JP2001127677A - Diversity receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diversity receiver having a small-sized and inexpensive configuration for performing control. SOLUTION: The diversity receiver is provided with frequency converters 10a, b, a phase shifter 102 that controls the phase of each output signal if the frequency converters, a synthesizer 103, an automatic gain controller 104 that amplifies the output level of the synthesizer 103 up to a prescribed level and outputs a synthesis level detection value, a demodulator 105 that applies orthogonal phase detection to the output of an automatic gain control amplifier to demodulate it, a waveform equalizer 106 that eliminates inter-code interference included in the signal from the demodulator, a correlation detector 107 that provides the output of a correlation value between the demodulator output and the output the waveform equalizer, and a phase controller 108 that controls the phase shifter on the basis of the output of the correlation detector and the synthesis level detection value. The diversity receiver monitors the correlation value equivalent to the impulse response in the time region of the waveform distortion within a signal band and controls the phase shifter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diversity receiver, and more particularly, to a diversity receiver that performs synthesis control based on waveform distortion after space diversity synthesis.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a diversity receiver using a conventional space diversity system. In addition,
FIG. 5 shows only a part related to the diversity reception processing in the diversity receiver, and other components are omitted.

[0003] Input signals S1 and S2 obtained by receiving (not shown) by two antennas arranged at a predetermined distance are input to a conventional diversity receiver.

A diversity receiver includes a frequency converter 501a to which an input signal S1 is input, a frequency converter 501b to which an input signal S2 is input, and a frequency converter 501b.
And a frequency converter 501 connected to the
a and a combiner 503 connected to the outputs of 501b;
An automatic gain control amplifier 504 for amplifying the output signal of the combiner 503 to a predetermined level;
, A waveform equalizer 506 for removing intersymbol interference included in the output signal of the quadrature demodulator 505, and a BPF 507a connected in parallel to the output terminal of the automatic gain control amplifier 504. , 507b, 507c
And detectors 508a, 508b, and 508c connected to the BPFs 507a, 507b, and 507c, respectively, and an infinite phase shifter based on the output signals of the detectors 508a, 508b, and 508c and the combined level detection value of the automatic gain control amplifier 504. A phase controller 509 outputs a tap coefficient for giving a phase rotation to 502.

[0005] Frequency converters 501a and 501b receive input wideband radio frequency band signals (input signals S1 and S2).
) Is converted to a signal in the intermediate frequency band. Infinite phase shifter 50
2 rotates the phase of the received signal supplied from the frequency converter 501b within a range of 360 °, and
The signal is controlled so as to be in the same phase as the received signal a. Synthesizer 5
03 synthesizes the reception signals converted into the intermediate frequency band from the frequency converters 501a and 501b. Automatic gain control amplifier 504 amplifies the level of the received signal combined by combiner 503 to a required value and outputs a combined level detection value.

The BPFs 507a to 507c have sufficiently narrow band characteristics with respect to a signal band to be transmitted, are set so that their center frequencies are different from each other, and extract signal components of each frequency band. The detectors 508a to 508c detect output signals of the connection-source BPFs 507a to 507c, and output the detection outputs to the phase controller 509. The phase controller 509 calculates a deviation in the signal band from each detection output value,
A control signal is output to the phase shifter 502 so as to rotate the phase in a direction in which the deviation is minimized, and the combined level is monitored from the combined level detection value from the automatic gain control amplifier 504.

Next, the operation of the configuration shown in FIG. 5 will be described. The input signal S2 is converted into a signal in the intermediate frequency band by the frequency converter 501b, and then input to the synthesizer 503. Further, the input signal S1 is converted into a signal in the intermediate frequency band by the frequency converter 501a, then directly input to the synthesizer 503, synthesized with the output signal of the infinite phase shifter 502, and output. This combined output is supplied to the automatic gain control amplifier 504.
To a required level. An output signal of the automatic gain control amplifier 504 is input to a demodulator 505 and subjected to quadrature detection. The signal subjected to the quadrature detection by the demodulator 505 is input to the equalizer 506, and is output as an output signal after intersymbol interference included in the output signal of the demodulator 505 is removed.

[0008] The output signal of the white motion gain control amplifier 504 is
The signals are further input to BPFs 507a to 507c. It has three types of BPFs having different center frequencies in order to extract the center of the transmission signal band and the signal components on both sides thereof.
The output signals of the BPFs 507a to 507c are detected by detectors 508a to 508c at the respective connection sources. Thereby, the level of each signal component is detected.

