit 3 on the transmission side is fully It can be driven more linearly with power.

  Further, during the second frequency conversion on the millimeter wave band radio receiving apparatus 10 side, the second IF multiplexed signal 74 itself is frequency down-converted by the reference signal 74c included in the second IF multiplexed signal 74. In this case, an optimum distribution ratio exists for the power distribution ratio between the desired signal and the reference signal.

  Accordingly, at the stage of generating the first IF multiplexed signal 71d in advance in the millimeter-wave band wireless transmission device 9 on the transmission side, the setting of (power of the first IF signal 71a) / (power of the reference signal 71c) is set. It is desirable to set an appropriate ratio to obtain an optimal power distribution ratio with high reception sensitivity. As a result, the frequency conversion efficiency (reception sensitivity) can be increased and the wireless transmission distance can be increased.

  In this embodiment, as an example, the level controller 95 and the attenuator of the level controller used in the amplifiers 203a and 203b may be configured by a T-type attenuator or a π-type attenuator with the resistance of the chip component. . The power combiners 204a and 204b included in the reference signal adding circuit 2d are preferably Wilkinson combiners whose output ports have isolation characteristics. As a result, signals leaking into the output ports of the power combiners 204a and 204b can be suppressed, and each functional circuit can be operated normally. Specifically, the first IF signal 71a can be prevented from leaking to the reference signal adding circuit 2d side by the power combiners 204a and 204b and the amplifiers 203a and 203b configured by the Wilkinson combiner. Furthermore, it is possible to prevent the added reference signal 71c from flowing back from the power combiner 204a to the frequency mixer 201.

  Here, in this frequency conversion, it is desirable to use a lower sideband signal. By using this lower sideband signal, the frequency characteristic of the first IF signal 71a after frequency conversion is inverted. By the inversion of the frequency characteristic, the first IF signal 71a, which is a wideband signal, is converted into an amplifier 203 having a level control function, up-conversion (transmitter side) and down-conversion (receiver side) to the millimeter wave band after the next stage The frequency characteristics (frequency flatness) of the frequency conversion / amplification characteristics at the side) can be improved. The reason will be described below.

  Normally, at high frequencies above the quasi-microwave band (UHF band), the signal level of a series of signals is higher than the frequency high frequency side in the frequency conversion process and amplification process in the wireless transmission device 9 and the wireless reception device 10. However, the loss is smaller on the low frequency side (the gain is increased in the case of amplification). Therefore, the loss is larger on the high frequency side than on the low frequency side (in the case of amplification, the gain is small). Therefore, while the flat frequency characteristic is ideal, the signal level of the one series of signals has a frequency characteristic that falls to the right when the horizontal axis is the frequency and the vertical axis is the signal intensity level. Note that the input signal 5e (frequency fIF1e) itself input to the wireless transmission device 9 is also a wideband signal of a series of multi-channel video signals, and thus has a level difference between the high frequency side and the low frequency side. The modulation signal has a lowered level on the high frequency side.

  Therefore, in order to improve the frequency characteristic and make it flat, by using the lower sideband in the first frequency conversion by the first frequency conversion circuit 2a on the transmission side (specifically, in the filter 202a). By selecting the lower sideband), the high frequency side and the low frequency side of the frequency characteristics after frequency conversion can be inverted. That is, in the signal processing process after the filter 202a in the first frequency conversion circuit 2a, a loss is large on the high frequency side of the signal with respect to the signal whose frequency characteristics are inverted on the low frequency side and the high frequency side (gain The characteristic that the loss is small (the gain is large) on the low frequency side is added. Thereby, the frequency characteristic of the input signal 5e at the time of the input is compensated, and a flatter frequency characteristic can be realized in the first IF multiplexed signal 71d and the radio multiplexed signal 72.

