JPH04170277A - Digital processing unit for audio signal - Google Patents

Abstract

PURPOSE:To attain digital processing and multiplexing processing by selecting a frequency for A/D conversion to an audio signal, a frequency for serial conversion to a digital audio signal, and a frequency for storage of the converted signal as an integral number of multiple of a frequency of a horizontal synchronizing signal and reading the stored signal at a frequency being an integral number of multiple of a frequency of a color subcarrier. CONSTITUTION:An A/D converter section 1 converts an analog audio signal Ai into a digital audio signal synchronously with a clock C1 for sampling whose frequency is three times the horizontal synchronizing signal frequency. A parallel/serial conversion section 2 converts a digital audio signal into a serial digital audio signal As synchronously with a frequency C2 being a multiple of 16 of a frequency of a clock C1 and the result is written in a memory section 3 synchronously with the clock C2. A clock generating section 6 outputs a clock C3 whose frequency is a multiple of 40 of a frequency of a color subcarrier S. Then a gate section T is controlled by a horizontal synchronizing signal H to send the clock C3 to the memory section 3 for the horizontal blanking period, then the signal is coded within the horizontal blanking period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for digitizing audio signals, and more particularly to an apparatus for digitizing audio signals in television equipment.

[Conventional technology]

Conventionally, when audio signals are digitized in television equipment, the audio signals are digitized using an independent sampling signal that is unrelated to the synchronization signal of the television.

[Problem to be solved by the invention]

As mentioned above, conventionally, when audio signals are digitized in television equipment, an independent sampling signal unrelated to the television synchronization signal is used to digitize the audio signals. In a television system in which control signals and the like coexist, there is a problem in that the digitized audio signals interfere with each other, causing noise.

An object of the present invention is to provide an audio signal digitization device that has good compatibility with video signals.

[Means to solve the problem]

The audio signal digitization device of the present invention includes means for generating a first clock having a frequency n times that of a television horizontal synchronizing signal (n is an integer of n≧2); means for converting an analog audio signal into an m-bit digital audio signal (m is an integer of m≧8);
means for generating a second clock m times the frequency of the clock; means for converting the digital audio signal into a serial digital audio signal in synchronization with the second clock; means for storing the serial digital audio signal using the digital signal; means for generating a third clock having a frequency p times that of the color subcarrier (p is an integer of p≧2); and a blanking period of the television horizontal synchronization signal. and means for reading out the signals stored in the storage means in synchronization with the third clock.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of the present invention, in which an analog audio signal Ai is sampled in synchronization with a clock CI and converted into a 16-bit digital signal.
A converting section 1, a clock generating section 4 that generates a clock CI having a frequency three times that of the television horizontal synchronizing signal H, and A-
The digital audio signal output from the D converter 1 is clocked c
2, a clock generator 5 that generates a clock C2 with a frequency 16 times that of the clock C1, and a clock generator 5 that converts the output signal As of the parallel-serial converter 2 into a serial signal As as a clock C2. A memory section 3 that stores signals in synchronization and reads out the stored signals in synchronization with a clock C3, a clock generation section 6 that generates a clock C3, and a gate section 7 that controls sending of the clock C3 to the memory section 3. It is equipped with

Next, the operation will be explained.

FIGS. 2(a) to 2(e) are timing charts of examples of the signals shown in FIG. 1. A-D converter 1 is 47.25
The input analog audio signal At ((a) in the same figure) is converted into a 16-bit digital audio signal in synchronization with the sampling clock CI ((C) in the same figure) of kHz (three times the horizontal synchronization frequency). Therefore, since the data is sampled at a sampling frequency of 44.1 kHz or more on a compact disc, high quality can be ensured.

The parallel/serial converter 2 converts the 16-bit digital audio signal into a serial digital audio signal As ((d) in the figure) in synchronization with the conversion clock C2 of 7'5t3kHz (16 times the frequency of the clock CI). The serial digital audio signal As is sent to the memory section 3 in synchronization with the clock C2.
written to.

On the other hand, the clock generator 6 generates a frequency of 143 MHz (3,58 MHz x 40
)'s clock C3 is output. Now 756JcHz
If the serial digital audio signal As written in the memory unit 3 in synchronization with the clock C2 is read out at a cycle of 143 MHz, it can be compressed to about 190 times in terms of time. Therefore, if the gate section 7 is controlled by the horizontal synchronizing signal H and the clock c3 is sent to the memory section 3 during the horizontal blanking period, encoding can be performed within the horizontal blanking period. Normally, the horizontal synchronization period is 63.5 μs, and the horizontal blanking period is approximately 11 μs, and the blanking period ratio is approximately 17%, so it is possible to multiplex a large number of digital audio signals in the horizontal blanking period. .

FIG. 4(e) shows an output serial digital audio signal A obtained by reading out the serial digital audio signal AS written in the memory section 3 in synchronization with the 143 MHz read clock c3 and encoding it. It shows.

〔Effect of the invention〕

As explained above, according to the present invention, the sampling frequency when converting an analog audio signal into a digital audio signal, the clock frequency when converting a digital audio signal into a serial digital audio signal, and the serial digital audio signal are stored in memory. The clock frequency for writing data into the TV is an integer multiple of the television horizontal synchronization frequency, and the clock frequency for reading out the stored serial digital audio signal from the memory at high speed is an integer multiple of the color subcarrier. By reading out from the memory at high speed during the blanking period of the horizontal synchronization signal, it is possible not only to digitize an audio signal that has good compatibility with a video signal, but also to easily multiplex it.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a timing chart of an example of signals of each part shown in FIG. 1...A-D converter, 2...Parallel-serial converter, 3...
・Memory section, 4, 5.6... Clock generation section, 7...
・Gate part NA+...Analog audio signal, AS...
Serial digital audio signal, H...horizontal synchronization signal,
S...Color subcarrier, ClO2, C3...Clock. =7-Attorney Susumu Uchihara

Claims (1)

[Claims] means for generating a first clock having a frequency n times that of a television horizontal synchronization signal (n is an integer of n≧2);
m is an integer of m≧8); means for generating a second clock having a frequency m times the frequency of the first clock; means for converting an audio signal into a serial digital audio signal; means for storing the serial digital audio signal in synchronization with the second clock; and a frequency p times the color subcarrier (p is an integer of p≧2). and means for reading out the signal stored in the storage means in synchronization with the third clock during the blanking period of the television horizontal synchronization signal. Features: Audio signal digitization device.