RU2365931C2 - Phase direction finding technique, phase direction-finder therefor - Google Patents

Abstract

FIELD: instrument engineering.

SUBSTANCE: offered method and device concern radio electronics and can be used for positioning of compound signal sources. A phase direction-finder that implements the offered phase direction finding technique accommodates properly connected receiving antennas spaced on a circle and one receiving antenna at its centre, three receivers, a reference generator, a pulse generator, an electronic switch, a 90° phase shifter, three phase detectors, an indicator, a heterodyne, a mixer, an intermediate-frequency amplifier, three multipliers, three band filters, a delay circuit.

EFFECT: improved sensitivity and precision of angular coordinate measurement by twofold increase of relative size of the register surface 2d/λ.

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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 methods of direction finding and phase direction finders (RF patents Nos. 2003131, 200672, 2010258, 2012010, 2134429, 2.155.352, 2175770, 2290658; Kinkulkin I.E. et al. Phase method for determining coordinates. M .: Sov radio, 1979 ; Space radio engineering complexes. Edited by S.I. Bychkov. M .: Sov. Radio, 1967, - p.134-138, Fig. 2.3.9. And others).

Of the known technical solutions, the closest to the proposed one is "Phase direction finding method and phase direction finder for its implementation" (RF patent No. 2290658, G01S 3/46, 2005), which are selected as a prototype.

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

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.

In this case, a contradiction arises between the requirements for the accuracy of measurements and the uniqueness of the reference angle α. Indeed, according to the above formula, the phase direction finding method and the phase direction finder are the more sensitive to changes in the angle α, the larger the relative size of the base d / λ. But with increasing d / λ, the value of the angular coordinate α decreases at which the phase difference Δφ exceeds 2π, t. e. ambiguity of counting occurs.

Known methods of direction finding and phase direction finder eliminate the specified contradiction between the requirements for measurement accuracy and the uniqueness of the reference angle α. However, they do not fully realize their potential opportunities for increasing the sensitivity and accuracy of measuring the angular coordinate α.

An object of the invention is to increase the sensitivity and accuracy of measuring the angular coordinate α by doubling the relative size of the measuring base 2d / λ.

The problem is solved in that the phase direction finding method, based in accordance with the closest analogue 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-shifted in phase by 90 ° , set in the azimuthal plane n of the receiving antennas around a circle of radius d with the possibility of their electronic rotation with an angular velocity Ω, around the receiving antenna located in the center of the circle, receive antennas are placed along circles, alternately with a frequency Ω, the signal received by 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 first phase-modulated voltage is isolated, the low-frequency voltage with frequency Ω and compare it in phase with the reference voltage, forming an accurate but ambiguous direction finding scale of the signal source, simultaneously the first phase-shifted signal the voltage is subjected to autocorrelation processing, a low-frequency voltage with a frequency Ω is extracted and compared in phase with the reference voltage, a rough but unambiguous direction finding scale for the signal radiation source is formed, differs from the closest analogue in that at each switching two receiving antennas located at the ends are used simultaneously diameter, the signal received by the second antenna is multiplied with an intermediate frequency voltage, a second phase-modulated voltage is isolated and multiplied with the first phase mode an isolated strain.

The problem is solved in that a phase direction finder containing, in accordance with the closest analogue, a first receiving antenna, a first receiver, a mixer, a second input of which is connected to the local oscillator output, an intermediate frequency amplifier, a first multiplier, a first bandpass filter, a delay line, and a second phase a detector, the second input of which is connected to the output of the first bandpass filter, a 90 ° phase shifter, a first phase detector, the second input of which is connected to the second output of the reference generator and an indicator, a reference oscillator, a pulse generator, an electronic switch, sequentially connected, n inputs of which are connected to n outputs of receiving antennas arranged around a circle of radii d with the possibility of electronic rotation around the first receiving antenna located at the center of the circle, and a second receiver, the output of which connected to the second input of the first multiplier, connected to the output of the first bandpass filter, a second multiplier, a second bandpass filter and a third phase detector, the second input of which the second is connected to the third output of the reference generator, and the output is connected to the second input of the indicator, differs from the closest analogue in that it is equipped with a third receiver, a third multiplier and a third bandpass filter, and a third receiver, a third multiplier, and a second are connected in series to the second output of the electronic switch the input of which is connected to the output of the intermediate frequency amplifier, and a third band-pass filter, the output of which is connected to the second input of the second multiplier.

The structural diagram of the phase direction finder that implements the proposed method of direction finding is presented in figure 1. The relative position of the receiving antennas 1.2i (i = 1, 2, ..., n) and the radiation source of the IRI is shown in Fig.2. An example of the electronic switch 7 is shown in Fig.3. Figure 4 shows the phase change of the output voltage after the electronic switch.

