RU2552102C1 - Apparatus for monopulse measurement of radial velocity of objects - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: apparatus for monopulse measurement of radial velocity of objects consists of two identical channels for processing probing and reflected chirp pulses, connected to first and second outputs of an electronic switch, wherein the probing chirp pulses arriving at the electronic switch and a chirp pulse reflected from a moving object are switched with the corresponding processing channel. Each processing channel consists of series-connected band-pass filter, multiplier, to one input of which chirp pulses are transmitted from the output of the band-pass filter, and to the second input of which the same pulse is transmitted, but delayed by a delay line, an integrator, a phase-locked-loop frequency control circuit, a frequency meter, wherein the output of the frequency meter of each channel is connected to the input of a comparator device, the output of which is connected to a decision device.

EFFECT: enabling measurement of radial velocity of a moving object while preserving the capability to measure range to the object.

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Description

The proposed device relates to the field of processing of radio signals and can be used in radar technology using signals with linear frequency modulation, for single-pulse measurement of the radial speed of a moving object simultaneously with determining the distance to it.

Known methods and radar stations for measuring the radial velocity of objects that are analogues of the proposed device (RF patents Nos. 2236694, 2211460, 2315333, 2362182, 2389040, 2427003, 2389039, 2060514, 2191405, 2429503, 2251710, 2309431). These methods are based on the use of signals without intrapulse modulation.

Known radar with linear frequency modulation of the probing signal (application for invention of the Russian Federation No. 93032921), the main disadvantage of which is the inability to measure the radial velocity of the object simultaneously with determining the distance to it.

A device is known which is a prototype of the proposed device - "Measuring the rate of linear change of frequency inside a pulse" (RF patent No. 2010243), comprising a forming unit, the information input of which is connected to the input signal bus, two counters and a subtraction unit, characterized in that in order to increase accuracy, a control and synchronization block, two digital delay lines, N + 1 “And” elements and a standby multivibrator are introduced into it, and the counters are made in the form of reversible ones, the output of the forming unit is connected to the sums the input of the first reversible counter and the input of the first digital delay line, the output of which is connected to the subtracting input of the first counter, summing the input of the second reversing 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 (N + 1) of the "And" element, the output of which through the block of the standby multivibrator is connected to the second inputs of the "And" elements from the first to the Nth, the outputs of the first and second reversible counters are connected respectively to the first and second ith 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 AND elements, 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 formation unit, and the second output is synchronized the inputs of the first and second digital delay lines and the second input of the (N + l) -th element "AND".

The disadvantage of this device is the inability to measure the magnitude of the deviation of the speed of the linear frequency change inside the pulse when it is reflected from a moving object, which is proportional to the value of the radial speed of the moving object.

Thus, the aim of the invention is to measure the radial velocity of a moving object by a single pulse by measuring the magnitude of the deviation of the speed of the linear frequency change inside the pulse when it is reflected from the moving object.

The goal is achieved by the fact that the device includes two identical channels for processing the probing and reflected linearly-frequency modulated pulses connected to the first and second outputs of the electronic key, each channel consists of series-connected: a band-pass filter, a multiplier (on which one input linearly a frequency-modulated pulse from the output of the band-pass filter, and to the second input the same pulse, but delayed in the delay line), integrator [1], phase-locked loop [2], meter Toty. In this case, the output of the frequency meter from the composition of each channel is connected to the input of the comparison device, designed to determine the difference of the speed of the linear change of frequency inside the probing and reflected pulses, the output of the comparison device is connected to the resolving device, which, based on the calculated value of the speed difference of the linear change of frequency of the frequency inside the probe reflected pulses makes a decision on the radial velocity of the object.

An object of the present invention is to provide a radar station with a single-pulse measurement of the radial velocity of an object by calculating the difference in speed of a linear change in frequency inside a probe and reflected linearly frequency modulated pulses, while maintaining the ability of a radar station to measure the distance to the object.

It is known that the instantaneous frequency inside the probing linear-frequency modulated pulse varies in time according to the law:

where ƒ ₀ is the carrier frequency, τ _u is the pulse duration, γ ₁ is the rate of linear frequency change inside the probe linearly frequency-modulated pulse.

The rate of linear frequency change inside the probing linear-frequency modulated pulse is calculated by the formula:

where Δƒ _d - frequency deviation, ƒ _max , ƒ _min - the maximum and minimum value of the pulse frequency, respectively.

