SU739430A1 - Device for digital measurement of difference in frequency of electrical oscillations - Google Patents

Description

The invention relates to electrical measuring technology and may be used in a low frequency difference meter.

A device for measuring the frequency deviation from the nominal value is known, comprising a unit for measuring the absolute value of the period deviation, a counter forming a deviation-10 code, and a unit comparing the counter code with the maximum deviation register code 1.

The disadvantage of the device is the presence in the blocks of lines of the locking limiting the range of operating frequencies.

A device for digitally measuring the difference in frequency of electrical oscillations is known.

The device is based on the principle 20 of discrete measurement of the phase shift between two signals with further processing in a reversible counter and obtaining a digital result proportional to the frequency difference. 25 of these signals.

The device contains a reversible counter, the inputs of which are connected to the output terminals through the logic circuit OR, time selectors, tri-O

control germ, pulse formers and output triggers, and output with a digital indicator, shaper of a temporary measuring interval, a generator of standard pulses, a comparator for the duration of a pack formed by T1mpu ls6vT decoders, delay elements and a NOT circuit.

The device uses delay elements calculated for specific values (1/6 T2, 5/6 Tg, 1/2 Tg, where Tj is the signal period of the second channel) 2.

A disadvantage of this device is the presence of delay lines, significantly narrowing the frequency range of the signals, since normal operation requires varying delays when changing the frequency. In addition, the device does not allow the accumulation of measurement measurements in order to increase the measurement accuracy.

The purpose of the invention is to expand the frequency range of input signals, while further improving the accuracy of measuring the difference in frequency of electrical oscillations. The goal is achieved by the fact that in the device containing two triggers, the counting inputs of which are connected to the input signal buses, respectively, the outputs of the first trigger through the first and second pulse drivers are connected to the first inputs of the first and second time selectors, the second inputs of which are connected via trigger control to the output of the first element OR, the first input of which is connected to the first output of the decoder, the second input of the first element OR is connected to the output of the Locked element, whose inputs are connected to the second The third outputs of the decoder, the inputs of which are connected to the first outputs of the pulse counter, and the outputs of the first and second time selectors are connected to the inputs of the second element OR, the output of the second trigger is connected to the input of the third pulse generator, the former of the measuring interval, the first and second outputs of which are connected respectively, to the first inputs of the third and fourth time selectors, the reference frequency generator, the correction unit and the indicator, a half-summer is entered into it, the bit inputs of which are connected Points to the second outputs of the pulse counter, read and reset of the half accumulator are connected to the third and fourth outputs of the measuring range generator, and half summator outputs are connected to the indicator inputs, and the input of the measuring range generator is connected to the output of the second element OR AND the pulse counter reset input, and the inputs of the measurement interval. in the forward and reverse codes of which are connected to the outputs of the third and fourth pulse selectors, the second inputs of which are combined and connected to the output of the third form pulse interrupter and to the interrogator interrogation input, the reference frequency generator outputs are connected to the counting input of the pulse counter whose correction reading inputs are connected to the outputs of the correction unit whose first input is connected to the second output of the interval former, the second and third inputs of the correction unit are connected correspondingly to the first inputs of the first interval and the second time selectors, the fourth and fifth inputs - respectively with the second inputs of the first and second time selectors, and the sixth and seventh inputs - from the input said first OR element. The goal is also achieved by the fact that the correction block contains the first time selector, whose inputs are the second and third inputs of the block, and the output through the first OR element is connected to the first inputs of the second, third and fourth time sectors 739430 of lecturers and the inputs of are the fifth and fourth inputs of the block, the second inputs of the second and third time selectors are connected to the outputs of the first and second correction triggers, respectively, the first inputs of which are connected respectively to the output The second and third time selectors are the outputs of the block, the second input of the second correction trigger is connected to the output of the fifth time selector, and the first input of the correction preparation trigger whose output is connected to the second input of the fifth time selector and the second input to the sixth output time selector, the first input of which is the first input, of the unit and connected to the first input of the seventh selector, the output of which is connected to the second input of the first correction trigger, and the second inputs of the sixth and seventh time GOVERNMENTAL selectors are sixth and seventh inputs of the correction unit. , FIG. 1 shows a block diagram of the device; FIG. 2 and 3 - timing charts of the device. The device consists of flip-flops 1 and 2, shapers 3-5 pulses, time selectors 6-9, control trigger 10, element 11 OR, pulse counter 12 with inputs 13-16, de-encoder 17 with outputs 18-20, half adder 21 with reset inputs 22, a measuring interval imager 23 with outputs 24-27, an indicator 28, an element 29 of the Prohibition, an OR element 30, a reference frequency generator 31, a correction block 32 containing selectors 33-39, an OR element 40, triggers 41 and 42 correction trigger 43. The device operates as follows. If the time shift between the pulse sequences at the outputs of the formers 3-5 changes monotonously and only in the range from 0 to 2Jf, then the first variant of operation is realized. In this case, the counting inputs of the triggers 1 and 2 receive pulse signals of the frequencies fj and fg, respectively. At the outputs of the input triggers 1 and 2, meander protivo-phase signals are formed, formers of 3-5 pulses convert meander signals into short pulses, corresponding to the time of zero-crossing (usually from the negative half-wave and positive). Thus, the period of the formation of the formed follower is equal to 2m, and. Next, the pulse signal of the second frequency channel is fed to the first temporary inputs