That is, in the process of generating the first IF multiplexed signal 71d shown in FIG. 3B from the one series of input signals 5e shown in FIG. 3A, the frequency arrangement of the signals is converted as follows.
(Signal) (Frequency)
First IF reference signal 71c: fLO1
First IF signal 71a: fLO1-fIF1e

  The reference signal 71c obtained by distributing the local oscillation signal from the reference signal source 2c used in the first frequency conversion by the power distributor 204b is added to the inverted first IF signal 71a. This can improve the frequency characteristics in the subsequent processing steps (amplification and frequency conversion). That is, in the subsequent frequency conversion / amplification process, a loss occurs on the high frequency side of the signal with respect to the first IF signal 71a in which the frequency arrangement is inverted between the low frequency side and the high frequency side with respect to the input signal 5e. The characteristics of increasing (low gain) and low loss (high gain) on the low frequency side are added. For this reason, the frequency characteristic of the signal becomes flatter. The signal inverted with respect to the input signal 5e in the wireless transmission device 9 is automatically converted to the original normal rotation by second frequency down-conversion using a reference signal 74c on the wireless reception device 10 side described later. It becomes a series of signals 76 (frequency fIF1e) returned to the transmission side input signal 5e (frequency fIF1e).

  The first IF multiplexed signal 71d shown in FIG. 3B is then input to the millimeter wave frequency conversion circuit 3a shown in FIG. In this millimeter wave frequency conversion circuit 3a, a frequency mixer 301, a band pass filter 302, and a millimeter wave amplifier 303 are connected in order from the input side to the output side. A local oscillator 7 is connected to the frequency mixer 301.

  In the millimeter wave frequency conversion circuit 3a, the first IF multiplexed signal 71d is frequency up-converted to the millimeter wave band by the local oscillator 7 and the frequency mixer 301, and then a desired multiplexed signal is filtered by the band pass filter 302. . In the frequency conversion to the millimeter wave band, the upper side band signal is used to improve the frequency characteristics described above. Then, after the multiplexed signal is amplified by the millimeter wave amplifier 303, it is emitted to the space as a wireless multiplexed signal 72 in the millimeter wave band by the transmitting antenna 4. Here, the transmission antenna 4 and the millimeter wave amplifier 303 constitute transmission means.

  In a desirable example, an N-order (N: natural number of 2 or more) harmonic mixer such as an even harmonic mixer is used as the frequency mixer 301. By using this Nth order harmonic mixer, the local oscillation frequency of the local oscillator 7 can be reduced to 1 / N. Specifically, in this example, the local oscillation frequency of the local oscillator 7 can be reduced to ½ by employing a second-order harmonic mixer. For example, if the millimeter-wave band wireless transmission device 9 and the millimeter-wave band wireless reception device 10 are such that the transmission wireless multiplex signal 72 and the reception wireless multiplex signal 73 are in the 60 GHz band, the frequency of the local oscillation signal output from the local oscillator 7 fL02 may be in the 25 GHz to 30 GHz band. Therefore, it is not necessary to directly oscillate the local oscillator 7 in the 60 GHz band, and a millimeter-wave band wireless transmission device with high frequency stability can be easily manufactured with easy mounting such as wire bonding.

In the process of generating the transmission radio multiplexed signal 72 shown in FIG. 3C from the first IF multiplexed signal 71d shown in FIG. 3B, the frequency arrangement of the signals is converted as follows.
(Signal) (Frequency)
Wireless reference signal 72c: fLO1 + fLO2
Wireless signal 72a: fLO1 + fLO2-fIF1e

  Next, the receiving side will be described. As shown in FIG. 2, the millimeter band radio receiver 10 as an example of the microwave band radio receiver includes a reception antenna 14, a frequency conversion / reception circuit 11 as a first down converter, a local oscillator 8, A reference signal reproduction / frequency conversion circuit 12 as a second down converter is provided.

  The frequency conversion / reception circuit 11 includes a low noise amplifier 110, a millimeter wave band pass filter 111, and a frequency mixer 112 connected in order from the input side to the output side. The local oscillator 8 is connected to the frequency mixer 112.

