SU847219A1

SU847219A1 - Device for measuring average frequency of running signals

Info

Publication number: SU847219A1
Application number: SU792780331A
Authority: SU
Inventors: Петр Михайлович Мадяр; Татьяна Алексеевна Мадяр
Original assignee: Предприятие П/Я М-5783
Priority date: 1979-06-18
Filing date: 1979-06-18
Publication date: 1981-07-15

Description

Изобретение относится к измеритель ной технике и может быть использовано в цифровых устройствах для измерения средней частоты следования импульсов в пачке или в серии пачек и|Э|пульсов, а также частоты следования непрерывной последовательности импульсов.The invention relates to measuring technique and can be used in digital devices for measuring the average pulse repetition rate in a packet or in a series of bursts and | E | pulses, as well as the repetition rate of a continuous pulse sequence.

Известно устройство для измерения средней частоты, содержащее три счетчика, элементы И, генератор эталонной частоты [1].A device for measuring the average frequency, containing three counters, elements And, a reference frequency generator [1].

Недостатки этого устройства - увеличение погрешности измерения при большом количестве пачек в одном измерении и ограничение функциональных возможностей.The disadvantages of this device are the increase in measurement error with a large number of packs in one dimension and the limitation of functionality.

Наиболее близким к предлагаемому техническим решением является устройство для измерения частоты, содержащее счетчики, элементы И, триггеры, генератор эталонной частоты [2].Closest to the proposed technical solution is a device for measuring frequency, containing counters, AND elements, triggers, a reference frequency generator [2].

Однако данное устройство значительно сложнее и обладает дополнительной погрешностью измерения за счет нестабильности (разброса) формирования конца мерного интервала времени из пачки измеряемых импульсов . Эта нестабильность получается за счет асинхронности импульсов измеряемой и эталонной частоты.However, this device is much more complicated and has an additional measurement error due to the instability (scatter) in the formation of the end of the measured time interval from the packet of measured pulses. This instability is obtained due to the asynchrony of the measured and reference frequency pulses.

Цель изобретения - повышение точ5 ности измерения.The purpose of the invention is to increase the accuracy of measurement.

Поставленная цель достигается тем, что в устройство для измерения средней частоты следования импульсов, содержащее генератор импульсов Ιθ эталонной частоты, соединенный через первый элемент и со счетными входами вспомогательного счетчика и счетчика эталонной частоты, триггер, прямой выход которого подключен к управляющему входу первого и второго элемента И, выход второго элемента И соединен со счетным входом счетчика измеряемой частоты и через первый элемент ИЛИ со входом установка нуля” вспомогательного счетчика, а вход второго элемента И соединен с первым входом третьего элемента И, второй вход которого соединен с инверсным выходом^-триггера, шина Установка нуля соединена с соответст25 вующими входами счетчиков эталонной и измеряемой частот и с входами первого и второго элементов ИЛИ, четвертый элемент И, введен элемент ИЛИ-НЕ, а счетчик эталонной частоты выполнен реверсивным, причем выходы третьего to и четвертого элементов И через элемент ИЛИ-HE соединены со счетным входом триггера, а прямой выход триггера подключен к первому входу четвертого элемента И, второй вход которого соединен с прямым выходом вспомогательного счетчика и первым управляющим входом реверсивного счетчика ’эталонной частоты, второй управляющий вход которого соединен с инверсным выходом вспомогательного счетчика, выход счетчика эталонной частоты соединенпчерез второй элемент ИЛИ с входом установка нуля триггера.This goal is achieved by the fact that in the device for measuring the average pulse repetition rate, comprising a pulse generator Ιθ of the reference frequency, connected through the first element and to the counting inputs of the auxiliary counter and the reference frequency counter, a trigger, the direct output of which is connected to the control input of the first and second element And, the output of the second element And is connected to the counting input of the counter of the measured frequency and through the first element OR to the input setting is zero ”auxiliary counter, and the input of the second cient and connected to the first input of the third AND gate, a second input coupled to an inverted output ^- a trigger bus coupled to Zeroing sootvetst25 vuyuschimi counters inputs and the measured reference frequencies and the inputs of the first and second OR elements, and the fourth element, the element introduced OR- NOT, and the reference frequency counter is reversible, with the outputs of the third to and fourth elements AND through the OR-HE element connected to the counting input of the trigger, and the direct output of the trigger connected to the first input of the fourth element AND, the second input which is connected to a direct output of the auxiliary counter and the first control input of the reversible counter 'reference frequency, a second control input coupled to an inverted output of the auxiliary counter, counter output reference frequency soedinenpcherez second OR gate with an input trigger setting zero.

