JPH0490625A - Interference compensating device - Google Patents

Abstract

PURPOSE:To simplify construction without necessitating a dual signal reception circuit by suppressing the interference wave in radio communication and receiving only the signal to be desired. CONSTITUTION:A first modulator 12 modulating the output signal of a first signal synthesis circuit 4 by a low frequency signal with low frequency compared with the interference wave, a second modulator 13 modulating this low frequency signal 90 deg. phase-transferring the output signal by the signal phase-transferred by 90 deg., a second signal synthesis circuit 16 synthesizing the modulation output of modulators 12,13, a signal reception circuit 5 taking the output of this circuit 16 as input to be converted to an intermediate frequency signal, an envelope detector 9 envelope-detecting this intermediate frequency signal, and two product detectors 7,8 respectively taking the output of the envelope detector 9 as input, product-detecting the low frequency signal and the phase of the low frequency signal after phase-transferred by 90 deg. to be outputted as control voltage, are provided. Thus, the dual signal reception circuit is not unnecessitated and the construction is simplified.

Description

[Detailed description of the invention] [Industrial application field] INDUSTRIAL APPLICATION This invention is utilized for the interference compensation apparatus of wireless communication.

In particular, the present invention relates to a device that suppresses interference waves and receives a desired signal.

[Conventional technology]

FIG. 2 is a block diagram of a conventional interference compensation device.

Conventionally, an interference compensator has had a configuration as shown in FIG. In FIG. 2, 1.2 is an input terminal, 3 is an amplitude phase control circuit, 4 is a signal synthesis circuit, 5A, 5B is a signal receiving circuit composed of an amplifier, a frequency converter, a bandpass filter, etc., 7.8 10 indicates a multiplicative detector, 10 indicates an interference wave compensation output terminal, and 17 indicates a 90° phase shifter.

Signals for normal communication are input to input terminal 1, but
Interference waves are also mixed in. Interference waves are mainly input to the input terminal 2. The interference wave input to input terminal 2 is branched into two systems,
One signal has its amplitude and phase controlled by an amplitude and phase control circuit 3, and is combined with the signal from the input terminal 1 by a signal synthesis circuit 4.

This composite signal and the other signal at input terminal 2 are frequency-converted and amplified by signal receiving circuits 5A and 5B, respectively, and then branched into two and detected by product detector 7.8. At this time, one of the four signals input to the product detector 7.8 is phase shifted by 90° by the 90° phase shifter 17. The output signal of the product detector 7.8 controls the amplitude and phase control circuit 3 so that the interference wave input from input terminal 1 and the interference wave input from input terminal 2 have the same amplitude and reverse phase. do.

As described above, a signal containing no interference waves can be obtained in the output of the interference wave compensation output terminal 10.

[Problem to be solved by the invention]

However, such conventional interference compensation devices require two systems of signal receiving circuits, and in order to accurately suppress interference waves, it is necessary to match the phase and amplitude fluctuation characteristics of both signal receiving circuits. Therefore, it has the disadvantage that it has a large number of components, making it difficult to adjust the fluctuations in its amplitude and phase characteristics.

The present invention solves the above-mentioned drawbacks, and aims to provide an interference compensating device that requires two signal receiving circuits (and has a simple configuration and easy adjustment).

[Means to solve the problem]

The present invention comprises a first input terminal (1) to which a first input signal mixed with interference waves in addition to the desired received wave is input, and a second input terminal (1) to which a second input signal having the interference wave as a main component is input. a second input terminal (2), and an amplitude that controls the second input signal based on the input control voltage and outputs a signal having approximately the same amplitude and almost inverted phase as the interference wave of the first input signal. Interference compensation comprising a phase control circuit (3) and a first signal synthesis circuit (4) that synthesizes the output signal of this amplitude phase control circuit and the first input signal and outputs an interference wave compensation signal. In the apparatus, a first modulator (12) modulates the output signal of the signal synthesis circuit with a low frequency signal having a lower frequency than the interference wave, and a signal obtained by shifting the phase of the output signal by 90 degrees. a second modulator (13) that modulates a frequency signal with a signal with a 90° phase shift; a second signal synthesis circuit (16) that synthesizes the modulation outputs of these two modulators (12, 13); a signal receiving circuit (5) which inputs the output of this second signal synthesis circuit and converts it into an intermediate frequency signal; an envelope detector (9) which performs envelope detection of this intermediate frequency signal;
Two product detectors each input the output of the envelope detector and perform product detection using the low frequency signal and a signal obtained by shifting the phase of the low frequency signal by 90', respectively, and output the control voltage as the control voltage. 7, 8).

