JPS61177829A - Combined diversity receiver - Google Patents

Abstract

PURPOSE:To widen the band width of BPF of a feedback circuit and to reduce a delay time by amplifying each received signal from antennas and applying to the first and second mixers in a combined diversity receiver. CONSTITUTION:Received signals from antennas 1, 2 are amplified by amplifiers 16, 17 and supplied respectively to the first mixers 3, 4 and the second mixers 9, 10. Output signals of amplifiers 16, 17 and a signal 14 from a feedback circuit 30 are mixed in the mixers 3, 4 and output signals are supplied to mixers 9, 10 through a BPF 5 and limiters 7, 8. Signals from limiters 7, 8 and signals from amplifiers 16, 17 are mixed in mixers 9, 10 Output of mixers 9, 10 is a synthesized by a synthesizer 11 and outputted to a detector as a signal 14 through a BPF 15 and a limiter of the circuit 30. In such a case, signals to mixers 9, 10 are made high by amplification 10, 11. Accordingly, the output level of mixers 9, 10 is made higher than spurious and operates stably at a high speed even when the band width of the BPF 15 is made wide enough to pass spurious.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a composite diversity reception method in which received signals from two or more antennas are combined in phase in order to improve reception quality in a wireless communication device where fading occurs. It is related to the device.

[Conventional technology]

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

Com+sun,, Vol, C0M-22, 1'18
1974 pp. 1099-1106). In the figure, 1.2 is a receiving antenna, 3.4 is a first mixer that takes the frequency of the difference between the received signals from the receiving antennas 1 and 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 and 10 each measure 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 fc of receiving antenna 1゜2,
is fed to the first mixer 3.4 and the second mixer 9.10. Here, fc is the carrier frequency of the Kugata signal,
m(tl is a modulation signal, and θ1 and θ2 are random phases due to fading. At this time, the output signal 14 of the limiter 13 of the feedback circuit 30 becomes the foZ function. 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, 1o via band pass filters 5, 6 and limiter 7°8. . The output signal of limiter 7.8 is
respectively (f c - rO) on ZL, (f c - f
o) /LL. Next, in the second mixer 9, 1o, the output signal of the limiter 7.8 and the above received signal are mixed to 0, and the output signals of the second mixer 9, 10 are both f
oZ becomes flat, and random phase θ1 due to fading
．． θ2 is removed. After this output signal is combined by a combiner 11, it is applied to a bandpass filter 12 and a limiter 1.
3 and is fed back to the first mixers 3 and 4.

[Problem that the invention seeks to solve]

The conventional synthetic diversity receiving device is configured as described above, and the bandpass filter 12 of the feedback circuit 30 is set to a bandwidth that removes spurious components (Suwa 1 Hattori, Communication Engineering Journal, C58l-55p).
p, 91-961981).

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. That is, now the delay time of the bandpass filter 5.6 is set to τ1. Assuming that the delay time of the bandpass filter 12 of the feedback circuit is τ2, this system must satisfy τ1>>τ2 according to Hal pern's analysis (see the above-mentioned literature). However, if τ2 is made small so that τ1>>τ2 is satisfied, the bandwidth becomes wider and the bandpass filter 1
2 allows spurious components to pass in addition to the desired signal. As a result, the reception level becomes low (as the desired signal level of the second mixers 9 and 10 also decreases, and the desired signal level passing through the bandpass filter 12 becomes lower than the level of the spurious component. Therefore, the limiter 13 lowers the desired signal level). There will be no amplification, and this method will no longer work.

This invention was made in order to solve the above-mentioned problems, and its purpose is to obtain a synthetic ubiquity receiving device that satisfies the conditions τ1>>τ2 and can prevent problems caused by spurious components. do.

[Means for solving problems]

The synthetic diversity receiving device according to the present invention widens the bandpass filter of the feed bank circuit so as to pass spurious components other than the desired signal, and also amplifies the received signal input from the antenna to the first mixer or the second mixer. The system is equipped with an amplifier.

[Effect]

In this invention, the bandpass filter of the feedback circuit has a wide band so as to pass spurious components as well, so the condition 2 is satisfied with τ1〉〉, and the received signal from the antenna is processed by the first mixer. Since amplification is performed, the desired signal level will not be lower than the level of the spurious component, and the device will operate normally.

〔Example〕

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

FIG. 1 shows a block diagram of a composite diversity receiver according to an embodiment of the present invention, and in the figure.

The same reference numerals as in FIG. 2 indicate the same or corresponding parts. Reference numeral 15 denotes a bandpass filter having a bandwidth that allows spurious components to pass in addition to the desired signal, and 16 and 17 a bandpass filter that filters the received signal before distributing it to the first mixer 3.4 and the second mixer 9.10. It is an amplifier that amplifies.

The operating principle of the apparatus of this embodiment having such a configuration is the same as that of the conventional apparatus, and only the different parts will be explained below. At the output of the second mixer 9.10 there is a desired signal and a spurious component.

When these signals are input to the band pass filter 15,
Since the band pass filter 15 of this embodiment has a wider band than the conventional one, spurious components are passed through without being removed.
This reduces the level of manpower needed to operate the receiving antenna 1.2. Then, as mentioned above, the desired signal level changes to filter 1.
However, in order to prevent this, the received signal is amplified by amplifiers 16 and 17, so that the level of the desired signal passing through the filter 15 is lower than the level of the spurious components. Therefore, the limiter 13 amplifies the desired signal, and this method becomes operable.

In this embodiment, the received signal is amplified and then input to the first mixer 3.4 and the second mixer 9. Even if the signal is made into a wider band, the desired signal level will never be lower than the level of the spurious component, and this receiver can also be used for FM broadcasting with a wide transmission band.

In the above embodiment, an amplifier is provided between the antenna and the first mixer, and the received signal is amplified before being distributed to the first mixer and the second mixer. The mixer may be provided at a position where the received signal input to the mixer is amplified.

Further, the present invention can also be applied to a receiver using an intermediate frequency, and the same effects as the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the synthetic diversity receiving device according to the present invention, each received signal from the antenna is amplified before signal processing by the first mixer, so that the band-pass filter of the feedback circuit is used to suppress spurious components. The band width can be made wide enough to pass the signals, and τ1>>τ2 can be satisfactorily achieved, which has the effect that the present device can also be used for receiving FM broadcasts and the like having a wide transmission band.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a composite diversity receiver according to an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional composite diversity receiver. 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, 16.17...Amplifier,
30...Feedback circuit.・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 first bandpass filters and each of the received signals, a synthesizer that combines the output of each of the second mixers, and a synthesizer that also combines the desired signal and other spurious components. a feedback circuit having a second bandpass filter having a bandwidth such that the synthesizer passes the output signal back to the first mixer; and a feedback circuit that returns the output signal of the synthesizer to the first mixer; 1. An amplifier for amplifying a received signal input to the receiver.