На фиг. 1 представлена блок-схема устройства; на фиг. 2 - временные диаграмма, поясняющие работу устройства.In FIG. 1 shows a block diagram of a device; in FIG. 2 is a timing chart explaining the operation of the device.

Устройство для измерения частоты следования импульсов содержит генератор 1 импульсов эталонной частоты, реверсивный счетчик 2 эталонной частоты, вспомогательный счетчик 3, счетчик 4 измеряемой частоты, триггер 5, элемент 6 ИЛИ-HE, элементы 7-10 И, элементы 11 и 12 ИЛИ, шины и 14 входа. Триггер 5 выполнен на элементах 15-22 И-НЕ.The device for measuring the pulse repetition rate comprises a reference frequency pulse generator 1, a reverse frequency counter 2, an auxiliary counter 3, a measured frequency counter 4, trigger 5, element 6 OR-HE, elements 7-10 AND, elements 11 and 12 OR, buses and 14 entrances. The trigger 5 is made on the elements 15-22 AND NOT.

Устройство работает следующим образом.The device operates as follows.

В исходном состоянии по управляющей шине 14 входа на устройство поступает сигнал уровнем логической 1, который устанавливает все разряда счетчиков 2 и 4 (через элемент 12 ИЛИ) счетчика 3 в обнуленное состояние, а также (через элемент 11 ИЛИ) на соединенные входы R, J, К триггера 5. При наличии сигнала уровнем логической 1 на соединенных входах J-K, вход триггера 5 блокируется и он не реагирует на входные тактовые импульсы, поступающие на вход Т. Сигнал уровнем логическая 1 на входе R основного трактируемого триггера устанавливает его в состояние ”0, и так как элементы и 21 открыты (отсутствуют сигналы 45 с выходов элементов 15 и 19) осуществляется Запись информации из основного триггера во вспомогательный, т.е. на прямом выходе 2 триггера 5 устанавливается сигнал уров- < нем логический 0. Таким образом, устройство принимает исходное состояние.In the initial state, a logic level 1 is supplied to the device via the control bus 14 of the input, which sets all the discharges of the counters 2 and 4 (through the OR element 12) of the counter 3 to the zero state, and also (through the 11 OR element) to the connected inputs R, J , K of trigger 5. If there is a signal with logic level 1 at the connected inputs JK, the input of trigger 5 is blocked and it does not respond to input clock pulses received at input T. A signal with logic 1 at input R of the main interpreted trigger sets it to the state ”0 and that and the elements 21 are open (no signals 45 from the outputs of elements 15 and 19) to record data from the main to the auxiliary trigger, i.e. at direct output 2 of trigger 5, a signal of level <logical 0 is set. Thus, the device assumes the initial state.

По команде Измерение сигнал уровня логическая ”1 снимается с шины входа. С этого момента времени снимается блокировка триггера 5 по входам J-K, снимаются сигналы обнуления счетчиков 2-4 и устройство готово к приему первой пачки импульсов измеряемой частоты.By the command Measurement the level signal is logical ”1 is removed from the input bus. From this moment in time, the trigger 5 lock on the J-K inputs is released, the zeroing signals of the 2-4 counters are removed, and the device is ready to receive the first packet of pulses of the measured frequency.

