SU1075446A1 - Receiving device for digital rotary television - Google Patents

Abstract

RECEPTION DEVICE OF DIGITAL ROTATING TV, containing serially connected demodulator and selection unit, the first output of which is connected to the information input of the video decoder, the output of which is connected to the information input of the block is reproducible. nor isoengy, the second output is to the input of the synchronization channel, the first output of which is connected to the sync input of the unit, playback of the image, and the second output to the synchronous input of the video decoder, the third output of the set, the lecture to the input of the audio track, and the video decoder includes digital processing, the information input of the digital processing unit is the information input of the video decoder, and the sync input is the sync input of the video decoder, o T and .4 a, so that, in order to increase Image quality when receiving low-resolution video signal coils by means of distortion-less distortion-type distortion, a luminance pulse generator is input to the video decoder, and the digital processing unit is in the form of a consecutive coej_n2 pulse generator, the input of which is the synchronous input of the digital processing unit The calculator, the second input of which is the information input of the digital processing unit, in the virtual memory register and. comparison unit, the output of which is the output of the digital processing unit. as well as the third memory register, included between the WTOE4 output of the calculator and the second input of the comparison unit, and the second pulse generator, whose input is combined with the input of the first pulse generator, the first output is connected to the readout signal inputs of the second and third memory registers, and the second the output is to the input of the counting pulses of the comparison unit, the input of the erasing pulses of which is combined with the inputs of the sweeping pulses in the second and third memory registers and 01 is connected to the second output of the first gene of the pulse generator, with it ge- input pulse generators of i luminance 4 is connected with the output digital processing unit; and the output of the luminance pulse generator, o: is the output of the video decoder.

Description

The invention relates to television and can be used to receive black and white digital broadcast television programs with a standard decomposition format.

A digital rotary television receiving device, comprising a demodulator connected in series, a selection unit comprising a gamma corrector, a video decoder including a digital-to-analog converter and a reproducing block l.

The closest to the invention to the technical essence is a television Hofo digital rotator receiver containing a serially connected demodulator and a selection unit, the first output of which is connected to the information input of a video decoder, the output of which is connected to the information input of the image playback unit, the second one - to the channel input synchronization, the first output of which is connected to the synchronous input of the reproducing unit of the image, and the second .- to the synchronous input of the video decoder, the third the output of the selection unit to the audio channel input, the video signal decoder includes a serially connected digital processing unit, a digital-to-analogue converter and an analog processing unit, the information input of the digital processing unit is the information input of the video decoder, and the sync input signal of the video decoder and .

However, when receiving small-scale video codes in known devices, image distortion occurs. type of false contour.

The purpose of the invention is to improve the image quality when receiving low-level video signal codes by reducing false contour type distortions.

The goal is achieved by the fact that in a receiver of a digital broadcast television containing a series-connected demodulator and a selection unit, the first output of which is connected to the information input of the video decoder, the output of which is connected to the information input of the image playback unit, the second output - to the input of the syncrony channel, the percly output of which is connected to the sync input of the image reproduction unit, and the second to the sync input of the video decoder, and the third output of the selection unit to the audio channel, where the video signal decoder includes a digital processing unit, the information input of the digital processing unit is the information input of the video signal decoder, and the synchronous input is a synchronous input signal of the video decoder, the pulse generator is inserted into the video decoder, connected to the first pulse generator, the input of which is the synchronous input of the digital processing unit, the first memory register, the calculator, the second input of which This is the information input of the digital processing unit, the second memory register and the comparison unit, the output of which is the output of the digital processing unit, as well as the third memory register connected between the second output of the calculator and the second input of the comparison unit, and the second pulse generator, input which is combined with the input of the first pulse generator, the first output is connected to the inputs of the read signal of the second and third memory registers, and the second output to the input of the counting pulses of the comparator, the input of the erase pulses s is combined with the erasing pulse inputs of the second and third registers and a memory connected to the second output of the first generator i.mpulsov said luminance input of the pulse generator connected to the output of digital processing block, and the luminance of the pulse generator output is the output of the video decoder.

The proposed implementation of a video decoder allows you to create a halftone image on a CRT screen using bar-shaped elements — luminance pulses. This possibility is connected with the peculiarity of the human eye to smear the borders of the hatching element over a certain neighborhood of the latter. The condition under which this phenomenon is observed can be expressed using the formula

e

(one)

6 0.007,

where c is the linear size of the stroke

element,

L is the distance of observation of the stroke element.

