RU2715057C1 - Correlation-phase direction finder - Google Patents

Abstract

FIELD: radio navigation.

SUBSTANCE: invention relates to radio navigation and can be used to determine angular coordinates of phase-shift keyed (PSK) radio signal sources with known coding laws in the presence of radio interference. Correlation-phase direction-finder comprises two antennae, two high-frequency HF-unit, two demodulators, two spectro-analyzers, spectrum comparison unit, two memory devices (MD), a control panel, a code generation unit, two matched filters which, at their outputs, generate cross-correlation functions between the input phase-shift keyed signal and the code contained therein, and a delay meter between the maxima of the cross-correlation functions, wherein output of control panel is connected to input of code generation unit, which output is connected to control inputs of matched filters, information inputs of first and second matched filters are connected to corresponding outputs of first and second high-frequency units, and outputs are connected to inputs of demodulators, one of inputs of delay meter is connected to output of spectral comparison unit, and two other inputs are connected to outputs of memory devices, respectively, wherein determining the angular coordinate of the radiation source at the output of the delay meter using the formula α=arcsin(τ/d), where τ is the difference in time of arrival of the wave front to two d-spaced apart receiving antennas.

EFFECT: high signal-to-interference ratio, eliminating ambiguity of bearing detection, wider range of measuring angular coordinates.

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Description

The invention relates to the field of radio navigation and can be used to determine the angular coordinates of sources of phase-shifted (FM) radio signals with known coding laws in the presence of radio interference.

A known phase direction finder [1], comprising two antennas, two high-frequency amplifiers, a phase detector, logarithmic video amplifiers, an analog adder, analog-to-digital converters, a pulse signal detector, a phase difference calculator, a power code generating unit, a correction code generating unit, and a digital adder interconnected in a certain way.

Known phase direction finder [2], containing the first and second antenna inputs, the first and second receiving devices, the local oscillator, the first, second and third frequency converters, the filter of the total frequency, the first and second narrow-band filters, phase meter.

These direction finders use the phase principle of direction finding, when a radio wave with a flat front forms coherent signals at the outputs of the antennas, the phase difference Δϕ between which depends on the direction α to the direction finding radiation source

where d is the distance between the antennas (base), λ is the wavelength.

The disadvantage of these direction finders is the impossibility of correctly determining the direction to the object at angles leading to a delay in the received signals longer than the length of the carrier frequency period.

Known correlation-phase direction finder [3], used as a prototype, containing two antennas, two high-frequency (RF) units, two demodulators, two spectrum analyzers, a unit for comparing spectra, two storage devices, a correlator. In this direction finder, the ambiguity caused by the periodic nature of the carrier frequency of the signal is eliminated, which is provided by demodulators that isolate the low-frequency component of the message located in the received signal.

A common disadvantage of the known phase direction finders is the inability to use the structure of the phase-shifted signal to determine the direction of its arrival in the presence of interference.

The technical result of the present invention is to determine the location of the sources of phase-shifted signals with previously known coding laws in the presence of radio interference.

The technical result is achieved by the fact that in the correlation-phase direction finder containing two antennas, two high-frequency RF units, two demodulators, two spectrum analyzers, a spectrum comparison unit, two memory devices, a control panel, a code generation unit, two matched filters are introduced providing at their outputs the formation of cross-correlation functions between the input phase-manipulated signal and the code contained in them, and a delay meter between the maxima of the cross-correlation functions, at the output of the control panel is connected to the input of the code generation unit, the output of which is connected to the control inputs of the matched filters, the information inputs of the first and second matched filters are connected to the corresponding outputs of the first and second high-frequency blocks, and the outputs are connected to the inputs of the demodulators, one of the inputs of the delay meter connected to the output of the spectra comparison unit, and two other inputs are connected respectively to the outputs of the storage devices.

The invention is illustrated in the figure. In FIG. 1 shows a functional diagram of the proposed correlation-phase direction finder.

The correlation-phase direction finder contains antennas 1 and 2, RF blocks 3 and 4, matched filters 13 and 14, a code generation unit 14, a control panel 15, demodulators 5 and 6, spectrum analyzers 7 and 8, a spectral comparison unit 9, memory devices ( Memory) 10 and 12, delay meter 11, the output of which is the information output of the direction finder.

Antennas 1 and 2 are connected respectively to the inputs of the RF units 3 and 4, the outputs of which are connected to the information inputs of the matched filters 13 and 14, the control inputs of which are connected to the outputs of the code generation unit 15, the input of which is connected to the output of the control panel 16, the outputs of the matched filters 13 and 14 are connected respectively to the inputs of demodulators 5 and 6, the outputs of which are connected respectively to the inputs of the spectrum analyzers 7 and 8, the outputs of which are connected to the inputs of the spectral comparison unit 9, the output of which is connected to the course E of the delay meter 11, the first information input X of which is connected to the output of the memory 10, the input of which is connected to the output of the demodulator 5, the second information input of the delay meter 11 is connected to the output of the memory 12, the input of which is connected to the output of the demodulator 6. The output of the delay meter 11 is the information output of the correlation-phase direction finder.

