JP2731208B2 - FM multiplex receiver - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM multiplex receiver, and more particularly to an FM multiplex receiver capable of automatically detecting and receiving signals of different systems.

[Summary of the Invention] The present invention relates to an FM multiplex receiver, which is capable of automatically switching and receiving signals of a fixed reception system and a mobile reception system for FM multiplex broadcasting, and , The receiver can be informed of which method can be received.

[Prior art] Conventionally, in a FM multiplex receiver, one receiver is made for one system, so when a signal of a different system is broadcast, it is impossible to receive it at all. Can not.

[Problems to be Solved by the Invention] Development of a fixed reception system for FM multiplex broadcasting has been completed, and development is proceeding in such a manner that a mobile reception system is not compatible with a signal system. In the future, they will not be broadcast at the same time due to incompatibility and may be switched over by time. Also, depending on the broadcasting station, only one of them may be constantly broadcast.

In order to receive a broadcast by such a method with a conventional receiver, the receiver must select or switch a receivable receiver.

An object of the present invention is to solve such a problem and enable a receiver to receive an FM multiplex broadcast without being aware of a difference in a system.

Means for Solving the Problems In order to achieve the above object, the present invention provides an FM multiplex receiver that uses two systems based on a signal included in a fixed reception system multiplex signal and a mobile reception system multiplex signal of FM multiplex broadcasting. Means for selecting a receiving circuit conforming to any of the above.

[Operation] According to the present invention, a receiving circuit suitable for one of the two systems is selected based on a signal included in a fixed reception system multiplex signal and a mobile reception system multiplex signal of FM multiplex broadcasting.

Example An example of the present invention will be described with reference to the drawings. FIG. 1 shows the configuration of an FM multiplex receiver according to one embodiment of the present invention.

The system switched according to the present embodiment is a signal shown in the spectrum diagrams of FIGS.
R multiplexed regardless of both types as shown in 4,404
It is assumed that control data for specifying each system is included in the DS signal. However, the RDS signal here is
It is not necessarily the same as FM multiplex broadcasting (subcarrier frequency 57 KHz) that is practically used in Europe.

In FIG. 1, reference numerals 101, 102, and 103 denote BPFs (bandpass filters) for extracting a fixed reception signal, a mobile reception signal, and an RDS signal from the FM multiplex signal. BPF
The RDS signal from 103 passes through the demodulation and decoding circuit of 108, and 109
Is input to the control data extracting circuit, which detects whether the fixed reception system or the mobile reception system is used, outputs a display output signal as a result of the detection, and outputs three BPF output changeover switches 1
Control data for switching each parameter of the carrier recovery circuits 10 and 104 and the data synchronous recovery circuit 106 so as to be adapted to the fixed reception system or the mobile reception system is output. The display output signal is input to an appropriate display device (for example, a lamp) to indicate whether fixed reception or mobile reception is performed.

A demodulation circuit 105 performs FM demodulation of a fixed reception signal or a mobile reception signal obtained through the BPF 101 or the BPF 102 and the switch 110, based on the carrier from the carrier recovery circuit 104. 107 is a decoding circuit (a data synchronous reproduction circuit 1 extracted from a signal from the circuit 105)
Data is decoded from the demodulated signal obtained by the demodulation circuit 105 (based on the clock from 06) and output. Note that the demodulation / decoding circuit 108 includes the above components 104, 105, 106, 1
It has the same configuration as 07.

The above receiver is for the case where control data is inserted into the RDS signal. However, as a second embodiment of the present invention, an example of the receiver for the case where there is no RDS signal itself is shown in FIG. Shown in The system switched according to the present embodiment is a signal shown in the spectrum diagrams of FIGS.

In FIG. 2, reference numerals 201 and 202 denote BPFs for extracting a fixed reception signal and a mobile reception signal from the FM multiplex signal, respectively.
It is. 204 is a carrier reproducing circuit, 205 is a demodulating circuit, 206 is a data synchronous reproducing circuit, and 207 is a decoding circuit, which are the same as those of the first embodiment.