When reflected from an object moving with a radial speed v _r, all spectral components of the pulses with a frequency ƒ are shifted in frequency by an amount Δƒ ₀ , determined by the Doppler effect [3]:

where λ is the wavelength, c is the speed of light.

Therefore, in the linearly-frequency-modulated pulse reflected from a moving object, the frequency values ƒ _max and ƒ _min change by

which corresponds to the rate of linear frequency change inside the pulse γ ₂ reflected from a moving object (Fig. 1)

From (5) it follows that the radial velocity of a moving object can be determined by the formula:

Therefore, with a known value of γ ₁ , the measured deviation Δγ allows you to calculate the radial velocity of a moving object v _r :

To calculate v _r , a device is proposed, the block diagram of which is shown in FIG. 2.

The following notation is used in the figure and in the text:

1. The electronic key;

2. Band-pass filter;

3. Delay line;

4. Multiplier;

5. Integrator;

6. The phase locked loop;

7. Frequency meter;

8. The comparison device;

9. The decisive device.

The device operates as follows.

Entering the electronic key 1 probe linearly frequency modulated pulse U ₁ (t) and reflected by a moving object linearly frequency modulated pulse U ₂ (t) are switched with the respective processing channel. The electronic key is controlled by the synchronizer of the radar station [4].

The probing linearly frequency-modulated pulse U ₁ (t) enters through the bandpass filter 2 to the first input of the multiplier 4, the second input of which receives the same pulse, but delayed in the delay line 3 by τ ₃ :

The multiplier 4 is connected to the input of the integrator 5, which gives a signal with a beat frequency ƒ _b at its output, which directly proportionally depends on the rate of change of the frequency of the linearly-frequency modulated pulse and on the delay time of the autocorrelator:

зондирующего линейно-частотно модулируемого импульса U₁(t).To measure the frequency of the radio pulse sequence allocated at the output of the integrator 5, it is converted into a continuous harmonic signal of the same frequency using the phase-locked loop 6 [2]. Received at the output of the phase-locked loop 6 frequency continuous harmonic signal is fed to the input of the frequency meter 7, which determines the beat frequency $$f_b{}_{{}_{\mathrm{one}}}$$

probing linearly frequency-modulated pulse U ₁ (t).

линейно-частотно модулируемого импульса U₂(t), отраженного от движущегося объекта.The second channel is similar in principle to the first, but the beat frequency is determined in it $${\mathrm{<figure-callout\; id="2"\; label="f\; b"\; filenames="00000014.png,00000015.png"\; state="\{\{state\}\}">f\; </figure-callout>}}_b{}_{{}_2}$$

linear frequency modulated pulse U ₂ (t) reflected from a moving object.

From the outputs of the elements 7 of both stages, the measured values of ƒ _b are fed to the input of the comparison device 8, which calculates the speed of the linear frequency change inside each received pulse:

after which the value of the deviation of the value of the linear frequency change inside the pulse reflected from the object relative to the probe pulse is determined:

The obtained value Δγ from the output of element 8 is fed to the input of the resolver 9, which calculates the radial velocity of the object v _r according to formula (7).

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 by introducing these additional nodes, which make it possible to calculate the deviation of the value of the linear frequency change inside the pulse reflected from the moving object relative to the probe pulse, which allows the radar station to measure the radial speed of the moving object from one pulse simultaneously with determining the distance to it.

Based on the above description and structural diagram, the proposed device can be made from known components using technological equipment known in the electronics industry and used in a radar station with linearly-frequency-modulated signals to measure the radial velocity of an object simultaneously with determining the distance to it.

Claims (1)

A single-pulse device for measuring the radial velocity of objects, consisting of two identical channels for processing the probing and reflected linearly-frequency-modulated pulses connected to the first and second outputs of the electronic key, while the probing linearly-frequency-modulated pulse arriving at the electronic key and reflected linearly from the moving object the frequency-modulated pulse is switched with the corresponding processing channel, and each of the processing channels consists of sequentially connected a bandpass filter, a multiplier, on one input of which a linearly-frequency-modulated pulse arrives from the output of the band-pass filter, and the second pulse receives the same pulse, but delayed in the delay line, integrator, phase-locked loop, frequency meter, and the meter output the frequencies from the composition of each channel is connected to the input of the comparison device, the output of which is connected to the deciding device.

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