RU2010243C1 - Meter of speed of linear change of frequency inside pulse - Google Patents

Abstract

FIELD: digital radio measurement technology. SUBSTANCE: meter of speed of linear change of frequency inside pulse has former 1, control and synchronization unit 2, two digital delay lines 3 and 5, two reversible counters 4 and 6, (n+1) AND gates 7 and 9, subtracter 8, single-shot multivibrator 10 with proper couplings. EFFECT: improved accuracy. 2 dwg

Description

 The invention relates to digital radio measurement technology and can be used to control and measure the rate of change of frequency within a pulse.

 A device is known (V. Likharev. Digital methods and devices in radar. - M.: Sov. Radio, 1973, p. 108, fig. 2.12 and p. 100, fig. 2.8), which contains a quantizer at two levels connected by an input with the input signal bus, and the output through the shaper with the input of the digital delay line and with the summing input of the reversing counter, the output of the digital delay line being connected to the subtracting input of the reversing counter, and the clock input being connected to the output of the control and synchronization unit, the outputs of the reversing counter being connected via The output device to the output buses.

 This device allows you to evaluate the current value of the frequency of filling the signal with an intrapulse frequency modulation (chirp signal), but its disadvantage is the low accuracy of the measurement.

 A device is known (ed. St. USSR 1503023, class G 01 R 23/00, 08/23/89), containing an electronically counting frequency meter, consisting of a block of frequency dividers, two counters of a reversible type, a memory register, an indicator, an overwrite pulse generator, a reset pulse shaper, a switch, two switching pulse shapers and two control pulse shapers.

 However, the disadvantage of this device is the low accuracy of measuring the rate of change of the frequency of the chirp signal.

 A device is known which is a prototype (ed. St. USSR 1449924, class G 01 R 23/00, 01/07/89), containing an input driver, the output of which is connected to the counting inputs of the first and second counting channels, each containing a series-connected selector, counter and a buffer register, moreover, the selecting inputs of both channels are connected to the corresponding outputs of the counting time shaper containing a reference oscillator, a ten-day frequency divider and a gate generator, the outputs of which are respectively the first one is the second output of the counting time shaper, the one-shot code rewriter, the input of which is connected to the second output of the counting time shaper, and the output is connected to the control input of the buffer register of the second channel, the one-shot reset pulse, the output of which is connected to the zeroing counter input of the second channel, the subtraction unit which is connected to the indicator, as well as the second one-shot of the code coding, the second one-shot of the reset pulse, the trigger, two switches, and the input of the second one-shot of the census of the code the first output of the counting time generator, and the output is connected to the input of the second one-shot reset pulse, to the R input of the trigger and to the control input of the buffer register of the first counting channel, the output of the second one-shot reset pulse is connected to the zeroing input of the counter of the first counting channel, the output of the first one-shot code rewriter connected to the input of the first one-shot reset pulse and to the S-input of the trigger, the direct output of the trigger is connected to the control input of the first switch, the first information input of which is connected is connected with the direct output of the first buffer register, and the second with the inverse output of the second buffer register, the inverse trigger output is connected to the control input of the second switch, the first information input of which is connected to the direct output of the second buffer register, the second information input is with the inverse output of the first buffer register , the outputs of the switches are connected respectively to the first and second outputs of the subtraction unit.

 However, this device has low accuracy in measuring the rate of change of the frequency of the chirp signal.

 The aim of the invention is to improve the accuracy of measuring the magnitude of the speed of a linear change in frequency within the pulse.

