JPH0641405Y2 - Multiplexer for stereo broadcasting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a multiplexer for stereo broadcasting, and more particularly to so-called stereo audio signals of left and right audio signals as well as digitized audio signals of educational programs. The present invention relates to a multiplexing device for stereo broadcasting for multiplexing.

[Conventional technology]

Normally, in stereo broadcasting, a signal of the sum of left and right audio signals is transmitted by a main channel signal for stereo, and a signal of a difference between left and right audio signals is transmitted by a subcarrier signal (38 KHz) for stereo. Furthermore, there is a pilot signal (19 KHz) for control when receiving a stereo broadcast, and these three signals are FM-modulated and broadcast as FM stereo broadcast radio waves. Recently, using this FM stereo broadcast radio wave, a second subcarrier signal (76 KHz) different from the above-mentioned subcarrier signal is set up, and another audio signal digitized to this second subcarrier signal is generated. A method has been developed in which PSK modulation is performed and the second subcarrier signal subjected to PSK is FM-multiplexed with an FM stereo broadcast signal and sent.

Conventionally, a second sub-carrier signal different from the stereo sub-carrier signal which is a frequency doubled of the pilot signal of such a system is based on the stereo pilot signal in order to secure a phase reference at the time of reception demodulation. Then, the frequency of the second subcarrier signal is corrected. Hereinafter, a component for PSK-modulating another digitized voice signal to the second subcarrier signal is called a digital voice modulator, and a component for FM-multiplexing a stereo broadcast is called a stereo FM modulator.

[Problems to be solved by the device]

In the above-described conventional stereo broadcast multiplexing apparatus, one stereo FM modulator corresponds to one digitized voice modulator. However, in actual operation, there are many operations in which the output of one digital audio modulation unit is distributed or switched to a plurality of stereo FM modulation units and input, so a pilot signal (19 KHz) is sent from one stereo FM modulation unit to digital audio. It is necessary to input to the modulator and correct the deviation between the second subcarrier frequency and the frequency of the pilot signal. However, there is a drawback in that it cannot be corrected each time the partner of each stereo FM modulator changes, and the deviation of the pilot signal becomes the deviation of the second subcarrier frequency.

[Means for Solving the Problems]

The stereo broadcasting multiplexer of the present invention comprises a pilot signal oscillator for outputting a pilot signal for FM stereo broadcasting, a clock oscillator for inputting the pilot signal, and outputting a clock signal and a carrier wave signal whose phases match the pilot signal. A digital converter for inputting the clock signal and converting an analog voice signal input from the outside into a digitized voice signal; and inputting the digitized voice signal and the carrier signal to the digitized voice as the carrier signal. P that outputs a PSK modulated signal that is the phase-modulated signal
A digital voice modulator including an SK modulator, the pilot signal and the PSK modulated signal are input, and a stereo main channel signal for FM stereo broadcasting and a subcarrier channel signal are combined and FM multiplexed. And a plurality of stereo FM modulators that output broadcast wave signals.

〔Example〕

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

FIG. 1 is a block diagram of an embodiment of the present invention. In the embodiment shown in FIG. 1, a pilot signal oscillator 1, a clock oscillator 2, a digital oscillator 3 having an analog voice input terminal 6, a digital voice modulator 5 including a PSK modulator 4, and a digital voice modulator 5 are provided. Input 2 signals of output terminal 7 for PSK modulation signal output and output terminal 8 for pilot signal output,
Stereo modulator 9 that synthesizes PSK modulated signal and performs FM modulation
Composed of and.

Next, the operation of this embodiment will be described. In the digital converter 3, the analog signal input from the input terminal 6 is A-
A D-converted and encoded PCM signal is created. In this case, the clock oscillator 2 is the same as the pilot signal oscillator 1 19
Input the KHz oscillation signal, and enter the second harmonic of 19KHz in phase.
The 38 kbit clock signal is output to the digital converter 3. Therefore, the digital converter 3 outputs a digital audio signal PCM by the clock signal 11 of 38 kilobits. The PSK modulator 4 includes a clock oscillator 2
The second carrier signal 12 of 76KHz which is the fourth harmonic of 19KHz obtained from is input, and the second carrier signal 12 is input to the above-mentioned PC.
It is 4-phase PSK-modulated by the M-converted digital audio signal and output to the output terminal 7. The stereo FM modulator 9 generates the stereo main channel signal and the stereo subcarrier signal described in the conventional example with reference to the pilot signal input from the pilot signal output terminal 8. Further, the 4-phase PSK signal from the output terminal 7 and the above-mentioned two stereo signals are combined and input to the FM modulator, and the multiplexed FM stereo broadcast signal is output from the FM multiplexed signal output terminal 10. By performing multiple FM modulation on a plurality of stereo FM modulators 9 by such a digital audio modulator 5, a plurality of multiplexed FM stereo broadcast signals based on one pilot signal can be obtained.

[Effect of device]

As described above, the present invention has a stereo broadcast pilot signal oscillator for the audio signal to be multiplexed in the digital audio modulation section, so that even if another audio signal is multiplexed in a plurality of stereo FM modulation sections, the conventional There is an effect that a stereo broadcast multiplexing apparatus that does not require frequency correction of the pilot signal and the second subcarrier frequency can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention. 1 ... Pilot signal oscillator, 2 ... Clock oscillator, 3 ...
Digital converter, 4 ... PSK modulator, 5 ... Digital audio modulator, 6 ... Input terminal, 7, 8 ... Output terminal, 9 ... Stereo FM modulator, 10 ... FM multiplexed signal output terminal.

Claims (1)

[Scope of utility model registration request] 1. A pilot signal oscillator for outputting a pilot signal for FM stereo broadcasting, a clock oscillator for inputting the pilot signal, and outputting a clock signal and a carrier signal in phase with the pilot signal, and the clock signal A digital converter for converting an analog voice signal input from the outside to a digitized voice signal, the digitized voice signal and the carrier signal are input, and the carrier signal is phase-modulated with the digitized voice signal. A digital voice modulator including a PSK modulator that outputs a PSK modulated signal, the pilot signal and the PSK modulated signal are input, and F
M stereo stereo multiplexing device for synthesizing a stereo main channel signal for stereo broadcasting and a subcarrier channel signal and outputting a FM multiplexed broadcast signal .