JP3412605B2 - Diversity receiving apparatus and method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiving apparatus and a diversity receiving method,
Particularly, the present invention provides a diversity receiving apparatus and a diversity receiving method suitable for performing combination control based on amplitude distortion after space diversity combining.

[0002]

2. Description of the Related Art In a communication line using radio, a diversity structure is used in order to improve C / N or mitigate waveform distortion due to fading of a propagation path. As a method of controlling the diversity combined phase, there is a method of performing phase control so as to minimize amplitude distortion within the signal band. In order to realize this, it is usually necessary to control the signal level for each diversity path and also control the combined phase.

A general AGC (Au) for controlling the signal level
tomatic Gain Control) An explanation of the amplifier is shown in FIG.
In FIG. 6A, when the received input signal is only the main wave, that is, there is no interference wave component due to fading or the like, the first and second
(A) Input 1 and (b) Input 2 input by the antenna of
The main waves S1 and S2 having different phases are controlled to have the same level. Further, as shown in FIG. 6B, when the received input signal includes an interference wave component, (a) the main wave S1 of the input 1 and the combined wave T1 of the interference wave E1 and (b) the main wave of the input 2 are input. Wave S
2 and the combined wave T2 of the interference wave E2 are controlled to the same level. Then, in both (A) and (B), the signal components of the input 1 and the input 2 controlled to the same level are combined (c) T.
a and Tb are used as received signals.

FIG. 7 shows the configuration of a conventional diversity receiver disclosed in Japanese Patent Laid-Open No. 59-230333. As shown in FIG. 7, the present receiving apparatus includes frequency converters 101a and 101b for converting radio frequency band signal inputs 1 and 2 into intermediate frequency band signals, and a frequency converter 101b.
An infinite phase shifter 105 for controlling the phase of the input 2 supplied from the device in the range of 360 ° so as to have the same phase as the input 1 of the frequency converter 101a;
, 101b, and a synthesizer 106 for synthesizing the input 1 and the input 2 respectively converted to the intermediate frequency band, and the synthesizer 10
6, an automatic gain control amplifier 107 that amplifies the level of the output signal of No. 6 to a required value and outputs the demodulated signal, a demodulator 108 that outputs a baseband signal demodulated from the intermediate frequency band output of the automatic gain control amplifier 107, and an automatic gain control amplifier. A level detector 109 and a distortion detector 110 for detecting the level and amplitude distortion of the output signal of 107, and a tap for controlling the amount of phase rotation of the infinite phase shifter 105 based on both outputs of the level detector 109 and the distortion detector 110. And a phase controller 111 that determines the coefficient.

Next, the operation of FIG. 7 will be described. The input 2 is input to the infinite phase shifter 105 after being converted into an intermediate frequency band signal by the frequency converter 101b. Further, the input 1 is converted into a signal in the intermediate frequency band by the frequency converter 101a, and then directly input to the combiner 106, and the infinite phase shifter 1
It is combined with the output signal of No. 05 and output. This combined output is amplified to the required level by the automatic gain control amplifier 107. The output signal of the automatic gain control amplifier 107 is
It is input to the demodulator 108, quadrature detected, and a demodulated signal is output.

The output signal of the automatic gain control amplifier 107 is input to the level detector 109 and the distortion detector 110. The level detector 109 is equivalent to a detector,
The composite signal level is detected and output. The strain detector 110 is
It is composed of three types of bandpass filters (hereinafter referred to as BPFs) having different center frequencies for extracting the center of the transmission signal band and the signal components on both sides thereof, and a detector connected to the output of each BPF. (Not shown) detects amplitude distortion within the band of the combined signal. The amplitude distortion can be changed by rotating the phase of the output signal of the frequency converter 101b by the infinite phase shifter 105.

