JPH1042260A - Multiplex transmitter for digital image signal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To average the influence for noise concentrated in terms of bands generated in a transmission line and to reduce considerable image quality degradation concentrated on a specified channel by converting the bit strings of respective channels to the bit strings of all channel combinations before frequency multiplexing the respective channels. SOLUTION: On a transmission side, the NTSC image signals of 3CHs are converted to serial digital image signals by A/D converters 11-13 and P/S converters 21-23. The signal bit strings of the respective CHs are shifted to the channel of a low-order direction for one bit each by a time unit in a signal converter 30 and converted to the CHA-C of the bit strings for which the bits of all the channels are combined in the state that the bit strings of the respective channels are shifted for one bit each. The CHA-C are frequency multiplexed and radio transmitted by a multiplex radio transmitter 40. On a reception side, they are received and reproduced to the NTSC image signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image signal multiplex transmission apparatus, and more particularly, to a frequency division multiplex digital image signal multiplex transmission apparatus using a wireless or wire line having a large amount of noise in a transmission path.

[0002]

2. Description of the Related Art Conventionally, a digital image signal multiplex transmission apparatus of this type has a plurality of NTSC image signals of a plurality of channels which are sampled at a predetermined bit, for example, 8-bit quantization level, and converted into parallel digital image signals. An analog / digital converter, a plurality of parallel / serial converters for converting the parallel digital image signal into a serial digital image signal, and digitally modulating the serial digital image signal with a carrier having a plurality of frequencies, respectively, and performing a modulation output. And a multiplexed wireless transmitter for frequency multiplexing and wirelessly transmitting the signals, and receiving radio waves from the multiplexed wireless transmitter and digitally demodulating them with a carrier corresponding to the transmitting side to output a serial digital image signal of a plurality of channels. And a plurality of radio receivers for converting the serial digital image signals into parallel digital image signals. A serial / parallel converter, and a the parallel digital image signal and the receiver constituted by a plurality of digital / analog converter and outputting the reproduced to an NTSC image signal.

[0003]

As described above, in the prior art, a digital image signal of a plurality of channels is frequency-division multiplexed and transmitted. Therefore, if a bit error occurs in the digital image signal due to noise on the transmission line, the image quality is reduced. Is significantly reduced. In many cases, the distribution of noise in a transmission path is concentrated in a band, so that a channel in a band in which noise is concentrated has a problem that image quality is significantly reduced as compared with other channels.

[0004]

SUMMARY OF THE INVENTION A digital image signal multiplex transmission apparatus according to the present invention comprises n analog / digital signals which sample an n-channel NTSC image signal at a quantization level of m bits and convert it into a parallel digital image signal. A converter, n parallel / serial converters for converting the parallel digital image signal into a serial digital image signal, digitally modulating the serial digital image signal with carriers of n kinds of frequencies, and frequency-multiplexing the modulated output. A multiplexed radio transmitter for receiving radio waves from the multiplexed radio transmitter, digitally demodulating with n kinds of carriers, and outputting an n-channel serial digital image signal; N serial / parallel converters for converting an image signal into a parallel digital image signal, and the parallel digital image signal And a digital image signal multiplexing transmission apparatus comprising n digital / analog converters for reproducing and outputting an NTSC image signal. The n channel serial digital image signal output from the analog / digital converter is inputted. The bit sequence of each serial digital image signal is sequentially shifted one bit at a time in the lower direction channel so that the bits of the same channel are shifted by one bit and the bits of each channel are arranged in order. a transmitter-side signal converter that converts the signal into n converted serial digital image signals and outputs the converted signal to the multiplexed radio transmitter; and the n-channel converted serial digital image signal output from the multiplexed radio receiver and receives each signal. By sequentially shifting the bit sequence in the upper direction channel by one bit at a time unit. Re and a reception-side signal converter serial digital image signal to be output to the serial / parallel converter after restoring the serial digital image signal of n-channel state aligned bits of the same channel.

[0005]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, the entire configuration is divided into a transmitting side and a receiving side, each of which is configured in two directions. In the figure, only one direction is shown. The number of channels of the NTSC image signal is 3CH.

First, on the transmitting side, analog-to-digital converters (A / D converters) 11 to 13 are provided with three NTSs.
The C image signals (CH1 to CH3) are sampled at 8-bit quantization levels. The next parallel / serial converter (P /
The S converters 21 to 23 convert the sampled parallel digital image signals from parallel to serial and convert them into three serial digital image signals.

