JP2000092586A - Sound/silence judging circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively realize a sound/silence judging circuit capable of surely judging sound/silence even when a DC component is included in an input sound signal. SOLUTION: The sound/silence judging circuit for a sound signal input channel is provided with a micro CPU 3 for outputting the upper limit and lower limit values of a digital maximum value of a prescribed sound signal level for judging sound/silence, a comparator circuit 4 for comparing the digital value of a sound signal inputted from the sound signal input channel with the digital maximum value upper limit and lower limit values outputted from the micro CPU 3, a flip flop(FF) 6 to be set up by an output from the comparator circuit 4, and a timer 5 for resetting the FF 6 at a prescribed time interval and repeating operation for triggering the micro CPU 3 within a short time. An output from the FF 6 is fed back to the micro CPU 3 and outputted as a sound/silence judging signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound / non-sound determination circuit for each audio signal line in a digital master device used in a radio broadcasting station or the like.

[0002]

2. Description of the Related Art Conventionally, for a large number of audio signal input lines in a radio broadcasting station or the like, it is necessary to judge the presence / absence of sound in all the lines so as not to cause a problem in the radio broadcast content. As a circuit for that purpose, there are a circuit using an analog circuit and a circuit using a digital circuit. The analog circuit detects and determines whether the signal level of the input analog signal is at a predetermined level, and the digital circuit converts the input digital signal into a DSP (Dig) signal.
It is determined by digital calculation using an italal signal processor.

[0003]

However, in the case of an analog circuit, a complicated adjustment process is indispensable. In the case of a digital circuit, a general-purpose DSP is very expensive. Is included, there is a problem in that the determination of sound / no sound is erroneous.

[0004] The present invention solves the above-mentioned conventional problems, and enables sound / silence to be reliably determined even if the input audio signal contains a DC component. It is an object to provide an inexpensive judgment circuit.

[0005]

A voice / silence determination circuit according to the present invention is a voice / silence determination circuit for an audio signal input channel, and has a digital maximum of a predetermined audio signal level for voice / silence determination. Micro C that outputs upper and lower limit values
PU, a comparison circuit for comparing the digital value of the audio signal input from the audio signal input channel with the digital upper and lower limit values from the micro CPU, and a flip-flop set by the output of the comparison circuit And a timer for resetting the flip-flop at a predetermined time interval and repeatedly performing an operation of triggering the micro CPU in a short time. An output of the flip-flop is fed back to the micro CPU to determine presence / absence of sound / non-speech. It is designed to be output as a signal.

According to the present invention, even if the input audio signal contains a DC component, it is possible to reliably determine the presence or absence of sound, and the CPU to be used is an inexpensive micro CPU with a low processing speed. And the signal processing is digital processing, so that there is no need for circuit adjustment.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a sound / non-speech determination circuit according to an embodiment of the present invention, and FIG. 2 shows a relevant portion of a broadcasting apparatus to which the sound / non-speech determination circuit of the present invention is applied. It is a block diagram. In FIG. 1, reference numeral 1 denotes an AD converter, 2 denotes a sound / non-speech determination circuit, which comprises a micro CPU 3, a comparison circuit 4, a timer, and a flip-flop 6.

The operation is as follows.
The digital maximum value and the minimum value of the audio signal level for determining whether the sound signal 3 is sound or non-sound are output to the comparison circuit 4. The digital value of the input audio signal
Are compared with the upper and lower limits of the digital maximum value, and the result, that is, the upper limit is over, the lower limit is over, both the upper and lower limits are over or both are set in the flip-flop 6 are set. Then, the set result is fed back to the micro CPU 3. In this comparison, the maximum value of the audio signal waveform is compared, and the level of the audio signal is not actually calculated from the digital value and compared, but it is necessary to determine whether the level of the audio signal is above or below a certain value. Is enough.

Although the input audio signal from the AD converter 1 is constantly changing due to various factors, by repeating the above operation many times in a short time, the input audio signal level becomes steady. The micro CPU 3 can determine whether the noise is caused by instantaneous noise, and the determination result is output as a sound / non-sound determination signal. The timer 5 is provided to repeat the above operation many times in a short time. For example, the operation of resetting the flip-flop 6 every 10 ms and triggering the micro CPU 3 is repeated for about 1 second, and the comparison circuit By feeding back the comparison result of No. 4 to the micro CPU 3 via the flip-flop 6, it is possible to determine the presence / absence of a sound with an error of about 5% from the stack. Next, when the above comparison result indicates that the upper limit value is exceeded or the lower limit value alone continues, it is determined that the DC signal is included in the audio signal, and the micro CPU 3 determines the difference between the upper limit value and the lower limit value. By making the comparison data in which the data is shifted in the direction of the overrun as it is, and outputting the comparison data to the comparison circuit 4, it is possible to determine the presence / absence of sound / no sound which is not affected by the drift of the DC component. Note that the CPU 3 performing such an operation can be sufficiently realized by an inexpensive micro CPU having a slow processing speed, which is advantageous in cost.

Such a sound / non-speech determination circuit 2 is applied to an audio signal input circuit of a digital master device of a broadcasting apparatus as shown in FIG. 2, and receives analog audio data input from a number of audio signal channels, for example. ADC
(Analog / Digital Converter) Unit 10, 1
DDA to which digital audio data is input
(Digital / Distribution / Amplifier) Units 20, 21, 22
Mounted on Each of these units outputs digital audio data, and the audio data selected by the switcher circuit in the next stage is broadcast.

On the other hand, the sound / non-speech determination circuit 2 mounted on each of these units performs a sound / non-speech judgment of the audio signal of each unit, and the result is sent to the maintenance device as a sound / silence judgment signal. Output. In the maintenance device, the sound / channel for the audio signal channel currently on air is
Pay particular attention to the silence judgment signal, and in the worst case,
In the case where the sound becomes silent, it is possible to easily take measures such as selecting an appropriate one from other sounded audio signal channels and switching to this.

As described above, according to the present embodiment, even if the input audio signal includes a DC component, it is possible to reliably determine the presence / absence of sound and the CPU used has a processing speed. It can be sufficiently realized by a slow and inexpensive micro CPU, and since the signal processing is also digital processing, there is no need for circuit adjustment.

[0014]

As described above, according to the present invention, the presence / absence of sound / non-speech can be reliably determined even when the input audio signal contains a DC component. An advantageous effect is obtained that it can be realized by a slow and inexpensive micro CPU.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a sound / non-sound determination circuit according to an embodiment of the present invention;

FIG. 2 is a block diagram showing a relevant part of a broadcasting device to which a sound / non-speech determination circuit of the present invention is applied;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 A / D converter 2 Sound / silence judgment circuit 3 Micro CPU 4 Comparison circuit 5 Timer 6 Flip-flop 10, 11, 12 ADC unit 20, 21, 22, DDA unit

Claims (1)

[Claims] 1. A sound / silence determination circuit for an audio signal input channel, comprising: a micro CPU for outputting a digital upper limit value and a lower limit value of a predetermined audio signal level for sound / silence determination; A comparison circuit for comparing the digital value of the audio signal input from the signal input channel with the digital maximum and minimum values from the micro CPU; a flip-flop set by the output of the comparison circuit; A timer for resetting the flip-flop at intervals and triggering the micro CPU in a short time is provided. The output of the flip-flop is fed back to the micro CPU and output as a sound / non-speech determination signal. A sound / non-speech determination circuit;