SU766024A1 - Follow-up frequency meter - Google Patents

Description

The invention relates to radio engineering.

The following input signal frequency meter is known, containing a series-connected mixer, an intermediate frequency amplifier, the first key, the control of which in parallel with the control input of the second key is connected via a signal detection unit to the second 10 output of the intermediate frequency amplifier, a digital discriminator, the counting input of which is connected to the block of reference frequencies, and the setup input is connected to the output of the memory block, a digital 5-filter extrapolator of the nth order and a code-frequency converter, Inline with the second input of the first mixer, as well as a block for targeting and measuring the frequency .120

However, the known follower frequency meter of the input signal does not have the necessary accuracy for determining the law of frequency variation.

The purpose of the invention is to improve the accuracy of determining the law of frequency variation.

To do this, in the following meter of the frequency of the input signal containing the DZ

serially connected mixer, intermediate frequency amplifier, the first key, the control input of which is paralyzed to the control input of the second key through a signal detection unit connected to the second output of the intermediate frequency amplifier, digital discriminator, the counting input of which is connected to the reference frequency unit, and : A tuning input is connected to the output of the memory unit, a digital filter extrapolator of the nth order and a code-frequency converter connected to the input of the first mixer, as well as a targeting and measuring unit Frequencies, between the output of the target indication and frequency measurement unit and the mixer input are connected in series an additional code-frequency converter and a mixer, another input of which is a device input, to the outputs of the targeting and frequency measurement units and digital filter extrapolator of the fifth order are connected adder, output

25 which is connected via a second key to the input of the target indication and frequency measurement unit.

The drawing shows a structural electrical circuit of the proposed following meter of the frequency of the input signal.

The following meter contains mixer 1, code-frequency converter 2, mixer 3 code-frequency converter 3, intermediate frequency amplifier 5, key b, signal detection unit 7, digital discriminator 8, reference frequency unit 9, memory block 10, digital filter - an extrapolator of the 11th order, a digital adder 12, a key 13, a block 14 for targeting and measuring frequency.

The following frequency meter operates as follows.

The operation of the device is divided into two stages (modes): detection of the input signal followed by synchronization by the Doppler frequency change, tracking of this change, measuring current values of the frequency and determining the law of change of the Doppler frequency of the input signal (in the drawing, the state of both keys corresponds to the signal detection mode) .

The input signal is fed to one input of the mixer 1, the second input of which receives the output signal of the coarse converter 2 code-frequency, the frequency of which is determined by the block 14 of targeting and measuring the frequency of the input signal, taking into account the expected Doppler shift value. The output signal of the mixer 1 is fed to the first input of the mixer 3, the second input of which receives the output signal of the exact code-frequency converter 4. When the Doppler frequency of the input signal coincides with its expected value at the output of amplifier 5, the intermediate frequency signal is output, which is fed to the input of signal detection unit 7.

When this signal exceeds this threshold, a control signal is generated at the output of block 7, which closes keys 6 and 13 and switches the tracking frequency meter to synchronization mode for tracking the Doppler shift and determining the law of variation of the Doppler frequency of the input signal. The intermediate frequency siggal in this mode through a closed key b is fed to the signal input of the digital discriminator 8, operating as a periodometer, the time (dimensional) intervals of which are an integer K of the intermediate frequency signal ff, p intervals are measured by counting the counting pulses of the reference frequency The input from block 9. In this case, the number N. proportional to the length of the measuring interval is compared in the discriminator 8 with a constant number NP written from block 10 of memory in the additional code. e before each measurement cycle. As a result, at the output of the discriminator 8, a number equal to the difference between the numbers of countable pulses / ow in the measuring interval and in the reference interval with the interval corresponding to the similar number of periods of the nominal intermediate frequency is formed in each measurement cycle :.

Kf.-i,

-l - i V

, -f r- / u;,). (- J

C-f ng fnJ

... ° np

The error signal AN in digital form from the output of the discriminator 8 enters the digital filter-extrapolator 11, containing in general

n reversible counters (accumulating adders) at the output of which a control number N is formed, proportional to the sum of single, double, triple, and so on up to

n-th order of integral of

mismatch. This number Ny transforms the 4 code-frequency transducer in such a way that the law of variation of the frequency of the output signal of the transducer 4 strictly corresponds to the law

change the signal to the input of the mixer 3. In this case, the next filter formed by mixer 3, amplifier 5 / discriminator 8, filter extrapolator 11

and code-frequency converter 4, tracks not the full Doppler frequency range of the input signal, but only the difference between the current value of the Doppler frequency of the input

the signal and the frequency of the target signal coming to the second input of the mixer 1 from the output of the code-frequency converter 2 and specified by the target number NU, block 14. The numbers generated at the output of the digital adder 12 N Ny + Mtsu and fed through the key 13 to the input of the block 14, in the synchronization mode, they strictly correspond to the current values of the Doppler frequency of the input signal. Nar Doo

with the current values of the digital samples of the Doppler frequency N with you-. The digital filter-extrapolator 11 moves through the adder 12 and the key 13 to the block 14 and the digital readings of all (p-1) first derivatives of the current values of the Doppler frequency are taken from the outputs of the reversible counters (accumulating adders) of the digital filter-extrapolator 11.

The feasibility of a servo frequency meter consists in increasing the accuracy of determining the law of frequency variation.

Claims (1)

1. USSR author's certificate 537432, cl. H 03 B 3/04, H 04 B 1/34, 1976 (prototype).