[0008] Next, the signal converter 30 is an A / D converter 1
The bit outputs of the P / D converters 21 to 23 are sequentially shifted to lower-order channels in a time period of 1/8 of the sampling period T of 1 to 13, that is, 1 bit transmission time unit. That is, as shown in FIG. 2, the bit sequence of each input serial digital image signal (CH1 to CH3) is sequentially shifted one bit at a time in the lower direction channel, thereby shifting the bits of the same channel by one bit. And converted into three converted serial digital image signals (CHA to C) in which the bits of each channel are arranged in order.

The multiplex radio transmitter 40 digitally modulates the converted serial digital image signals (CHA to C) using three types of carrier waves having different frequencies, frequency-division multiplexes them, and transmits them by radio.

Next, on the receiving side, the multiplex radio receiver 50
Returns the radio wave from the transmitting side and demodulates the three frequency-division multiplexed converted serial digital image signals (CHA to C). On the transmitting side, the signal converter 60 shifts the bit sequence of CHA-C one bit at a time on the transmission side to the channel of the higher order, and returns the original serial digital image signal (CH1).
To 3).

The S / P converters 71 to 73 convert these three serial digital image signals into parallel / parallel digital image signals by serial-to-parallel conversion. Finally, the three digital-to-analog converters (D / A converters) 81 to 83 convert the parallel digital image signals to analog and reproduce the NTSC image signals from CH1 to CH3.

FIG. 3 is a block diagram showing an internal circuit of the signal converter 30. A 3-bit shift register 302 in which the output of the third bit is connected to the input of the first bit, and a data latch circuit 301 in front of the shift register 302
And a data latch circuit 303 for outputting the bit-shifted 3 bits, and a gate 304 for producing a shift timing in the cyst register 302, and performs the above-described signal conversion.

[0013]

As described above, in the digital image signal multiplex transmission apparatus according to the present invention, before performing frequency division multiplexing, the bit sequence of each channel is converted into the bit sequence of each channel combination shifted by one bit at a time. By
The effect of noise concentrated in a band generated in the transmission path can be dispersed and averaged for each channel. Therefore, there is an effect of reducing the image quality deterioration applied to a specific channel.

[Brief description of the drawings]

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

FIG. 2 is a characteristic diagram of the signal converter in FIG.

FIG. 3 is a block diagram of the signal converter in FIG. 1;

[Explanation of symbols]

11 to 13 analog / digital converter (A / D converter) 21 to 23 parallel / serial converter (P / S converter) 30 signal converter 40 multiplex radio transmitter 50 multiplex radio receiver 60 signal converter 71 to 73 Serial / parallel converter (S / P converter) 81-83 Digital / analog converter (D / A converter)

Claims (2)

[Claims] 1. An analog-to-digital converter for sampling an n-channel NTSC image signal at an m-bit quantization level and converting it into a parallel digital image signal, and converting the parallel digital image signal into a serial digital image signal N parallel / serial converters for conversion, a multiplexed radio transmitter for digitally modulating the serial digital image signal with carrier waves of n kinds of frequencies, frequency-multiplexing the modulated output, and wirelessly transmitting the multiplexed radio signal; A multiplexed radio receiver that receives radio waves from the receiver, digitally demodulates the signals with n types of carriers, and outputs an n-channel serial digital image signal; and n serial / digital converters that convert the serial digital image signal into a parallel digital image signal. A parallel converter, and n digital / digital converters for reproducing and outputting the parallel digital image signal to an NTSC image signal. In a digital image signal multiplex transmission apparatus comprising a analog converter, an n-channel serial digital image signal output from the analog / digital converter is input, and a bit string of each serial digital image signal is converted into one bit in time unit. Each bit of the same channel is shifted by one bit by successively shifting to the lower channel one by one and converted into n serial digital image signals in which the bits of each channel are arranged in order. A transmitter-side signal converter that outputs to a transmitter, and the converted serial digital image signal of n channels that is output from the multiplexed radio receiver are input, and the bit sequence of each signal is sequentially shifted to upper-order channels by one bit at a time unit. As a result, the serial channels of the n channels in which the bits of the same channel are lined up are arranged. Digital image signal multiplex transmission apparatus characterized by the restore the barrel image signal and a reception-side signal converter serial digital image signal to be output to the serial / parallel converter. 2. The transmission-side signal converter includes a first latch circuit that receives the serial digital image signal of n channels and latches each bit at a predetermined timing, and outputs an n-th bit output to a first bit. An n-bit shift register connected to an input and receiving each output signal of the first latch circuit and shifting each bit by a shift timing signal; and latching a bit string of each channel bit-shifted by the shift register at a predetermined timing A second latch circuit for outputting n converted serial digital image signals;
2. The digital image signal multiplex transmission apparatus according to claim 1, further comprising a gate circuit that generates the shift timing signal from a clock input from outside and a bit shift control signal.