SU1663783A1 - Tv signal frequency deviation meter - Google Patents

Abstract

This invention relates to a television (TV) technique. The purpose of the invention is to improve the measurement accuracy. The meter contains a frequency converter unit 1, the first and second switches 2 and 6, the comparator 7, memory block 8, frequency comparison signal generator 9, switching signal generator 10, frequency synthesizer 11, control block 17, which, according to a predetermined algorithm, implements two measurement modes instantaneous frequency in a periodic TV signal - measurement of "top" and "bottom" (measurement of the maximum and minimum instantaneous frequency). Both modes are implemented by the "bit balancing" method in N cycles, where each balancing cycle is determined by a switching pulse generated by the generator 10. These modes are performed several times, after which the measurement results are statistically processed and the TV signal frequency deviation value is calculated. 2 hp f-ly, 2 ill.

Description

one

(21) 4627592/09

(22) 12/27/88

(46) 07.15.91. Bul №26

(72) V.I.Berezin, V.P. Bogdanov, F.A. Vakulenko, Yu.N. Kraevsky and V.S. Chizhov

(53) 621.397-6 (088.8)

(56) Technique of cinema and television, 1980, No. 8, p.38, fig. 3

(54) MEASURING DEVIATION OF FREQUENCY TELEVISION SIGNAL

(57) The invention relates to a television (TV) technique. The purpose of the invention is to improve the measurement accuracy. The meter contains a block 1 of the frequency converter, the first and second switches 2 and 6, the comparator 7, the block 8 of memory, the driver 9

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Comparison signal, 10 switching signal generator, frequency synthesizer 11, control block 17, which, according to the algorithm, implements two modes of measuring the instantaneous frequency in a periodic TV signal — measuring from above and below (measuring the maximum and minimum instantaneous frequencies). Both modes are implemented using the bit balancing method in N cycles, where each balancing cycle is determined by the switching pulse generated by the generator 10. These modes are performed several times, after which the measurement results are statistically processed and the TV signal frequency deviation value is calculated. 2 hp f-ly, 2 ill. .

g

fe

Os

about with

VI 00 00

The invention relates to television technology and can be used to control the frequency variation of partially modulated TV signals of radio transmitters.

The purpose of the invention is to improve the measurement accuracy.

Figure 1 shows the structural electrical circuit of the meter; 2 shows timing diagrams explaining his work.

The frequency deviation meter of the television signal (Fig, 1) contains a frequency converter unit 1, first switch 2, intermediate frequency amplifier 3 (amplifier), amplitude limiter (AO) 4, frequency detector (CD) 5, second switch 6, comparator 7, unit 8 memory, shaper 9 of the frequency comparison signal, switching signal generator 10, frequency synthesizer 11, which consists of a controlled intermediate frequency generator 12, a controlled frequency divider 13, a phase detector (PD) 14, a crystal oscillator 15 and a frequency 16 filter , Lock control 17 which includes the address decoder 18, the block 19 output deviation code block 20 output frequency code input unit 21, the comparison frequency signal input unit 22 of the switching pulse and the calculated divisor 23.

The meter works as follows.

At the intermediate frequency after processing the TV signal in block 1 (Fig. 1), two modes are implemented: the first is the measurement from above, i.e. measurement of the maximum instantaneous frequency in a periodic TV signal fjB (t) (FIG. 2a); the second is Measurement from below, i.e. measurement of the minimum instantaneous frequency. These modes are carried out several times, after which the measurement results are statistically processed and the frequency deviation of the TV signal is calculated.