  The reference signal reproduction / frequency conversion circuit 12 includes an intermediate frequency amplifier 159, a signal distribution circuit 161, a transmission line 162, a frequency mixer unit 12a, and an amplifier 195 connected in order from the input side to the output side. The transmission line 162 constitutes the first path P1. Further, a transmission line 163, a band pass filter 171, an amplifier 180, and a transmission line 163 constituting the second path P2 are connected in order between the signal distribution circuit 161 and the frequency mixer unit 12a.

  The frequency mixer unit 12a includes a mixer MX and a capacitor 196. The input side of the amplifier 195 is connected to the output side of the frequency mixer section 12a, and the output terminal 500 is connected to the output side of the amplifier 195.

  The duplexer 190 is connected to the output terminal 500 of the millimeter wave band wireless receiver 10, and the satellite broadcast / terrestrial broadcast tuner 30 of the TV receiver 31 is connected to the duplexer 190. .

  In the millimeter wave band radio receiving apparatus 10, the millimeter wave band radio multiplexed signal 73 received by the receiving antenna 14 is input to the frequency conversion / reception circuit 11. That is, the radio multiplexed signal 73 is amplified by the low noise amplifier 110 at one end. Next, the desired signal filtered by the millimeter wave band-pass filter 111 is frequency down-converted to the second intermediate frequency band by using the local oscillation signal (frequency fLO3) from the local oscillator 8 by the frequency mixer 112. Then, the second IF multiplexed signal 74 which is an intermediate frequency multiplexed signal is generated.

  The frequency down-conversion for the millimeter-wave band radio multiplexed signal 73 is a down-conversion for selecting the radio multiplexed signal 73 as the upper side band as shown in FIGS. 4 (A) and 4 (B). Therefore, the local oscillation frequency fLO3 on the reception side shown in FIG. 4 (A) is lower than the radio multiplexed signal 72 on the transmission side shown in FIG. 3 (C). As shown in FIG. 3C, the radio multiplexed signal 72 includes a radio reference signal 72c (frequency (fLO1 + fLO2)) and a radio signal 72a (frequency (fLO1 + fLO2-fIF1e)). In FIGS. 3 and 4, white arrows indicate the signal arrangement direction.

  Further, in a preferred embodiment, an N-order (N is a natural number of 2 or more) harmonic mixer such as an even harmonic mixer is employed as the frequency mixer 112. In this case, the local oscillation frequency of the local oscillator 8 can be set to 1 / N. As a specific example, the local oscillation frequency of the local oscillator 8 can be halved by making the frequency mixer 112 a second harmonic mixer. Therefore, the radio receiver 10 having high frequency stability can be easily manufactured by easy mounting such as wire bonding. This is the same as the frequency conversion / transmission circuit 3 on the transmission side described above.

The received radio multiplex signal 73 shown in FIG. 4 (A) is frequency down-converted to the second intermediate frequency band to generate a second IF multiplex signal 74 shown in FIG. 4 (B). Through this generation process, the second IF multiplexed signal 74 is converted into the following frequency arrangement.
(Signal) (Frequency)
Second IF reference signal 74c: fLO1 + fLO2-fLO3
Second IF signal 74a: (FLO1 + FLO2-FLO3) -fIF1e

  The second IF multiplexed signal 74 output from the frequency conversion / reception circuit 11 is once amplified by the intermediate frequency amplifier 159 and divided into two by the signal distribution circuit 161. The signal distributor 161 is constituted by a Wilkinson type two distributor having an isolation characteristic of, for example, about 20 dB between the output ports. This signal distributor 161 can suppress unnecessary leakage signals at each output port and allow each circuit to operate normally. A branching amplifier having the functions of both the intermediate frequency amplifier 159 and the signal distributor 161 may be employed. Although not shown, the branch amplifier is composed of one input unit and two output units, and the output circuit of the two output units takes two outputs from parallel transistors. For this reason, very large isolation between ports can be ensured between the output ports of the two output units.