The present invention also provides the first and second modulators (12,
13) can both be amplitude modulators.

Furthermore, in the present invention, a third signal synthesis circuit (6) for synthesizing the output of the second signal synthesis circuit (16) and the second input signal is provided at the input of the signal receiving circuit (5). can be

Further, in the present invention, the signal receiving circuit may include automatic gain control means.

Furthermore, the present invention can include means for invalidating the output of the amplitude and phase control circuit when the second input signal is below a predetermined level.

[Effect]

The first modulator (12) modulates the output signal of the first signal synthesis circuit (4) with a low frequency signal whose frequency is lower than that of the interference wave, and the second modulator (13) modulates the output signal of the first signal synthesis circuit (4). Signal 9
A signal whose phase is shifted by 0° is modulated by a signal whose phase is shifted by 90° from the above-mentioned low frequency signal.

A second signal combining circuit (16) combines the modulated outputs of the first and second modulators. The combined output is an interference wave modulated with a low frequency signal. Now, switch (20
) is in the "off" state. The signal receiving circuit (5) receives the output of the second combining circuit and converts it into an intermediate frequency signal. The envelope detector (9) performs envelope detection on this intermediate frequency signal.

The product detectors (7, 8) each cut the DC component of the detection output of the envelope detector and perform product detection using the low frequency signal and a signal obtained by shifting the phase of the low frequency signal by 90°, respectively, and detect the low frequency signal. The DC component of this multiplicative detection output is taken out by the filter and applied to the amplitude and phase control circuit as a control voltage.

Also, considering the case where the switch (20) is "on", the third signal synthesis circuit (6) is connected to the second signal synthesis circuit (16).
and the second input signal are combined and applied to the signal receiving circuit. Automatic gain control means can be provided in the signal receiving circuit to ensure stable compensation operation against level fluctuations of the second input signal.

Furthermore, when the second input signal is below a predetermined level, it is assumed that there is no interference wave and the output signal of the amplitude phase control circuit is invalidated.

As a result of the above, two systems of signal receiving circuits are not required, and the configuration is simple and adjustment can be made easily.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of an interference compensation device according to an embodiment of the present invention. FIG. 3 is a block diagram of the amplitude and phase control circuit of the interference compensator of the present invention.

In FIG. 1, the interference compensator has an input terminal 1 as a first input terminal to which a first input signal mixed with interference waves in addition to the desired received wave is input, and a second input terminal whose main component is the interference wave. Input terminal 2 serves as the second input terminal for inputting the input signal of
and an amplitude phase control circuit 3 which controls the second input signal based on the input control voltage and outputs a signal having substantially the same amplitude and substantially inverted phase as the interference wave of the first input signal.
and a signal synthesis circuit 4 as a first signal synthesis circuit which synthesizes the output signal of the amplitude phase control circuit 3 and the first input signal and outputs an interference wave compensation signal, and outputs this interference wave compensation signal. and an interference wave compensation output terminal 10.

Here, the features of the present invention include a first modulator that modulates the output signal of the signal synthesis circuit 4 with a low frequency signal whose frequency is lower than that of the interference wave;
A modulator 12, 13, a 90° phase shifter 11, 15, and a low frequency signal oscillator 14 as a second modulator that modulates a signal whose phase is shifted by 90 degrees with a signal whose phase is shifted by 90 degrees, A signal synthesizing circuit 16 serves as a second signal synthesizing circuit for synthesizing the modulated outputs of the modulators 12 and 13, a signal receiving circuit 5 receives the output of the signal synthesizing circuit 16 as an input and converts it into an intermediate frequency signal, and a signal receiving circuit 5 serves as a second signal synthesizing circuit for synthesizing the modulated outputs of the modulators 12 and 13. An envelope detector 9 detects an envelope, and the outputs of the envelope detector 9 are inputted through high-pass filters 21 and 22, respectively, and the phases of the low-frequency signal and the low-frequency signal are shifted by 90°. Two product detectors 7.8 are provided, each of which performs product detection on the signal and outputs it as the control voltage via a low-pass filter 23, 24 and a DC integration circuit 25, 26. Also, modulators 12, 13 are both amplitude modulators here.

