RU2535302C1 - Short-range location system for detection of objects - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: device includes a noise generator, the signal of which is added to a saw-tooth modulating signal, and devices for processing as to relative width of an energy spectrum band of a Doppler signal as an analyser, which ensures recognitions of a target with highlights from interference distributed in space, as well as provides for abrupt cut-off of sensitivity function beyond working range limits and operation invariancy of an independent information system in relation to an amplitude of received signal within working range.

EFFECT: improving interference immunity.

2 cl, 5 dwg

Description

Technical field

The invention relates to the field of near location and can be used in information-measuring tools and systems operating in the modes of active target recognition with shiny dots against broadband and distributed in space interference, as well as in the conditions of operation of repeaters that simulate a signal reflected from the target.

State of the art

The currently existing autonomous information systems (AIS) of near location (BL) with modulation according to the periodic law have a significant drawback, expressed in the spatial periodicity of the range sensitivity function. The frequency of the sensitivity function leads to the fact that the formulation of active or passive interference from distances exceeding the operating range of the AIS reduces the signal-to-noise ratio at the input of the decision path and can cause false alarms of the AIS. There is also a problem of the non-invariance of the existing AIS BL with respect to the amplitude of the received signal (see V.K. Khokhlov. Detection, recognition and direction finding of objects in the near location. M., MSTU named after N.E.Bauman, 2005, pp. .291).

The closest in technical essence to the device under development is a short-range radar system (SBRL) with frequency modulation (FM) and spectral processing (Kogan I.M. Near-radar (theoretical basis) .- M., Sovetskoe Radio, 1973. - 272 p. , p.60), selected for the prototype. AIS BL contains a transmitting part, consisting of a frequency modulator, a generator, a transmitting antenna, and a receiving part of AIS BL, consisting of a receiving antenna, a low-noise amplifier, a mixer, N spectral processing channels and a signal analyzer (AC) that implements joint signal processing. Each spectral processing channel consists of a frequency multiplier, a harmonic filter amplifier, a Doppler frequency detector-amplifier; a frequency modulator modulates with a periodic signal. The speaker determines the distance to the object by calculating the ratio of the amplitudes of the signals at the outputs of the Doppler channels.

The disadvantage of this device is the periodicity of the range sensitivity function and, as a consequence, low noise immunity. The most dangerous are the active interference from powerful relay stations that re-emit the received signal in the direction of the AIS, simulating the signal from the target. Passive interference outside the operating range when working on low-contrast targets with shiny points is also dangerous. Therefore, to ensure the required noise immunity when working on targets with shiny points, it is necessary to form a sensitivity function equal to zero outside the working range of the AIS.

Disclosure of invention

The essence of the invention is a near-location system for detecting and recognizing near-location objects with continuous emission of a radio signal from the FM via periodic and noise processes and processing the Doppler signal according to the relative bandwidth of the energy spectrum.

The technical problem solved in the present invention is to increase the noise immunity when working on targets with brilliant points outside the working range in the presence of a background of broadband and distributed in space interference, as well as in the conditions of operation of repeaters that simulate a signal reflected from the target. The invariance of AIS operation with respect to the signal level is also achieved.

The problem is solved due to the active recognition of targets with shiny points in the relative bandwidth of the Doppler signal.

For its implementation, a near-location system for detecting objects, containing a transmitting part, including a frequency modulator, a carrier frequency generator, a transmitting antenna, a receiving part, consisting of a receiving antenna connected in series, a low-noise amplifier and a mixer, a multi-channel spectral processing system, each of which channels contains a frequency multiplier, a bandpass filter, a Doppler frequency filter amplifier, a signal processing unit connected to an output device, connected up to it is filled in the transmitting part of the system by a noise generator, adder, amplifier and coupler, while the outputs of the noise generator and frequency modulator are connected to the input of the adder, the output of which is connected to the output of which is connected to the input of the carrier frequency generator, the output of the latter is connected through a coupler to a mixer of the receiving part , the second output of the coupler is connected to the input of the amplifier of the transmitting part of the system, the channels of spectral processing of the receiving part are supplemented in each channel by mixers and inertial detectors, m bandpass filter, mixer, filter-amplifier of the Doppler frequency signal are connected in series, while the output of the frequency multiplier is connected to the second input of the mixer, and the output of the filter-amplifier of the Doppler frequency signal is connected to the input of the inertial detector and to the input of the signal processing unit, made in the form of a block processing the relative bandwidth of the energy spectrum of the Doppler signal, an adder, threshold devices, an OR circuit, and an I circuit whose output is output to the output device are also introduced into the system wu, and the outputs of the inertial detectors are connected to the inputs of the adder, the output of which through a threshold device is connected to one of the inputs of the And circuit, the outputs of the processing units of each channel of the multi-channel spectral processing system are connected through threshold devices to the OR circuit, the output of which is connected to the other input of the And system.