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, and a second the input of which is connected to the output of the band-pass filter 15, the phase shifter 8 by 90 °, the first phase detector 9, the second input of which is connected to the second output of the reference generator 5, and an indicator 10, the reference generator 5 connected in series a pulse generator 6, an electronic switch 7, 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 with the possibility of electronic rotation around the first receiving antenna 1, located in the center a circle, and a second receiver 4, the output of which is connected to the second input of the first multiplier 14, connected in series to the output of the first band-pass filter 15, the second multiplier 18, the second band-pass filter 19 and the third phase detector 20, the second input of which is connected to the third output of the reference generator 5, and the output is connected to the second input of the indicator 10, the third receiver 21, the third multiplier 22, the second input of which is connected by the output of the intermediate frequency amplifier 13, and the third band-pass filter 23, the output of which is connected to the second output, connected in series to the second output of the electronic switch 7 second multiplier 18.

The proposed method is implemented as follows.

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

0≤t≤T _c ,

where U _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} - manipulated component phase mapping for con phase shift keying in accordance with a modulation code, and φ _k (t) = const at kτ _E <t <(k + 1) τ _E and can vary abruptly at t = kτ _Oe , i.e. at the borders 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 (ii = 1, 2, ..., n) around the receiving antenna 1;

α - bearing (azimuth) to the radiation source of the IRI;

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, 4 and 21, and then to the first inputs of the mixer 12, the multipliers 14 and 22, respectively.

соответствуют диаметрально противоположным расположением антенн 2.2 и 2.10 относительно приемной антенны 1, размещенной в центре окружности.Signs "+" and "-" before the quantities

correspond diametrically opposite to the location of the antennas 2.2 and 2.10 relative to the receiving antenna 1 located in the center of the circle.

The electronic switch 7 can be performed by various means. One of the options is the use of semiconductor diodes, which have a low capacitance, a small resistance to the current of the forward direction and a large resistance to the current of the reverse direction. An example of an electronic switching circuit is shown in FIG. 3. Each pair of antennas is connected to the input of the receivers 4 and 21 through the same switching circuits, which are shown in Fig. 3 for only two antennas 2.2 and 2.10. The points A ₁ and A _{2 of the} switching circuits are connected through the resistors R ₁ and R ₂ to a pulse generator, from which a negative voltage is supplied during the entire switching period T, with the exception of only a short period τ. Positive pulses of duration τ are supplied sequentially to each pair of antennas and for the switching period T pass to all n antennas.

The negative voltage at points A ₁ and A ₂ locks the diodes D ₁ , D ₂ , D ₃ and D ₄ , disconnecting the antenna chains 2.2 and 2.10 from the input of the receivers 4 and 21 and including the load resistors R ₃ and R ₄ in the antenna chain, and unlocks diodes D ₅ and D ₆ , which close the points A ₁ and A ₂ to the ground. Inductors L ₁ and L ₂ are used for transmitting direct current diodes.

A positive pulse makes the diodes D ₁ , D ₂ , D ₃ and D ₄ conductive.

Antennas 2.2 and 2.10 are connected to receivers 4 and 21 when the resistors R ₃ and R _{4 are} short-circuited. At the same time, the diodes D ₅ and D ₆ are locked and a short circuit to ground is eliminated. The change in the voltage phase at the input of receivers 4 and 21 occurs irregularly in accordance with the connection of a new pair of antennas after a period of time τ. Figure 4 shows the phase change of the output voltage after the electronic switch 7.

With any switching method, high frequency voltages of alternating phase are received at the inputs of receivers 4 and 21, i.e. phase modulated. The modulation period is equal to the switching period, and the initial phase of the modulation curve is equal to the bearing. Phase-modulated oscillations are also frequency-modulated, since the frequency equal to the time derivative will be variable with a variable phase.

The second input of the mixer 12 from the output of the local oscillator 11 receives voltage

u _Г (t) = U _г сs (ω _Г t + φ _Г ),

where U _Г , ω _Г , φ _Г - 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) = U _p cos [(ω _pr ± Δω) t + φ _k ( t) + φ _pr ], 0 <t <T _c ,

;Where

;

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

φ _CR = φ _s -φ _g ,

which is fed to the second input of the multipliers 14 and 22. At the output of the multipliers 14 and 22, phase-modulated (FM) oscillations are formed at a frequency ω _{G of the} local oscillator 11:

0≤t≤T _c ,

Where

which are distinguished by bandpass filters 15 and 23, respectively.

Therefore, useful information about the angle α is transferred to the stable frequency ω _{Г of the} local oscillator 11. Therefore, the instability of the carrier frequency of the received signals caused by various destabilizing factors does not affect the direction finding result, thereby increasing the accuracy of determining the location of the IRI radio emission source.

Phase-modulated oscillations u ₄ (t) and u ₅ (1) arrive at two inputs of the multiplier 18, at the output of which a voltage is generated

0≤t≤T _c ,

;Where

;

which is allocated by the bandpass filter 19 and fed to the first input of the phase detector 20.

Therefore, for the set of using at the same time for each switching of two antennas located at the ends of the diameter 2d, the relative size of the measuring base increases by 2 times (2d / λ).