the selectors 6 and 7, 35 and 34, and the signal of the first channel of frequency f // 2 to the input of the time selectors 8 and 9 and simultaneously to the input of the interrogation 18 of the potential impulse decoder 17. Depending on the phase of the control voltage on the second inputs of the time selectors 6 and 7, 35 and 34, coming from the direct and inverse outputs of the trigger; pa

10 controls, f2 / 2 pulse sequences shifted

on f glad, skipped through the circuit

11OR to the reset input of the pulse pulse 12 and to the input of the driver

23 of the time measurement interval, which consists of dividing decades and the automation circuit, From the direct and inverse outputs 24 and 25 of the first trigger of the ten-day frequency divider, the control voltage goes to the second inputs of the time selectors .8 and 9, which, depending on the phase of this voltage pulses of frequency f / / 2 are sent to the readout input of counter 12, if in the direct code - to input 13, if in the reverse - to input 14. From outputs 26 and 27 of the automatic driver of the former 23, pulses with a period Tyj arrive at the reset inputs 22 half adder 21, and on in od read counter 12 from the generator 31 receives the pulses with period Tj follows a period of time between the two pulses are triggered. Information on the phase mismatch (binary code) in parallel form is taken from counter 12 at the moments of arrival of the pulses of the first channel of frequency f / 2 and arrives at. processing in cumulative half-adder 21.

The operation of subtracting binary codes is carried out in cumulative half adder 21 by inverting the code of one of the addends and assigning a sign to each addend. The binary code in the cumulative half adder 21 at the end of the measuring period is proportional to the frequency difference of the input signals, that is, N Af K, where K is the proportionality coefficient.

If additionally TC fj T / -10, then N d f Yu. Moreover, the magnitude of the code of the frequency difference depends on the magnitude of the measurement interval, which makes it possible to distinguish frequencies similar in its value.

If during the measurement interval Tyj, the phase difference of the two input signals reaches values close to 0 or, then the second operation is realized. The information outputs of the counter 12 are connected to the potential inputs of the potential pulse decoder 17, to the polling input of which the pulses of the first channel of frequency f, / 2 are received. At the time of arrival of the polling pulse, an impulse appears at the pulse outputs 18-20

moreover, if at this moment the number in the counter 12 is less than the minimum response threshold N N, -, then the pulse; output is at 18, if K ,; N N, then the impulse is at outputs 18 and 19, if N, then the impulse is at outputs 18-20.

Therefore, if the number in the counter 12 at the time of the survey of the potential pulse decoder 17 N,

then the pulse from output 18 through the Inhibit logic element 29, the circuit 30 OR goes to the counting input of the control trigger 10, which switches the selectors 6, 7, 35, 34 and changes the phases of the signals of the second channel to f, then the process of changing the phase shift continues until the next switching . At the same time, the pulse from the output of the circuit 29 The ban enters the device

32 of the result correction to the input of the time selector 36 of the correction control and depending on the phase of the control voltage at its second input sets the trigger 43 to the state one, which by its output

opens the time correction selector 33. The correction time selector 33 passes the signal from the output of the circuit 40 OR to the input 15 of the readout data of the correction in the forward code of the counter 12. Thus, the correction is made to a value equal to Tg / Tet. A correction pulse from the output of the correction selector 33 simultaneously sets the trigger 43 to the zero state.

