RU2189609C1 - Phase direction finder - Google Patents

Abstract

FIELD: radiolocation, radio navigation, applicable for determination of angular co-ordinates of the source of radiation of a phase-manipulated signal. SUBSTANCE: phase direction finder has the first 1, second 2 and third 22 receiving antennas, the first 3, second 4 and third 23 receivers, the first 5, second 6, third 14, fourth 24 and fifth 30 multipliers, the first 7, second 8 and third 25 narrow-band filters, phase shifter by 90 deg, the first 10 and second 26 phase detectors, the first 11, second 16, third 27 and fourth 32 indicators, the first 12 and second 28 correlators, the first 13 and second 29 adjustable delay units, the first 15 and second 31 low-pass filters, the first 18 and second 34 measuring instruments, the first 17 and second 33 extreme regulators. EFFECT: expanded functional capacities of the direction finder due to direction finding of the source of radiation of a phase-manipulated signal in space and estimation of its parameters. 5 dwg

Description

 The proposed direction finder relates to the areas of radar, radio navigation and can be used to determine the angular coordinates of the radiation source phase-shift keyed (FMN) signal.

 Known devices for direction finding of radiation sources of signals (ed. Certificate of the USSR 164.326, 558.584, 1.555.695, 1.591.664, 1.591.665, 1.602.203, 1.679.872, 1.730.924, 1.746.807, 1.832.947; patents RF 2.006.872, 2.003.131, 2.012.010, 2.010.258, 2.165.628 Space trajectory measurements, edited by P. A. Agadzhanov et al., Moscow: Sov. Radio, 1969, pp. 244-245 ; Kinkulkin I.E. et al. Phase method for determining coordinates. -M.: Sov. Radio, 1979 and others).

 The basic device is the "Phase direction finder" (RF patent 2.165.628, G 01 S 3/00, 2000), which is selected as a prototype.

 The specified direction finder provides a solution to the contradiction between the requirements for measurement accuracy and the uniqueness of reading the angular coordinate of the radiation source of the FMN signal by using two measuring scales: the phase measurement scale is accurate, but ambiguous, and the time scale of measurements is rough but unambiguous.

 However, this direction finder allows you to direction finding the radiation source of the FMN signal only in this plane and does not provide the ability to determine the parameters of the direction-finding FMN signal.

 An object of the invention is to expand the functionality of the direction finder by direction finding the radiation source of the phase-shifted signal in space and evaluating its parameters.

The problem is solved in that the phase direction finder containing the measuring and first direction-finding channels, while the measuring channel consists of a series-connected first receiving antenna, a first receiver, a first multiplier, the second input of which is also connected to the output of the first receiver, the first narrow-band filter and phase shifter on 90 ^o, DF first channel consists of series-connected second receiving antenna, a second receiver, the second multiplier, the second input of which is also connected output of the second receiver of the second notch filter, the first phase detector, a second input coupled to the first output of the phase shifter 90 ^o, and the first indicator of the series-connected to the output of a second receiver of the first variable delay unit, a second input thereof via a first extreme regulator connected to the output the first low-pass filter, the third multiplier, the second input of which is connected to the output of the first receiver, the first low-pass filter and the first measuring device, while a second indicator is connected to the second output of the first adjustable delay unit, equipped with a frequency detector, a trigger, a recording unit and a second direction-finding channel, consisting of a third receiver antenna, a third receiver, a fourth multiplier connected in series, the second input of which is also connected to the output of the third receiver, third narrow-band filter , the second phase detector, the second input of which is connected to the second output of the phase shifter by 90 ^o , and the third indicator, of which are connected in series to the output of the third receiver of the second adjustable delay unit, the second input of which is connected through the second extreme regulator to the output of the second low-pass filter, the fifth multiplier, the second input of which is connected to the output of the first receiver, the second low-pass filter and the second measuring device, and to the second output of the adjustable unit the fourth indicator is connected to the delay, the frequency detector, the trigger and the registration unit are connected in series to the output of the first receiver, the receiving antennas are placed in the form of a geo metric right angle, at the apex of which is the first receiving antenna of the measuring channel, common to the receiving antennas of direction finding channels.

 The structural diagram of the proposed phase direction finder is shown in FIG. 1. The relative position of the receiving antennas is shown in Fig.2. Direction finding characteristics are shown in FIGS. 3 and 4. Timing diagrams explaining the operation of the measuring channel are shown in FIG. 5.

The phase direction finder contains one measuring and two direction finding channels. The measuring channel consists of a series-connected first receiving antenna 1, the first receiver 3, the first multiplier 5, the second input of which is also connected to the output of the receiver 3, the first narrow-band filter 7 and the phase shifter 9 by 90 ^o . To the output of the first receiver 3, a frequency detector 19, a trigger 20, and a registration unit 21 are connected in series. Each direction finding channel consists of a second 2 (third 22) receiving antenna, a second (third) receiver 4 (23), a multiplier 6 (24), the second input of which is also connected to the output of the receiver 4 (23), a narrow-band filter 8 (25 ), a phase detector 10 (26), the second input of which is connected to the first (second) output of the phase shifter 9 by 90 ^° , and indicator 11 (27). An adjustable delay unit 13 (29) is connected to the output of the receiver 4 (23), the second input of which is connected through the extremal regulator 17 (33) to the output of the low-pass filter 15 (31), the multiplier 14 (30), the second input of which is connected to the output receiver 3, a low-pass filter 15 (31) and a measuring device 18 (34). An indicator 16 (32) is connected to the second output of the adjustable delay unit 13 (29). The sequentially connected adjustable delay unit 13 (29), the multiplier 14 (30) and the low-pass filter 15 (31) form a correlator 12 (28).

