RU2290658C1 - Phase mode of direction finding and phase direction finder for its execution - Google Patents

Abstract

FIELD: the proposed mode and arrangement refer to the field of radio electronics and may be used for definition of position of sources of emitting complex signals.

SUBSTANCE: the phase direction finder realizing the proposed phase mode of direction finding, has receiving aerials, receivers and a supporting generator, an impulse generator, an electronic commutator, a phase changer on 90^○, a phase detector and an indicator, a heterodyne, a mixer, an amplifier of an intermediate frequency, multipliers and band filters and a line of delay.

EFFECT: elimination of antagonism between requirements to accuracy of measuring and unique angle reading at phase mode of direction finding of sources of emitting of complex signals.

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Description

The proposed method and device relates to the field of electronics and can be used to determine the location of radiation sources of complex signals.

Known phase direction finding methods and phase direction finders (RF patents Nos. 2003131, 2006872, 2010258, 2012010, 2134429, 2155352, 2175770; Kinkulkin I.E. et al. Phase method for determining coordinates. M .: Sov. Radio, 1979; Space radio engineering complexes, edited by S.I. Bychkov, Moscow: Sov. radio, 1967, p.134-138, fig. 2.3.9 and others).

Of the known technical solutions, the closest to the proposed ones are the phase direction finding method and the phase direction finder for its implementation (Space radio systems. Edited by S.I. Bychkov. M .: Sov. Radio, 1967, p.134-138, Fig. 2.3 .9), which are selected as prototypes.

In the phase direction finding method, the phase difference Δφ of the signals received by two spatially separated antennas is determined by the expression

Δφ = 2π · d / λ · Sinα,

where d is the distance between spaced antennas (measuring base);

λ is the wavelength;

α is the angle of arrival of radio waves relative to the normal to the base.

However, the known phase method of direction finding and phase direction finder for its implementation is characterized by a contradiction between the requirements for the accuracy of measurements and the uniqueness of the reference angle α. Indeed, according to the above formula, the phase method and the phase direction finder are the more sensitive to a change in the angle α, the larger the relative base size d / λ. But with increasing d / λ, the value of the angular coordinate α decreases at which the phase difference Δφ exceeds 2π, i.e. ambiguity of counting occurs.

An object of the invention is to eliminate the contradiction between the requirements for measurement accuracy and the uniqueness of the angle reading in the phase method of direction finding of radiation sources of complex signals.

The problem is solved in that according to the phase direction finding method, based on receiving signals at two antennas remote from each other at a distance d, amplifying and limiting them in amplitude, comparing the signals transmitted through two channels in phase, while the signal from one of the channels pre-phase shifted by 90 °, installed in the azimuthal plane of n receiving antennas around a circle of radius d with the possibility of their electronic rotation with an angular velocity Ω around a receiving antenna located in the center of the circle, commute detachable antennas arranged around a circle, alternately with a frequency Ω, the signal received by a fixed antenna is converted in frequency, an intermediate frequency voltage is extracted, multiplied by it with signals alternately received by n receiving antennas arranged around a circle, phase-modulated voltage is extracted, multiplied by voltage local oscillator, select a low-frequency voltage with a frequency of Ω and compare it in phase with the reference voltage, forming an accurate, but ambiguous signal direction finding scale of the radiation source and, at the same time, the phase-modulated voltage is subjected to autocorrelation processing, a low-frequency voltage is emitted with a frequency of Ω, it is compared in phase with the reference voltage, forming a rough but unambiguous direction finding scale for the signal source.