Импульсы измеряемой частоты (U_Eна фиг. 2) через открытый элемент 10 И, схему 6 ИЛИ-HE поступают на счетный вход (U_B на фиг. 2) триггера 5. Так как триггер 5 по счетному входу запускается только положительным перепадом напряжения, то он переходит в состояние 1 в момент окончания первого импульса измеряемой частоты (и_г на фиг. 2). с этого момента времени сигнал уровнем логического 0 с инверсного выхода триггера 5 закрывает элемент 10 И и последующие импульсы измеряемой частоты не воздействуют на триггер 5. Напряжение уровнем логическая 1 с прямого выхода триггера 5 открывает · элементы 7-9 И и на счетные входы счетчиков 2 и 3 поступают импульсы эталонной частоты от генератора 1 (1)_д на фиг. 2) , Так как элементы 7-9 И открываются триггером 5 в момент окончания первого импульса измеряемой частоты, то на счетный вход счетчика 4 поступают импульсы измеряемой частоты, начиная со второг.о импульса (U_e на фиг. 2). в этом случае счетчик 4 считает количество периодов измеряемой частоты в пачке, т.е. не регистрирует первый импульс начала измерения.The pulses of the measured frequency (U _E in Fig. 2) through the open element 10 AND, circuit 6 OR-HE are fed to the counting input (U _B in Fig. 2) of trigger 5. Since trigger 5 at the counting input is triggered only by a positive voltage drop, then it goes into state 1 at the end of the first pulse of the measured frequency (and _r in Fig. 2). from this moment in time, a signal with a logic level of 0 from the inverted output of trigger 5 closes element 10 AND and subsequent pulses of the measured frequency do not affect trigger 5. Voltage level logic 1 from the direct output of trigger 5 opens elements 7-9 I and to the counting inputs of counters 2 and 3, reference frequency pulses from the generator 1 (1) _d in FIG. 2), since the elements 7-9 And are opened by trigger 5 at the moment of the end of the first pulse of the measured frequency, then the pulses of the measured frequency, starting from the second pulse (U _e in Fig. 2), are sent to the counting input of the counter 4. in this case, counter 4 counts the number of periods of the measured frequency in the packet, i.e. does not register the first pulse of the start of measurement.

Одновременно на управляющий вход Установка нуля вспомогательного счетчика 3 поступают импульсы измеряемой частоты, каждый импульс которой обнуляет его, причем на все время воздействия импульса сброса счетчик 3 находится в обнуленном состоянии. Емкость счетчика 3 выбирается такой, чтобы за время отсутствия импульса сброса он заполнялся импульсами эталонной частоты менее чем на половину (N-j на фиг. 2) . С момента окончания последнего импульса пачки, счетчик 3 заполняется импульсами эталонной частоты, а счетчик 2 до определенного момента времени суммирует (N₂ на фиг. 2), а потом вычитает эти импульсы.At the same time, the measured frequency pulses are received at the control input Zeroing the auxiliary counter 3, each pulse of which zeroes it, and the counter 3 is in the reset state for the entire duration of the reset pulse. The capacity of the counter 3 is selected so that during the absence of a reset pulse it is filled with pulses of the reference frequency by less than half (Nj in Fig. 2). From the moment the last burst pulse ends, the counter 3 is filled with pulses of the reference frequency, and the counter 2 sums up to a certain point in time (N ₂ in Fig. 2), and then subtracts these pulses.

Когда емкость вспомогательного счетчика 3 заполнена на половину, т.е. в него занесено количество импульсов равное 2^11-4 (где η - количество двоичных разрядов в счетчике 3), триггер старшего разряда счетчика 3 изменяет свое состояние и переключает реверсивный счетчик 2 в режим вычитания. С этого момента из счетчика 2 вычитаются импульсы (NjHa фиг. 2) и это продолжается до тех пор, пока вспомогательный счетчик 3 не переполнится. Переполнение счетчика 3 происходит после занесения в него количества импульсов, равного 2 ¹¹ ,. в результате чего триггер старшего разряда счетчика 3 вновь изменяет свое состояние и переключает счетчик 2 в режим сложения. Прямоугольный импульс (и^ фиг. 2), сформированный на выходе вспомогательного счетчика 3, пройдя через открытый элемент 9 И, схему 6 ИЛИ-НЕ своим задним фронтом переводит по счетному входу триггер 5 в нулевое исходное состояние (U₂ на фиг. 2). Элементы 7-9 Й закрываются, а элемент 10 И открывается - в устройст⁴ве закончился процесс измерения частоты импульсов первой пачки. За время нахождения триггера старшего разряда счетчика 3 в состоянии “1 (счетчик 2 включен в режим вычитания) , из счетчика 2 вычлись все импульсы, занесенные в него с момента окончания последнего импульса пачки (Up на фиг. 2) измеряемой частоты.When the capacity of the auxiliary counter 3 is half full, i.e. it contains the number of pulses equal to 2 ^11-4 (where η is the number of binary bits in the counter 3), the trigger of the highest bit of the counter 3 changes its state and switches the reverse counter 2 to the subtraction mode. From this moment, pulses are subtracted from counter 2 (NjHa of FIG. 2) and this continues until the auxiliary counter 3 overflows. Counter 3 overflow occurs after entering the number of pulses equal to 2 ¹¹ ,. as a result, the high-order trigger of counter 3 changes its state again and switches the counter 2 to the addition mode. A rectangular pulse (and ^ of Fig. 2) generated at the output of the auxiliary counter 3, passing through the open element 9 AND, the circuit 6 OR-NOT with its trailing edge translates the trigger 5 to the zero initial state at the counting input (U ₂ in Fig. 2) . Elements 7-9 th are closed, and element 10 And opens - in device ⁴ ve the process of measuring the frequency of the pulses of the first packet has ended. During the time when the trigger of the high order of counter 3 was in the state “1 (counter 2 is included in the subtraction mode), all pulses entered into it from the moment the last pulse of the packet (Up in Fig. 2) of the measured frequency were subtracted from counter 2.