The second input of the phase detector 20 from the third output of the reference generator 5 is supplied with a reference voltage

u ₀ (t) = U ₀ cosΩt.

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

u _н1 (α) = U _н1 cosα,

Where

proportional to the angular coordinate α, which is fixed by indicator 10. Thus, a direction finding scale is formed, which is an accurate but ambiguous scale.

At the same time, the phase-modulated oscillation u ₄ (t) is subjected to autocorrelation processing using an autocorrelator consisting of a delay line 16 and a phase detector 17.

называемая индексом фазовой модуляции, характеризует максимальное значение отклонения фазы от нулевого значения, происходящего при электронном вращении приемных антенн 2.i (i=1, 2,…, n) вокруг приемной антенны 1 (фиг.2).In the phase-modulated oscillation u ₄ (t) the value

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 (Fig.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 (Fig. 3). The control pulses are generated by the pulse generator 6 from the harmonic voltage generated by the reference generator 5 (figure 4)

u ₀ (t) = U ₀ cosΩt.

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 d / λ values 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 oscillation u ₄ (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 a value

where d ₁ <d,

, обеспечивающее однозначную пеленгацию источника радиоизлучений ИРИ. На выходе фазового детектора 17 образуется гармоническое напряжениеwhere the inequality holds

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

₇ u (t) = U ₇ cos (Ωt-α), 0≤t≤T c,

Where

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

u _n2 (α) = U _n2 sinα,

Where

proportional to the angular coordinate α, which is fixed by the indicator 10. Thus, a direction finding scale is formed, which is a rough but unambiguous scale.

Thus, the proposed method and device in comparison with the prototypes provides an increase in the accuracy of direction finding of the IRI radiation source. This is achieved by doubling the measurement base 2d.

The phase shift of the oscillations received by the antennas located at the ends of the diameter 2d is

The values of 2d and λ are known, therefore, by measuring the phase shift Δφ, it is easy to determine the directional cosine and angle α:

And the ambiguity arising from reading the angular coordinate α is eliminated by the autocorrelation processing of the received complex signals. Moreover, the proposed technical solutions are invariant to instability of the carrier frequency of the received signals, in view of their modulation (manipulation) and the width of the spectrum, and the exact and unambiguous measurement of the angular coordinate α is carried out at a stable frequency Ω of the reference oscillator.

Due to the convolution of the spectrum of a complex FMN signal, it is converted into narrow-band phase-modulated (FM) voltages, which makes it possible to isolate them using band-pass filters, 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. The 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 ° in phase, set n receiving antennas in the azimuth plane of a circle of radii d with the possibility of their electronic rotation with an angular velocity Ω around a receiving antenna located in the center of the circle, receive antennas are arranged around the circle, alternately with a frequency of Ω, the signal received by the antenna is placed at the center of the circle, it is frequency-converted, an intermediate frequency voltage is extracted, it is multiplied with signals alternately received by n receiving antennas located around the circle, a low-frequency voltage is extracted with a frequency of Ω, and it is compared in phase with the reference voltage, forming an accurate but ambiguous the direction finding scale of the signal radiation source, the first phase-modulated voltage is isolated, while the first phase-modulated voltage is subjected to autocorrelation processing, the low-frequency voltage with frequency Ω, compare it in phase with the reference voltage, forming a rough but unambiguous direction finding scale for the signal radiation source, characterized in that during each switching, two of n receiving antennas are located at the ends of the diameter of the circle along which they are installed, providing a twofold increase in the relative size of the measuring base, the signal received by the second antenna is multiplied with an intermediate frequency voltage, a second phase-modulated voltage is isolated, and e of the first phase-modulated voltage, emit a low-frequency voltage with the frequency Ω and compared in phase with a reference voltage, forming accurate, but ambiguous scale DF signal source radiation. 2. Phase direction finder containing a first receiving antenna in series, a first receiver, a mixer, the second input of which is connected to the local oscillator output, an intermediate frequency amplifier, a first multiplier, a first bandpass filter, a delay line, a second phase detector, the second input of which is connected to the output of the first a band-pass filter, a 90 ° phase shifter, a first phase detector, the second input of which is connected to the second output of the reference generator, and an indicator, a reference generator, a generator, and pulses, an electronic switch, n inputs of which are connected to n outputs of receiving antennas arranged around a circle of radius d with the possibility of their electronic rotation around the first receiving antenna located in the center of the circle, and a second receiver, the output of which is connected to the second input of the first multiplier, connected in series to the output of the first bandpass filter, a second multiplier, a second bandpass filter and a third phase detector, the second input of which is connected to the third output of the reference generator, and the output is connected to the second input of the indicator, characterized in that during each switching, two of n receiving antennas are used simultaneously located at the ends of the diameter of the circle along which they are installed, providing a twofold increase in the relative size of the measuring base, while the second output of the electronic switch is connected in series a third receiver, a third multiplier, the second input of which is connected to the output of the intermediate frequency amplifier, and a third band-pass filter, the output of which is connected to the second input of the second multiplier.

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