The signal processing unit according to the relative bandwidth of the energy signal of the Doppler signal can be made in the form of two identical channels for processing positive and negative half-periods connected in parallel, each of which contains a comparator, first and second control units, a pulse shaper, a reversible drive, a common generator, the outputs of which are connected to the inputs of the reversible drives of each channel, zero-organ, error totalizer, adder, subtractor, drive, the output of which the second is connected to the input of each threshold device of the multi-channel spectral processing system, while the comparator output is connected to the first inputs of the control units and the pulse shaper, the second input of the first control unit is connected to the output of the zero-organ, the first output of the first control unit is connected to the second input of the second block control, the output of the latter is connected to the positive input of the reversible drive, the output of which is connected via a zero-organ to the first input of the error adder, the second output of the first control unit connected with the second input of the pulse shaping, and with the negative input of the reversing accumulator, and the output of the pulse shaper is connected to the second input of the error adder, while the outputs of the comparators of both channels are connected to the second input of the adder, the outputs of the common generator are connected to the third input of the reversing accumulator, the outputs of the adder errors and the adder are connected to the inputs of the subtracting device, the output of which is connected to the input of the drive. The invention is illustrated by drawings, where

figure 1 is a structural diagram of a near location system for detecting objects;

figure 2 is a graph of the relative bandwidth of the energy spectrum of the Doppler signal from the arrival delay of the probe signal with combined FM;

figure 3 is a graph of the coefficient of the initial regression of the intervals between the zeros of the Doppler signal from the relative width of its strip; for a signal with a Gaussian spectrum and for a signal with a rectangular spectrum;

figure 4 - implementation of the signal processing circuit for the relative bandwidth of the energy spectrum;

5 is a diagram illustrating the operation of the signal processing circuit according to the relative bandwidth of the energy spectrum.

The implementation of the invention

The near-location system for detecting objects contains a frequency modulator in the form of a generator 1 of the periodic law of frequency modulation (FM), a noise generator 2, a modulation repetition frequency generator 3, an adder 4, a controlled carrier frequency generator 5; directional coupler 6, power amplifier 7, transmitting antenna 8, receiving antenna 9, low-noise amplifier 10, mixer 11, multi-channel spectral processing system, each channel of which contains a frequency multiplier 12 (positions 12.1 ... 12.N), a bandpass filter 13 (positions 13.1 ... 13.M), a mixer 14 (positions 14.1 ... 14.N) and a filter amplifier 15 of the Doppler frequency signal (positions 15.1 ... 15.N), an inertial detector 16 (positions 16.1 ... 16.N), the processing circuit 17 relative the bandwidth of the energy spectrum of the Doppler signal (positions 17.1 ... 17.N), threshold device property 18 (positions 18.1 ... 18.N), OR circuit 19, adder 20, threshold device 21 and AND circuit 22.

The number of channels in the device is determined by the range of fixed ranges and the resolution of the device in range. As you know, the range resolution of sawtooth FM devices depends on the frequency deviation:

where R is the resolution in range; c is the speed of light; Δf is the frequency deviation.

For example, in order to fix the ranges of 3, 6 and 9 meters with an accuracy of 1 m, a three-channel system with a frequency deviation of a sawtooth FM at 150 MHz, with channels tuned to 3, 6 and 9 harmonics of the difference frequency signal received from the mixer, respectively, is required eleven.

The signal at the output of the mixer 11 is a set of harmonics with frequencies that are multiples of the repetition frequency of the sawtooth FM and shifted due to the Doppler additive. In each Doppler frequency channel, a harmonic corresponding to the channel number is extracted from this signal using a filter 13, and the received signal undergoes a second frequency conversion on mixer 14, and a Doppler frequency signal is extracted from it by Doppler frequency filter amplifiers 15.

The results of experimental studies have shown that in the near location, when the target has brilliant points and the use of narrow radiation patterns, the relative band of the energy spectrum of the Doppler signal α _c <0.3; for interference: α _p > 1.

