JPH08316936A - Method and device for simultaneous transmission of picture data and sound data - Google Patents

Abstract

PURPOSE: To simultaneously transmit picture data and sound data in the spread spectrum system. CONSTITUTION: An analog picture signal and a sound signal are digitized and compressed and are collected into one composite digital signal by a synthesis processing part 20, and an error correction code is added to this signal, and it is subjected to spread spectrum modulation and is transmitted. The reception side receives this signal to subject it to spread spectrum demodulation and error correction processing and separates it into picture data and sound data in a separation processing part 30 and expands respective data and converts them into analog signals to output them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for simultaneously transmitting image data and audio data and an apparatus therefor, and particularly suitable for synthesizing image data and audio data and transmitting them in a spread spectrum wireless communication system. And a device for simultaneous transmission of image data and audio data.

[0002]

2. Description of the Related Art In a crime prevention / security system, a disaster prevention system, or a system that provides voice guidance along with the display of video signals, image data is spread spectrum, which makes it easy to keep confidentiality and makes effective use of frequencies. A method of transmitting by a wireless communication system using the method is under study.

FIG. 3 is a block diagram showing a schematic configuration of a radio communication system using a spread spectrum method of image data. An input analog video signal is digitized by an image input section 1 and further a luminance / color difference signal or an RGB signal. Is separated into each component of. Each image data digitized and separated into each component is compressed by the compression unit 2, spread spectrum modulated by the spread spectrum modulation unit 33, and transmitted from the antenna. On the receiving side, the spread-spectrum demodulation unit 4 spread-spectrum demodulates the image data transmitted by the spread-spectrum method to obtain compressed digital image data. The compressed digital image data is decompressed by the image data decompression unit 5 into uncompressed digital image data, converted into an analog video signal by the image data output unit 6, and output.

As a method of compressing and decompressing image data, for example, the transmitting side orthogonally transforms by discrete cosine transform (DCT) to encode a DCT coefficient, and the receiving side decodes this code to inversely transform the DCT coefficient. There is a thing to restore the original picture by this.

[0005]

In the image data transmission system using the above-mentioned conventional spread spectrum system,
Transmission of images only, no consideration of transmission of audio. However, in a crime prevention security system or the like, it is necessary to simultaneously transmit audio data together with image data.
In order to deal with this, in the conventional technique, it is necessary to transmit voice data through another line, which causes a problem that the device becomes complicated.

An object of the present invention is to provide a method and apparatus for simultaneously transmitting image data and voice data, which can simultaneously transmit image data and voice data using a spread spectrum method.

[0007]

According to the present invention, on the transmitting side,
The analog image signal and the analog audio signal are each digitized and then multiplexed to generate a composite digital signal, which is modulated by a spread spectrum system and transmitted by a wireless transmission line. The spread-spectrum demodulation of the received radio signal modulated by the above is performed to take out the above-mentioned composite digital signal, the taken-out composite digital signal is separated into an image digital signal and an audio digital signal, and the separated image digital signal and audio digital signal are respectively separated. Disclosed is a simultaneous transmission method of image data and audio data, which is characterized in that it is converted into an analog signal and output.

Further, according to the present invention, the spread spectrum system is a low frequency frequency hopping system, and the frame period of the composite digital signal is equal to the frequency hopping period of the low frequency frequency hopping system. Disclosed is a method for simultaneous transmission of image data and audio data, characterized in that the signals and audio digital signals are included in a number of pulses corresponding to their clock frequencies.

[0009]

Since the image signal and the audio signal are multiplexed and then modulated and transmitted by the spread spectrum system, the receiving side carries out the spread spectrum demodulation and then outputs the separated two signals, both the image signal and the audio signal are outputted. It can be transmitted by spread spectrum method without time shift.

In particular, when a low-speed frequency hopping method is used as the spread spectrum method and the hopping period is the same as the frame period of the composite signal of the image digital signal and the audio digital signal, the synchronous system as a whole system is constructed. It will be easy.

[0011]

EXAMPLES The present invention will be described in detail below with reference to examples. FIG. 1 is a block diagram showing an embodiment of a simultaneous transmission apparatus for image data and audio data according to the present invention. In the figure, the input analog video signal input to the transmitting side is
It is digitized by the image input unit 1, further separated into luminance / color difference signal components, or red (R), green (G), and blue (B) signal components, and compressed by the image data compression unit 2. The process up to this point is the same as the conventional technique described in FIG. 3, and the compression method uses DCT conversion / encoding.

On the other hand, the input analog audio signal is subjected to processing such as input level adjustment by the audio input unit 10, and is compressed by the audio data compression unit 11 by encoding processing such as adaptive difference PCM (ADPCM). Converted to voice data.

The synthesis processing section 20 includes an image data speed conversion section 21, an audio data speed conversion section 23, and an image / audio synthesis section 2.
It consists of two. Although the compressed image data and audio data are signals having different pulse periods, the synthesizing unit 20 multiplexes and synthesizes these two data as described later in detail, and converts them into one pulse train.
Then, in this multiplex synthesis, a frame including image data, audio data, a sync signal, etc. is formed for each time slot of an appropriate length.

