JPH0461425A - Radio receiver - Google Patents

Abstract

PURPOSE:To allow the user to listen to a broadcast in an excellent reception state by receiving a broadcast station corresponding to a frequency data from an RDS decoder when a trigger pulse is outputted from a trigger generator. CONSTITUTION:The receiver is provided with an antenna 1, a front end 2, an intermediate frequency amplifier 3, a multiplexer 4, a radio data system(RDS) 5, a trigger generator 6 and a PLL circuit 7. When a trigger pulse is outputted from a trigger circuit 6 while an S meter output from a detector 3b1 connected to the position of a wide filter 3a1 is decreased and an output from a comparator 3d is inputted to the circuit 6, a broadcast station corresponding to the frequency data from the RDS decoder 5 is received. Thus, a broadcast with an excellent reception state is listened to.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a radio receiver, in particular, a radio receiver that receives data from broadcasting stations forming a network called a radio data system (hereinafter simply referred to as RDS). This invention relates to an improvement in a vehicle-mounted radio receiver that automatically selects and receives radio waves from broadcasting stations with high electric field strength.

[Prior Art] Conventionally, a radio receiver incorporating the above-mentioned RDS circuit has generally had a configuration as shown in FIG.

In the figure, A is an antenna, and B is a front end consisting of a high-frequency amplification stage, mixer, and local oscillation stage, which selects and amplifies radio waves of the desired frequency, attenuates other signals, and converts them to intermediate frequencies. It is something. C is an intermediate frequency amplification stage connected to the output of the front end B, and is composed of a filter C1 connected to the output of the front end B, and a detector C2 connected to the output of the filter C1. There is. D is an RDS decoder that demodulates data from broadcasting stations forming a network from data superimposed on broadcast signals, and E is the detector C.
By detecting the currently received S meter output when the electric field strength from the RDS decoder D is decreasing, the frequency data of other broadcasting stations having a strong electric field strength in the network from the RDS decoder D The PLL [i-path] sends an output to tune the front end B.

Next, to explain the operation based on the above configuration, now,
When a certain broadcasting station is being received, the PLL circuit E
D stores the receiving frequencies of broadcasting stations forming a network with the broadcasting station currently being received. When the electric field strength of the broadcasting station currently being received decreases, the S meter output decreases and the output is output to the PLL circuit.
The PLL circuit E sends out an output to receive other broadcasting stations with strong electric field strength that are networked to the front end. Therefore, the front end B receives radio waves from other broadcasting stations having a strong electric field strength.

[Problem to be solved by the invention]

By the way, in the conventional example described above, there is a broadcasting station close to the frequency of the current broadcasting station, and even though the electric field strength of the broadcasting station being received has decreased, the radio waves from the adjacent broadcasting station are In the case of interference, the S meter output will not decrease even if the field strength of the broadcasting station being received is weak and the reception condition is poor. There was a problem in that the broadcast had to be listened to in a bad condition.

[Purpose of the invention]

The present invention is intended to solve the above-mentioned problems, and its purpose is to automatically select channels using RDS and maintain good reception even when reception conditions deteriorate due to the arrival of adjacent interference radio waves. It is an object of the present invention to provide a radio receiver that can listen to broadcasts and reliably receive RDS data.

[Summary of the invention]

The radio receiver of the present invention is intended to achieve the above-mentioned object, and its gist is to distribute the output from the front end to a wide filter and a narrow filter,
First, the outputs from the memory filters are demodulated by a detector, and the difference between the demodulated outputs is subtracted by a subtracter. If the cough subtraction result is larger than a predetermined value by the comparator, the adjacent broadcasting station Assuming that there is more interference, RD
Automatic channel selection is performed by S, and the RDS signal input at this time is obtained from the output of a wide filter so that the RDS data will not be significantly damaged.

[Embodiments of the invention]

Hereinafter, an embodiment of a radio receiver according to the present invention will be described with reference to FIG.

Reference numeral 1 denotes an antenna, and 2 denotes a front end, which are the same circuits as in the conventional example described above. Reference numeral 3 denotes an intermediate frequency amplification stage connected to the output of the front end 2, which is constructed as follows. That is, a wide filter 3a1, a narrow filter 3a2, and detectors 3b1 and 3b connected to the outputs of the wide filter 3a1 and narrow filter 3a2.
2, a subtracter 3c that detects the difference between the outputs from the detectors 3b1 and 3b2, a comparator 3d that sends out an output when the output from the subtracter 3c is larger than a predetermined value, and the comparator According to the output from 3e, the detector 3bz or 3
It is comprised of a switch means 3e which selects the output from b2 and sends it to the multiplex 4 at the subsequent stage.

A multiplexer 4 converts the audio signal detected by the detector 3b1 or 3b2 selected by the switch means 3f into a stereo signal.

5 is the same RDS decoder as in the conventional example, and 6 is the output from the comparator 3d and the S from the detector 3bs.
A trigger generator 7 sends out a trigger pulse when the output when the meter output decreases is input, and when the trigger pulse from the trigger generator 6 is input, the trigger generator 7 sends out the trigger pulse currently received from the RDS decoder 5. These are P, LL circuits that send out outputs to tune the front end 2 to a frequency list networked with a broadcast station.