Consider the effect of the frequency deviation of the noise FM on the relative bandwidth of the energy spectrum of the Doppler signal. Let the noise fraction of modulation be described by a random process ξ (t). Then, provided

where ω _max is the maximum frequency of the spectrum of the modulating function ξ (t); Δω _ξ is the frequency deviation of the noise process; the noise FM is broadband, and the spectrum S _ξ (ω) of the modulated oscillation is described by the Gauss function:

where ω ₀ is the carrier frequency.

Consider a false signal received from a repeater operating outside of its operating range. The Doppler frequency ω _d in such a signal is determined by the expression:

- время задержки принимаемого сигнала; R₀ - расстояние до ретранслятора; ΔR - изменение расстояния до ретранслятора за время τ.Where

- delay time of the received signal; R ₀ is the distance to the repeater; ΔR is the change in the distance to the repeater during time τ.

(где Δω_д - эффективная ширина полосы спектра доплеровского сигнала), определяется выражением:The relative bandwidth of the energy spectrum of the Doppler signal, defined as

(where Δω _d is the effective bandwidth of the spectrum of the Doppler signal), is determined by the expression:

B _d (0) is the value of the correlation function of the Doppler signal with zero argument, the maximum value of the spectrum of the Doppler signal, S _d is the spectrum of the Doppler signal, ω _min , ω _max are the minimum and maximum frequencies of the spectrum of the Doppler signal.

и времени задержки τ₀ приведена на фиг.2. Расчеты проводились для диапазона доплеровских частот Δf_д=5…100 кГц. Анализ графиков показывает резкое увеличение значений относительной ширины полосы α при постоянной девиации шумовой ЧМ Δf_ξ и изменении дальности до ретранслятора R₀, начиная со значенийDependence of the relative bandwidth of the energy spectrum α of the Doppler signal on the frequency deviation of the noise FM

and the delay time τ _{0 is} shown in figure 2. The calculations were carried out for the range of Doppler frequencies Δf _d = 5 ... 100 kHz. The analysis of the graphs shows a sharp increase in the values of the relative bandwidth α with constant deviation of the noise FM Δf _ξ and a change in the range to the repeater R ₀ , starting with the values

до отношений сигнал/помеха в полосе Доплера, равных единице. Регрессионные системы обеспечивают инвариантность рабочих характеристик к средней частоте энергетического спектра и дисперсии процессов на входе, не требуют времени на адаптацию (на слежение за задержкой сигнала), позволяют сократить время на обработку и обрабатывать нестационарные случайные процессы. Помеха на частоте Доплера произвольной мощности при относительной ширине полосы α≥1 не вызывает ложных срабатываний в системе при обработке не менее 20 интервалов между нулями входной реализации.Therefore, when choosing the band of the noise process in accordance with (6), it is possible to form a sensitivity function that provides noise selection by the relative bandwidth of the energy spectrum. The implementation of the processing circuit of the energy spectrum signal in the form of regression or neural network paths for recognizing Doppler signal signals by the relative bandwidth of the energy spectrum of the input implementation makes it possible to detect a narrowband (α _c <0.3) Doppler signal against a background of broadband interference

to signal-to-noise ratios in the Doppler band equal to one. Regression systems ensure the invariance of the performance characteristics to the average frequency of the energy spectrum and the dispersion of the input processes, do not require adaptation time (to monitor the signal delay), reduce processing time and process non-stationary random processes. Interference at a Doppler frequency of arbitrary power with a relative bandwidth α≥1 does not cause false positives in the system when processing at least 20 intervals between the zeros of the input implementation.

Given a threshold value in the relative band α _n = 0.3, based on the requirements for ensuring noise immunity of the AIS within the operating ranges, when working against a background of distributed spatial and relay interference, the value of the frequency deviation of the noise FM can be determined from (6) and Fig. 2 . The advantage of the proposed method for the formation of the selection function (FS) is the small deviation of the noise FM (for working ranges from 0 to 15 meters Δf _ξ = 5 MHz), which does not cause an additional increase in the signals of spurious amplitude modulation.

Further processing in the channels of the Doppler signal occurs as follows. The Doppler signal is input to the processing circuit 17 according to the relative bandwidth that estimates the coefficient of the initial regression of the intervals between the zeros of the input signal; threshold device 18 compares the value of the coefficient of initial regression of the intervals between zeros with a given threshold; when the threshold level is exceeded, the threshold device 18 gives a positive level to the input of the OR circuit 19, from the output of which a positive signal passes to the output device only if the signal exceeds the threshold level at the input of the device 21. The decision on the sufficiency of the signal energy is made using inertial detectors 16, calculating the magnitude of the signal in each channel of the Doppler signal and transmitting it to the inputs of the adder 20. The output of the latter is compared with a threshold in the device 21, the output of which prohibits or disables creases passage detection signal output from the AND circuit 22 to the output device.