The error correction code adding section 41 adds an error correction code to each frame of the digital signal which has been multiplexed and synthesized. As this encoding method, for example, Reed-Solomon encoding, Viterbi encoding, or the like is used. The digital signal thus generated is spread-spectrum-modulated by the spread-spectrum modulator 3 in the same manner as in the prior art and transmitted from the antenna.

On the receiving side, the spread spectrum signal received is subjected to spread spectrum demodulation by the spread spectrum demodulation section 4, and the error correction processing section 4 is applied to the output digital signal.
In step 2, error correction processing is performed. This output corresponds to the digital signal multiplexed and synthesized on the transmitting side.

The separation processing unit 30 includes an image / audio separation unit 31,
It is composed of an image data speed conversion unit 32 and an audio data speed conversion unit 33, and separates the image data and the audio data multiplexed and synthesized on the transmitting side as described later. The separated image data is expanded in the image data expansion unit 5 and output as an analog video signal from the image output unit 6, while the separated audio data is expanded in the audio data expansion unit 12 and output from the audio output unit 13. It is output as an analog audio signal.

Next, the composition processing section 20 and the separation processing section 30.
As a premise for the detailed operation description of the above, a spread spectrum communication system will be briefly described. Spread spectrum communication methods include direct spread (DS) method and frequency hopping (F)
H) method, and the FH method further includes a fast frequency hopping (FFH) method and a slow frequency hopping (SF) method.
H) method is available. In the DS method, spread spectrum is performed by switching a transmission signal with a pulse train that is faster than the transmission signal. The FH method is a method of spreading the spectrum by switching the carrier frequency in a fixed order. The FFH method performs frequency switching a plurality of times within one bit of transmission information, and the SFH method uses a plurality of transmission information bits as one. It is a method of transmitting by frequency. Figure 4 shows FH
The operation of the method is schematically shown, and the carrier frequency f is sequentially switched to f _B , f _D , f _J , ... For each time slot width T ₀ . In the FFH method, T ₀ is smaller than the 1-bit width of the transmission information, and in the SFH method, T ₀ is larger than the 1-bit width of the transmission information.

Next, the operation of the synthesis processing section 20 will be described.
FIG. 2 is a time chart showing the operation of the composition processing unit 20 in this embodiment. Here, the frequency hopping period T ₀ is 3 ms in the SFH system, while compressed image data is 448 Kbps and compressed audio data is 16 Kbps. Then, in the synthesis processing unit 20, S
It is assumed that the frequency hopping period T ₀ of the FH system is set as one frame for multiplexing and combining to generate a digital signal of 625 Kbps including a synchronizing signal and the like.

Therefore, the image data speed conversion unit 21 is
Image data for every T ₀ = 3 ms 448 × 10 ³ × 3 × 10
^-3 = 1344 bits are cut out and the speed of this is converted into a pulse train of 625 Kbps. Also, the voice data speed conversion unit 2
3 is audio data 16 × 10 ³ × 3 × for each T ₀ = 3 ms
10 ^-3 = 48 bits are cut out, and this is 625 Kbps
Velocity conversion to the pulse train of. Regarding the speed of these image data and audio data, a buffer memory capable of writing / reading independently is used, and writing is performed at a clock of 448 Kbps or 16 Kbps for image data or audio data, and 625 for reading.
It can be converted by using Kbps. Further, this read operation is alternately performed, such as reading 1344 bits of image data and then reading 48 bits of audio data, and combining them into one bit stream by the image / audio synthesizing unit 22, thereby performing multiplexing synthesis. Be seen. However, the speed-converted pulse of these image data and audio data becomes 1344 + 48 = 1392 bits in one frame 3 ms, but the pulse train of 625 Kbps is 1875 in 3 ms.
Since it is a bit, there is a remainder only with image data and audio data. In the synthesizing unit 22, a bit sync signal, a frame sync signal, an error correction bit, a frequency hopping period, and the like are assigned to the remaining portion, as shown in the output pulse of FIG.

The signals multiplexed and combined as described above are transmitted by spread spectrum communication, and spread spectrum demodulated by the spread spectrum demodulation section 4 on the receiving side.
First, the error correction processing unit 42 performs error correction. This error correction process is conventionally known. Next, the separation processing unit 30 separates the multiplexed and combined digital signal into image data and audio data, which is the reverse operation of the combination described in FIG. That is, the video / audio separation unit 31 detects the frame synchronization signal of the error-corrected digital signal, and the image data and the audio data are separated using this synchronization signal. In this state, both the image data and the audio data are pulse trains having a speed of 625 Kbps, and there is a space for each frame. That is, in the image data,
It becomes a burst signal of 4 bits each, and 4 for voice data.
It is output as a burst signal of 8 bits each. Therefore, the image data speed conversion unit 32 and the audio data speed conversion unit 3
In 3, the buffer memory similar to that of the transmitting side synthesis processing unit is used, and each burst signal is sent to the buffer memory at 625 Kbps.
Write at the clock of, and then the image data is 448Kbps
By reading the audio data at the clock of 16 Kbps, the normal image data and audio data without interruption can be restored. Since these image data and audio data are compressed, they are expanded as described above, converted into analog signals, and output.

