SU1172010A1 - Pulse-frequency phase-lock loop - Google Patents

Abstract

1. A FREQUENCY-PULSE AUTO-CONSTRUCTED FREQUENCY device containing two mixers, the first inputs that are combined and are the device input, the second inputs are connected to the quadrature outputs of the controlled generator, and the output of each through a low-pass filter is connected to the inputs of the auto-tuning error generator and the input the block of determining the square of the envelope of the signal, the output of which is connected to the input of the Schmidt trigger, as well as the serially connected block for estimating the instantaneous error frequency and the control block, Which is connected to the input of a controlled generator, characterized in that, in order to improve the measurement accuracy of the instantaneous flow rates, it additionally includes serially connected between one output of the pulse former and the input of the unit for estimating the instantaneous frequency of the first element OR, the second the input of which is connected to another output of the auto-tuning error pulse generator, the first delay element, the first RS trigger, the S input of which is connected to the output of the Schm trigger dta, and the second RS flip-flop, and between the output of the first element OR and the R-input of the second RS flip-flop, the first element And the second delay element, as well as the automatic control error connected in series between one output of the pulse driver and the input of the control unit readout, the second element And , a discrete filter and a third RS trigger, whose S input is connected to the second output of the discrete filter (a left filter, between the other output of the auto-tuning error pulse generator and the second input of the discrete filter, the third And element is turned on, and ezhdu second output diskh h retnogo filter and clock inputs of the block estimates the instantaneous frequency error, and the control unit included N0 second OR gate, the other input of the CCW torogo connected to the first output of the digital filter, wherein the second inputs of the first, second and third ° elements And are connected to the output of the first RS-flip-flop, 2. The device according to claim 1, characterized in that the unit for estimating the instantaneous error frequency contains a series-connected time interval meter and a permanent memory, and the control unit consists of a series-connected accumulating adder, inputs which is connected to information outlets

Description

A fixed memory and a D / A converter, the control inputs of the time interval meter, the persistent storage device and the accumulating adder are combined and are clock inputs, the other input of the time interval meter is the installation of O, and the other input of the accumulating adder is input of addition-subtraction .

The invention relates to a radio metering technique and is intended for receiving and processing signals from laser Doppler velocity meters for turbulent flow of a liquid or gas. The purpose of the invention is to improve the measurement accuracy of instantaneous flow rates. FIG. Figure 1 shows the structures on the electrical circuit of the frequency-pulse device for automatic frequency control; in fig. 2 - timing diagrams explaining the principle of operation of the device. The pulse-frequency auto-tuning device contains mixers 1 and 2, low-pass filters 3 and 4, a controlled generator shaper of 6 self-tuning error pulses (FIOA), block 7 determining the Schmidt trigger signal ( TSH) 8 first 9 and second 10 RS-triggers, first 11 second 12 and third 13 elements and first delay element 14, first element OR 15, second delay element 16, discrete filter (DF) 1 third RS-trigger 18, second element OR 19, unit 20 for estimating the instantaneous error rate, unit 21 of the control, meter 22 times there are intervals (IVI), read-only memory (ROM) 23, a cumulative adder 24, and a digital converter (D / A converter) 25. In the diagrams of FIG. 2 the following notation is adopted: A (t) is a single-frequency Doppler signal at the output of filters 3 and low frequencies; 8, (t}) is the pulse sequence at the output of the first element OR 15 at the moments of the transition of the Doppler signals through zero; SjCt) - the form of the signal at the output of TS 8; 8 (t) - the form of the signal at the output of the first RS-flip-flop 9; the pulse sequence at the output of the first element And 11; Sj (t) is the signal form at the output of the second RS flip-flop 10; O / (c) and 8-j (tj) - pulse sequences at the outputs of FIOA 6 in. the time of transition of orthogonal low-pass filter signals through zero bg (t) is the logical signal of the sign of the pulse sequences S / (t) and S (t) at the output of the third RS flip-flop 18; N (t) is the numerical value of the codes read from ROM 23 at the address configured in IVI 22; and y, is the control signal at the output of the DAC 25. The device operates as follows. The Doppler signal A (t) cos q (t), where A (t) is the envelope and ((t) - the phase of the oscillation is multiplied in mixers 1 and 2 by the oscillations sinCfyr t) cos ({i (.p (t), The oscillations with the difference phase KA (t) (t) -CpyrCt) and K A (t) (t) -qiyr (t) are extracted from the quadrature outputs of the controlled oscillator 5, and using filters 3 and 4 of the lower frequencies. block 7, determining the square of the signal envelope, both oscillations are squared and summed, which gives the square of the Doppler envelope) J, where Kj is the transmission coefficient of the circuits.

