SU1066435A1 - System for synchronizing time scales by tv channels - Google Patents

Abstract

The invention relates to the technique of television and communications, can be used for synchronization of time scale of secondary and working patterns and allows to increase the accuracy of synchronization of time scales. The time scale synchronization system for television channels contains a time interval meter I and a first block 2 of the time and frequency pattern and a first television receiver 3, a second block 5 of the pattern are connected to its input of time and frequency connected consecutively for a synchronization generator 8, a source 9 of television signals, a block 10 for input of time signals and a television transmitter 11 and also a block 15 for calculating time, in addition therein consecutively connected between the first output of the second block 5 of the time and frequency pattern and the input of the synchronization generator 8 a pulse shaper 12 of the corrected image signal and block 7 of the synchronization pattern signals, successively between the output of the first block 2 of the time and frequency pattern and the second input of block 10 of the time signal input of block 4 of the direction signals.

Description

The invention relates to television and communication technology and can be used to synchronize the time scales of secondary and working standards, as well as exemplary means of measuring time and frequency using reference signals transmitted over television broadcast channels together with television signals generated according to television standards. repeating frame sync pulses is not a multiple of the repetition frequency of the reference time signals. The known system of synchronization of time scales over television channels, containing the first block of time and frequency standard, the first television receiver, the second block of time and frequency standard, connected in series with a synchronous generator and a source of television signals, and also a television transmitter Cl The disadvantage of this system is the inability to resolve ambiguity of counting on the second interval and, therefore, necessary preliminary assignment of local clocks via other communication channels, which leads to low accuracy synchronization time scales. Closest to the invention is a system for synchronizing time scales over television channels using time signals and frequencies transmitted as part of television signals, which contains a time interval meter and connected to its inputs a first unit of time and frequency standard and a first television receiver, the second unit standard time and frequency, included in series the clock generator, the source of television signals LEV1, the input unit of time signals and television transmitter, as well as the score belt. The disadvantage of the known VL € 1tS system is the low synchronization accuracy of weaving time, associated with the final quantization of information about the time of marker pulses and the limited number of transmitted series of code corrections on the transmitting side and with the inevitable error of restoring the time of marker pulses to the receiving side due to the limited number of times the code correction series and their discrete nature, determined by the bandwidth of the transmitting and receiving paths. This circumstance does not allow to increase the accuracy of the existing devices for synchronizing time scales across TV channels. The aim of the invention is to improve the synchronization accuracy of time scales. ; To do this, the timing system is synchronized via TV channels. It contains the time interval meter and the first time and frequency standard unit and the first television receiver, the second time and frequency standard unit connected in series with the clock generator, television source, signals, input unit The time signals and the television transmitter, as well as the time counting unit, are connected in series between the first output of the second time and frequency standard unit to the input of the synchro generator; Only a frame correction signal and a block of reference synchronization signals, sequentially between the outputs of the first block of the time and frequency standard and the second input of the time input block of the control signal block whose second input is connected to the output of the time interval meter, and the output to the second input of the frame correcting signal generator , the driver is corrected (its time signal, the second output of which is connected to the input, and the second input - to the first output of the second block of the time and frequency standard, and the block ormirovani time signal, a second input of which is connected to the second output of the second block of time and frequency reference, and a second television receiver, whose output is connected to the input of the count time audio block. The drawing shows a structural electrical circuit of the system for synchronizing time scales through television channels. The synchronization system of time scales contains a time interval meter 1, connected to its two inputs, a block 2 of time and frequency standards and a television receiver 3, as well as a block of 4 control signals, the first and second inputs of which are connected respectively to the outputs of block 2 and the are-interval meter; 1. These blocks are located at the control station. On the transmission side, the system contains a series of time and frequency reference blocks 5, a frame correction signal generator 6, a synchronization reference signal block 7, a clock generator 8, a television signal source 9, a time signal input block 10, and a television transmitter 11, as well as connected in series between the output unit 4 and the second input unit 10 of the generator 12 of the corrective time signal, the second output and input of which are connected respectively to the input and the first output of the unit 5, and unit 13 form They are connected to the second output of block 5. The second input of the imaging unit 6 is connected to the output of block A. On the receiving side, the time scale synchronization system contains a television receiver 1A connected in series and a time counting unit 15 that operates ahead of time by a predetermined magnitude. The device works as follows. Reference signals with a frequency of 5 MHz from the first output of the block 5 of the standard of time and frequency of the transmitting telecentre are simultaneously supplied to the first input of the imaging unit 6 of the frame correction signal and the second input of the imaging unit 12 of the correction signal

time, in which quality can be used, for example, electronic phase shifters operating on the principle of sequential switching of input signals at a given speed, which provides a phase shift of the output signals by any given value

e pt

where n is the number of clock pulses; T - the repetition period of the input

signals electronic switch phase shifter. Signals with a frequency of 5 MHz from the output of the imager 6 of the frame correction signal are fed to the input of the block 7 of the reference synchronization signals, E of which, for the NTSC standard, a frequency synthesizer with a conversion factor of 53/88 can be used, which ensures the output of the color subcarrier signals with a frequency of 3.579545. ., mhz

The output of block 7 is connected to the input of a synchronous generator 8, the output signals of which are fed to a source of 9 television signals, where a complete television signal is formed, which is then fed to the first input of block 10 of input time signals and then to a television transmitter 11.

video pulses and modulated (according to the duration of the second signals of the unit 5 of the standard time and frequency of the transmitting telecentre ..