According to this embodiment, image data and audio data can be simultaneously transmitted by a spread spectrum method. At the same time, in the above embodiment, the SFH method is used, and the hopping period is the same as one frame period of the image data and the audio data, so that the modulation / demodulation of the spread spectrum method is synchronized and the multiplexing synthesis of the image data and the audio data is performed. By making the frame synchronization for the same, the configuration of the entire system can be simplified.

Even in the case of the SFH system, if the spread spectrum synchronization and the multiplexing / combining frame synchronization are processed by completely different mechanisms, this does not necessarily have to be the same. The present invention can also be applied to the DS system or the FFH system, but in these cases, the spread spectrum synchronization becomes independent of the multiplexing synchronization.

[0023]

According to the present invention, a still image or a moving image and voice can be simultaneously transmitted by a spread spectrum method without causing a time lag between them, and the spread spectrum method can be used. This has the effect of facilitating the realization of a system that takes advantage of the confidentiality of communication.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an image data and audio data simultaneous transmission apparatus according to the present invention.

FIG. 2 is a time chart showing a synthesis process of image data and audio data on the transmitting side.

FIG. 3 is a block diagram showing a configuration of a conventional image data and audio data simultaneous transmission apparatus using a spread spectrum system.

FIG. 4 is an explanatory diagram of a low speed frequency hopping (SFH) method.

[Explanation of symbols]

 1 image input unit 2 image data compression unit 3 spread spectrum modulation unit 4 spread spectrum demodulation unit 5 image data expansion unit 6 image data output unit 10 audio input unit 11 audio data compression unit 12 audio data expansion unit 13 audio data output unit 20 synthesis Processing unit 21, 32 Image data speed conversion unit 22 Image and sound synthesis unit 23, 33 Audio data speed conversion unit 30 Separation processing unit 31 Image and sound separation unit 41 Error correction code addition unit 42 Error correction processing unit

Claims (5)

[Claims] 1. A transmitting side digitizes an analog image signal and an analog audio signal, respectively, multiplexes them to generate a composite digital signal, modulates the generated composite digital signal by a spread spectrum system, and transmits it by a radio transmission line. At the receiving side, the received radio signal modulated by the spread spectrum method is spread spectrum demodulated to take out the above synthetic digital signal, and the taken synthetic digital signal is separated into an image digital signal and an audio digital signal, and the separation is performed. The simultaneous transmission method of image data and audio data, wherein the image digital signal and the audio digital signal are converted into analog signals and output. 2. The spread spectrum system is a low frequency frequency hopping system, the frame period of the composite digital signal is equal to the frequency hopping period of the low frequency frequency hopping system, and an image digital signal and an audio signal are contained in each of the frames. 2. The simultaneous transmission method for image data and audio data according to claim 1, wherein the pulses of the digital signal are included in a number corresponding to the clock frequency. 3. The image digital signal and the audio digital signal which are multiplexed and synthesized on the transmitting side are digital signals which are respectively digitized and then compressed. On the information side, the separated image digital signal and audio digital signal are 3. The simultaneous transmission method for image data and audio data according to claim 1, wherein the data is expanded and then converted into an analog signal for output. 4. An image after an error correction code is added to the composite digital signal on the transmitting side and then transmitted by a spread spectrum method, and the composite digital signal on the receiving side subjected to spread spectrum demodulation is subjected to error correction processing. 3. The simultaneous transmission method for image data and audio data according to claim 1 or 2, wherein separation is performed into a digital signal and an audio digital signal. 5. A first means for digitizing and then compressing an input analog image signal, a second means for digitizing and then compressing an input analog audio signal, and said first and second means. Third means for multiplexing and combining the image digital signal and the audio digital signal output from the means into one combined digital signal, and for adding an error correction code to the combined digital signal generated by the means And a fourth means, and a fifth means for modulating and transmitting the digital signal from the means by a low-speed frequency hopping method in which frequency hopping is performed at a period equal to a frame period of the digital signal, and the transmitting unit is constituted. And a sixth means for receiving and demodulating the signal modulated by the slow frequency hopping method, and an output from the means. Seventh means for performing error correction processing on the digital signal, eighth means for separating the image digital signal and the audio digital signal from the digital signal output from the means, and the means for separating the digital signal and the audio digital signal. Means for decompressing the image digital signal taken out and converting it into an analog image signal for output, and decompressing the audio digital signal separated and taken out by the eighth means for analog. A simultaneous transmission device for image data and audio data, comprising: a receiving unit comprising: tenth means for converting and outputting the audio signal.