The calculation by the formula (1) shows that in real conditions of watching television programs its requirements are always met. Consequently, a halftone image can be synthesized by changing the number of bar elements (luminance pulses) within a certain limited interval — an image element equivalent to the beam aperture in analog devices. In this case, the minimum brightness of the image element is obtained in the absence of luminance pulses, and maximum - when the entire image element is filled with luminance pulses. The reason for the appearance of false contours on images in traditional digital rotary television receivers when the video code is reduced is the presence of clear boundaries between adjacent picture elements. The proposed device is in principle devoid of this drawback, since the image elements do not have clear boundaries between themselves. Such an approach to image synthesis reduces the number of quantized signal levels during transmission. In this case, the limitation is the minimum number of gradations of image luminance required by the human eye to fully perceive the transmitted plot. In various sources of scientific and technical literature, the minimum number of brightness gradations ranges from 6 to 10. The proposed device can play without distortion of the video signal transmitted by a low-bit code, for example, a four-bit one, which makes it possible to reduce the communication bandwidth by half. FIG. 1 shows a structural electrical circuit of a receiver of a digital broadcast television; FIG. 2 is an illustration of the reproduction of the image in FIG. 3 charts of receiving luminance pulses The receiving device comprises a demultiplier 1, a selection unit 2, a video signal decoder 3 including a digital processing unit 4 consisting of a calculator 5, a second memory register 6, a third memory register 7, comparison unit 8 , the first register 9am, the first pulse generator 1C, the second pulse generator 11, the luminance pulse generator 12, the image reproducing unit 13, the synchronization channel 14, and the audio channel 15. The receiving device is working in the following way. To the input of the demodulator 1, the digital codes of the television program created at the transmitting center are received from the communication line. After pre-processing (amplification, demodulation, etc.), the signal is fed to the input of the selection unit 2. Here, the received program is unpacked into image, sync, and sonic signals, which go into processing channels: to the information input of the decoder 3 video signals, inputs of the synchronization channel 14 and audio channel 15, respectively, the video signal are such that they carry indirect information about the brightness characteristics of the objects being surveyed, the code determines the current value of brightness in the image. In the proposed receiver, this input code determines the number of luminance pulses, in each image element. At the same time, at the transmitting center, the analog video signal is quantized, for example, at 16 levels according to the logarithmic law, and the increments in the values of the video signals at the transition from one quantization level to another are set constant. This video coding organization ensures the correct transmission of the luminance characteristics of the transmitted plot by luminance pulses and is in accordance with the requirements of the Weber-Fechner law. The value of p can be both even and odd. However, in all cases the luminance pulses produced by the generator 12 luminance pulses must be located in the center of the image element, i.e. symmetrically about the center of the image element. Otherwise, redistribution of energy from a given element to a neighbor can occur, i.e. distortion will occur. This condition leads to the fact that in the case of an even number of luminance pulses the center of the image element coincides with the border between luminance pulses, and in the case of an odd number, the midpoint of the luminance pulse. The second case inevitably leads to the requirement that the generator 12 pulses of luminance should start and stop with temporal accuracy no worse than imp. pk v .4rts.- where bc d p is the duration of the luminance pulses, T is the synthesis time of the image element in the frame line of a standard rotary television, W is the maximum number of luminance pulses in the image element. In order to determine the start and stop times of the generator 12, the luminance pulses with the required accuracy in the digital processing unit 4 are calculated and processed by the counting pulses with the duration "lWn.P

which determine the operating time of the luminance pulse generator 12. When this is done, a maximum value is applied to the second input of the 5th pin from the output of the first register, 9 memory with the frequency of arrival of the image elements / specified by the first generator of IQ pulses; For the possible number of pulses within the image element N. The operation of the first pulse generator 1O is synchronized by connecting its input to the second output of the synchronization channel 14. The numerator 5 according to the formula

“O1p tech). Lost TeK7

  f -... where n-jQp is the number of counting pulses,

determining the beginning of the filling of the image element with luminance pulses, the remaining number of the total pulses,

defining the end of the filling of the image element

by pulses of light, makes calculations.

The obtained values of q dp remain from the first and second outputs of calculator 5 and are recorded in the second and third registers b and 7 of memory, respectively, and the erase results of previous calculations are sent to the inputs of the erasing pulses from the second output of the first generator of 10 pulses. These pulses are generated at a frequency of following the received video signal codes of the image elements. The second pulse generator 11, synchronized by connecting its input to the second output of the synchronization channel 14, generates counting pulses, which are removed from its second output and are fed to the input of the counting pulses of the comparison unit 8. In addition, the second pulse generator 11, by connecting its first output to the readout signal inputs of the second and third memory registers 6 and 7, reads the written values of the adp block 8 of the comparison. The reading is carried out at the first and the second input of block B in comparison with the frequency of the counting pulses. Comparison unit 8 compares the number of counting pulses accumulated during the time of the current image element with the value of the ipzopip. In case of coincidence, successively generated are the control signals that are taken from the output of the comparison unit 8 to start and stop the generator 12 luminance pulses. The result of the accumulation of counting pulses during the synthesis of a pre-existing image element is destroyed by applying erasing pulses from the second output of the first generator Yu

pulses to the input of the erasing pulses of the block 8. The processing of luminance pulses by the generator of 12 luminance pulses is carried out over a period of time

