SU1490679A1 - Device for converting video signal to digital code - Google Patents

Abstract

The invention relates to automation and computing, in particular to devices for converting a video signal into a digital code. The aim of the invention is to improve the accuracy and noise immunity of the device. The goal is achieved in that a device containing a peak detector, a pulse generator, an analog-to-digital converter, a first counter, a first decoder, a first AND element, a first pulse shaper, the first and second conversion blocks, and the first OR element, trigger, second and third elements AND, second, third and fourth elements OR, second and third decoders, second, third and fourth pulse shapers. The input of the device is the input of the peak detector, the outputs of the first and second blocks of the conversion — the synchronization outputs of the device, and the output of the analog-digital converter — the information output of the device. The use of the device in the equipment for the digital processing of meteorological satellite picture information improves the accuracy and noise immunity of detecting the synchronizing pulses of the rows of image signals. 3 il.

Description

the second, third and fourth shaper 20, 21, 22 n 23 pulses and trigger 24.

The device works in the following way.

The full line of the image signal generated by a NOAA meteorological satellite contains (Figure 2) a clock channel CA of a television channel, a SC signal of the result of scanning of open space in a television radiation band, information line A of a television band, a telemetry signal TA of a television channel, a sync pulse of an IR infrared channel , the KB signal of the result of scanning open space in the infrared radiation range, the information line B of the infrared channel and the signal of TV bodies infrared cable measurements.

The structure of the clock pulse SA television channel presented in Fig.2,6. It contains seven elements, the power of each of which is 2tc, (t 0,24038 x

The sync pulse of the infrared channel CB contains seven elements (Fig. 2) of the duration Bt,

FIG. 3 shows a clock channel signal CA of a television channel, which bends to correspond to the elements of a synchro circuit; in FIG. 3, j is the output voltage of the peak detector, in FIG. 3, in the sequence of output pulses of the controlled oscillator (the solid line shows the control pulses of the analog-to-digital converter, the dashed ones are the decoder) J in FIG. 3, g, - are sequences of pulses corresponding to high and low counts of the input signal j in Fig. 3, and is a sequence of pulses corresponding to the beginning of arrival of high counts after low ones; in FIG. 3, k - a sequence of gated pulses, in FIG. 1, a sequence of pulses, corresponding to the detection of a sync serial element; in FIG. 3, n is the potential corresponding to the detection of a synchronizing pulse of a row.

The input video signal, which is an amplitude-modulated oscillation (Fig. 3, d), is fed to

to

, 20

25 )

15

35

40

- thirty

,

4906794

3 pulse generator (fig.Z). The generator 3 generates two parallel pulse sequences phased out with a carrier oscillation (Fig. 3, P) and controlling the operation of the analog-digital converter 4 and the third decoder 9. The decoder 9 outputs pulses corresponding to high and low values to its separate outputs. input video signal (Fig. 3, g, j.). These two parallel pulse sequences are used to detect elements of a synchronizing pulse line, which is characterized by the alternation of high and low values of digital samples (Fig. 2, b) from the output of the analog-to-digital converter 4. The output pulses from worder 9 are fed to the counting inputs. the first and second counters 5 and 6, the outputs of the bits of which are connected to the first and second decoder 7 and 8. Depshfratora 7 and 8 give out to their separate outputs high voltage potentials code corresponding to the number of conversion cycles of the input signal for the duration of one element of the line clock pulse, for example, at a conversion frequency of 2.4 kHz (one conversion cycle per period

input carrier) and dl45

50

55

element properties

2 t p or

3 t

ABOUT

1 or 2 digital samples are possible (depending on the phase element to the sequence of control pulses of the analog-digital converter 4). To the second separate outputs, decoders 5 and 6 give out potentials when the number of high or low counts exceeds the number of conversion cycles during one element of the synchronizing pulse of the line, which indicates that this segment of the line does not belong to the class of elements of the synchronizing pulse of the line. Therefore, the pulse of the third driver 22 (FIG. 3), issued when the counter code 6 reaches the number of high samples for one element of the synchronizing pulse of the row (FIG. 3,), passes the first element 14, open by the decoder 7 (FIG. 3, k), in the presence of a counter 5 corresponding to a transform,) :). 4t Mt HT.4 about a null urn of a sniffer pulse, and counted by the third recalculation unit 19, the recalculation coefficient of which determines the threshold level of the synchronizing pulse of a row by its number items. In the case of longer line segments with low or high counts, the second and fourth formers 21 and 23, when their input voltages jump, produce pulses that are collected by the second element OR 11, which sets up the initial state of the counters