Thus, as soon as a Doppler signal appears at the input of any (n-th) channel of the analyzer, the relative bandwidth of which is such that the regression coefficient of the intervals between zeros is sufficiently large, the threshold device of the nth channel will give a single logical output level. The obtained logic level can be supplied to the output device only if the energy channel is triggered (16, 20, 21).

As information on the relative bandwidth of the energy spectrum, you can use the value of the coefficient of the initial regression of the intervals between the zeros of the Doppler signal [1]. Figure 3 shows graphs of the dependence of the value of the coefficient of initial regression of the intervals between zeros and the relative bandwidth of the energy spectrum for the Gaussian and rectangular spectra. It is seen that with an increase in the relative bandwidth, the initial regression coefficient decreases according to a law close to linear.

As an embodiment of the processing circuit 17 according to the relative bandwidth of the energy spectrum of the Doppler signal, a circuit is proposed in the functional form shown in FIG. 4. Diagrams explaining her work are depicted in figure 5.

The signal processing circuit 17 according to the relative bandwidth of the energy spectrum of the Doppler signal consists of two identical channels operating in turn to process positive and negative half-cycles. Each channel contains a comparator 23, (positions 23.1 and 23.2) control units 24 (positions 24.1 and 24.2) 25 (positions 25.1 and 25.2), a pulse shaper 26 (positions 26.1 and 26.2), a common generator 27, the outputs of which are connected to the inputs of the reversing drives 28 (positions 28.1 and 28.2) of each channel, null-organ 29 (positions 29.1 and 29.2), error adder 30, adder 31, subtractor 32, drive 33, the output of which is connected to the input of threshold device 18.

The output of the comparator 23 is a functional transformation of the form:

where x (t) is the input signal of the comparator; U ₀ - the amplitude of the signal at the output of the comparator; U _P0 - the threshold of the comparator (figure 5, b).

(где σ_c - дисперсия сигнала на выходе) с достаточной точностью можно считать, что длительности импульсов на выходе компаратора 23.1 равны соответствующим интервалам между нулями входной реализации. С началом положительного полупериода реализации сигнала блоки управления 24.1 и 25.1 включают реверсивный накопитель 28.1, и последний начинает заполняться (фиг 5, в). При переходе через нуль входной реализации изменяется направление заполнения реверсивного накопителя 28.1. В момент его обнуления нуль-орган 29.1 формирует импульс, который поступает на сумматор ошибки 30, сюда же поступают импульсы (фиг.5, г) с формирователя 26.1. Если длительность предыдущего полупериода больше последующего, сумматор ошибки 30 формирует импульсную последовательность, изображенную на фиг.8, е; в противном случае формируется последовательность, изображенную на фиг.5, д. Импульсы ошибки через преобразователь уровня поступают на вход вычитающего устройства 32. Если генератор 27 представляет собой генератор тактовых импульсов, то при заполнении реверсивного накопителя для двух соседних интервалов между нулями τ_i и τ_i+1 тактовые частоты равны f и $${\beta }_{{\tau }_i/{\tau }_{i+1}}f$$

соответственно (здесь $${\beta }_{{\tau }_i/{\tau }_{i+1}}$$

- коэффициент начальной множественной регрессии i-го интервала на i+1-й). Если генератор 27 представляет собой источник тока, то при заполнении реверсивного накопителя 28.1 токи для интервалов между нулями τ_i и τ_i+1 будут равны I и $${\beta }_{{\tau }_i/{\tau }_{i+1}}I$$

соответственно. При этом длительность импульса последовательности ξ(t) на выходе устройства 30 будет равна модулю ошибки регрессионного представления интервалов между нулями.At $${\mathrm{<figure-callout\; id="0"\; label="U\; P"\; filenames="00000017.png,00000018.png"\; state="\{\{state\}\}">U\; </figure-callout>}}_P^0{\sigma }_c^{-2}\to 0$$