Further, a signal synthesizing circuit 6 is provided at the input of the signal receiving circuit 5 as a third signal synthesizing circuit that synthesizes the output of the signal synthesizing circuit 16 and the second input signal.

Further, the signal receiving circuit 5 includes automatic gain control means.

Further, a switch 18 connected to the output of the envelope detector 9 is provided as means for invalidating the output of the amplitude phase control circuit 3 when the second input signal is below a predetermined level.

FIG. 3 is a block diagram of the amplitude and phase control circuit of the interference compensator. In FIG. 3, 31 is an input terminal, 32 is a signal branch circuit, 33a to 33d are fixed phase shifters, and 34a is a signal branch circuit.
34d is a PIN diode attenuator, 35 is a signal combiner, 36a and 36b are control signal input terminals, and 37 is an output terminal. The structure and operation of FIG. 3 are explained in detail in Japanese Patent Publication No. 16580/1983.

The operation of the interference compensation device having such a configuration will be explained. In Fig. 1, the interference wave input to input terminal 2 is 2
The signal is branched and input to the amplitude phase control circuit 3 and the signal receiving circuit 5. This two-branched signal can be expressed in complex form as follows.

■A-IA eJ4t iA Amplitude Ω of the interference wave input to the double-blade terminal 2: In the interference wave angular frequency amplitude phase control circuit 3, for the control voltages v1 and v2,
The output signal is controlled and output as follows.

Iv = Kv (V+ +j V2)
IA' Kv V I A eJ"'
-: Control sensitivity of the amplitude phase control circuit Ve'f=v, + j V2 The output signal of this amplitude phase control circuit 3 is sent to the signal synthesis circuit 4.
It is combined with the signal from input terminal 1.

At this time, the interference wave signal from input terminal 1 is expressed by the following formula, 1, = i, e"'lt"') Amplitude α of interference wave input to 1M2 input terminal l: Input to input terminal 1 The phase difference composite signal of the interference wave and the interference wave input to the input terminal 2 is expressed by the following equation.

It =ix e"""'-Kv V iA e"
Qt-φ)=: r 6 J (Ωt+θ) However, rejθ= iX e”-KvV iA e'
When this composite signal is branched into two systems and the phase of one of the two branched signals is shifted by 90 degrees, each signal can be expressed as follows.

IIl,' = (1/vT) r sin (
Ωt+θ)IR2-(1/J7) r cos
(Ωt+θ) The output signal of the low frequency signal oscillator 14 with a phase difference of 90° and this output signal are added to each signal by 90°.
``If the signal whose phase has been shifted by the phase shifter 15 is subjected to amplitude modulation from ``on'' to ``off'' by the modulators 12 and 13, it can be expressed as the following equation.

IR+' = (1/VT) rS i n (Ω
t+θ)/(2n-1))cos(2n-1)ω
t] L, = (1/'-'T) rcos (Ωt+θ
) / (2n-1)) s in (2n-1)
Qt) ω: Modulation signal angular frequency When these two amplitude-modulated signals are synthesized by the signal synthesis circuit 16, and this synthesized signal and the input signal of the input terminal 2 are synthesized by the signal synthesis circuit 6, the following equation is obtained. Become.

S-(iA/V'T)s i nΩt+ (r/4'-
'2) (sin (Ωt+θ) ten cos(Ωt+θ)si
n(Ωt+(2n-1)'CLlt10)] When this combiner is subjected to, for example, square law detection by the envelope detector 9, the following equation is obtained.