The phase controller 111 outputs a tap coefficient, which is the amount of phase rotation, and the infinite phase shifter 105 follows this coefficient.
Rotates the phase of input 2 and changes the amplitude distortion. The phase controller 111 determines a tap coefficient that minimizes amplitude distortion. However, when the combined signal level is lower than the threshold value, the tap coefficient is determined so that the combined signal level becomes maximum.

As another example of the conventional diversity receiver, an example of the diversity receiver disclosed in Japanese Patent Laid-Open No. 61-131625 is shown in FIG. 8, the basic configuration is similar to that of FIG. 7, but
The configuration is different from that of FIG. 1 in that variable gain amplifiers 702a and 702b are provided for level control of the input 1 and the input 2.
In this diversity receiver, the output signal level and amplitude distortion of the combiner 106 are monitored by the level detector 109 and the distortion detector 110, and when the received signal level is sufficiently high, the amplitude distortion is minimized, that is, the interference. The variable gain amplifier 702 controls the phase of the infinite phase shifter 105 so that the waves have opposite phases and equalizes the magnitudes of the interference waves having opposite phases.
a and 702b are controlled by the controller 711. Further, the amplitude detectors 713a and 713b detect the signal level before combination, and the variable gain amplifiers 702a and 702b are detected.
Controller 7 so that the non-linear distortion generated by
11 controls the variable gain amplifiers 702a and 702b.

[0009]

However, in the above-described diversity receiver of the conventional system shown in FIG. 7, interference such as multipath fading occurs at each of the input 1 and the input 2, and the levels are the same. In some cases, by controlling the phase so that the interference wave components included in the received signal cancel out of each other, it is possible to remove the amplitude distortion after synthesis, but since there is no level control means for the received signal in the first place, When the levels of the interference waves included in the received signals are different, the interference wave components cannot be removed completely, and there is a drawback that amplitude distortion due to the interference waves occurs even after the combination.

Further, Japanese Patent Laid-Open No. 61-1316 shown in FIG.
In the diversity receiver disclosed in Japanese Unexamined Patent Publication No. 25, the signal level and amplitude distortion after combination are monitored, and when the signal level is sufficiently high, a level that minimizes the amplitude distortion is monitored while monitoring one parameter called amplitude distortion. Since both the control and the phase control are performed at the same time, it takes time for the amplitude distortion to converge, and in the worst case, it does not converge, and both level and phase continue to vibrate.

Therefore, the present invention has been made to solve the problems of the prior art, and its object is to determine the main wave level of the received signal by using the correlation between the received signal and the reference signal. It is an object of the present invention to provide a diversity receiving apparatus and a diversity receiving method in which the amplitude distortion is alleviated and the line quality is excellent by aligning and canceling the opposite phases of the main waves and using only the interference wave as the combined output.

[0012]

According to the present invention, there is provided a diversity receiving apparatus for receiving the same signal by the first and second antennas installed at appropriate intervals, wherein the received signal is received. Frequency conversion means for converting signals into respective predetermined frequencies, gain varying means for setting respective gains of the converted respective converted signals, synthesizing means for synthesizing the output signals having the gains set, and the synthesizing means The demodulation means for demodulating the combined signal thus obtained, the modulation means for re-modulating the demodulated demodulated signal, and the correlation between the re-modulated output and each output of the gain varying means, and in accordance with the correlation output, A diversity receiver including a correlating means for controlling the gain varying means is obtained.

The correlation means is configured to have means for calculating a correlation between the remodulated reference signal and the delayed output of the output signal delayed to correspond to the symbol of the reference signal. It is characterized by being

Further, the present invention is characterized by further comprising phase shift amount conversion means for detecting the output level and distortion of the synthesizing means and controlling the phase of one output of the gain varying means according to the detected output.