(where σ _c is the dispersion of the signal at the output), with sufficient accuracy, we can assume that the pulse durations at the output of the comparator 23.1 are equal to the corresponding intervals between the zeros of the input implementation. With the beginning of the positive half-cycle of the signal implementation, the control units 24.1 and 25.1 turn on the reversible drive 28.1, and the latter begins to fill up (Fig. 5c). When the input implementation passes through zero, the filling direction of the reverse drive 28.1 changes. At the time of its zeroing, the null-organ 29.1 generates an impulse that arrives at the error adder 30, and impulses (Fig. 5, d) from the former 26.1 come here. If the duration of the previous half-cycle is longer than the next, the adder 30 generates a pulse sequence shown in Fig.8, e; otherwise, the sequence shown in Fig. 5 is generated. Error pulses through the level converter are fed to the input of the subtracting device 32. If the generator 27 is a clock pulse generator, then when filling the reversible drive for two adjacent intervals between zeros τ _i and τ _{i + 1} clock frequencies are f and $${\beta }_{{\tau }_i/{\tau }_{i+\mathrm{one}}}f$$

accordingly (here $${\beta }_{{\tau }_i/{\tau }_{i+\mathrm{one}}}$$

is the coefficient of the initial multiple regression of the i-th interval by i + 1-th). If the generator 27 is a current source, then when filling the reverse drive 28.1, the currents for the intervals between the zeros of τ _i and τ _{i + 1} will be equal to I and $${\beta }_{{\tau }_i/{\tau }_{i+\mathrm{one}}}I$$

respectively. Moreover, the pulse duration of the sequence ξ (t) at the output of the device 30 will be equal to the error modulus of the regression representation of the intervals between zeros.

The second channel of the circuit works similarly, but with negative half-cycles of the input signal.

From the outputs of the comparators 23.1, and 23.2 through the adder 31 to the input of the subtracting device 32 receives a single signal 1 (t).

The signals are sequentially fed to the drive 33, which is connected to the input of the threshold device 18, gives the resulting positive level to the input of the OR circuit 19.

Thus, the protection of AIS from false alarms by artificial and natural broadband and spatially distributed interference is enhanced.

Claims (2)

1. A near-location system for detecting objects, comprising a transmitting part including a frequency modulator, a carrier frequency generator, a transmitting antenna, a receiving part consisting of a receiving antenna connected in series, a low-noise amplifier and a mixer, a multi-channel spectral processing system, each of which has a multiplier frequency, bandpass filter, filter amplifier of the Doppler frequency signal, signal processing unit, characterized in that a noise generator, sum a amplifier, an amplifier and a coupler, while the outputs of the noise generator and the frequency modulator are connected to the input of the adder, the output of which is connected to the input of the carrier frequency generator, the output of the latter is connected through the coupler to the mixer of the receiving part of the system, the second output of the coupler is connected to the input of the amplifier of the transmitting part of the system, the channels of the spectral processing of the receiving part are supplemented in each channel by mixers and inertial detectors, moreover, a band-pass filter, a mixer, a filter amplifier of the Doppler frequency signal in series, while the output of the frequency multiplier is connected to the second input of the mixer, and the output of the filter-amplifier of the Doppler frequency signal is connected to the input of the inertial detector and to the input of the signal processing unit, made in the form of a processing unit according to the relative bandwidth of the energy spectrum of the Doppler signal, the system includes an adder, threshold devices, an OR circuit, and an I circuit whose output is output to an output device, the outputs of inertial detectors being connected to the inputs of the adder, the output of which through a threshold device is connected to one of the inputs of the And circuit, the outputs of the processing units of each channel of the multichannel spectral processing system are connected through threshold devices to an OR circuit, the output of which is connected to the other input of the And system. 2. The near-location system for detecting objects according to claim 1, characterized in that the signal processing unit according to the relative bandwidth of the energy spectrum of the Doppler signal is made in the form of two identical channels for processing positive and negative half-periods of the input signal connected in parallel, each of which contains a comparator, first and second control units, a pulse shaper, a reversible drive and a zero-organ, the processing unit also contains a generator, the outputs of which are connected to the inputs each channel, error accumulator, adder, subtractor, drive, the output of which is connected to the input of the threshold device of the multi-channel spectral processing system, while the output of the comparator is connected to the first inputs of the first and second control units, and the pulse shaper, the second input of the first control unit connected to the output of the zero-organ, the first output of the first control unit is connected to the second input of the second control unit, the output of the last is connected to the positive input of the reverse the amplifier, the output of which through the zero-organ is connected to the first input of the error adder, the second output of the first control unit is connected to the second input of the pulse shaper, and to the negative input of the reversing drive, and the output of the pulse shaper is connected to the second input of the error adder, while the outputs of both comparators channels are connected to the second input of the adder, the outputs of the generator are connected to the third input of the reversible drive, the outputs of the error adder and the adder are connected to the inputs of the subtractor, the output of which oh connected to the input of the drive.

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