JP2765037B2 - Antenna diversity receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna diversity receiver, and more particularly, to an antenna diversity receiver configured to select a system by comparing signal quality.

[Conventional technology]

Conventionally, as an antenna diversity receiver that performs reception by selecting a plurality of reception systems, one configured to detect a reception level of a signal received by an antenna of each reception system and to select a system having the highest reception level. is there. Further, there has been proposed a device in which the output of an intermediate frequency signal obtained by frequency conversion in each receiving system is detected and a signal having the highest signal level is selected.

[Problems to be solved by the invention]

The above-mentioned conventional antenna diversity receiver always selects a reception system having a high reception level or a high signal level and demodulates and reproduces the signal, so that even if the reception level is high, the signal quality is high. If it is not always good, there is a problem that correct demodulation and signal reproduction cannot be performed.

That is, the case where the signal quality is not good even though the reception level is high means that the reception level is higher than the case where only the direct wave is added due to the addition of the delayed wave to the direct wave under the multiplex propagation path environment, or When there is a transmitting station that causes interference in addition to a transmitting station to be received, a case where a large amount of interference waves are received by a receiving system having a high receiving level may be considered.

SUMMARY OF THE INVENTION An object of the present invention is to provide an antenna diversity receiver capable of performing correct demodulation and signal reproduction.

[Means for solving the problem]

An antenna diversity receiver according to the present invention includes a plurality of reception systems each having an antenna, a receiver, a demodulator, and a Viterbi decoder, a switch for selecting a signal output of these reception systems, and an output from each Viterbi composite device. A signal which has a correlation with the signal quality is compared, and a comparator which outputs a selection signal for selecting a reception system having the best signal quality to the switch is configured as a signal having a correlation with the signal quality. One of the difference between the maximum value and the minimum value, the maximum value of the difference between the maximum path metric and each other metric, the increase rate of the maximum metric, and the correlation between the decoded data re-encoded sequence and the received data sequence. Used.

[Action]

In this configuration, a signal having a correlation with the signal quality output from the Viterbi decoder of each reception system is compared in a comparator, and the selection in a switch is controlled to select the reception system with the best signal quality. Can be received.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the antenna diversity receiver of the present invention. Here, in order to simplify the description, an example of two systems is shown.

A receiver 2a, a demodulator 3a, and a Viterbi decoder 4a are sequentially connected to the antenna 1a of the first system. Similarly, a receiver 2b, a demodulator 3b, and a Viterbi decoder 4b are sequentially connected to the antenna 1b of the second system.

The Viterbi decoders 4a and 4b of each system have their decoding output terminals connected to a switch 6, and the switch 6 selects the first system or the second system so that reception is performed. . In addition, each Viterbi decoder 4
The signal quality output terminals a and 4b are connected to a comparator 5, which compares signals correlated with signal quality as described later, and based on the comparison result, the switch 6
Is configured to be able to output a selection signal.

Here, the antennas 1a and 1b are installed at a plurality of positions separated by λ / 4 to λ / 3 (λ is a wavelength) or more so that output signals are substantially uncorrelated. Alternatively, each of the antennas is configured by an antenna having beam directivity and installed in different directions.

According to this configuration, in the first system and the second system,
Each of the convolutionally coded digital signals is sent to an antenna
After being received by the receivers 2a and 2b through 1a and 1b and demodulated by the demodulators 3a and 3b, Viterbi decoding is performed by Viterbi decoders 4a and 4b.

The Viterbi decoders 4a and 4b calculate and output, for example, a difference between the maximum value and the minimum value of the path metric at each step of the Viterbi algorithm as a signal having a correlation with the signal quality (hereinafter referred to as a correlation signal). I do. If there are many code errors before decoding, the value of this correlation signal (the difference between the maximum value and the minimum value of the path metric) tends to be small, and this can be used as a signal representing the signal quality. For the correlation between path metric value and signal quality,
"Yasuda;" Study of Error Correction Method by Viterbi Decoding "KDD
Research Institute, Research Report No. 110, pp. 90-109, 1983 ".

The value of the correlation signal output from each of the Viterbi decoders 4a and 4b is input to a comparator 5, where the value of each correlation signal is divided into bits or an average value when divided into blocks. And the system having the largest correlation signal value is selected. Then, this selection signal is output to the switch 6, and the switch 6 is operated to select one of the first and second systems, and to select the decoded data of the system.

At this time, since the Viterbi decoder has a delay corresponding to the length of the path memory, the output of the selection signal also needs to be delayed according to the delay of the decoded signal.

Therefore, in this configuration, since the system having the largest correlation signal value is selected for reception, the system having the best signal quality can be selected regardless of the reception level, and the reception with less errors can be realized.

In the above embodiment, the difference between the maximum value and the minimum value of the path metric is used as the correlation signal. However, as the correlation signal, other than the total value of the difference between the maximum metric and each other metric, the maximum value The metric increase rate, the correlation between the decoded data re-encoded sequence and the received data sequence, and the like can be used.

Further, in the above-described embodiment, two reception systems are used, but it goes without saying that three or more reception systems may be used.

〔The invention's effect〕

As described above, according to the present invention, the correlation signals output from the Viterbi decoders of the respective receiving systems are compared in the comparator, and the receiving system having the best signal quality is selected and received. Thus, it is possible to know the signal quality that could not be known, and to obtain a reproduced signal with less errors.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of one embodiment of the present invention. 1a, 1b ... antenna, 2a, 2b ... receiver, 3a, 3b ... demodulator, 4a, 4b ... Viterbi decoder, 5 ... comparator, 6 ...
switch.

Claims (1)

(57) [Claims] 1. A plurality of receiving systems each having an antenna, a receiver, a demodulator, and a Viterbi decoder, a switch for selecting a signal output of these receiving systems, and a signal quality output from each of the Viterbi decoders. Comparing a signal having a correlation, and a comparator that outputs a selection signal for selecting a reception system having the best signal quality to the switch, as a signal having a correlation with the signal quality, a maximum value of a path metric and It is characterized by using one of a difference between a minimum value, a total value of a difference between a maximum path metric and each other metric, an increase rate of a maximum metric, and a correlation between a decoded data re-encoded sequence and a received data sequence. Antenna diversity receiver.