SU1691766A1 - Wave-impulse frequency meter - Google Patents

Abstract

The invention relates to radio measurement technology and can be used to measure the carrier frequency of single and periodically repeated radio pulse signals. The aim of the invention is to expand the functionality. Radio pulse frequency meter contains adders 1 and 13, an envelope detector 2, amplifier 3 with automatic gain control, delay line 4, key 5, mixer b, low-pass filter 7, intermediate frequency amplifier 8, digital frequency meter 9, frequency divider 10, phase detector 11 , a frequency detector 12, a proportional-integrating filter 14, a local oscillator tuning element 15 16. Introducing additional nodes into the radio frequency counter allows you to expand its functionality by measuring the parameters of a single pulse lsa. 2 Il.

Description

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ON Os

The invention relates to a radio measuring technique and can be used to measure the carrier frequency of single and periodically repeated radio pulse signals.

The purpose of the invention is to expand the functionality.

Figure 1 shows the structural scheme of the radio frequency counter; Fig. 2 shows voltage diagrams illustrating the principle of its operation.

Radio pulse frequency meter contains the first adder 1, envelope detector 2, amplifier 3 with automatic gain control, delay line 4, key 5, mixer b, low pass filter 7, intermediate frequency amplifier 8, digital frequency meter 9, frequency divider 10, phase detector 11, frequency detector 12, second adder 13, proportional-integrating filter 14, local oscillator adjustment element 15, local oscillator 16

The first input of the first adder 1 is connected to the source of the radio pulse signal, the envelope detector 2 is connected to the first input of the first adder 1, the output of which is through an amplifier 3 with automatic gain control and a serially connected delay line 4 and the switch 5 is connected to the second input of the adder 1, this input the key 5 is connected to the output of the envelope detector 2, the output of the first adder 1 is connected to the first input of the mixer 6, the output of which is connected through a serially connected low-pass filter 7 and an amplifier 8 intermediate the frequency is connected to the input of a digital frequency meter 9, the output of the low-pass filter 7 is connected simultaneously to the first input of the phase detector 11 and to the input of the yy, digital detector 12, the output of the digital frequency meter 9 through the frequency divider 10 connected to the second input of the phase detector 11, phase detector outputs 11 and the frequency detector 12 are connected to the inputs of the second adder 13. An output connected via a series-connected integrating filter 14, a local oscillator tuning element 15 and a 16 local oscillator to the second mixer 6.

Radio pulse frequency meter works as follows.

The input single radio pulse signals Uc (t) (Fig. 2a) with carrier frequency fx are simultaneously fed to the first input of the first adder 1 and to the input of the envelope detector 2. From the output of the adder 1, the radio pulse signals are received through a series-connected amplifier 3 s

automatic gain control and a delay line 4 to the second input of the key 5, to the first input of which the output voltage of the envelope detector 2 is applied. Depending on the position of the key 5, these voltages are applied to the second input of the first adder 1,

As a result of repeated passage of a radio pulse signal through amplifier 3 with automatic gain control, delay line 4 and key 5, a periodic radio pulse U (t) with a period determined by the signal delay t3B of delay line 4 is formed from the single radio pulse signals (Fig.26). The amplitude of the radio pulse signals using amplifier 3 with automatic gain control is set to the same.

At the output of the adder 1, the pulse sequence continues for as long as key 5 is in the open state.

In general, this signal can be

present as

IgmTs cos (Us t - t3 (q-1). at t3 (q-1) t

t3 (q-l) + ru. Opris 13 (q-1) + TU t 3q,

where q 1,2,3, .., N is the number of radio pulses in the packet.