 The goal is achieved by the fact that in the speed meter of a linear change in frequency inside the pulse, containing a forming unit, the information input of which is connected to the input signal bus, two counters and a subtraction unit, a control and synchronization unit, two digital delay lines, N + 1 AND elements, and the multivibrator standby unit, while the counters are reversible, the output of the forming unit is connected to the summing input of the first reversing counter and the input of the first digital delay line, the output of which is connected to the subtracting the first counter, summing the input of the reverse counter and the input of the second digital delay line, the output of which is connected to the subtracting input of the second reversing counter and the first input of the (N + 1) th AND element, the output of which is connected through the block of the waiting multivibrator to the second inputs of And elements with the first through the Nth, the outputs of the first and second reversible counters are connected respectively to the first and second groups of inputs of the subtraction unit, the outputs of which from the first to the Nth are connected to the first inputs of the corresponding elements AND, the outputs to toryh meter connected to the outputs, the first output of the control unit and synchronization is connected to a control input forming unit, and the second output - with the clock inputs of the first and second digital delay line and a second input (N + 1) -th element I.

 Comparison of the proposed technical solution with the prototype and analogues allows us to conclude that it meets the criterion of novelty and has significant differences. A positive effect is achieved through the introduction of these additional nodes, which allows to increase the accuracy of measuring the magnitude of the speed of a linear change in frequency inside the pulse.

 In FIG. 1 shows a block diagram of a meter measuring the speed of a linear change in frequency within a pulse; in FIG. 2 shows the timing diagrams of his work.

 The linear frequency change rate meter inside the pulse contains a quantization and generation unit 1 connected by an information input to the input signal bus, controlling the input with the corresponding output of the control and synchronization unit 2, and the output with the input of the digital delay line 3 and the summing input of the reversible counter 4. Output the digital delay line 3 is connected to the subtracting input of the reverse counter 4, with the input of the digital delay line 5 and the summing input of the reverse counter 6, which synchronizes the input of the digital line and 3 delays are connected to the corresponding output of the control and synchronization unit 2, and the output of the digital delay line 5 is connected to the subtracting input of the reversing counter 6 and to the first input of circuit I. 7. The outputs of the reversing counters 4 and 6 are connected to the corresponding inputs of the subtracting unit 8, each of N outputs of which are connected to the first inputs of each of the N circuits AND 9. The outputs of the latter are N outputs of the meter, and their second inputs are combined and connected through block 10 of the standby multivibrator to the output of circuit And 7, the second input of which is connected to the clock iziruyuschim input of second digital delay line 5 of howling and the corresponding output of the control unit 2, and synchronization.

 The meter operates as follows.

 Suppose that all digital nodes are set to zero, and zeros are recorded in all digital delay lines.

Этот сигнал по входной шине поступает на вход блока 1 квантования и формирования, на выходе которого появляются сигналы в виде последовательности нулей и единиц. Положим, что единицам соответствуют положительные значения действительной части экспоненты, а нулям - отрицательные. При этом в блоке 1 происходит формирование сигналов, моменты появления которых во времени на выходе блока 1 синхронизированы с моментами времени синхроимпульсов, поступающими из блока 2 на управляющие входы цифровой линии 3 задержки с частотой, выбираемой из условия выполнения теоремы Котельникова, т. е. с частотой не менее 2f_макс. При этом согласовывается асинхронный режим поступления входных импульсов с синхронным режимом работы цифровых узлов так, чтобы на каждые полпериода несущей частоты входного ЛЧМ-сигнала вырабатывался один импульс, который записывается одновременно по сигналу синхроимпульса из блока 2 в линию 3 задержки и реверсивный счетчик 4, как показано на фиг. 2б. Максимальное время задержки в линиях 3 и 5 Δt< 0,5T_и. Поступающие на вход линий ≈3 задержки сигналы продвигаются вдоль нее под действием синхросигналов, поступающих с выхода блока 2.Suppose that at the instant t _o at the meter inlet (FIG. 2a) enters a chirped signal with an unknown center frequency f _x, located within the range f _max -f _min and unknown speed of change of M _x signal duration time T _and which can be written as
U (t) =