The detected signal level information is transmitted to a phase controller 50.
9 is applied. The phase controller 509 calculates a level difference from the input signal level information of the three frequency components. The greater the level difference, the greater the waveform distortion in the signal band. The state of the waveform distortion can be changed by rotating the phase of the output signal of the frequency converter 501b by the infinite phase shifter 502. For this reason, phase rotation information is output from the phase controller 509,
According to the phase rotation information, the infinite phase shifter 502 rotates the phase of the input signal S2, and changes the waveform distortion by the phase controller 5.
Monitor at 09. The phase controller 509 controls so that the waveform distortion is always minimized. However, when the combined level is lower than the threshold value, control is performed so that the level becomes maximum.

The above-mentioned conventional diversity receiver is described in detail in Japanese Patent Application Laid-Open No. Sho 59-230333.

[0011]

The conventional diversity receiver requires at least three types of narrow-band BPFs and detectors in order to detect in-band waveform distortion. These are usually passive circuits in the IF band. It consists of. Therefore, in general, there is a problem that strict specifications are required to suppress variations in the BPF characteristics and the corresponding detector characteristics, and there is a problem that the cost is high, and there is also a problem that it is difficult to reduce the size and the cost by increasing the circuit scale. Was.

As described above, an object of the present invention is to provide a small-sized and low-cost diversity receiver having a diversity combining control circuit which does not degrade line quality.

[0013]

To achieve the above object, a diversity receiver according to the present invention comprises: first and second frequency conversion means for converting the frequency of a received signal for each diversity path into a predetermined frequency; A phase shifter for controlling a phase of an output signal of the second frequency converter, a synthesizer for synthesizing an output of the phase shifter and an output of the first frequency converter, and outputting the synthesized signal; Automatic gain control amplification means for amplifying the output signal level to a predetermined level and outputting a combined level detection value; demodulation means for performing quadrature phase detection on the output of the automatic gain control amplification means for demodulation; Waveform equalizing means for removing intersymbol interference included in a signal, correlation detecting means for outputting a correlation value between an output of the demodulating means and an output of the waveform equalizing means, and an output of the correlation detecting means Characterized in that it comprises a phase controlling means for controlling the phase state of the phase shifting means and a mixing level detection value from said automatic gain control amplifying means.

According to this configuration, the waveform distortion of the synthesized signal is detected by comparing the correlation value between the output signal of the waveform equalizing means and the output signal after synthesis before and after the reference time. be able to. The correlation detecting means can be implemented as an LSI, and does not require an IF-band circuit, resulting in a small-sized and low-cost apparatus.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a diversity receiver using the space diversity system of the present invention. Here, only the portion related to the diversity reception processing in the diversity receiver is shown, and the configuration of other antennas, high-frequency receivers, and the like is omitted.

The diversity receiver according to the present invention comprises a frequency converter 101a (frequency conversion means) having an input signal S1 as an input, a frequency converter 101b (frequency conversion means) having an input signal S2 as an input, and a frequency converter. 101b
, A synthesizing unit 103 (synthesizing unit) connected to the output terminals of the frequency converters 101a and 101b, and a combined output connected to the synthesizing unit 103. An automatic gain control amplifier 104 for amplifying the signal to a predetermined level, a quadrature demodulator 105 (demodulation means) connected to an output terminal of the automatic gain control amplifier 104, and a signal from an output signal of the quadrature demodulator 105 A waveform equalizer 106 (waveform equalizing means) for removing intersymbol interference, and a correlation detector 107 (correlation detecting means) for outputting a correlation value between the output of the quadrature demodulator 105 and the output of the waveform equalizer 106 ) And a phase controller 108 for controlling the phase shift state of the infinite phase shifter 102 based on the output of the correlation detector 107 and the composite level detection value from the automatic gain control amplifier 104.
(Phase control means).

Here, the frequency converters 101a and 101b
When input signal S1 and input signal S2 are input,
The radio frequency is converted into the intermediate frequency for each path. The reception band of the input signal is a wide band signal as in the related art.

The infinite phase shifter 102 includes a frequency converter 101
The phase of the output signal b is controlled based on the output of the phase controller 108. The combiner 103 combines the output signal of the infinite phase shifter 102 and the output signal of the frequency converter 101a. Automatic gain control amplifier 104 amplifies the combined received signal to a predetermined level. The quadrature demodulator 105 performs quadrature detection on the combined output signal amplified to a predetermined level and outputs a demodulated signal (RP, RQ). Waveform equalizer 106 removes intersymbol interference included in the demodulated signal. As the waveform equalizer 106, for example, a decision feedback type equalizer is used.