The problem is solved in that the phase direction finder containing the first receiving antenna and the first receiver in series, the second receiver, the second receiving antenna, the 90 ° phase shifter in series, the first phase detector and indicator, is equipped with a reference generator, a pulse generator, an electronic switch, n receiving antennas arranged around a circle of radius d with the possibility of electronic rotation around a receiving antenna located at the center of the circle, a local oscillator, a mixer, an amplifier, etc. intermediate frequency, two multipliers, two bandpass filters, a delay line, a second and third phase detectors, and a pulse generator, an electronic switch, n inputs of which are connected to the outputs of n antennas placed on a circle, are connected to the first output of the reference generator, the second receiver, the first a multiplier, a first bandpass filter, a delay line and a second phase detector, the second input of which is connected to the output of the first bandpass filter, and the output is connected to the phase shifter by 90 °, and the second the input of the first phase detector is connected to the second output of the reference oscillator, the mixer is connected in series to the output of the first receiver, the second input of which is connected to the local oscillator output, and the intermediate frequency amplifier, the output of which is connected to the second input of the first multiplier, the second multiplier is connected in series to the output of the first bandpass filter the second input of which is connected to the output of the local oscillator, the second bandpass filter and the third phase detector, the second input of which is connected to the third output th generator, and the output is connected to the second input of the indicator.

The structural diagram of the phase direction finder that implements the proposed phase direction finding method, is presented in figure 1. The relative position of the receiving antennas 1, 2.i (i = 1, 2, ..., n) and the radiation source of signal N is shown in FIG. 2.

The phase direction finder comprises in series a first receiving antenna 1, a first receiver 3, a mixer 12, a second input of which is connected to the output of the local oscillator 11, an intermediate frequency amplifier 13, a first multiplier 14, a first band-pass filter 15, a delay line 16, a second phase detector 17, a phase shifter 8 to 90 °, the first phase detector 9, the second input of which is connected to the second output of the reference generator 5, and the indicator 10. A pulse generator 6, an electronic switch 7 are connected in series to the first output of the reference generator 5 n inputs of which are connected to the outputs of n receiving antennas 2.i (i = 1, 2, ..., n) located on a circle of radius d, and a second receiver 4, the output of which is connected to the second input of the first multiplier 14. To the output of the first a bandpass filter 15 is connected in series with a second multiplier 18, the second input of which is connected to the output of the local oscillator 11, the second bandpass filter 19 and the third phase detector 20, the second input of which is connected to the third output of the reference oscillator, and the output is connected to the second input of the indicator 10.

The proposed method is implemented as follows.

Received complex signals, for example, with phase shift keying (PSK):

U ₁ (t) = υ _c · Cos [(ω _s ± Δω) t + φ _k (t) + φ _s ],

U ₂ (t) = υ _c · Cos [(ω _c ± Δω) t + φ _k (t) + φ _c + 2π · d / λ · Cos (Ωt-α)], 0≤t≤T _c ,

where υ _c , ω _c , φ _c , T _c - amplitude, carrier frequency, initial phase and signal duration;

± Δω - instability of the carrier frequency of the signal due to various destabilizing factors;

φ _k (t) = {0, π} is the manipulated component of the phase that displays the law of phase manipulation in accordance with the modulating code, and φ _k (t) = const for k · τ _e <t <(k + 1) · τ _e and can change abruptly at t = k · τ _e , i.e. at the boundaries between elementary premises (k = 1, 2, ..., N-1);

τ _e , N - the duration and number of chips that make up a signal of duration T _c (T _c = N · τ _e );

d is the radius of the circle on which the receiving antennas are located 2.i (i = 1, 2, ..., n), (measuring base);

 Ω is the speed of the electronic rotation of the receiving antennas 2.i (i = 1, 2, ..., n) around the receiving antenna 1;

α - bearing (azimuth) to the signal source;

from the outputs of the receiving antennas 1, 2.i (i = 1, 2, ..., n) directly and through the electronic switch 7 are fed to the inputs of the receivers 3 and 4, and then to the first inputs of the mixer 12 and the multiplier 14, respectively. The second input of the mixer 12 from the output of the local oscillator 11 receives voltage

U _g (t) = υ _g Cos (ω _g t + φ _g ),

where υ _g , ω _g , φ _g - amplitude, frequency and initial phase of the local oscillator voltage.