The Top Measurement mode is implemented by the bit balancing method in N clock cycles, where each balance bar is set by a switching pulse (Fig. 2b) generated by the generator 10. At the same time, the frequency synthesizer 11, consisting of the controlled divider 13, PD 14, quartz generator 15, filter 16 and controlled generator 12, under the control of block 17, forms a stepwise changing frequency fCT, -, l - 1 - N (Fig. 2a), which in N ticks with the maximum possible accuracy (determined by the value N) to the value of the measured maximum instant constant frequency

Tv signal. At the same time fCT | is defined as follows: rfcri fo

TST2 - fcri + Dtmaks

Aymake

fcr,

 tstM 4-slgn ()

d)

TCTIM

where I 3 - N;

fo is the average intermediate frequency of the TV signal;

AfMaKc is a value greater than or equal to half of the maximum possible value of the frequency deviation of the TV signal;

sign

fsch ST | - /

the function of the increment sign, which is defined in blocks 9 and 17.

During the switching pulse operation (Fig. 2b), the frequency fen from the output of the frequency synthesizer 11 through switch 2, UPCH 3, AO 4, PD 5 and switch 6 is converted to the corresponding voltage UCT /, goes to block 8, is remembered and goes to first input of comparator 7. In the absence of a switching pulse at the control inputs of switches 2 and 6, the second input of comparator 7 receives a TV signal tvvm converted to the corresponding voltage UrB (t), which is compared with the UCT stored in block 8. The comparison signal with output of comparator 7 comes and the first input of block 9, the second input of which receives switching pulses from the output of generator 10, and the third and fourth inputs receive a mode code from a decoder 18. When UtT (t) UcT / the output of block 9, a corresponding comparison signal is generated (Fig. ) which arrives at block 21. Block 22 receives a signal from oscillator 10. Interrogating blocks 21 and 22, calculator 23 determines the presence of a coincidence signal and works out the comparison cycles and setting the next frequency of the synthesizer 11 frequencies according to the system of equations (1).

The bottom measurement mode is implemented in a similar manner. Here, fcii is defined as follows:

fcri - fcto

fci2 fen + dtmax

fTBft) 4 Af,

Max

(2)

t zi -.i - / TBV.VA

fen-fen., + 51 dp (t) -

where I 3- N.

These modes are implemented several times, after which the calculator 23 performs statistical processing of the obtained measurement results and calculates the value of the TV signal frequency deviation, which is output to the consumer via block 19.

Claims (3)

Invention Formula 1. A television signal frequency deviation meter containing a frequency converter unit whose input is a television signal input, an intermediate frequency amplifier connected in series, an amplitude limiter and a frequency detector, characterized in that, in order to improve the measurement accuracy, the first switch is inserted connected in series to a second memory switch, a comparator, a frequency comparison driver, a control unit, and a frequency synthesizer, the output of which is connected to the first signal the primary input of the first switch, the second signal input of which is connected to the output of the frequency converter unit, and the output of the first switch connected to the input of the intermediate frequency amplifier, while the second output of the second switch is connected to the second input of the comparator, the output of the generator of switching pulses is connected to the control inputs the first and second switches, the second input of the frequency comparison signal generator and the second input of the control unit, the second output of which is the output of the measured deviation code pilots at, and the third and fourth outputs of the control unit are connected respectively to the third and the fourth input of the frequency comparison signal. 2. Pop-1 meter, characterized in that the frequency synthesizer contains series-connected quartz generator, phase detector, low frequency filter, controlled intermediate frequency generator and controlled frequency divider, the output of which is connected to the second input of the phase detector, while the control input of the controlled frequency divider is the input of a frequency synthesizer, the output of which is control output intermediate frequency generator. 3. Pop-1 meter, characterized in that the control unit comprises a calculator, the first and second inputs of which are connected to the outputs of the frequency comparison input block and the switching pulse input block, respectively, whose information inputs are the first and second inputs of the control block The first and fourth outputs of which are, respectively, the output of the frequency code output block, the output of the output block of the deviation code and the first and second outputs of the address decoder, the third - sixth outputs of which are connected Respectively with the control inputs of the switching pulse input unit, the frequency comparison signal input unit, the deviation code output unit and the frequency code output unit, the first, second and third inputs of the address decoder are connected respectively to the address outputs, the write signal output and the calculator read signal output , the first and second information outputs of which are connected respectively to the information inputs of the output unit of the deviation code and the output unit of the frequency code.