The correlation detector 107 has two symbols at intervals of two symbols.
This is a configuration of a delay unit with taps, and detects the correlation between the output of the quadrature demodulator 105 and the output of the waveform equalizer 106 at each tap. Specifically, the correlation detector 107 includes a delay unit 109 for delaying the signal from the quadrature demodulator 105 by the delay time of the waveform equalizer 106, and two outputs to the output of the delay unit 109.
It comprises a delay unit 110 for giving a delay of a symbol length, and first and second complex correlators 111a and 111b connected to the input / output unit of the delay unit 110.

The first complex correlator 111a correlates the output signal (reference signal, DP, DQ) of the waveform equalizer 106 with the signal one symbol after the output signal of the delay unit 109 corresponding to the symbol. Is detected. Further, the second complex correlator 111a outputs the output signal (reference signal,
DP, DQ) and the delay unit 109 corresponding to the symbol.
Is detected with the signal one symbol before the output signal.

The phase controller 108 controls the amount of phase shift of the infinite phase shifter 102. The amount of phase shift is determined by the correlation detector 10
7 is controlled so as to minimize the correlation output value.

FIG. 2 shows a complex correlator 111a or 111b.
FIG. 3 is a block diagram showing the details of FIG.

The correlators 201a to 201d receive the received signal R
The respective correlations between P and RQ and the reference signals DP and DQ are calculated. The correlators 201a to 201d can be easily configured by, for example, exclusive OR. Correlation value generators 202a-2
02d performs an averaging process of correlation values from the outputs of the correlators 201a to 201d. This correlation value generator 202a
To 202d can be constituted by, for example, an up-down counter. The synthesizer 203 includes the correlation value generators 202a to 202
The sum of squares of each output of 2d is calculated, and the result (wn) is output.

FIG. 3 is a block diagram showing details of the phase controller 108. The phase controller 108 includes a switch 301 (switching means) that receives the composite level detection value output from the automatic gain control amplifier 104 and the correlation value (w1, w2) of each tap output from the correlation detector 107 as inputs. This switch 3
01, an arithmetic processing unit 302 (arithmetic processing means) for calculating the amount of phase shift based on the phase control information selected in step 01, and a phase shifter 102 for infinite phase shifter 102 based on the phase shift information output from the arithmetic processing unit 302 It comprises a tap coefficient generator 303 (tap coefficient generating means) for outputting a tap coefficient for giving a rotation.

Next, the operation of the diversity receiver shown in FIG. 1 will be described. In a communication line using radio, a receiver having a diversity configuration is used to improve S / N or reduce waveform distortion due to fading of a propagation path. When the waveform distortion is small, the frequency converter 1
In order to combine the received signal from 01a and the received signal from the infinite phase shifter 102, the correlation detector 107 monitors the correlation value between the output signal of the quadrature demodulator 105 and the output signal of the waveform equalizer 106. The output signal of the waveform equalizer 106 is
A signal from which intersymbol interference included in the received signal has been removed,
In a normal line quality state, it can be said that the transmission symbol is the same.
By using this as a reference signal and correlating with a demodulated signal including intersymbol interference, the demodulated waveform distortion is estimated. In a state where there is no waveform distortion, both the first and second correlator outputs in the correlation detector 107 become zero because there is no correlation with the reference signal. Therefore, the phase of the received signal is controlled by the infinite phase shifter 102 so that the first and second correlator output signals are always minimized.

Next, when the waveform distortion cannot be ignored,
The absolute values of the first and second complex correlator output signals increase. In this case, when the waveform equalizer 106 is realized by a decision feedback equalizer, the first correlator output is increased,
Control is performed in a direction to reduce the output of the second correlator. As a result, the decision feedback equalizer input can be treated as minimum phase transition type fading, and in contrast to this, a strong equalization capability can be exhibited as characteristic of the decision feedback equalizer, and the line quality can be improved. Can be kept.

FIG. 4 is a diagram showing a correlation output signal of the correlation detector 107. FIG. 4A shows a case where there is no waveform distortion.
FIG. 4B shows the case where the non-minimum transition type waveform distortion is large, and FIG. 4C shows the case where the minimum transition type waveform distortion is large.