Further, according to the present invention, there is provided a diversity receiving method in which the same signal is received by the first and second antennas installed at appropriate intervals, and the received signal is predetermined. A frequency conversion step for converting the gain of each of the converted signals, a combining step for combining the output signals for which the gain is set, and the combined signal A demodulation step for demodulating, a modulation step for re-modulating the demodulated demodulated signal, a correlation between the re-modulated output and each output of the gain varying step, and the gain varying step of the gain varying step according to the correlation output. A diversity receiving method is obtained, characterized in that it comprises a controlling correlation step.

Then, the correlation step is configured to include a step of calculating a correlation between the re-modulated reference signal and a delayed output of the output signal delayed to correspond to a symbol of the reference signal. It is characterized by being

Further, the method further comprises a phase shift amount conversion step of detecting the output level and distortion of the synthesizing step and controlling the phase of one output of the gain varying step according to the detected output. ..

The operation of the present invention will be described. When the received signal of each diversity path contains many interference wave components, the correlation value between the received signal and the reference signal obtained by remodulating the demodulated signal is used to cancel the main waves of the received signal. By controlling the gain so that the main wave level of the signal is the same and performing the phase control so that the signal has the opposite phase, only the pure interference wave component is used as the combined signal, so the amplitude distortion after combination is Is eliminated, and the line quality can be maintained satisfactorily.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, it is a block diagram showing a configuration of a diversity receiving apparatus as an embodiment of the present invention. Here, only the part related to the diversity reception process of the diversity receiving device is shown, and other configurations are omitted.

The diversity receiver according to the present invention comprises:
Frequency converter 101 having inputs 1 and 2 respectively
a, 101b, gain changers 11a, 11b connected to the frequency converters 101a, 101b, respectively, an infinite phase shifter 105 connected to the variable attenuator 102b, a variable attenuator 102a and an infinite phase shifter 105. Connected synthesizer 106
An automatic gain control amplifier 107 for amplifying the output signal of the combiner 106, a demodulator 108 connected in parallel to the output terminal of the automatic gain control amplifier 107, and a level detector 109.
A distortion detector 110, and a phase controller 111 connected to the outputs of the level detector 109 and the distortion detector 110,
The modulator 113 is connected to the output of the demodulator 108.

The gain varying devices 11a and 11b are variable attenuators 102a and 102b and delay devices 103a and 10b, respectively.
3b, correlators 104a and 104b, and gain controller 10
5a and 105b.

Next, the operation of the diversity receiver shown in FIG. 1 will be described. When the input 1 and the input 2 are applied, the frequency converters 101a and 101b convert from the radio frequency to the intermediate frequency for each diversity path. The gains of the variable attenuators 102a and 102b are set so that the output signal levels of the corresponding frequency converters 101a and 101b become predetermined levels. The infinite phase shifter 105 controls the phase of the output signal of the variable attenuator 102b. The combiner 106 combines the output signal of the infinite phase shifter 105 and the output signal of the variable attenuator 102a.

The automatic gain control amplifier 107 amplifies the combined output signal to a predetermined level. The demodulator 108 quadrature-detects the combined signal amplified to a predetermined level. The level detector 109 and the distortion detector 110 detect the combined signal level and in-band amplitude distortion. The phase controller 111 controls the phase shift direction of the infinite phase shifter 105. This phase shift direction is
The outputs of the level detector 109 and the distortion detector 110 are monitored and controlled so that the amplitude distortion is minimized. However, when the combined signal level is lower than a predetermined value, the direction of increasing the signal level is prioritized and the phase shift direction is controlled. The modulator 113 modulates the demodulator output quadrature-detected by the demodulator 108 again and sends it to the correlators 104a and 104b as a reference signal.

Here, the correlator 104 in the gain varying device 11a
a is the reference signal from the modulator 113 and the output signal of the variable attenuator 102a so as to correspond to the symbol thereof.
Correlate with the output delayed by 03a. At this time, the delay amount is set in advance in the delay device 103a so that the correlation can be detected at the timing of the same symbols. This state is shown in FIG.