The angular coordinate α of the radiation source of the radio waves, which is the direction-finding object, is determined by measuring the difference in the times of arrival of the wave front to the two receiving antennas 1 and 2 spaced apart by distance d. The desired angle is found from the results of the delay estimate τ

α = arcsin (τ / d).

The correlation-phase direction finder works as follows.

Antennas 1 and 2 receive radio emission from a direction finding object. The phase modulation code used to transmit information from the object and the value of the carrier frequency are assumed a priori known.

An FM radio signal with a known coding law, together with noise, is fed to two spatially separated antennas 1 and 2 and then to two RF blocks 3 and 4. Selected by known carrier frequencies and amplified in RF blocks 3, 4, the signals are sent to matched filters 13 and 14, in which, upon a command from the control panel 16 from the code generation unit 15, a previously known code of the received FM radio signal is entered. The matched filters 13 and 14 provide the formation of cross-correlation functions between the input phase-manipulated signal and the code contained in the matched filters. Cross-correlation functions enter the demodulators 5 and 6 to eliminate high-frequency components and highlight their envelopes.

The obtained low-frequency signals are sent to the spectrum analyzers 7 and 8 to determine their spectrum during the analysis time t and simultaneously in the memory 10 and 12, in which they are delayed by time t. Then, after the analysis time t has elapsed, the results of the determination of the spectra are sent to the spectral comparison unit 9, the purpose of which is to calculate a quantitative indicator, the value of which could be used to judge how similar the signal spectra obtained as a result of the coordinated filtering and demodulation of high-frequency radio signals received by the direction finder. When block 9 makes a decision about the high degree of similarity of the spectra, signal E is formed at its output, allowing the operation of the delay meter 11.

The permission for the operation of the delay meter 11 is issued only in the case of the identity of the spectra, and the identity of the spectra is improved through the use of matched filters. If, according to the results of the comparison, in block 9 it will be established that the spectra of the demodulated signals are not sufficiently similar, then the signal E for enabling the operation of the delay meter 11 is not issued and the information coming from the outputs of the memory 10 and 12 is not involved in the delay measurement.

The purpose of the delay meter 11 is to determine the relative time shift between the cross-correlation functions supplied to its information inputs X, Y. The specified time shift is an estimate of the delay τ, the value of which determines the desired angle α.

It can be seen from the above description that, to estimate the time shift, not high-frequency radio signals are used, but radio signals that have been correlated by using matched filters, providing the desired phase-manipulated radio signal with a previously known code against interference in the form of cross-correlation functions, and demodulation that eliminates high-frequency fluctuations. This ensures an increase in the signal-to-noise ratio and elimination of the ambiguity of the bearing determination caused by the frequency of high-frequency carriers, and, therefore, the range of measurement of angular coordinates is expanded.

Literature

1. Patent No. 2362179 of the Russian Federation, IPC G01S 3/46. Phase direction finder / Smirnov V.N., Sedunov E.I. (RF); FSUE Central Design Bureau of Automatics (RF). - No. 2007144853; Declared December 3, 2007. Publ. 07/20/2009, Bull. No. 20, - 8 p.: 3 ill.

2. RF patent 2454715, IPC G06G 7/78, G01S 3/00. Phase direction finder / Berezovsky V.A., Zolotarev I.D., Lapshin S.A., Privalov D.D. (RF); Open Joint-Stock Company Omsk Scientific Research Institute of Instrument Engineering (RF). - No. 20111118696; Announced on 05/10/2011. Publ. 06/27/2012, Bull. No. 18, - 6 p.: 1 ill.

3. Patent No. 2474835 of the Russian Federation, IPC G01S 3/46. Correlation-phase direction finder / Chebotarev A.S., Avanesyan G.R., Zhukov A.O., Turlov Z.T., Smirnova O.V. (RF). - No. 20111139169; Announced on 2009/26/2011. Publ. 02/10/2013, Bull. No. 4, - 7 p.: 2 ill.

Claims (1)

The correlation-phase direction finder contains two antennas, two high-frequency units, two demodulators, two spectrum analyzers, a spectrum comparison unit, two storage devices, the antennas are connected to the inputs of the high-frequency units, the outputs of the demodulators are connected respectively to the inputs of the storage devices and spectrum analyzers, the outputs of the spectrum analyzers are connected to the inputs of the unit spectra comparison, characterized in that a control panel, a code generation unit, two matched filters are additionally introduced into it, providing the formation of the cross-correlation functions of the phase-shifted signals and the delay meter, the output of the control panel is connected to the input of the code generation unit, the output of which is connected to the control inputs of the matched filters, the information inputs of the first and second matched filters are connected to the corresponding outputs of the first and second high-frequency blocks, the outputs of the first and the second matched filters are connected by the corresponding inputs of the first and second demodulator, one of the inputs of the delay meter It is connected to the output of the spectrum comparison unit, and the other two inputs are connected respectively to the outputs of the storage devices, and the angular coordinate in the radiation source of the radio waves is determined at the output of the delay meter by the formula α = arcsin (τ / d), where τ is the difference in the arrival time of the wave front to two spaced receiving d antennas.

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