These radio pulses arrive at the first input of the mixer 6, the second input of which receives the harmonic signal Ur (t) Urcos Wr t from tunable to

the frequency of the local oscillator 16, covered by frequency-phase-locked loop,

Since the input signal is pulse-type, the output voltage of the low-pass filter 7 has the form of video pulses

the envelope of which corresponds to the readings of the voltage of the differential frequency (Fig. 2B). The voltage is in the form of a bundle of video pulses, while the key 5 is open in the time interval 0 t TB after several circulations,

equally

U (t) § jUcUr

(q-1) t3 -1 t- {o-1),

 + (q-1) X b

ABOUT)

where “v is the frequency of the local oscillator;

ftfc is the frequency of the input signal; ti is the duration of the radio pulse.

Thus, at the output of the low-pass filter 7, time-discretized time intervals with an interval of 3 and level quantized pulses are formed (Fig. 2d), the envelope of which has a beat frequency

SB (OC - 0) g.

The voltage generated over the period of the beat frequency at the output of the intermediate frequency amplifier 8 can be found after the inverse Laplace transform in the form

Ui (t) e Uc Ur D cos (o t + dr).

where a is the damping amplifier;

a 6 27r-f6 is the resonant frequency of the amplifier;

D is the signal amplitude dispersion.

At the output of the intermediate-frequency amplifier 8, a harmonic low-frequency process occurs. The digital frequency meter 9 operating in the period measurement mode can measure the duration of the response period Tb 2 l / soy TPR.

The reading of the digital frequency meter 9 operating in the period measurement mode is equal to

Nc m 5 m

fk

Tk f6

where fK is the 1 / TK frequency of a quartz digital frequency meter 9 used to generate quantization pulses that fill the Tx interval;

m is the number of averaged periods.

In order to stabilize the intermediate frequency in the proposed -frequency meter, as in the prototype, a frequency phase-locked loop is used, consisting of phase and frequency detectors 11.12 of the second adder 13, proportional-integrating filter 14 and heterodyne adjustment element 15.

The voltage according to the formula (1) is fed simultaneously to the first input of the phase detector 11 and to the input of the frequency detector 12. The signal generated from the quartz oscillator of the digital frequency meter 9 using the frequency divider 10 serves as the reference signal of the phase detector 11. The output voltages of the phase and frequency detector 11,12 are fed to the inputs of the second adder 13, the output voltages of which, after integration by the proportional-integrating filter 14, are fed to the input of the heterodyne tuning element 15, which leads to a change in the frequency of the heterodyne

16. In the capture and hold mode, fnp - fo and the voltage at the output of the frequency detector is zero. Since the frequency-phase-locked loop system contains a proportional-integrating filter 14, the zero voltage at the output of the phase detector 11 is possible only in steady state in the absence of changes in the measured frequency. In this case, the capture and hold mode is carried out only along the main channel, since fx f fe with fr fc. and the capture and retention of the mirror channel at fr fc is impossible, because the system of frequency-phase locked loop becomes unstable.

The introduction of additional nodes into the proposed radio frequency counter in comparison with the prototype allows extending its functionality by measuring the parameters of a single pulse.

Claims (1)

Claims of the invention A radio pulse frequency meter comprising a mixer, an intermediate frequency amplifier, a frequency meter, a phase detector, the output of which is connected to the first input of the second adder, the second input of which is connected to the output of the frequency detector. and the output is through a serially connected proportional-integrating filter, a local oscillator restructuring element, a local oscillator with a second mixer input, characterized in that, in order to expand its functionality, it additionally introduces a first adder, an envelope detector, a key, a delay line, an amplifier with automatic gain control, low-pass filter and frequency divider, the input of which is connected to the output of the digital frequency meter, and the output - to the second input of the phase detector, the output of the mixer through the lower filter frequency is connected to the first input of the phase detector, the input of the frequency detector and the input of the intermediate frequency amplifier, the output of which is connected to the input of a digital frequency meter, the first input of the mixer is connected to the output of the first adder, and through series-connected amplifier with automatic gain control, delay line and the key is with the second input of the first adder, the first input of which is connected to the input of the device and through the envelope detector to the second input of the key. F t, etc t AND Cfnch (t)   - / / N F g, Uanuw TB R rg GU i Put.2