S2= (iA ”/2) s in2Ω as 10(iA
r/4) sinΩt[5in(Ωt+θ)+cos (
Ωt+θ)+ (4/π) sin(Ωt+ (2n-
1) ωt+θ) ](r”/32) [s i
n (Ω to 10θ) + cos (Ωt+θ) + (4/
π) sin(Ωt+(2n-1)(let+θ)]2 The DC component of S2 is extracted by a low-pass filter, and automatic gain control (AGC) is applied so that the output of this DC component is constant.

In other words, the DC voltage extracted by the low-pass filter is 1^2/ma However, iA>r Based on this, the amplification gain by AGC is K / 0f7 However, K = constant Then, S2 becomes the following equation.

S2=2s i nΩt+ (K2r/21A)si
nΩt(sin(Ω=10) +cos (Ωt+θ)+(4/π)sin(Ωt+
(2n-1)act+θ)]+ (K2r 2/
16 i A') [5in (Ωt + θ) + cos (Ωt + θ) 10 (4/π) sin (Ωt + (2n-1) act + θ)] 22 DC components are cut by a high-pass filter 21.22 such as a capacitor. , a modulation signal, i.e. a low frequency signal oscillator 14
A product detector 7.8 performs product detection using the output signal and a signal whose phase is shifted by a 90° phase shifter 15, and the DC component of this detection output is passed through a low-pass filter 23, 24 and a DC integral. Obtained by circuits 25 and 26. That is, the control voltages E1 and E2 output from the product detector 7.8 are expressed by the following equations.

E+ = (K2 r/rr21A) cosθE2 =
(K2 r/yr2 i,)s i nθ However, i
A>r When these two output signals E, , E2 are amplified with an appropriate gain G and controlled by adding them to the above-mentioned control voltages v1 and v2, the output signal of the signal synthesis circuit 4 becomes the following formula, i, = 1) LeJ(flL+g) KVviA
eJ(Qt, ))−Kv(K2 G/rr2)r
ej("θ)"" 1 (kr K2G/ π2)
) 1 eJIQt-e) control loop gain, 2G/
If π2 is set appropriately, (2) becomes "0", the interference wave is finally suppressed, and a signal containing only the desired wave is obtained from the interference wave compensation output terminal 10.

Further, if phase modulation of "rQJ -rπ" is performed, the modulated signal is obtained. That is, when detecting S with As1nQt, S' = iA/2J"; E+ (r/8 J7) [(
cosθ+sinθ)+(4/π)CO8(2n-1
) Qt and sin (2n-1) Qt, and interference wave compensation is possible through a similar process.

Interference wave compensation is also possible by modulation using a sine wave rather than a modulated wave including harmonics such as "on"-"off" or r OJ -rπ" modulation.

Furthermore, in the above explanation, the case of square law detection using the envelope detector 9 was explained, but as a method for obtaining the envelope, a signal As1nΩt (A: Even if we obtain the constant) and detect it using this, the same result will be obtained as cos ((2n-1) ω
t+θ)] However, terms including high frequency components, that is, 2Ω frequency components are omitted. This DC component i A/
2J”: When applying AGC with i (however, iA>r),
S' = to -4-(K,/41A)C(4/π)cos
((2n-1) ωt+θ)] Except for this DC component, the modulation signal, that is, the output signal of the low frequency signal oscillator 14 and a signal obtained by shifting the phase of this output signal by a 90° phase shifter 15, are used in the product detector 7. 8, product detection is performed to obtain the DC component.

(Hereinafter, this page margin) El = (K, /π2iAXl+1/9+1/25
+ l /49+) s i nθ '=0', 125 (K r/ iA) s i
nθE2 = (Kr/π21A) (1+1/9+1/
25+1/49+) CO5θ #0.125 (K r/ iA) co sθ
In this way, similarly to the above explanation, voltages proportional to (r/1A)c○Sθ and (r/IA)Sinθ can be obtained, and interference waves can be suppressed.

Moreover, although the case where AGC is performed in a high frequency band and an intermediate frequency band has been described, it is also possible in a low frequency band or a DC signal. For example, the DC voltage E1 when AGC is not applied in the high frequency band and the intermediate frequency band is expressed by the following equation when using square law detection.