This signal is fed through the input bus to the input of quantization and formation block 1, at the output of which signals appear as a sequence of zeros and ones. Suppose that the units correspond to the positive values of the real part of the exponent, and the zeros correspond to negative ones. At the same time, in block 1, signals are generated, the instants of which in time at the output of block 1 are synchronized with the time instants of the clock pulses coming from block 2 to the control inputs of the digital delay line 3 with a frequency selected from the condition of Kotelnikov’s theorem, i.e. at least 2f _max . At the same time, the asynchronous input pulse arrival mode is synchronized with the digital nodes synchronous operation mode so that for each half-period of the carrier frequency of the input LFM signal, one pulse is generated, which is recorded simultaneously from the synchronization pulse from block 2 to delay line 3 and a reverse counter 4, as shown in FIG. 2b. The maximum delay time in lines 3 and 5 is Δt <0.5T _and . The signals arriving at the input of ≈3 delay lines move along it under the influence of clock signals coming from the output of block 2.

At the same time, these signals are fed to the summing input of the reverse counter 4, which begins to count the number of periods of the input oscillation. At each current point in time t, where t _o ≅ t ≅ t _o + Δ t, counter 4 contains a code proportional to the integer number of periods of high-frequency filling. At time t = t _o + Δ t at the output of line 3 there is a signal delayed by time Δt (Fig. 2c), which is fed to the second delay line 5, to the subtracting input of counter 4 and summing the input of counter 6. The line 5 has time the delay is also equal to Δ t. At its summing input, synchronizing pulses from the output of block 2 are received with the same clock frequency, which shift the signal pulses along this delay line. At times t _o + Δt <t <t _o + + 2 Δ t at the outputs of counter 6 is a code proportional to the number of periods of high-frequency filling.

At the same time, counter 4 contains a code equal to the frequency difference of the signals at its inputs, i.e., a code proportional to
{2Πf _x (t ₀ + Δt + t) + 0.5M _x (t ₀ + Δt + t) ² } - {2Πf _x (t ₀ + Δt) + 0.5M _x (t ₀ + t) ² } =
= 2Πf _x Δt + M _x t ₀ Δt + 0.5M _x Δt ² + M _x t ₀ t. the value of which increases with increasing time t. Obviously, the maximum value of the code that can be stored in the counter 4, depends on the values of T and f _{max and} determines the requirements for its bit depth.

At the time t = t _o + 2Δt (Fig. 2d), the signal pulse reaches the end of the delay line 5 and is fed to the subtracting input of the counter 6 and to the input of the circuit 7. At this time, a code proportional to the difference in the signal frequencies appears at the outputs of the counter 6 at its inputs, i.e., a code proportional to
{2Πf _x (t ₀ + Δt) + 0.5M _x (t ₀ + Δt) ² } - {2Πf _x t ₀ + 0.5M _x (t $\genfrac{}{}{0ex}{}{\text{2}}{\text{0}}$ } =
= 2Πf _x + M _x t ₀ Δt + 0.5M _x Δt ² .

At the same time, counter 4 contains a code equal to the frequency difference of the signals at its inputs, i.e., a code proportional to
{2Πf _x (t ₀ + 2Δt) + 0.5M _x (t ₀ + 2Δt) ² } - {2Πf _x (t ₀ + Δt) + 0.5M _x (t ₀ + Δt) ² } =
= 2Πf _x Δt + M _x (t ₀ + Δt) Δt + 0.5M _x Δt ² = 2Πf _x Δt + M _x t ₀ Δt + 1.5M _x Δt ² .

The obtained values from the outputs of the counters 4 and 6 in the form of parallel digital codes are fed to the inputs of the subtraction unit 8. A code is generated at the outputs of this block, the value of which is proportional to the difference of the codes of numbers received from the outputs of counters 4 and 6, and which is equal to
{2Πf _x Δt + M _x t ₀ Δt + 1.5M _x Δt ² } - {2Πf _x Δt + M _x t ₀ Δt + 0.5M _x Δt ² } = M _x Δt ² .