  Next, the second IF multiplexed signal 74 is distributed by the signal distribution circuit 161 to the transmission line 162 that forms the first path P1 and the transmission line 163 that forms the second path P2, and in the first path P1, The signal is input to the frequency mixer unit 12a as it is. On the other hand, in the other second path P2, the band pass filter 172 passes the component of the frequency (fLO1 + fLO2-fLO3), which is the reference signal 74c, of the second IF multiplexed signal 74. The reference signal 74 c is amplified by the amplifier 180 and operates as a local oscillation signal of the frequency mixer unit 12 a synchronized with the second IF multiplexed signal 74. That is, the reference signal 74c is input to the frequency mixer unit 12a, and the frequency mixer unit 12a down-converts the second IF multiplexed signal 74 to convert the transmission side input signal 5e (frequency fIFe) to the output signal 76 ( Reproduction as frequency fIFe). The reproduced output signal 76 (frequency fIFe) is amplified by the amplifier 195 as necessary and output from the output terminal 500. For example, the output signal 76 is demultiplexed or distributed by a demultiplexer (or distributor) 190 and connected to the satellite broadcast wave / terrestrial broadcast tuner 30 in the TV receiver 31.

  Here, a signal processing process for reproducing a plurality of broadcast waves from the second IF multiplexed signal 74 will be described. The second IF multiplexed signal 74 is frequency down-converted by a reference signal 74 c included in the signal 74. The process of generating the output signal 76 as a demodulated signal (frequency fIFe) by this frequency down-conversion can be expressed as follows.

  That is, the second IF multiplexed signal 74 shown in FIG. 4B is frequency down-converted by the reference signal 74c, so that the frequency of the reference signal 74c (fLO1 + fLO2−fLO3) to the frequency of the first IF signal 74a. ((fLO1 + fLO2−fLO3) −fIF1e) is subtracted, and an output signal 76 of the frequency fIF1e is generated as shown in FIG.

  As described above, in the process of frequency down-converting the second IF multiplexed signal by the reference signal 74c included in the second IF multiplexed signal 74, the reference signal 74c is amplified by the amplifier 180 to increase the power level. As a result, the frequency mixer unit 12a can be operated linearly. It is to be noted that the amplifier 180 has a narrow-band amplification characteristic with a specific band of 10% or less, and it is more desirable if it is an operation characteristic that extracts and amplifies only the reference signal 74c in combination with the filter 171.

  The reference signal reproduction / frequency conversion circuit 12 is configured to down-convert the second IF multiplexed signal 74 with a reference signal 74c included in the second IF multiplexed signal 74. Therefore, as shown in FIG. 4C, the frequency downconverted output signal 76 (frequency fIF1e) also includes a DC (direct current) component generated by frequency conversion of the reference signal 74c with the reference signal 74c. It will be. For this reason, it is desirable that the frequency conversion mixer unit 12a includes a capacitor 196 that cuts a DC component.

  In the signal distribution circuit 161 configured by the Wilkinson distributor, the distribution circuit 161 is a starting point, and the second IF multiplexed signal 74 is divided into two in the same phase. Here, there are first and second paths from the distribution circuit 161 to the frequency mixer section 12a. That is, the first path P1 is a path having a path length L2 from the distribution circuit 161 to the mixer MX via the transmission line 162, and the second path P2 is the transmission line 163, the filter 171 and the amplifier. This is a path having a path length L3 that reaches the mixer MX via 180 and the transmission line 163.

  The total path length L1 (= L2 + L3), which is the sum of the path length L2 of the first path P1 and the path length L3 of the second path P2, corresponds to the lowest frequency of the second IF multiplexed signal 74. It is desirable that the wavelength be less than or equal to λ. In this case, the loop of the total path length L1 including the first path P1 and the second path P2 is 1 · λ or less, and an unnecessary oscillation wave due to the parasitic oscillation loop is hardly generated. Here, the path lengths L2 and L3 are precisely electrical lengths, but may be physical lengths.