In this case, time-modulated time signals with a repetition rate of 1 kg are used at the receiving side to resolve the counting ambiguity at the second time interval.

five

The time signals extracted from the television signal by the television receiver 3. At the monitoring point, enter the BTopoii input of the time interval meter 1, the first input of which receives signals from the unit 2 of the time and frequency standards. At the same time, these signals are sent to the first input of the control signal unit 4.

five

The time interval measured in the time interval meter 1 contains information about the time of passage of signals from the transmitting side to point 0 of the control and information about the discrepancy between the time scales of block 2 of the time and frequency standard and block 5 of the time standard and frequency of the transmitting telecentre. The measured time interval in digital At the second input of block 10, the time signal with a repetition rate of 1 kHz from the output of block 13 of the time signal generation is input. The first BKHOD of the block with 13 forms of g, kt: ala time with a frequency of 1 kHz; received signals with frequencies of 3 mHz from the first output of the FtOFFEATER 12 of the corrective sigpa.hrmsia, and the second input (modulating) of block 13 with a repetition frequency of 1 kHz sub-clock signals from the second code C.TOKJ of the time standard and frequency, which obs-s: tsichat modulation of the output frequency of the time signals with a repetition frequency of 1 kHz of the time signal forming unit 13. Thus, as part of a full television signal (TV) emitted by a television} transmitter 1 1 in the allowed time interval for a frame extinguishing pulse, time signals with a repetition period of 1 kHz are arranged, taking into account the transmission time of the signals from the transmission side to the control point from the output of the time interval meter 1, it is fed to the second input of the control signal unit 4. 1 In block 4, the input signals are converted into signals convenient for transmission via a telephone line connecting the control point with the transmitting side, for example, to tones of a fixed length or telegraph code. The starting signals for the control signals are determined by the second signals of the reference unit 2 time and frequency5 which are fed to the first input of the control signal unit 4. These signals from the output of block 4 are fed to the first input of the transmitter 12 of the transmitting side correction time signal, where they change the phase of the 5 mHz frequency signals that arrive at the first input of the block 13 to generate time signals until the second signals from the output of this block coincide with the second signals of the block 2 of the standard time and frequency. In this case, the coarse phasing of the second signals of the time and frequency standard block 5 is performed by the control signals from the first output of the driver 12 time correction signals, the moment of arrival of which the second signals of the time standard block 2 in paragraph SSSR OLYA. To set time signals with a repetition rate of 1 kHz in the allowed interval for transmission: during the frame blanking period, the frame sync pulses are displaced in time by supplying the frame correction signal 6 with additional control signals of the output 4 of the block 4 time with a repetition rate of 1 kHz remains incessant. In the known HJMeHeHHe devices, the temporal timing of cam sync pulses leads to a change in the temporal position of the time signals with a repetition rate or 25 Hz Tc, they are formed by subsequent division of frames of 1X sync pulses to 1 Hz. The additional control signals change the phase of the output signals of the former 6 of the frame correction signal until the time signals with a repetition rate of 1 kHz coincide with the frame sync pulses of the television signals. After that, the transmission of additional control signals is stopped and the interposition of time signals and frame sync pulses remains unchanged and, thus, a continuous transmission of one time signal per second as part of television signals during a personnel blanking period of 1 kHz is repeated. In this case, another signal from the 1 kHz pulse sequence, etc., will be transmitted to the next. In other words, the transmission of time signals in TV signals once a second is provided by the stroboscopic effect that occurs when combining time signals with a repetition rate of 1 kHz and frame signals with a repetition rate of 59.94005994. ,,., For the color television standard NTSC period The repetition of time signals transmitted in the composition of TV signals 1 time per second is determined from the expression: -1 -1 f the repetition period of the time signals; f, is the frequency of repetition of the fields of TV signals, is equal to. 59 ,, 94005994 ... Гщ N - the number of fields of TV signals equal to 60. In turn, ff is related to the line frequency of the NTSC television raster, equal to, and the double line frequency 2 fj ratio. The double line frequency is determined from - 25; t where fg is the frequency of the color subcarrier is different To 5 MHz, where K sd / 581 (is the coefficient chosen by the short-circuit considerations of less noticeable interference from the chrominance signal. Joint solution (1), (2), (3) z ( 2n + 1) N - 40 In the expression (4) all the input is smaller than the value of integers and finite numbers, so the exact value of the repetition period of signals The times that coincide with each field of NTSC stavard signal once per second is 1 ms, which corresponds to a repetition rate of time signals of 1 kHz. On the receiving side, television signals are received that include time signals whose output is from TV transmitter antennas 11 are combined with the time scale of the time and frequency standard block 2. With the help of the television receiver 14, time signals are taken from the full TV signal and fed to the input of the time counting unit 15 operating in time with a predetermined time value. The time counting unit can be, for example, a serially connected quantum oscillator and a controlled frequency divider. For example, a frequency divider made up of parallel reversible counters of the K155IE6 type, having an input for pre-recording a specified number corresponding to the signal transit time from the transmitting to the receiving antennas, can be used as a controlled divider frequency. In this case, the received time signals are input to the record of the controlled frequency divider, where a predetermined number is set in advance, and the further division of the input frequency signals is performed taking into account the entered number. Thus, the time of the local clock output signals will be ahead by a specified amount of the time of the input of the recording of the counter of time signals transmitted as part of television signals, and coincide with the moment of output of the second signals of the block 2 of the time and frequency of the control point. Thus, the block 15 of the time of the receiving point will be synchronized on a time scale of the block 2 of the time standard and the frequency of the control point.

Claims (1)

SYNCHRONIZATION SYSTEM FOR TIME SCALES BY TELEVISION CHANNELS, containing a time interval meter and connected to its inputs a first block of a standard time and frequency and a first television receiver, a second block of a standard of time and frequency, connected in series with a clock generator, a source of television