, Ost ChagL imp.4rk

Rab-Kst - ap1 sch.imp

L

 P

Tech Imp.rk

The operating sequence from the output of the generator 12 pulses is supplied to the "first input of the image reproducing unit 1 (to the modulator of the electron-beam tube), producing a half-tone image of the pattern to be accepted (Fig. 2). Any quantitative combination of luminance pulses.

(from 2 to 15) within the element of the image, one character: it defines one of the levels of brightness of the halftone image.

The operation of unit 13 is synchronized by connecting it to the first OUT of channel 14 of synchronization.

To illustrate the processes / images in the channel of the proposed device, in FIG. 3 shows time diagrams. In addition, in FIG. 30 is a diagram illustrating the operation of the first generator of 10 pulses (a sequence of pulses is depicted, predetermined time interval for the synthesis of the image element t); in fig. ZK -.a diagram illustrating the operation of the second generator 11 pulses (depicts a sequence of counting pulses of duration ,,, Fig. 3b shows the moments of coincidence in block 8 comparing the current number of counting pulses with the recorded second and third registers b and 7 memory and numbers counting pulses determining the beginning and end of the filling of the image element with luminance pulses; Fig. 31 illustrates the operation of the comparison unit 8 (the generation of control pulses for starting and stopping the generator 12 of luminance pulses is shown ) Fig. Za illustrates the operation of the luminance pulses generator 1J (a sequence of luminance pulses is depicted, which are durable. pk filling the central part of the image element).

Using the proposed receiver of a digital broadcasting television, when the transmission bandwidth is reduced, the communication line is doubled by encoding each pixel using four, rather than eight-bit digital code, to reproduce the image without false contours.

fj

phi 3

Claims (1)

A DIGITAL ROTARY TELEVISION RECEIVER containing a serially connected demodulator and a selection unit / first. The output of which is connected to the information input of a video signal decoder, the output of which is connected to the information input of the playback unit. image, the second output is to the input of the synchronization channel, the first output of which is connected to the sync input of the block. image reproduction, and the second to the sync input of the video decoder, the third output of the selection block to the input of the audio channel, the video decoder includes a digital processing unit, the information input of the digital processing unit is the information input of the video decoder, and the sync input is the sync input of the video decoder, about τη, and moreover, in order to improve the image quality when receiving low-bit codes of a video signal by reducing distortions such as a false contour, in the receiver introduced luminance osignala pulse generator, a digital processing unit configured to form a first series-connected pulse generator, the clock input of which is a digital processing unit, the first memory register, the calculator, the second input of which is the data input of the digital processing unit and the second memory register. block comparison, the output of which is the output of the digital processing unit. as well as the third memory register, included between the second output of the calculator and the second input of the comparison unit, and the second pulse generator, the input of which is combined with the input of the first pulse generator, the first output is connected to the inputs of the read signal of the second and third registers memory, and the second output is to the input of the counting pulses of the comparison unit, the input the input of the generator of brightness pulses is connected ί to the output of the digital processing unit,; and the output of the luminance pulse generator is the ’output of a video decoder. 1C75446 is the home of the video decoder, and the sync input is the sync input of the video decoder, a brightness pulse generator is inserted into the video decoder, and the digital processing unit is made in the form of series-connected first pulse generator, the input of which is the sync input of the digital processing unit, the first memory register, the computer, the second I input which is the information input of the digital processing unit, the second memory register and the comparison unit, the output of which is the output of the digital processing unit, as well as the third a memory register included between the second output of the calculator and the second input of the comparison unit, and the second pulse generator, the input of which is combined with the input _(the house of the first pulse generator, the first output is connected to the inputs of the read signal of the second and third memory registers, and the second output to the input of the counted pulses of the comparison unit, the input of the erasing pulses of which is combined with the inputs of the erasing pulses of the second and third memory registers and connected to the second output of the first pulse generator, and the input of the pulse generator brightness connected to the output digital signal processing unit, and the output pulses of the generator is the output luminance video decoder. the proposed implementation of the 'video decoder allows you to create a grayscale image on a CRT screen using line elements - brightness pulses. This possibility is related to the peculiarity of the human eye to smear the boundaries of the dashed element in some neighborhood of the last romance