Таким образом, за цикл измерения 'одной пачки в счетчик 4 занесено количество импульсов, равное сумме периодов импульсов в измеряемой пачке, а в счетчике 2 - количество им-’ пульсов, пропорциональное сумме периодов импульсов измеряемой частоты в этой пачке.Thus, for the measurement cycle of one burst, the number of pulses equal to the sum of the pulse periods in the measured packet is recorded in counter 4, and the number of pulses proportional to the sum of the pulse periods of the measured frequency in this packet is recorded in counter 2.

При поступлении на вход устройства следующих пачек импульсов измеряемой частоты работа устройства происходит аналогично описанному, причем этот процесс повторяется до тех пор, пока в счетчик 2 не занесено определенное наперед заданное количество импульсов эталонной частоты, например N_o. При занесении в счетчик 2 количества N импульсов на его выходе происходит изменение сигнала с 0 на 1.Upon receipt of the following bursts of pulses of the measured frequency at the input of the device, the operation of the device occurs as described, and this process is repeated until a predetermined predetermined number of pulses of the reference frequency, for example, N _o , is entered. When the number of N pulses is recorded in counter 2, the signal changes from 0 to 1 at its output.

Этот сигнал уровнем логической 1” по управляющему входу устанавливает (переключает) триггер 5 в нулевое состояние, при котором элементы 7-9 И закрываются, элементы 10 И открываются. На этом процесс измерения полностью заканчивается и триггер 5 остается в нулевом состоянии, из-за наличия сигнала уровнем логической ”1 на его управляющем входе.This signal with a logic level of 1 ”at the control input sets (switches) trigger 5 to the zero state, in which elements 7-9 AND are closed, elements 10 AND are opened. This completes the measurement process and trigger 5 remains in the zero state, due to the presence of a signal with a logic level of “1 at its control input.

Таким образом,, за время измерения NoThus, during the measurement No

Т_о = -j— = N_o Т_эт (где f_?T - частота генератора 1), счетчик 4 регистрирует количество периодов импульсов измеряемой частоты всех измеренных· пачек.T _o = -j— = N _o T _et (where f _{? T} is the frequency of the generator 1), counter 4 registers the number of periods of pulses of the measured frequency of all measured · packs.

Так как счетчик 3 обнуляется каждым импульсом измеряемой частоты, то его показания N3 в конце времени измерения равно числу импульсов эталонной частоты, поступивших на счетчик 3 от момента прихода последнего импульса измеряемой частоты до конца измерения. По величине N 3 можно с точностью до периода эталонной частоты Т_эт определить суммарную длительность Т ·£ всех N* периодов измеряемой частотыSince the counter 3 is reset to zero by each pulse of the measured frequency, then its readings N3 at the end of the measurement time is equal to the number of pulses of the reference frequency received at the counter 3 from the moment the last pulse of the measured frequency arrives until the end of the measurement. From the value of N 3 it is possible, up to a period of the reference frequency T _et , to determine the total duration T · £ of all N * periods of the measured frequency

Тв = То- Ν₃Τ₃τTV = T- Ν ₃ Τ ₃ τ

Измеряемая частота равна отношению числа полных периодов к их суммарной длительности f - —ИХ--*The measured frequency is equal to the ratio of the number of full periods to their total duration f - —EX — *

Благодаря точному измерению суммарной длительности целого числа периодов измеряемой частоты предлагаемое устройство позволяет с заданной точностью в широком диапазоне частот измерять частоту следования непрерывной последовательности импульсов, одной пачки и серии пачек самых различных длительностей.Due to accurate measurement of the total duration of an integer number of periods of the measured frequency, the proposed device allows with a given accuracy in a wide range of frequencies to measure the repetition rate of a continuous sequence of pulses, one burst and a series of bursts of various durations.

