JPS6236364Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a receiver for a traffic information system implemented in West Germany, and is designed to forcibly switch to a monaural state when receiving traffic information. .

The outline of the traffic information system is as follows. West German broadcast stations usually broadcast regular programs such as music, but at certain times there are stations that broadcast traffic information. Therefore, for example, when a driver is listening to a certain broadcast on a car radio, he or she can check whether or not this broadcast station is a traffic information broadcast station. It would be convenient to know whether information can be heard or not. Therefore, the traffic information broadcasting station shall always transmit a 57KHz pilot signal (referred to as SK signal) as an identification signal (even when broadcasting a normal program), and the receiver side will transmit this SK signal. The system is configured to detect a signal and turn on, for example, a lamp, thereby making it possible to identify the traffic information broadcasting station. On the other hand, in the current West German traffic information system, the 57KHz SK signal is converted to 125Hz.
A signal (referred to as a DK signal) that is amplitude-modulated using the same signal is simultaneously transmitted only when transmitting traffic information. This DK signal is used, for example, as follows. That is, the receiver is tuned to a traffic information broadcasting station, and normally the playback sound from the tape player is applied to the speaker to listen to the tape playback sound, and when the traffic information broadcast starts, it is transmitted at the same time. detecting the DK signal being received, and switching the signal path so that the radio reception sound, that is, the traffic information sound, is applied to the speaker instead of the tape playback sound, thereby causing the traffic information sound to interrupt the tape playback sound. I can do it. Further, even if the tape playback sound is played at a low volume, the volume can be increased using the DK signal so that the traffic information sound can be clearly received at a high volume.

Incidentally, while music and other regular programs are broadcast as stereo signals, traffic information is broadcast as monaural signals. Even when traffic information is being broadcast, the stereo pilot signal (19KHz) continues to be transmitted. Therefore, the stereo demodulation circuit of the radio receiver remains in operation even when traffic information is being broadcast. On the other hand, it is generally known that noise in a radio receiver increases more in a stereo reception state than in a monaural reception state. Furthermore, with regard to multipath distortion, better reception can be expected in the monaural reception state. Therefore, in the past, even when traffic information was received as a monaural signal, it was received in a noisy stereo reception state, which was inconvenient. Therefore, in the present invention, when receiving traffic information, the system is forcibly set to a monaural reception state.

Hereinafter, a detailed description will be given with reference to embodiments shown in the drawings.
In the figure, 1 is a high frequency amplifier circuit, 2 is a local oscillation circuit, 3 is a mixing circuit, and 4 is an intermediate frequency amplification/detection circuit, from which a stereo composite signal is output. 5 is a multiplex circuit which creates L and R channel signals from the composite signal. 6L and 6R are magnetic heads for the L and R channels, 7 is an equalizer amplifier circuit, 8 is a low frequency amplifier circuit, and 9L and 9R are speakers for the L and R channels. By the way, an SK decoder 10 (for example, IC.LA2100 manufactured by Tokyo Sanyo Electric Co., Ltd.) is installed between the intermediate frequency amplification/detection circuit 4 and the multiplex circuit 5.
) has been inserted. This SK decoder 10 has the function of detecting the SK signal and lighting up the display lamp PL of the traffic information broadcasting station.
It has a function of outputting a signal detection output, that is, a DK signal. On the other hand, the DK decoder 11 (for example, IC.LA2211 manufactured by Tokyo Sanyo Electric Co., Ltd. can be used) controlled by the output of the SK decoder 10 is
It has a function of detecting a drop in signal level and generating an alarm sound, and a function of detecting a DK signal, switching the signal path and increasing the volume.

If the SK signal is currently detected by the SK decoder 10, the terminal SK' becomes zero level, the lamp PL lights up, and the traffic information broadcasting station is displayed. At this time, if the traffic information broadcasting station is transmitting a normal program, the tape playback sound input to the second input terminal (TAPE.IN) is output from the first output terminal OUT ₁ , and the speaker 9L, 9R
is applied to Now, when traffic information actually begins to be transmitted, the DK signal transmitted at the same time is input from terminal DK' to terminal DK, and when this is detected in the DK decoder 11, the signal path is switched. Radio reception sound, that is, traffic information sound input to the first input terminal (FM.IN) is output to the first output terminal OUT ₁ .
More output will be generated. At this time, even if the variable resistors VR ₁ and VR ₂ are at the minimum level, the traffic information sound is outputted from the second output terminal OUT ₂ as the volume increase so that the traffic information can be heard clearly. Ru.

Therefore, in the present invention, the second output terminal
The signal output from OUT ₂ is guided to the rectifier circuit 12, and this rectified output is applied to the gate circuit 13.
The output of the terminal SK' is also input to this gate circuit 13. Therefore, the output of the gate circuit 13 is
This signal indicates that traffic information is being received.
Therefore, this signal can be used as a switching signal from a stereo reception state to a monaural reception state.
For example, when using IC.LA3361 manufactured by Tokyo Sanyo Electric Co., Ltd. as the multiplex circuit 5, the 9th
When this signal is applied to the th terminal, the operation of the voltage controlled oscillator for creating a switching signal for stereo demodulation is stopped, and a monaural reception state is established.

Note that to detect the DK signal, for example, an AM synchronization detection circuit using a phase-locked loop may be used. The example uses IC.LA2211, and since this IC does not have a DK signal detection output terminal, the rectified output of the traffic information sound as the volume increase is used.
Although the DK signal detection output was used instead to switch to the monaural state, it is of course possible to switch to the monaural state by directly using the DK signal detection output output from the AM synchronization detection circuit.

According to the present invention described above, when receiving traffic information, it is forcibly switched to a monaural state, so that good reception with less noise and multipath distortion can be expected.

[Brief explanation of the drawing]

The figure shows a block diagram of a receiver according to the present invention. 5 is a multiplex circuit, 10 is an SK decoder, 11 is a DK decoder, and 12 and 13 are a rectifier circuit and a gate circuit that constitute a switching circuit.

Claims (1)

[Scope of utility model registration request] Traffic information comprising: a decoder circuit that detects an identification signal indicating that traffic information is being broadcast; and a switching circuit that switches from a stereo reception state to a monaural reception state in response to the detection output of the decoder circuit. System receiver.