In FIG. 2A, when there is no interference wave component such as intersymbol interference in the received signal, the data bit string a1, a2, a3, a of the output of the variable attenuator 102a shown in (a).
4, a5, a6, ... Are delayed by the delay device 103a, and the data bit string of the output of the delay device 103a shown in FIG.
The data bit string ≡1, ≡2 of the reference signal shown in (c) of the modulator 113 output, which is the signal estimated as the received signal,
The contents of the data coincide with ≡3, ≡4, ≡5, ≡6, .... At this time, the correlation value W output from the correlator 104a is 1
Becomes

Further, when the received signal includes an interference wave component as shown in FIG. 2B, for example, as shown in FIG. 3, it is generated with a delay of time T with respect to the main wave 301 of amplitude 1 in the propagation path. Assuming that the interference wave component 302 having the amplitude h is included, the data bit sequence a1, a2, a3, a of the transmission signal is generated.
Since the interference wave component h delayed by the time T is added to the data bit sequence of the next received signal, the data bit sequence of the received signal is a1 + ha.
0, a2 + ha1, a3 + ha2, a4 + ha3, ...

Therefore, in FIG. 2B, the data bit string of the output of the variable attenuator 102a shown in (a) is a1 + h.
a0, a2 + ha1, a3 + ha2, a4 + ha3, a
5 + ha4, a6 + ha5, ..., This data bit string is delayed by the delay device 103a, and the data bit string output from the delay device 103a shown in (b) and the data bit string ≡1 of the reference signal shown in (c). , ≡ 2, ≡ 3, ≡ 4, ≡ 5, ≡
6, the contents of the data do not match, and the correlation value W output from the correlator 104a at this time is 0≤W <1, and the correlation value W changes linearly between 0 and 1.

Returning to FIG. 1, the gain controller 105a changes the variable attenuator 102a according to the correlation value output from the correlator 104a.
It outputs a control signal for controlling the gain of. Here, when the correlation value output from the correlator 104a is 1, that is, when the received signal has no interference wave component such as intersymbol interference, the variable attenuator 102 is used.
The gain of a is set to a value such that the input 1 takes a standard level diagram, the input 1 includes an interference wave component, and the gain of the variable attenuator 102a is increased as the correlation value approaches 0.
That is, the level of input 1 is set to be lowered.

Similarly, the correlator 10 in the gain varying device 11b is used.
Also in 4b, the reference signal from the modulator 113 is correlated with the output signal obtained by delaying the output signal of the variable attenuator 102b corresponding to the symbol by the delay device 103b.
The gain controller 105b outputs a control signal for controlling the gain of the variable attenuator 102b corresponding to the detected value output by the correlator 104b. Thereafter, the same movement as the input 1 side is performed.

As a result of the above, the frequency converters 101a, 10
The output signals of 1b correspond to the variable attenuators 102a, 1
In 02b, the main wave level is set to be the same. This state is shown in FIG. In FIG. 4A, the phase difference between the main wave S1 of the input 1 and the interference wave E1 is θ1, and (b)
, The phase difference between the main wave S2 of the input 2 and the interference wave E2 is θ
In the case of 2 (at this time, S1 ≠ S2), the levels of the main waves are the same (S1 =
S2) so that the variable attenuator 102a or 102b
Sets the gain.

FIG. 5 is a diagram showing an example of the impulse response of the received input signal of each diversity path. Input 1 indicates that the interference wave 402 is delayed by τ1 with respect to the main wave 401. Similarly, the input 2 indicates that the interference wave 404 is delayed by τ2 with respect to the main wave 403. When constructing the system of the present invention, the delay time of each main wave is made to match as shown in FIG. τ1 and τ2 are fades
Since they do not necessarily change and match depending on the radio wave propagation condition such as ging, the phases are controlled so as to cancel the main waves in order to remove the amplitude distortion after combination.