In this method, there is no RDS signal, and therefore control data for specifying the method is not inserted in the multiplexed FM signal. So 204
Whether the carrier regeneration circuit of the present invention is capable of carrier regeneration, and 206
The switch control circuit 208 determines whether or not the data synchronous reproduction circuit can reproduce the synchronous clock. That is, the switch control circuit 208 maintains the state when both circuits 204 and 206 can reproduce the carrier and the clock, and when the circuits 204 and 206 cannot reproduce the carrier and the clock, the BPF output switch 209 and the carrier reproduction circuit 204 and the data synchronous reproduction circuit Switch each parameter of 206. This allows RDS
An FM multiplexed signal having no signal can be adapted to either the fixed or mobile system. In FIG. 2, it is obvious that the switch control circuit 208 may make a determination only on carrier reproduction or only on synchronous reproduction. In FIG. 2, a carrier reproduction circuit or a synchronous reproduction circuit is separately provided at a stage subsequent to the two BPFs 201 and 202, and the circuit is switched according to the presence or absence of the carrier reproduction signal or the presence or absence of the synchronous reproduction signal. It goes without saying that the signal from any one of the BPFs may be decoded.

Further, as a configuration for simultaneously reproducing the RDS signal described in FIG. 1, instead of judging based on data multiplexed on the RDS signal, a 76KHz carrier, a carrier for a mobile reception system, or a 57KHz carrier, or a clock signal of these clock signals is used. Depending on the presence / absence, the receiving side may determine which system is multiplexed and switch to the subsequent circuit.

A method using only a filter can be considered.
It is unknown at present what kind of modulation method the mobile reception system will be, so it is under development.For example, if a subcarrier of 85.5 KHz is used, a filter centered on the 57 KHz subcarrier frequency, a 76 KHz subcarrier frequency Always observe the output of the filter centering on the filter and the filter centering on the 85.5KHz filter, and by the magnitude of the output level,
Subsequent circuit operations may be switched. In this case, the 76 KHz system and the 85.5 KHz system are incompatible with each other, and therefore, either is determined by the level difference. However, since the 57 KHz system is compatible with both systems, the output is always possible.

[Effects of the Invention] According to the present invention, a receiver can receive FM multiplex broadcasting without being conscious of the difference in the system. In addition, the broadcasting station side has been able to perform a fulfilling broadcast by switching the system according to the content of the broadcast. For example, the broadcasting required for automobiles such as traffic information uses a mobile reception system, and the use of a fixed reception system when a higher bit rate is required, such as voice broadcasting and facsimile, has expanded the range of multiplex broadcasting services. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of an FM multiplex receiver according to a first embodiment of the present invention, second is a circuit diagram of an FM multiplex receiver according to a second embodiment of the present invention, The figure shows the multiplexed signal spectrum of the fixed reception method, FIG. 4 shows the multiplexed signal spectrum of the mobile reception method, FIG. 5 shows the multiplexed signal spectrum of another fixed reception method, and FIG. FIG. 3 is a diagram showing a multiplexed signal spectrum of the mobile reception system of FIG. 101, 102, 103 ... BPF, 104 ... carrier reproduction circuit, 105 ... demodulation circuit, 106 ... data synchronous reproduction circuit, 107 ... decoding circuit, 108 ... demodulation decoding circuit, 109 ... control data extraction circuit.

Claims (4)

(57) [Claims] In an FM multiplex receiver, there is provided means for selecting a receiving circuit adapted to one of the two systems based on a signal included in a fixed reception system multiplex signal and a mobile reception system multiplex signal of FM multiplex broadcasting. FM multiplex receiver characterized by having. 2. The FM multiplex receiver according to claim 1, wherein said means performs the selection based on a signal multiplexed at 57 KHz in the received multiplex signal. 3. The apparatus according to claim 1, wherein said means performs the selection based on at least one of a carrier reproduction signal and a data synchronous reproduction signal from the received multiplex signal.
FM multiplex receiver as described. 4. The FM multiplex receiver according to claim 1, wherein said means includes means for displaying a result of the selection.