At the output of the mixer 12, voltages of combination frequencies are generated. The amplifier 13 is allocated the voltage of the intermediate (differential) frequency

U _pr (t) = υ _pr · Cos [(ω _pr ± Δω) t + φ _k (t) + φ _pr ], 0≤t≤T _s ,

where υ _pr = 1 / 2K ₁ · υ _s · υ _g ;

K ₁ - gear ratio of the mixer;

ω _CR = ω _with -ω _g - intermediate (difference) frequency;

φ _CR = φ _s -φ _g ,

which is fed to the second input of the multiplier 14. At the output of the multiplier 14 is formed phase-modulated (FM) oscillation at a frequency ω _{g of the} local oscillator 11

U ₃ (t) = υ ₃ · Cos [ω _g t + φ _g + 2π · d / λ · Cos (Ωt-α)], 0≤t≤T _s ,

where υ ₃ = 1 / 2K ₂ · υ _c · υ _pr ;

K ₂ - transfer coefficient of the multiplier,

which is allocated by the band-pass filter 15 and supplied to the first inputs of the phase detector 17, delay line 16 and multiplier 18. The second input of the latter is supplied with the voltage U _g (t) of the local oscillator 11. A harmonic voltage is generated at the output of the multiplier 18

U ₄ (t) = υ ₄ · Cos [2π · d / λ · Cos (Ωt-α)], 0≤t≤T _s ,

where υ ₄ = 1 / 2K ₂ · υ ₃ · υ _g ,

which is allocated by the band-pass filter 19 and supplied to the first input of the phase detector 20. The reference voltage is applied to the second input of the phase detector 20 from the third output of the reference generator 5

U ₀ (t) = υ ₀ Cos Cost

A constant voltage is generated at the output of the phase detector 20

U _н1 (α) = υ _н1 · Cosα,

where υ _н1 = 1 / 2К ₃ · υ ₄ · υ ₀ ;

K ₃ - the transfer coefficient of the phase detector,

which is fixed by indicator 10. Thus, a direction finding scale is formed, which is an accurate but ambiguous scale.

The simultaneous phase-modulated oscillation U ₃ (t) is subjected to autocorrelation processing using an autocorrelator consisting of a delay line 16 and a phase detector 17.

In the phase-modulated voltage U ₃ (t), the quantity m _φ = 2π · d / λ, called the phase modulation index, characterizes the maximum value of the phase deviation from the zero value that occurs during the electronic rotation of the receiving antennas 2.i (i = 1, 2, .. ., n) around the receiving antenna 1 (figure 2).

Receiving antennas 2.i (i = 1, 2, ..., n) are alternately switched with a frequency Ω using an electronic switch 7 controlled by an n-phase pulse generator 6. The control pulses are generated by the 6 pulse generator from the harmonic voltage generated by the reference generator 5

U ₀ (t) = υ ₀ Cos Cost

However, for d / λ> 1/2, the ambiguity of the reference angle α occurs. The elimination of this ambiguity by reducing the d / λ ratio usually does not justify itself, since the main advantage of the wide-base direction finder is lost. In addition, in the range of meter and especially decimeter waves, it is often not possible to take small values of d / λ due to design considerations.

In connection with the stated reason, the problem arises of decreasing the phase modulation index without decreasing the relative size of the measuring base d / λ. This is achieved by autocorrelation processing of the phase-modulated voltage U ₃ (t) using the delay line 16 and the phase detector 17. Moreover, the delay time τ of the delay line 16 is chosen so as to reduce the phase modulation index to

m _φ1 = 2π · d ₁ / λ,

where d ₁ <d,

where the inequality holds

d ₁ / λ <1/2,

providing unambiguous direction finding of the signal source. The output of the phase detector 17 produces a harmonic voltage

U ₅ (t) = υ ₅ Cos (Ωt-α), 0≤t≤T _c ,

where υ ₅ = 1 / 2К ₃ · υ ₃ ² ,

which through the phase shifter 8 through 90 ° enters the first input of the phase detector 9, the second input of which from the third output of the reference generator 5 is supplied with a reference voltage U ₀ (t). At the output of the phase detector 9, a constant voltage is formed

U _n2 (α) = υ _n2 · Sinα,

where υ _Н2 = 1 / 2К ₃ · υ ₅ · υ ₀ ,

which is fixed by indicator 10.