Therefore, the infinite phase shifter 105 is set by the phase controller 111 so that the main waves S1 and S2 having the same level due to the set gain of the variable attenuators 102a and 102b are canceled out, that is, opposite phases. , The phase shift of the input 2 is performed, and the synthesizer 106 synthesizes it with the input 1. As a result, as shown in FIG. 4C, only the interference wave components E1 and E2 remain,
T which is a composite component of these is used as a received signal.
The composite signal component T is composed of only a pure interference wave component, and the amplitude distortion is removed.

[0033]

As described above, according to the present invention, the gain is controlled so that the main wave levels of the respective received signals are the same, and the phases are controlled so as to cancel the main waves in opposite phase. Since only a pure interference wave component is used as a composite wave, there is an effect that amplitude distortion can be suppressed.

Further, according to the present invention, since the gain control and the phase control of the received signal for each diversity path are independently performed, the convergence to the optimum phase is accelerated and the interference such as fading is prevented. Since the tracking speed is improved, there is also an effect that it is possible to prevent the deterioration of the line quality.

[Brief description of drawings]

FIG. 1 is a block diagram of a diversity receiver of the present invention.

FIG. 2 is an operation explanatory diagram of a correlator according to the present invention.

FIG. 3 is an explanatory diagram of an impulse response when an interference wave component is included.

FIG. 4 is an explanatory diagram of an operation of canceling an antiphase by making the main wave level the same.

FIG. 5 is an explanatory diagram of an impulse response of a received input signal of each diversity path.

FIG. 6 is an explanatory diagram of a general AGC amplifier.

FIG. 7 is a block diagram of a conventional diversity receiver.

FIG. 8 is a block diagram of another conventional diversity receiver.

[Explanation of symbols]

11a, 11b Gain variable device 101a, 101b frequency converter 102a, 102b variable attenuator 103a, 103b delay device 104a, 104b correlator 105 infinite phase shifter 106 synthesizer 107 automatic gain control amplifier 108 demodulator 109 level detector 110 strain detector 111 Phase controller 112 carrier oscillator 113 modulator

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04B ⁷ /02-7/12 H04L 1/02-1/06

Claims (6)

(57) [Claims] 1. A diversity receiver for receiving the same signal by means of first and second antennas installed at appropriate intervals, each frequency converting the received signal received into a predetermined frequency. Converting means, and gain varying means for setting the gain of each of the converted respective converted signals,
Synthesizing means for synthesizing the output signal having the gain set,
The demodulation means for demodulating the synthesized combined signal, the modulation means for re-modulating the demodulated demodulated signal, and the correlation between the re-modulated output and each output of the gain varying means are obtained, and in accordance with this correlation output And a correlating means for controlling the gain varying means. 2. The correlation means includes means for calculating a correlation between the remodulated reference signal and a delayed output of the output signal delayed to correspond to a symbol of the reference signal. The diversity receiver according to claim 1. 3. A phase shift amount conversion means for detecting an output level and distortion of the synthesizing means and controlling the phase of one output of the gain varying means according to the detected output. Item 3. The diversity receiver according to item 1 or 2. 4. A diversity receiving method for receiving the same signal by first and second antennas installed at appropriate intervals, wherein a frequency for converting the received signal into a predetermined frequency. A converting step, a gain varying step for setting respective gains of the respective converted converted signals, a synthesizing step for synthesizing the output signals with the gain set, and a demodulating step for demodulating the synthesized signal. A modulation step of re-modulating the demodulated demodulated signal, and a correlation step of correlating the re-modulated output with each output of the gain varying step and controlling the gain varying step according to the correlation output. A diversity receiving method comprising: 5. The correlation step includes a step of calculating a correlation between the remodulated reference signal and a delayed output of the output signal delayed to correspond to a symbol of the reference signal. The diversity receiving method according to claim 4. 6. A phase shift amount conversion step of detecting the output level and distortion of the synthesizing step and controlling the phase of one output of the gain varying step according to the detected output. Item 4. The diversity receiving method according to Item 4 or 5.