Claims

The invention relates to a measurement technique and can be used in digital devices to measure the average pulse frequency in a packet or in a series of packets and pulses, as well as the pulse frequency of a continuous sequence of pulses. A device for measuring the average frequency is known, which contains three counters, elements AND, the generator of this ion frequency l}. The disadvantages of this device are an increase in measurement error with a large number of packs in one dimension and limited functionality. The closest to the proposed technical solution is a device for measuring frequency, containing counters, elements AND, trigger frequency reference generator 2. However, this device is much more complicated and has an additional measurement error due to the instability (spread) of the end of the measuring time interval from the packet measured pulses. This instability is obtained by asynchrony of the pulses of the measured and reference frequency. The purpose of the invention is to improve the measurement accuracy. The goal is achieved in that a device for measuring the average pulse frequency, containing a reference frequency generator, connected via the first element I to the counting inputs of an auxiliary counter and a reference frequency counter, has a trigger, the forward output of which is connected to the control input of the first and second element AND, the output of the second element AND is connected to the counting input of the meter of the measured frequency and through the first element OR to the input the zero setting of the auxiliary counter, and the input of the second element A and connected to the first input of the third AND gate, a second input coupled to an inverted output of the flip-flop, the tire Installation zero sootvetstvuyuschiASh connected to the input of the counter and the measured reference frequencies and the inputs of the first and second OR elements, the fourth element. And, an OR-NOT element is entered, and the reference frequency counter is reversible, with the outputs of the third and fourth elements AND connected through the OR input element to the counting trigger input, and the direct output of the three hera is connected to the first input of the fourth element And, the second the input of which is connected to the output of the auxiliary counter and the first control input of the reversible counter of the reference frequency, the second control input of which is connected to the inverse output of the auxiliary counter, the output of the reference frequency counter is connected; ( A second OR element with an input is a trigger zero setting, Fig. 1 is a block diagram of the device, and Fig. 2 is a timing diagram1F1 explaining the operation of the device.The device for measuring the pulse frequency includes a generator of 1 pulses of the reference frequency reversible counter 2 of the reference frequency frequencies, auxiliary counter 3, counter 4 of the measured frequency, trigger 5, element 6 OR-NOT, elements 7-10 AND, elements 11 and 12 OR, input buses 13 and 14. Trigger 5 is executed on elements 15-22 AND-NOT. The device works as follows. In the initial state, the control bus 14 of the input to the device receives a signal by the logic level 1, which sets all bits of the counter 2 VI A (through element 12 or) of counter 3 to zero, and also (through element 11 or ) to the connected inputs R, J, K of the trigger 5. If there is a signal of logical level 1 on the connected inputs JK, the input of the trigger 5 is blocked and it does not respond to the input clock pulses fed to the input T. The signal level logical 1 at the input R of the main the interpreted trigger sets it to the state O, and t As the elements 17 and 21 are open (the signal C of the outputs of the elements 15 and 19 is missing) the information from the main trigger to the auxiliary is recorded. on the direct output 2 of the trigger 5, the signal is set to a logic level O. Thus, the device assumes the initial state. . At the command Measurement, the signal ur n logical 1 is removed from the bus 14 of the input. From this moment in time, the blocking of the trigger 5 is removed by the inputs J-K, the zeroing signals of the counters 2-4 are removed and the device is ready to receive the first batch of pulses of the measured frequency. The pulses of the measured frequency (Ug in Fig. 2) through the open element 10 I, the circuit 6 OR-NOT arrive at the counting input (Ug in Fig. 2) of the trigger 5. Since the trigger 5 at the counting input is triggered only by a positive voltage drop, then it enters state 1 at the moment when the first pulse of the measured frequency ends (Up in Fig. 2). From this point in time, the signal by the logic level O from the inverted output of the trigger 5 closes element 10 I and subsequent pulses of the measured frequency do not affect trigger 5. The voltage level of logical 1 from the direct output of trigger 5 opens elements 7-9 AND and the counting inputs counters 2 and 3 are received pulses of the reference frequency from the generator 1 (CD in Fig. 2). Since elements 7-9 AND are opened by trigger 5 at the moment when the first pulse of the measured frequency ends, pulses of the measured frequency arrive at the counting input of counter 4, starting from the second pulse (Ue in Fig. 2). in this case, counter 4 counts the number of periods of the measured frequency in the packet, i.e. does not register the first pulse of the start of measurement. At the same time, the control input for setting the zero of the auxiliary counter 3 receives pulses of the measured frequency, each pulse of