El - (iA r/2rr2) cos θ Based on the DC component iA”/2 of the square law detection output, 2 K/l A
" (K is constant). As a result, the DC voltage E1 becomes as follows, and the same result is obtained.

El = (Kr/π21A)cosθ The above explanation is A
Regarding the case where GC is performed, it is possible to compensate for interference waves without performing AGC. However, since the loop gain fluctuates in response to level fluctuations of the input interference wave, the compensation operation becomes unstable. For this reason, a more stable compensation operation can be obtained by applying AGC.

Further, in the case where the transmission of an interfering signal is stopped, the interference compensator operates against thermal noise and the like, which may have a harmful effect on the desired wave. For this reason, it is better to perform interference compensation only when interference waves exist. In other words, the interference wave level of the input signal of input terminal 2 is detected, and when no interference wave is detected, the level of the interference wave of the input signal of input terminal 2 is detected.
It is necessary to prevent the input signal from the input terminal 20 from being combined with the input signal from the input terminal 20. Specifically, the control voltage of the AGC is monitored, and when a voltage corresponding to a predetermined level higher than the noise level is detected, the switch 18 provided for the output signal of the amplitude phase control circuit 3 is controlled to be turned on. There are ways to do this.

〔Effect of the invention〕

As explained above, the present invention has excellent effects in that two signal receiving circuits are not required, and the configuration is simple and adjustment is easy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an interference compensation device according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional interference compensation device. FIG. 3 is a block diagram of the amplitude and phase control circuit of the interference compensator. 1.2... Input terminal, 3... Amplitude phase control circuit, 4
．． 6.16...Signal synthesis circuit, 5.5A, 5B...
Signal receiving circuit, 7.8... Multiplier detector, 9... Envelope detector, 10... Interference wave compensation output terminal, 11.15
．． 17... 90° phase shifter, 12.13... Modulator,
14...Low frequency signal oscillator, 18.20...Switch, 21.22...High pass filter (HPF), 23.2
4...Low pass filter (LPF), 25.26...DC integration circuit, 31...Input terminal, 32...Signal branch circuit, 33a-33d...Fixed phase shifter, 34a- 34d
...PIN diode attenuator, 35... Signal combiner, control signal input terminal for 36a, 36b, 37...
・Output terminal. Patent applicant: Nippon Telegraph and Telephone Corporation Representative Patent attorney: Naotaka Ide

Claims (1)

[Claims] 1. A first input terminal (1) into which a first input signal mixed with an interference wave in addition to the desired received wave is input, and a second input signal whose main component is the interference wave. The second input terminal (2
), and an amplitude phase control circuit (3) that controls the second input signal based on the input control voltage and outputs a signal having substantially the same amplitude and substantially inverted phase as the interference wave of the first input signal. and a first signal combining circuit (4) that combines the output signal of the amplitude phase control circuit and the first input signal to output an interference wave compensation signal, the signal combining circuit comprising: A first modulator (12
) and a second modulator (13) that modulates a signal obtained by shifting the phase of the output signal by 90 degrees with a signal obtained by shifting the phase of this low frequency signal by 90 degrees;
A second signal synthesis circuit (16) synthesizes the modulated outputs of (13)
), a signal receiving circuit (5) which receives the output of this second signal synthesis circuit and converts it into an intermediate frequency signal, an envelope detector (9) which detects the envelope of this intermediate frequency signal, and this envelope detector (9) which detects the envelope of this intermediate frequency signal. Two product detectors (7, 8) each receive the output of the detector and perform product detection using the low frequency signal and a signal obtained by shifting the phase of the low frequency signal by 90 degrees, and output the control voltage as the control voltage. ). 2. The interference compensation device according to claim 1, wherein the first and second modulators (12, 13) are both amplitude modulators. 3. Claim in which a third signal synthesis circuit (6) for synthesizing the output of the second signal synthesis circuit (16) and the second input signal is provided at the input of the signal reception circuit (5). 1. The interference compensation device according to 1. 4. The interference compensation device according to claim 3, wherein the signal receiving circuit includes automatic gain control means. 5. When the second input signal is below a predetermined level,
4. The interference compensator according to claim 3, further comprising means for invalidating the output of said amplitude and phase control circuit.