JPS61172441A - Synthesis diversity receiver - Google Patents

Abstract

PURPOSE:To use the titled device even to an FM broadcast with a wide transmission band by providing a trap circuit making a band pass filter of a feedback circuit broad to pass through a spurious component and eliminating the spurious component to a feedback circuit. CONSTITUTION:The feedback circuit 30 is provided with a band pass filter 15 made broader than a conventional filter so as to pass through a desired signal and a spurious component and a trap circuit 16 stopping the passing of the spurious components fIF and (fc+fIF) giving disturbance to a signal through band pass filters 5, 6. The band pass filter 15 is made broad so as to satisfy the condition of r1>>r2 and W<<B, the spurious component is passed through, and the trap circuit 16 captures the spurious components of fIF and (fc+fIF). Thus, the output component of the trap circuit 16 is 2fIF, fo, 3fIF and fc to eliminate the disturbance wave to a signal in the band of the band pass filters 5, 6.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a communication device in which fading occurs.
The present invention relates to a combining diversity receiving device that combines received signals of two or more diversity branches in the same phase in order to improve reception quality.

[Conventional technology]

Figure 2 shows, for example, Halpern (IEEE
Trans.

Co*s+un, , Vol, C0M-22,? h8
1974 pp. 1099-1106). In the figure, 1.2 is a receiving antenna, 3 and 4 are first mixers that take the frequency of the difference between the received signal from this receiving antenna 1.2 and the output signal of a feedback circuit, which will be described later, and 5.6 is this first mixer. 1 is a bandpass filter connected to the output of the mixer 3.4, 7.8 is a limiter, and 9.10 is the frequency of the difference between the output signal of the limiter 7.8 and the output signal from the receiving antenna 1.2. 11 is a synthesizer that combines the outputs of the second mixers 9 and 10, 30 is a feedback circuit that feeds back the output signal to the first mixer 3.4, and the feedback circuit 30 is a band-pass filter. 12 and a limiter 13. 14 is an output signal.

Next, the operation will be explained. Each received signal of receiving antenna 1゜2 fc, Otsukoho Y9, fc, 4dando LL
is supplied to the first mixer 3.4 and the second mixer 9.10. Here, fc is the carrier frequency of the input signal,
m (t) is a modulation signal, θ1. θ2 is a random phase due to fading. Further, at this time, the output signal 14 of the limiter 13 of the feedback circuit 30 becomes the foZ signal. fo is the output frequency of the feedback circuit 30.

In the first mixer 3.4, the received signal is correlated with the output signal of the limiter 13, and the output is inputted to the second mixer 9.10 via the bandpass filters 5, 6 and the limiter 7°8. . The output signal of limiter 7.8 is
(fc-fO)lLL, (fC-fO)lL, respectively
In the second mixer 9, 10, the output signal of the limiter 7.8 and the received signal are mixed, and the second
The output signals of the mixers 9 and 10 are both foZ2, and the random phase θ1 . θ2 is removed. After this output signal is synthesized by a synthesizer 11, it passes through a band pass filter 12 and a limiter 13, and then passes through a first
It is fed back to mixer 3.4.

[Problem that the invention seeks to solve]

The conventional synthetic diversity receiver is configured as described above, and the bandpass filter 12 of the feedback circuit 30 is set to a bandwidth that eliminates spurious components (see Japanese Patent Laid-Open No. 125536/1983). .

However, when such a conventional synthetic diversity receiving apparatus is used to receive broadcasts such as FM broadcasts having a wide transmission band, the following problems occur. here,
Assuming that the transmission bandwidth of the received signal is W and the center frequency of the bandpass filter 5.6 is fIF, the output components of the second mixers 9 and 10 are as shown in FIG. Then, the delay time of the bandpass filter 5゜6 is τ1, and the bandpass filter 12
If the delay time of is τ2 and the bandwidth is B, then this method is
From Halpern's analysis (see above-mentioned literature), τ1)
τ2, that is, W<B, must be satisfied.However, if τ2 is made smaller so as to satisfy τ1)τ2, the bandwidth B increases, and as shown in FIG. Spurious components now exist within width B in addition to the desired signal. In such a case, that is, when the bandpass filter 12 passes the spurious flF component (fc+flF) component shown in FIG. 3, the flF component passes through the first mixer 3.4 and enters the band of the bandpass filter 5.6. , which becomes a disturbance wave. Also, the (fc+flF) component is mixed with the received signal in the first mixer 3.4, and its output becomes the fIF component, so
It also falls within the band of the bandpass filter 5.6 and becomes an interference wave.