5i 6 and block 19 conversion. Counter

6 is also reset to the initial state with the help of the first shaper 20 at each jump of its input voltage through the fourth element OR 13, and the counter 5 - by the pulse of the third shaper 22 through the third element OR 12. After the block 19 is triggered, the trigger 24 tilts (Fig. 3, A), which indicates the accumulation of a specified number of elements of the synchronizing pulse line. Next, it is determined that the detected series of elements belong to one of two types of line clock. This is done in the first and second blocks.

17 and 18 conversions, to the inputs of which impulses of high and low counts are received from the outputs of the third decoder 9 through the second and third elements I 15 and 16 opened with a trigger 24. For the synchronization pulses CA and CB follow (figure 2, a) signals KA and KB of space scanning in television and infrared radiation. At the same time, the signal KA is transmitted by a low level of the input signal, and the signal KB is high. Therefore, after detecting a series of elements of a synchronizing pulse of a row, blocks 17 and 18 of the recalculation will count the pulses depending on the signal belonging to one of the types of channels. In this case, the recalculation unit 17, counting the number of low samples, is set to its original state by high counting pulses, and the recalculation unit, 18, counting the high sample pulses, is set to its original state: this low sample pulses.

G10STOYAN110GO level in the signal scanning space. After one of the blocks 17 and 18 are recalculated, their output impulse is output to the output terminal of the device clock sync pulses and, through the first element OR 10, sets the trigger 24 to the initial state. The device is prepared to detect the subsequent clock line of the input signal.

In parallel, digital samples of the input signal transformed into a code from the output of the analog-digital converter 4 are output to the output code of the device.

The use of the invention improves the accuracy and noise immunity of detecting the synchronization pulses of rows of image signals. The invention can be used in equipment for digital processing of meteorological satellite image information.

Claims (1)

Invention Formula A device for converting a video signal into a digital code containing a peak detector, whose input is an input of a device, a pulse generator, a control input of which is connected to the input of a peak detector, an analog-to-digital converter, whose information input is connected to the output of a peak detector, a control input connected with the first output of the pulse generator, and the output is the information output of the device, the first counter, the first decoder, the information input of which is connected to the output of the first counter -ka, the first element And, the first input of which is connected to the first output of the first decoder, the first pulse shaper, the input of which is connected to the first output of the first decoder, the first and second blocks of conversion, the outputs of which are the synchronizing outputs of the device, the first element OR, the first and The second inputs of which are connected to the outputs of the first and second conversion blocks, respectively, characterized in that, in order to improve the accuracy and noise immunity of the device, it contains a third conversion block, information the input of which is connected to the output of the first element And, the trigger, the first input of which is connected to the output of the third conversion unit, and the second input is connected to the output of the first element OR, the second element And, the first input of which is connected to the output of the trigger, and the output connected to the information input of the first the conversion unit, the second pulse shaper, whose input is connected to the second output of the first decoder, the third pulse shaper, the output of which is connected to the second input of the first element AND, the second element OR the first input of which It is connected to the output of the second pulse driver, and the output is connected to the setup input of the third recalculation unit, the fourth pulse driver, the output of which is connected to the second input of the second OR element, the third OR element, the first input of which is connected to the output of the second OR element, the second input is connected to the output the third pulse shaper, and the output is connected to the setup input of the first counter, the fourth OR element, the first input of which is connected to the output of the second OR element, and the second input is connected to the output of the first pulse shaper, the second counter, the setup input of which is connected to the output of the fourth element OR, the second decoder, whose information input is connected to the output of the second counter, the first output connected to the input of the third pulse shaper, and the second output connected to the output of the second counter connected to the input of the third (pulse generator, and the second output is connected to the input of the fourth pulse driver, the third element And, the first input of which is connected to the output of the trigger, and the output d is connected to the information input of the second conversion unit, and the third decoder, whose information input is connected to the output of the analog-digital converter, the control input (polling) is connected to the second output of the pulse generator, the first output is connected to the information input of the first counter, the second input of the second element And the installation input of the second conversion unit, and the second output is connected to the information input of the second counter, the second input of the third element And and the installation input of the first conversion unit. CPut. 2  I l ii iii I I I I I I I pppppt II II I I I