This is how the direction finding scale is formed, which is a crude but unambiguous scale.

Thus, the proposed method and device in comparison with the prototypes provide improved accuracy of direction finding of the radiation source of complex signals. This is achieved by increasing the measuring base d. And the resulting ambiguity in reading the angular coordinate α is eliminated by using n receiving antennas 2.i (i = 1, 2, ..., n), which are installed in the azimuthal plane along a circle with a radius d (measuring base) with the possibility of their electronic rotation with an angular velocity Ω around the receiving antenna 1, located in the center of the circle, and autocorrelation processing of the received complex signals.

Moreover, the proposed technical solutions are invariants of the instability of the carrier frequency of the received signals due to their modulation (manipulation) and the width of the spectrum, and the full and unambiguous measurement of the angular coordinate α is carried out at the frequency Ω of the reference oscillator.

Due to the convolution of the spectrum of a complex FMN signal, it is converted into a narrow-band phase-modulated (FM) voltage, which makes it possible to isolate it with a band-pass filter, filtering out a significant part of noise and interference, i.e. to increase the real sensitivity of the frequency-phase direction finder with a relatively low signal to noise ratio.

Claims (2)

1. Phase direction finding method based on receiving signals, amplifying and limiting them in amplitude, comparing signals transmitted through two channels in phase, while the signal of one of the channels is pre-phase shifted by 90 °, characterized in that it is installed in the azimuth plane n receiving antennas around a circle of radius d with the possibility of their electronic rotation with an angular velocity Q around a receiving antenna located in the center of the circle, receiving antennas are arranged around the circle, alternately with frequency Q, the signal received the antenna located in the center of the circle is converted in frequency, the intermediate frequency voltage is isolated, it is multiplied with signals alternately received by n receiving antennas located around the circle, the phase-modulated voltage is isolated, it is multiplied with the local oscillator voltage, the low-frequency voltage is isolated with frequency Q and compared its phase with the reference voltage, forming an accurate, but ambiguous direction finding scale of the signal radiation source, at the same time phase-modulated voltage is subjected to an autocom correlation processing, allocate a low-frequency voltage with a frequency Q, compare it in phase with the reference voltage, forming a rough, but unequivocal direction finding scale of the signal source. 2. A phase direction finder, comprising the first receiving antenna and the first receiver in series, the second receiver, the 90 ° phase shifter in series, the first phase detector and indicator, characterized in that it is equipped with a reference generator, a pulse generator, an electronic switch, n receiving antennas, placed around a circle of radius d with the possibility of rotation around the first receiving antenna located in the center of the circle, a local oscillator, a mixer, an intermediate frequency amplifier, two multipliers, two band-pass filters, a delay line, a second and third phase detectors, and a pulse generator, an electronic switch, n inputs of which are connected to n outputs of antennas arranged in a circle, a second receiver, a first multiplier, a first band-pass filter, are connected in series to the first output of the reference generator a delay line and a second phase detector, the second input of which is connected to the output of the first band-pass filter, and the output is connected to the phase shifter by 90 °, the second input of the first phase detector is connected to a second output of the reference oscillator, a mixer is connected in series to the output of the first receiver, the second input of which is connected to the local oscillator output, and an intermediate-frequency amplifier whose output is connected to the second input of the first multiplier, the second multiplier is connected in series to the output of the first bandpass filter, the second input of which is connected to the local oscillator output, a second bandpass filter and a third phase detector, the second input of which is connected to the third output of the reference oscillator, and the output is connected to the second indicator input.

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