If the number in the counter is 12 in the poll item, the potential-pulse. 17 N decoder, then the pulse from the output of element 29 through the circuit

30 OR, the control trigger 10 and the time selectors 6, 7, 35, 34 switch the phase of the signals of the second channel to Jf and at the same time, via the time control selector 36, set the trigger 43 to state one. The first impulse of the antiphase sequence through the time selector 38 will set the trigger 41 to one and at the same time close

the trigger 42, the second pulse from the output of the OR circuit 40 through the temporary correction selector 39 is fed to the read input of the correction data in the reverse code 16 and simultaneously sets

a zero trigger 41, so a correction is made to the value of B N, Qp -Tg / Tzt-.

If the number in the counter 12 at the moment of polling of the potential pulsed decoder is 17 M ", (" N Mgg, ah, then the output of the element 29 will not inhibit the pulse and, therefore, the first variant of the device operation is performed.

Claims (2)

FIG. 2 shows the signal plots at various points in the circuit, marked with letters (a, b, c, ...) for case f, 7 (t, Tj,). For consistency, a certain ratio between T. and TL (Ta, / Tug 20) is selected and the code values in the counter of 12 pulses are shown (For example: +1, -15, ...). Timing diagrams (see Fig. 3) explain the operation of the proposed device with the ratio f, fj. (Tr) As can be seen from the diagram, the device allows to accumulate the measurement result over n frequency periods, which improves the accuracy of measurement of the difference between close frequencies. Claim 1. Device for digitally measuring the difference in frequency of electrical oscillations, containing two triggers, the counting inputs of which are connected to the input signals, respectively, the outputs of the first trigger through the first and second pulse drivers are connected to the first inputs of the first and second time selectors whose inputs through the control trigger are connected to the output of the first element OR, the first input of which is connected to the first output of the descrambler, the second input of the hepBoro element OR is connected to the output of the element pret, the inputs of which are connected to the second and third outputs of the decoder, the inputs of which are connected to the first terminals of the pulse counter, and the outputs of the second and second time selectors are connected to the POWER TRAY OR, the output of the second trigger is connected to the input of the third pulse generator; shaper measuring interval, the first and second outputs of which are connected respectively to the first inputs of the third and fourth time selectors, the reference frequency generator, the correction unit and the indicator, which is, in order to expand the frequency range of the input signals and to improve the measurement accuracy, a half-adder is inserted into it, the bit inputs of which are connected to the second outputs of the pulse counter, the read and reset inputs of the half-adder are connected to the third and fourth outputs of the generator the output interval, and the outputs of the half-adder are connected to the indicator inputs / and the input of the imaging unit of the measurement interval is connected to the output of the second OR element, and to the counting input of the pulse counter, the read inputs in the forward and reverse codes of which are connected to the outputs of the third and fourth pulse selectors, the second the inputs of which are combined and connected to the output of the third pulse generator and to the polling input of the decoder, the outputs of the reference frequency generator are connected to the counting input of the pulse counter, the inputs of the pulse the correction of which is connected to the outputs of the correction unit, the first input of which is connected to the second output of the measuring interval imaging unit, the second and third inputs of the correction unit are connected respectively to the first inputs of the first and second time selectors, the fourth and fifth fifth inputs, respectively, to the second inputs of the first and second time selectors, and the sixth and seventh inputs. - with the inputs of the first element OR. 2. The device according to claim 1, o1; li4 and K1, it is because the correction unit contains the first time selector, whose inputs are the second and third inputs of the block, and the output through the first element OR is connected to the first inputs of the second, third and the fourth time selectors and the output of the fifth time selector whose inputs are the five and fourth inputs of the block, the second inputs of the second and third time selectors being connected to the outputs of the first and second correction triggers. respectively, the first inputs of which are connected respectively to the outputs of the second and third time selectors and are outputs of the block, the second input of the second correction trigger is connected to the output of the fifth time selector and to the first input TpTirrepa of correction preparation, the output of which is connected to the second input of the fifth time selector and the second input is with the output of the sixth time selector, the first input of which is the first input of the block and is connected to the first input of the seventh selector, the output of which is connected to the second input ervogo correction trigger, and the second inputs of the sixth and seventh time selectors are sixth and seventh inputs of the correction unit. Information sources taken into account during the examination 1. USSR author's certificate No. 535522, cl. G 01 R 23/10. 2. USSR author's certificate 495616, CLGS OT R 23/10, 15,12.75. I fie. i §  vta ×) n 04 / C