  In the microwave band wireless communication system of the above embodiment, the input signal 5e has been described as a signal having the terrestrial broadcast wave 5a and the satellite broadcast wave 5b. However, the input signal 5e is composed of two satellite broadcast waves and satellite broadcast waves. May be a combination of a CATV (Cable Television) signal or the like, or may be a modulated wave signal at an IF (intermediate frequency) stage or RF (high frequency) such as a wireless LAN, for example, as an input modulated wave signal. . In the above embodiment, a radio communication system that transmits and receives a millimeter-wave band radio signal has been described. However, the radio signal is not limited to the millimeter-wave band, and the present invention has a microwave frequency band including the millimeter-wave band. The present invention can be applied to a system that transmits and receives wireless signals.

It is a schematic block diagram of the microwave radio | wireless communications system of this invention. It is a block diagram of the microwave band radio | wireless communications system of this embodiment. FIG. 3A is a frequency arrangement diagram showing the input signal 5e to the transmission device 9 of the above embodiment of the present invention, and FIG. 3B is the first IF multiplexed signal 71d in the transmission device 9 of the above embodiment. FIG. 3C is a frequency arrangement diagram of the radio multiplexed signals 72 in the transmission apparatus 9 of the above embodiment. 4A is a frequency allocation diagram of the radio multiplexed signal 73 in the receiving apparatus 10 according to the embodiment of the present invention, and FIG. 4B is a frequency multiplexed signal of the second IF multiplexed signal 74 in the receiving apparatus 10. FIG. 4C is a frequency allocation diagram of the output signal 76 in the receiving apparatus. It is a block diagram of the conventional microwave band radio | wireless communications system. FIG. 6A is a diagram illustrating an input-side spectrum of an amplifier included in the wireless transmission device 100 of the conventional wireless communication system, and FIG.

Explanation of symbols

1a Terrestrial broadcasting antenna 1b Satellite broadcasting antenna 2 Reference signal addition / power level control circuit 2a Frequency conversion circuit 2c Reference signal source (frequency fLO1)
2d Reference signal addition circuit 3 Frequency conversion / transmission circuit 4 Transmitting antenna 5 Frequency array 5a, 5b ... Input modulation wave signal 7, 8 ... Local oscillator 9 Millimeter wave radio transmitter 10 Millimeter wave radio receiver 11 Frequency conversion / Reception circuit 12 Reference signal reproduction / frequency conversion circuit 12a... Frequency mixer section 14 reception antenna 500 output terminal 71a first IF signal (lower sideband signal)
71c Reference signal 71d First IF multiplexed signal 72 (Transmission) Radio multiplexed signal 73 (Reception) Radio multiplexed signal 74 Second IF multiplexed signal 74a First IF signal (lower sideband signal)
74c Reference signal 76a, 76b ... input modulation wave signal (receiving side)
95 Level controller 110 Low noise amplifier 111 Millimeter wave band pass filter 112 Millimeter wave frequency mixer 126 Input signal short circuit 161 Power divider 159 (Reception side) Intermediate frequency amplifier 171 Band pass filter 190 Divider
201 Frequency mixer 202a Band pass filters 203a and 203b Intermediate frequency amplifiers on transmission side 204a and 204b Power divider (synthesizer)
301 Frequency mixer 302 Band pass filter 303 Millimeter wave amplifier

Claims (1)

An input terminal;
A first up-converter that up-converts the input signal input to the input terminal,
The first up-converter is
A local oscillator that oscillates a reference signal;
A mixer that multiplies the input signal and the reference signal to generate a modulation frequency signal;
A filter that passes only the modulation frequency signal generated by the mixer;
An input signal level adjuster configured of a T-type attenuator or a π-type attenuator configured by a resistor and an amplifier and adjusting the level of the input signal or the modulation frequency signal;
A distributor for distributing the reference signal;
A reference signal level adjuster for adjusting the level of the reference signal distributed by the distributor;
A synthesizer that synthesizes the reference signal output from the reference signal level adjuster and the modulation frequency signal;
The filter is disposed between the mixer and the combiner;
The input signal level adjuster is disposed between the input terminal and the combiner ,
The signal level of the modulation frequency signal and the signal level of the reference signal are adjusted by the input signal level adjuster and the reference signal level adjuster, and the power S of the modulation frequency signal and the power T of the reference signal are The power ratio S / T is set to 1 or less .

Images