SU832767A2 - Device for monitoring phasing of transmitting and receiving facsimile apparatuses - Google Patents

Description

The invention relates to the transmission of images via communication channels and can be used in systems for the transfer of facsimile images.

According to the main author. St. No. 524330, there is known a phasing control device for transmitting and receiving fax machines, for example for transmitting newspaper strips, comprising a synchronous frequency test pulse shaper and a receiver phase pulse shaper connected through the first AND element to the input of the test signal pulse packet level shaper, output which is connected to the input of the second element And, the other input of which is connected to the source of the video signal, and the transmitter of the duration of the phase pulses of the transmitter a, the side of the shaper of the reciprocal phase position of the transmitter and receiver are connected to the outputs of the phase pulse durations of the receiver and transmitter. through the counter connected to the alarm unit [1], however, the known device has a lack of control accuracy.

The aim of the invention is to improve the accuracy of control by eliminating the phase incursion from frequency instability.

This goal is achieved by the fact that a phasing pulse frequency divider and an erasure pulse shaper J are introduced into the phasing monitoring device of the transmitting and receiving fax machinesJ, while the input of the phase pulse repetition frequency divider is connected to the output of the phase pulse generator for the phase pulses of the receiver, and its output 3 832767 4 to the input the pulse shaper of the sti-pulses and at its output there is no injury, the output of which is connected to the reset input of the memory block for skimming the transmitter out of phase transmitter and nick.

The drawing shows a block diagram of the proposed device.

The phasing control device for transmitting and receiving fax machines contains a driver 1 of the pulse width of the test signal of synchronous frequency, driver 2 of the pulse duration of the receiver, the first element And 3, former 4 level packet pulses of the test signal, the second element And 5, the source • 6 video signal, shaper 7 duration of the phase pulses of the transmitter, block 8 for the formation of the mutual phase position of the pulses 20. 'Phasing of the transmitter and receiver, block 9 for memorizing frame dephasing transmitter and receiver unit 10 memory row rasfa • ζ yōkan transmitter and receiver 25 blok'11 comparison, the counter 12, the alarm unit 13, frequency divider 14, phase pulse ,. shaper 15 erasure pulses.

The control device operates in the following manner. 'no signals are generated.

When a raffination occurs, the phase position of the phasing pulses of the transmitter changes by a value of -Uk ”. and receiver. Then, at the output of the forming unit 8, a packet of 5 4-Sp-htVM pulses is formed, which enters the memorization unit TO. When reading information from blocks 9 and memorizing at the inputs of the comparison unit 11, packets with 5 = иi6 + + 5р-Ц1М'1 pulses are formed. At the output of the block, a difference of 5p-S- (5 + 6p) pulses appears; the number of which is counted in the counter 12 and is reproduced by the signaling unit 13.

Through N | lines due to the instability of the clock frequency of the transmitter and the receiver, the phase ratio of the phasing pulses changes by Δ X (N / C) where D X is the dephasing increment by one line due to instability. In order for the value ΔχΝ / φ not to be perceived as a misphase, the divider 14 and the shaper 15 generate an impulse for erasing the information of the memorizing unit 9 every N / <p lines, after which the process of starting recording and reading is repeated.

After the process of starting phasing is completed, the starting circuit is closed and both phase pulses arrive at the inputs of the forming unit 8. The difference signal is generated as a result of the allowable spread of phasing, is gated, and a packet of pulses is formed at the output of the forming unit 8. This packet arrives at the inputs of memory blocks 9 and 10 and is recorded in the corresponding memory cells. Information written to the block. 9 memorization, is stored during (N · Ц,) from the scan line, where X is the total number of lines in the frame, ty is the coefficient that determines the number of lines through which erasing and new recording should be performed. The information recorded in the block 10 memorization, after

The passage of each lowercase phase j ^ pulse is erased. Since the same * 7 Information is recorded in the Y-blocks 9 and 10 (in the absence of any phase difference and frequency discrepancies), the inputs * of the comparison block 11 receive the same amount for each daf

The technical and economic effect when using the proposed phasing control device for transmitting and receiving fax machines consists in more precise control of the mutual phase position of the deploying devices in the process of recording images, as well as in an additional reduction in the time of using a broadband communication channel when operating in operational mode and reducing operational time to detect deviations of the synchronization system in a preventive mode.

Claims (1)

1. USSR author's certificate 524330, cl. H 04fi 1/36, 1976. /four YU