As a means for detecting the waveform distortion in the signal band, a correlation value corresponding to an impulse response in a time domain is monitored instead of the BPF which is a detection means in a frequency domain. As a result, it is possible to implement the alternative means as an LSI, and it is possible to realize reduction in size and cost.

Although the infinite phase shifter 102 controls the phase of the intermediate frequency, it can also be controlled by controlling the phase of a local signal applied to the frequency converter 101b.

[0030]

According to the present invention, as a means for detecting waveform distortion in a signal band, a BPF which is a detection means in a frequency domain is used.
Instead of monitoring the correlation value corresponding to the impulse response in the time domain, the narrow band BPF conventionally used,
A detector is not required, and an LSI can be implemented using a digital circuit. Therefore, the diversity receiver can be significantly reduced in size and cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of complex correlators 111a and 111b shown in FIG.

FIG. 3 is a block diagram of the phase controller 8 of FIG. 1;

FIG. 4 is a diagram illustrating the operation of the correlation detector 107 in FIG.

FIG. 5 is a block diagram of a conventional diversity receiver.

[Explanation of symbols]

 101a, b frequency converter 102 infinite phase shifter 103 synthesizer 104 automatic gain control amplifier 105 quadrature demodulator 106 waveform equalizer 107 correlation detector 108 phase controller 109 delay unit 110 delay unit 111a, b complex correlator 201a, b, c, d correlator 202 a, b, c, d correlation value generator 203 combiner 301 switch 302 arithmetic processing unit 303 tap coefficient generator 501 a, b frequency converter 502 infinite phase shifter 503 combiner 504 automatic gain Control amplifier 505 Quadrature demodulator 506 Waveform equalizer 507a, b, c BPF 508a, b, c Detector 509 Phase controller

Claims (6)

[Claims] 1. A diversity receiver that performs synthesis control based on waveform distortion after synthesis of a plurality of input signals using a space diversity system, wherein the demodulated output after synthesis and intersymbol interference included in the demodulated output are compensated. Correlation detection means for outputting a correlation value with the output, and a phase of the plurality of input signals such that the waveform distortion after the synthesis is reduced based on the output of the correlation detection means and the detection output of the signal level after the synthesis. And a phase control means for controlling the phase difference. 2. First and second frequency converting means for converting the frequency of a received signal for each diversity path to a predetermined frequency, and phase shifting means for controlling the phase of an output signal of the second frequency converting means. Combining means for combining and outputting the output of the phase shift means and the output of the first frequency conversion means;
Automatic gain control amplification means for amplifying the output signal level of the synthesis means to a predetermined level and outputting a synthesized level detection value; demodulation means for quadrature phase detection and demodulation of the output of the automatic gain control amplification means; A waveform equalizer for removing intersymbol interference included in a signal from the demodulator, a correlation detector for outputting a correlation value between an output of the demodulator and an output of the waveform equalizer, and A diversity receiver comprising: phase control means for controlling a phase shift state of the phase shift means from an output and a combined level detection value from the automatic gain control amplification means. 3. The correlation detecting means comprises: a first delay means for adjusting the time between the output of the demodulation means and the output of the waveform equalization means; and a two-symbol interval between the output of the first delay means. Second delay means for providing a delay of the following; first correlation means for obtaining a complex correlation between an output of the first delay means and an output of the waveform equalization means; an output of the second delay means; 3. The diversity receiver according to claim 2, further comprising second correlation means for calculating a complex correlation with an output of the waveform equalization means. 4. The plurality of correlators for obtaining a complex correlation between the output of the first and second delay means and the output of the waveform equalization means, respectively, A plurality of correlation value generators each performing an averaging process on an output of each of the plurality of correlation value generators, and a combiner for calculating a sum of squares of outputs of the plurality of correlation value generators and outputting the sum as a correlation output. 3. The diversity receiver according to 3. 5. A switching means for selecting and inputting any one of each correlation output of the correlation detecting means and a composite level detection value from the automatic gain control amplifying means, and an input by the switching means. Arithmetic processing means for calculating an amount of phase shift for controlling the phase shifting means in accordance with the selected content; and tap coefficient generating means for outputting a tap coefficient given to the phase shifting means from the amount of phase shift by the arithmetic processing means The diversity receiver according to claim 2, comprising: 6. The diversity receiver according to claim 2, wherein said waveform equalizer uses a decision feedback equalizer.