Next, the operation will be explained based on the above-mentioned configuration. FM radio waves from a broadcasting station inputted from the antenna are amplified and output after radio waves of a desired frequency are selected in the front end 2.

Then, the FM signal of the selected broadcasting station is input to the detector 3b1 via the wide filter 3a1, or input to the detector 3b2 via the narrow filter 3a2.

Then, the FM signals from the respective filters 3a193a2 are demodulated by the detectors 3b1 and 3b2, and then sent to the subtracter 3C.
is input.

Here, if there is no adjacent broadcasting station whose broadcasting frequency is close to each other, the output signal level from the wide filter 3at and the narrow filter 3a2 is between -, so the output from the subtracter 3C is small, and therefore No output is sent out, the switch means 3e is switched to the detector 3b1 side, and the signal from the detector 3b1 is output to the multiplex 4.

On the other hand, if there is an adjacent broadcasting station whose broadcasting frequency is close to each other, the output from the detector 3bx that is outputted via the wide filter 3a1 has a signal from the adjacent broadcasting station as shown in (a) of FIG. Although the signals are superimposed, the narrow filter 3a
The output from the detector 3b1 which is output via the second
As shown in Φ) in the figure, signals from adjacent broadcasting stations are not superimposed.
Therefore, when the outputs of the detector 3bs and the detector 3b2 are subtracted by the subtracter 3C, the difference output is sent out. This output is compared with a reference value in the comparator 3d, and from the reference value, the subtracter 3C sends out the difference output. When the output from 3C is large, the output is sent from the comparator 3d, and the switching means 3e is switched to the narrow filter 3a2 side. Besides this, narrow filter 3
Since the signals outputted through a2 and the detector 3b2 are input to the multiplex 4, radio waves from adjacent broadcasting stations are removed and only broadcasts from the desired broadcasting station can be received and listened to.

Next, a case will be described in which the electric field strength from the broadcast station currently being received decreases.

When the electric field strength from the broadcasting station decreases, the S meter output from the detector 3b decreases, so the output from the trigger generator 6 is sent to the PLL circuit 7, while the RDS decoder 5 detects the broadcasting station currently being received. A frequency list of broadcasting stations that have formed a network with is sent to the PLL circuit 7, so the PLL circuit 7 sets the receiving frequency of the front end 2 to the broadcasting station corresponding to the frequency list, and receives the same program. Can be listened to continuously.

Also, a case will be described in which the S meter output from the detector 3bs does not decrease even though the electric field strength from the broadcast station currently being received has decreased due to interference from an adjacent broadcast station.

In this case, the output from the comparator 3d is sent out from the comparator 3d and inputted to the trigger generator 6, and the trigger pulse is sent from the trigger generator 6 to the PLL circuit. 7 is input. Therefore, the front end 2 uses the RDS by the same operation as described above.
The broadcast station corresponding to the frequency data from the decoder 5 is received, and the same program can be listened to continuously.

〔Effect of the invention〕

As described above, the present invention distributes the output from the front end between the wide filter and the narrow filter, demodulates the output from each filter using a detector, and subtracts the difference between the demodulated outputs using a subtracter. Then, when the subtraction result reaches a preset level or higher by the comparator, it is assumed that there is interference from an adjacent broadcasting station, and the switch means is configured to output the output from the narrow filter side to the subsequent multiplex. As a car radio receiver, it eliminates the difficulty of listening due to interference, and even when the field strength of the broadcasting station currently being received has decreased and there is interference from neighboring broadcasting stations, it can be used as a car radio receiver. Since it is possible to receive broadcast stations corresponding to the frequency data from the RDS decoder, it is possible to listen to the same program continuously, and at this time, the input signal of the RDS decoder uses the output from the wide filter. Therefore, it always operates at a low distortion rate and has the advantage of not significantly damaging multiplexed data.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing the output of the same detector, and FIG. 3 is a block diagram showing an example of a conventional example. 2...Front end, 3...Intermediate frequency amplification stage, 3
a1...Wide filter, 3a2...Narrow filter, 3b1, 3b2...Detector, 3C...Subtractor,
3d... Comparator, 3e... Switch means, 4...
Multiplex, 5...RDS decoder, 6...
Trigger generator, 7...PLL circuit.

Claims (1)

[Claims] A wide filter and a narrow filter into which the output from the front end is input, a detector connected to each filter to demodulate the output from the filter, a subtracter for obtaining a difference between the outputs from the detector, and the wide filter. an RDS decoder that takes in frequency data from the output from a detector connected to the side; a comparator that sends out an output when the output from the subtracter exceeds a preset reference level; A switch means for outputting the signal from the detector connected to the narrow filter side to the multiplex by an output, and a switch means for outputting the signal from the detector connected to the narrow filter side to the multiplex, and when the S meter output from the detector connected to the wide filter side decreases and the signal from the comparator and a trigger circuit that outputs a trigger pulse when an output is input, and when the trigger pulse from the trigger circuit is output, the broadcasting station corresponding to the frequency data from the RDS decoder is received. Features a radio receiver.