which nullifies it, and for the entire duration of the effect of the reset pulse the counter 3 is in the zero state. The capacity of the counter 3 is chosen such that during the absence of the reset pulse it is filled with pulses of the reference frequency of less than half (N-1 in Fig. 2). From the moment the last pulse of the stack ends, the counter 3 is filled with the pulses of the reference frequency, and the counter 2 to a certain point in time sums up (NJ in Fig. 2), and then subtracts these pulses. When the capacity of the auxiliary counter 3 is half full, i.e. it contains the number of pulses equal to (where n is the number of binary bits in counter 3), the trigger of the high bit of counter 3 changes its state and switches the reversible counter 2 to subtract mode. From this point onwards, pulses are subtracted from counter 2 (N2 in FIG. 2) and this continues until sub-counter 3 overflows. Counter 3 overflows after entering the number of pulses equal to 2,. as a result, the trigger of the higher bit of the meter 3 changes its state again and switches the counter 2 to the addition mode. A rectangular pulse (and Fig. 2), formed at the output of the auxiliary counter 3, passed through the open element 9 AND, the b OR-NOT scheme, with its falling edge, converts the trigger 5 to the zero initial state via the counting input (U in Fig. 2) . Elements 7-9 I are closed, and element 10 I is opened, the device has finished the process of measuring the frequency of the pulses of the first packet. During the time when the most significant trigger of counter 3 is in state 1 (counter 2 is in subtraction mode), all pulses stored in it from count 2 since Up the last pulse of the packet (Up in Fig. 2) of the measured frequency have been subtracted. . Thus, during the measurement cycle of one bundle, the number of pulses in the counter 4 is equal to the sum of the periods of the pulses in the measured packet, and in the counter 2 - the number of pulses proportional to the sum of the periods of the pulses of the measured frequency in this packet. When a pulse of measured frequency pulses arrives at the device input, the device operates as described above, and this process repeats until a predetermined number of reference frequency pulses, for example Ng, are recorded in counter 2. When entering into the counter 2 the number of N pulses at its output, the signal changes from 0 to 1. This signal, by logic level 1 at the control input, sets (switches) trigger 5 to the left state, in which elements 7-9 AND close, elements 10 and open. This completes the measurement process and the trigger 5 remains in the zero state, due to the presence of a signal with a logic level 1 at its control input. Thus, during the measurement time NO Tg -j- (where is the frequency of oscillator 1), the counter 4 records the number of pulse periods from the measured frequency of all the measured packs. Since counter 3 is nullified with each pulse of the measured frequency, its readings Me at the end of the measurement time is equal to the number of pulses of the reference frequency received at counter 3 from the moment of arrival of the last pulse of the measured frequency to the end of the measurement. According to the N-3 value, it is possible to determine the total duration Tjj of all Nj (periods of the measured frequency Tc To –MtTet measured frequency equal to the ratio of the number of full periods to their total duration, up to the period of the reference frequency Tet). Thanks to precise measurement of the total duration of the integer The measured frequency permits the proposed device to measure with a given accuracy in a wide range of frequencies, the following frequency of a continuous sequence of pulses, one pack and a series of packs of the most various durations Formula of Invention Device For measuring the average pulse frequency, comprising a pulse generator, a reference frequency, connected via the first element AND to the counting inputs of an auxiliary counter and a reference frequency counter, a trigger, whose direct output is connected to the control input of the first and second element , the output of the second element AND is connected to the counting input of the meter of the measured frequency and through the first element OR to the input Setting zero of the auxiliary counter, and the input of the second element AND is connected the first input of the third element And, the second input of which is connected to the inverse output of the trigger, bus Set zero is connected to the corresponding inputs of counters of the reference and measured frequencies and to the inputs of the first and second elements OR, the fourth element AND, differing in that increase the accuracy of measurement, an OR-NOT element is inserted into it, and the reference frequency counter is reversible, the outputs of the third and fourth elements AND are connected through the OR input element to the counting trigger input, and the forward output of the trigger is The first input of the fourth element I, the second input of which is connected to the forward output of the auxiliary counter and the first control input of the reversible counter of the reference frequency, the second control input of which is connected to the inverse output of the auxiliary counter, the output of the counter of the reference frequency is connected through the second element OR to input setting zero trigger. Sources of information taken into account in the examination 1. USSR author's certificate number 524139, cl. G 01 R 23/02.

2. USSR author's certificate for application number 2644441, cl. G 01 R 23/02.