This invention was made to solve the above problems, and satisfies the conditions τ1)τ2 (W<B),
Moreover, it is an object of the present invention to obtain a composite ubiquity receiving device that can prevent problems caused by spurious components.

[Means for solving problems]

The synthetic diversity receiver according to the present invention has a bandpass filter of a feedback circuit with a wide band so that spurious components can also pass therethrough, and a trap circuit for removing spurious components is provided in the feedback circuit and the like.

(Operation) In this invention, since the bandpass filter of the feedback circuit has a wide band so as to pass spurious components as well, the condition τ1)τ2(W<B) is satisfied, and the spurious components that become interference waves after feedback is removed by a trap circuit.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a block configuration diagram of a composite diversity receiver according to an embodiment of the present invention. In the figure, the same reference numerals as in FIG. 2 indicate the same or corresponding parts. The configuration of the feedback circuit 30 is different, and in the feedback circuit 30, 15 is a band-pass filter whose band has been made wider than the conventional one so as to pass the desired signal and spurious components, and 16 is the filter 15.
Spurious component element IF, (fc+fI
This is a trap circuit that prevents the passage of F).

In the device of this embodiment having such a configuration, the operating principle is the same as that of the conventional device, but the bandpass filter 15 has a τ1
), the band is widened so as to satisfy the condition of 2 (W<<B), and therefore the spurious components shown in FIG. 3 are passed. These spurious components and the desired signal are input to the trap circuit 16, and the trap circuit 16 captures the stripe 11 ass component of fIF, (fc+fIF). Therefore, the output components of the trap circuit 16 are 2 fIF, to, 3 flF,
It becomes a component of fc, and interference waves to the signal within the band of the bandpass filter 5.6 are removed.

As described above, in the device of this embodiment, the bandwidth of the bandpass filter 15 is widened, so that the delay time τ1 of the filter 5.6 is
The relationship between the delay time τ2 of the filter 15 and the delay time τ2 of the filter 15 is τ1)τ2.
6, the spurious components that become interference waves are removed by the trap circuit 16.
It can also be used for M broadcasting, etc.

Although the trap circuit 16 is provided after the bandpass filter 15 in the above embodiment, it may be provided before the bandpass filter or after the limiter 13. Also,
A trap circuit 16 may be provided at each output of the second mixer 9.10.

Further, in the above embodiment, the bandpass filters 5 and 6 are provided before the limiter 7.8, but they may be provided after the limiter 7.8, and furthermore, the bandpass filters 5 and 6 may be provided after the limiter 7.8.
3 may be an amplifier.

Moreover, the present invention can be applied to a receiver using an intermediate frequency, and the same effects as the above embodiment can be obtained. [Effects of the Invention] As described above, according to the synthetic diversity receiving device according to the present invention, In addition to widening the bandpass filter of the feedback circuit, the trap circuit removes spurious components that interfere with the signal of the bandpass filter connected to the first mixer, which passes through the bandpass filter. FM receiver with wide transmission band
It has the advantage that it can also be used for receiving broadcasts, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a synthetic diversity receiving device according to an embodiment of the present invention, FIG. 2 is a block diagram of a conventional synthetic diversity receiving device, and FIG. 3 is a diagram showing the second mixer output component of the device. It is. 1.2...Receiving antenna, 3,4...First mixer, 5.6...Band pass filter, 9.10...Second
Mixer, 11...Synthesizer, 15...Band pass filter that passes spurious components, 16...Trap circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A first mixer that mixes each of the received signals from at least two or more antennas and a signal from a feedback circuit described below, and a first band-pass filter connected to the output of each of the first mixers. , a second mixer that mixes the output signal of each of the band-pass filters and each of the received signals, a synthesizer that combines the outputs of each of the second mixers, and a synthesizer that also passes the desired signal and other spurious components. a feedback circuit having a second bandpass filter having a bandwidth and feeding back the output signal of the synthesizer to the first mixer;
What is claimed is: 1. A synthetic diversity receiver comprising: a trap circuit for removing spurious components that become interference waves with respect to a bandpass filter.