JPH07162326A - Sound noise generation preventing device for satellite broadcasting - Google Patents

Abstract

PURPOSE:To prevent the generation of a sound noise from a receiver at the time of changing a sound mode from a monophonic mode to a stereophonic mode by inhibiting the insertion of a PN signal only for a prescribed time at the time of changing the sound mode. CONSTITUTION:On the transmitting side of satellite broadcasting, a sound mode signal 11 is inputted to a mode change detecting part 12, and at the time of detecting a change in a sound mode, a pulse signal is outputted for a certain fixed time. On the other hand, a PN code generating part 14 generates a PN code 15 and a PN signal detecting part 16 finds out AND between the pulse signal and the PN code 15 and outputs a PN signal 17. Thereby at the time of changing the sound mode, the PN signal 17 is fixed to a low level for a certain fixed time. The PN signal 17 is inserted into the outside of a sound data area by a PN signal adding part on the transmitting side. When the sound mode is changed from the monophonic mode to the stereophonic mode like a system for always inserting a PN signal, the instantaneous generation of a nuisance sound noise like 'bachi' in the receiver can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio noise generation prevention device for satellite broadcasting, and more particularly to an audio noise generation prevention device on the transmission side in satellite broadcasting.

[0002]

2. Description of the Related Art Conventionally, in satellite broadcasting, in order to prevent pseudo sync detection at the receiver when switching between the station and the channel of the receiver, as shown in FIG. 2, audio data 21 is input to add a PN signal. In the section 22, the PN signal output from the PN code generating section 23 is constantly inserted outside the audio data area to output the audio data 24. 3 is a diagram showing the signal formats of the input audio data and the output audio data in FIG.

[0003]

In the conventional method of always inserting the PN signal, when the audio mode is changed from mono to stereo, the switching of the audio mode precedes the switching of the audio data. There was a problem that voice noise generated by decoding a PN signal called "Bachi" was generated in the machine for a moment.

[0004]

SUMMARY OF THE INVENTION An audio noise generation preventing apparatus for satellite broadcasting according to the present invention comprises a mode change detecting section for inputting an audio mode signal, detecting an audio mode change, and outputting a pulse signal for a certain period of time. , A PN code generator for generating a PN code and the logical product of the pulse signal and the code, and P
And a signal output section for outputting an N signal.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 shows an audio noise generation prevention apparatus according to an embodiment of the present invention.

In the figure, a voice mode signal 11 is input to a mode change detection section 12 and a voice signal change is detected and a pulse signal 13 for a certain period of time is output. On the other hand, the PN code 15 and the pulse signal 13 from the PN code generator 14 are set to P
The N signal output unit 16 calculates the logical product and outputs the PN signal 17. Therefore, when the voice mode changes,
The PN signal 17 is fixed at low level.

This PN signal 17 is transmitted by the transmitting side as shown in FIG.
The PN signal adding unit 22 of No. 1 inserts the data outside the voice data area.

[0008]

As described above, according to the present invention, when the voice mode change is detected from the voice mode signal and the voice mode is changed, the PN signal is fixed to the low level for a certain period of time, so that the transmitting side is not affected. Even if the PN signal is inserted outside the audio data area, it is possible to prevent the audio noise generated in the receiver when the audio mode changes from mono to stereo.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a block diagram on the transmission side and a conceptual diagram of audio data for explaining a conventional technique.

FIG. 3 is a diagram showing formats of input audio data and output audio data in FIG.

[Explanation of symbols]

 12 Mode Change Detection Section 14 PN Code Generation Section 16 PN Signal Output Section 22 PN Signal Addition Section 23 PN Code Generation Section

Claims (2)

[Claims] 1. In transmitting satellite broadcast audio data,
An audio noise generation prevention device for satellite broadcasting, characterized in that insertion of a PN signal is prohibited for a predetermined time when the audio mode changes. 2. A mode change detection unit for inputting a voice mode signal and detecting a voice mode change and outputting a pulse signal for a certain period of time at a satellite broadcast transmission side, and a PN code generation unit for generating a PN code. An audio noise generation preventing apparatus for satellite broadcasting, comprising: a PN signal output unit that outputs a PN signal by taking a logical product of the pulse signal from the mode change detection unit and the PN code from the PN code generation unit. .