At the same time, at the time t = t _o + 2Δ t, the signal pulse coincides with the pulse from the output of block 2 at the inputs of circuit I 7, and a signal appears on its output (Fig. 2e), which is fed to the input of block 10 of the waiting multivibrator, at the output of which after a time ΔT equal to the calculation time in the block 8 subtracting the difference code, an enable signal appears (Fig. 2e). This signal is fed to the inputs of AND 9 circuits connected together, at the second inputs of which is the result of calculating the difference code from the outputs of the subtraction unit 8, which appears at the outputs of the meter (Fig. 2g).

The duration of the signal from the output of the unit 10 of the standby multivibrator, which determines the duration of the code at the output of the meter, can be selected less than or equal to the value of T _and -2 Δt- ΔT. At the end of the signal at the output of block 10 of the standby multivibrator, this block is ready for operation after a time interval of 4 Δ t.

Since the value of the delay time Δt in lines 3 and 5 is a predetermined value and constant (Δ t = const), it can be written that the unknown quantity M _{x is} determined with a scale factor C = Δ t ² . In the case of Δ t = 1, the code at the output of AND 9 is directly proportional to the unknown value M _x . Since the algebraic sum in the exponent of the complex exponent is used in the above expressions, then in the case when the value of M _x has the opposite sign, the operation of the meter is similar to that described previously, except that there is an And 9 circuit determining the sign at the output. When the slope of the LFM signal changes during the measurement (V-shaped LFM signal), the sign at the output of this AND 9 circuit will change.

At the moment of time t = t _o + T _and , i.e., when the chirp signal ends, the signals no longer arrive at the summing input of counter 4 and the code value in it begins to decrease. Simultaneously with the output of block 10 of the standby multivibrator, the enable signal to the I 9 circuit stops coming. This signal may end earlier than the analyzed signal. Block 10 standby multivibrator can be controlled from block 2 control and synchronization.

At time t = t _o + T _and + Δ t, counter 4 returns to its initial state, and in counter 6, the code value begins to decrease. At time t = t _o + T _and + 2Δ t, counter 6 returns to its initial state, zeros are recorded in delay lines 3 and 5, circuit 7 stops transmitting pulses from control and synchronization unit 2, and the meter is ready to accept the next LFM for processing signal.

Feasibility can be assessed by comparison with the prototype. Since the prototype does not have nodes that can measure the rate of change of the frequency of the chirp signal, the arrival times of which are not determined, then in cases where the analyzed signal does not fall into the time gates produced by the shaper of the counting time, an error occurs in determining the value of M _x . In the proposed meter, which is designed to analyze M _x single or rarely repeated signals, this effect is not. Therefore, it allows you to measure with higher accuracy in a wide range of frequencies and determine the type of frequency modulation by the type of parameter change, which indicates the high technical and economic efficiency of the proposed meter. (56) Copyright certificate of the USSR N 1503023, cl. G 01 R 23/00, 1989.

 USSR copyright certificate 1449924, cl. G 01 R 23/00, 1989.

Claims (1)

 SPEED METER OF LINEAR FREQUENCY CHANGE INSIDE THE PULSE, containing a forming unit, the information input of which is connected to the input signal bus, two counters and a subtracting unit, characterized in that, in order to increase accuracy, a control unit and two clocks are inserted into it; + 1 AND elements and a standby multivibrator unit, moreover, the counters are made in the form of reversible ones, the output of the forming unit is connected to the summing input of the first reversible counter and the input of the first digital delay line, the output of which din with the subtracting input of the first counter, summing the input of the second reversible counter and the input of the second digital delay line, the output of which is connected to the subtracting input of the second reversing counter and the first input of the (N + 1) second element, there is no other the inputs of the elements AND from the first to the Nth, the outputs of the first and second reversible counters are connected respectively to the first and second groups of inputs of the subtraction unit, the outputs of which from the first to the Nth are connected to the first inputs of the corresponding elements And, the outputs of which are connected to the outputs of the meter, the first output of the control and synchronization unit is connected to the control input of the forming unit, and the second output is connected to the synchronizing inputs of the first and second digital delay lines and the second input (I. + 1)

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