By transitions through zero quadrature oscillations, pulse sequences d (tj) and Sf (t,) are formed at the output of FIOA 6, which at the output of the first element OR 15 form a pulse sequence; (t.).

A signal blank 52 (t) is formed from the square envelope signal by the TS 8, in which the leading and trailing edges are blurred due to the multiple triggering from noise and residual pulsations of the second harmonic of the Doppler signal.

In addition, the first and last pulses S (tj) received from orthogonal signals (shown in Fig. 2 with solid and dashed lines) have low reliability due to the strong influence of noise, the uncertainty of the initial phase and the amplitude of oscillation. These pulses must be eliminated, since they do not carry information about the phase relationships of the signals. For this, the signal from the TS 8 is fed to the S input of the first RS flip-flop 9, and to its R input, the signal from the output of the first TIG 15 through the first delay element 14. . The form 8 (t) thus formed is fed to the first 11, second 12 and third 13 elements AND as a resolution signal. As a result, pulse sequences 4 (t), Sg (t;), Sj (tj) are formed. Using the sequence S (tj) of the second delay element 16 and the second RS flip-flop 10, a blank signal form (t) is generated. DF 17 eliminates the interlaced pulses that are characteristic of the fluctuations of the phase of the signal. Then using the third RS flip-flop 18 form a logical signal sign of the pulse

sequences Oi (ti) and S,. (t;) about 4 g t

The output pulse of the sequence is removed from the output of the second element OR 19.

In this way, additional filtering of the auto-tuning error pulses from the phase noise of the Doppler signal is achieved, and the blank of the signal oj (t), the pulse sequence §4 (tt) and the logic signal Su (t) are synchronized.

In IVI 22, a time interval code is formed (t ,. - t p &t; which is the address at which the data previously formed or written in ROM 23 is counted. A sample corresponds to each address (inversely proportional to the measured time interval r /, where K is a constant coefficient. If the phase shift during a t is equal to lf / 2, then the oscillation frequency of the Doppler signal at the output (liter 3 and 4 low frequencies is equal to ;. 1Л.

Therefore, the numerical value of the sample code is determined by the ratio is the estimate-iT

The instantaneous difference frequency of the input Doppler signal and the signal of the controlled oscillator 5. A sampling of frequency estimates are summed based on their sign in the accumulative adder 24 and converted in the DAC 25 into a control signal. The speed of movement of the circuit towards equilibrium in such a scheme is determined by the value of dso.

Due to the fact that the proposed device performs additional filtering of the pulse sequences of the auto-tuning error and their mutual synchronization over which then an estimate of the instantaneous frequency of the imbalance and sign is formed, the probability of tracking the Doppler signal frequency is significantly reduced and thereby increasing the reliability of the device.

FIG.

Claims (2)

1. FREQUENCY-PULSE AUTOMATIC FREQUENCY DEVICE, containing two mixers, the first inputs of which are combined and are the input of the device, the second inputs are connected to the quadrature outputs of the controlled oscillator, and the output of each through a low-pass filter is connected to the inputs of the auto-error pulse shaper and the inputs of the square definition block the envelope of the signal, the output of which is connected to the input of the Schmidt trigger, as well as the serially connected unit for estimating the instantaneous error frequency and the control unit, the output of which connected to the input of a controlled generator, characterized in that, in order to increase the accuracy of measuring the instantaneous flow rates, it is additionally introduced the first OR element, the second OR connected to the other output of the auto-error pulse former, the first delay element, the first RS-trigger, the S-input of which is connected to the output of the Schmidt trigger, and the second RS-tr ger, and between the output of the first OR element and the R-input of the second RS-trigger, the first And element and the second delay element, as well as the second And element, a discrete filter and the third RS -trigger, the S-input of which is connected to the second output of the discrete filter, the third element And is connected between the other output of the pulse shaper of the auto-tuning error and the second input of the discrete filter, and between the second output is a discrete the second filter OR, the other input of which is connected to the first output of the discrete filter, while the second inputs of the first, second, and third AND elements are connected to the output of the first RS trigger. 2. The device according to claim 1, characterized in that the unit for estimating the instantaneous error frequency comprises a series-connected time interval meter and read-only memory, and the control unit consists of a series-connected accumulating adder, the inputs of which are connected to the information outputs aU 1172010> a constant memory device and a digital-to-analog converter, the control inputs of a time interval meter, a constant memory device, and an accumulating adder are combined and are clock inputs, the other input of the time interval meter is the input of setting 0, and the other input of the accumulating adder is an addition-subtraction input.