 Phase direction finder works as follows.

где V₁(t), V₂(t-τ₁), V₃(t-τ₂), Wc, φ₁, φ₂, Tc - огибающие, несущая частота, начальные фазы и длительность сигналов;

- время запаздывания сигнала, приходящего на антенну 2 по отношению к сигналу, приходящему на антенну 1 (фиг.2);

- время запаздывания сигнала, приходящего на антенну 22 по с отношению к сигналу, приходящему на антенну 1;
d₁...d₂ - измерительные базы;
γ, β - углы прихода радиоволн в азимутальной и угломестной плоскостях;
с - скорость распространения света;
φк(t) = {0, π} - манипулируемая составляющая фазы, отображающая закон фазовой манипуляции в соответствии с модулирующей функцией (кодом) M(t) (фиг. 5, а), причем φк(t) = const при Kτ_э<t<(K+1)τ_э и может измениться скачком при t = Kτ_э, т.е. на границах между элементарными посылками (К=1, 2, ... N-1);
τ_э, N - длительность и количество элементарных посылок, из которых составлен сигнал длительностью Tc(Tc = N•τ_э);
с выходов приемных антенн 1, 2 и 22 поступают на входы приемников 3, 4 и 23, где они усиливаются и ограничиваются по амплитуде:
U₄(t) = V_o•cos[Wc•t+φк(t)+φ₁],
U₅(t) = V_o•cos[Wc(t-τ₁)+φк(t-τ₁)+φ₂],

где = V_o - порог ограничения.Received FMN signals:
U ₁ (t) = V ₁ (t) • cos [Wc • t + φк (t) + φ ₁ ],
U ₂ (t) = V ₂ (t-τ ₁ ) • cos [Wc (t-τ ₁ ) + φк (t-τ ₁ ) + φ ₂ ],

where V ₁ (t), V ₂ (t-τ ₁ ), V ₃ (t-τ ₂ ), Wc, φ ₁ , φ ₂ , Tc - envelopes, carrier frequency, initial phases and signal duration;

- the delay time of the signal arriving at the antenna 2 with respect to the signal arriving at the antenna 1 (figure 2);

- the delay time of the signal arriving at the antenna 22 with respect to the signal arriving at the antenna 1;
d ₁ ... d ₂ - measuring base;
γ, β — angles of arrival of radio waves in the azimuthal and elevation planes;
c is the speed of light propagation;
φk (t) = {0, π} - manipulated component phase mapping law phase shift keying in accordance with the modulation function (code) M (t) (Figure 5 a.), wherein φk (t) = const at Kτ _e < t <(K + 1) τ _e and can change abruptly at t = Kτ _e , i.e. at the borders between elementary premises (K = 1, 2, ... N-1);
τ _e , N is the duration and number of chips that make up the signal of duration Tc (Tc = N • τ _e );
from the outputs of the receiving antennas 1, 2 and 22 go to the inputs of the receivers 3, 4 and 23, where they are amplified and limited in amplitude:
U ₄ (t) = V _o • cos [Wc • t + φк (t) + φ ₁ ],
U ₅ (t) = V _o • cos [Wc (t-τ ₁ ) + φк (t-τ ₁ ) + φ ₂ ],

where = V _o is the limit threshold.

где V₁=1/2 K₁•V₀ ²;
К₁ - коэффициент передачи перемножителей, которые представляют собой вторые гармоники канальных напряжений.These signals in the multipliers 5, 6 and 24 are multiplied by themselves. As a result of this, at the outputs of the multipliers 5, 6 and 24, the following resulting voltages are generated (Fig. 5, c):
U ₇ (t) = V ₁ • cos [2Wc • t + 2φ ₁ ],
U ₈ (t) = V ₁ • cos [2Wc (t-τ ₁ ) + 2φ ₂ ],

where V ₁ = 1/2 K ₁ • V ₀ ² ;
To ₁ - the transfer coefficient of the multipliers, which are the second harmonics of the channel voltage.

It should be noted that the width of the spectrum Δfc of the received FMN signals U ₁ (t) ÷ U ₃ (t) is determined by the duration τ _{e of} their elementary premises,
Δfc = 1 / τ _e
whereas the width of the spectrum of the second harmonics is determined by the duration T of _the signal:
Δfg = 1 / T _s .

Therefore, when multiplying the FMN signals themselves, their spectrum collapses N times:
Δfc / Δfг = N.
This circumstance makes it possible to isolate harmonic oscillations U ₇ (t) ÷ U ₉ (t) using narrow-band filters 7, 8 and 25, filtering out a significant part of noise and interference.

If the harmonic oscillations U ₇ (t) and U ₈ (t), U ₇ (t) and U ₉ (t) from the outputs of the narrow-band filters 7, 8 and 25 are directly applied to the phase discriminators 10 and 26, we obtain at the output of the latter:
Uout ₁ (γ) = V ₂ • cos (2π • d ₁ / λsinγ),
Uout ₁ (β) = V ₂ • cos (2π • d ₂ / λsinβ),
where V ₂ = 1/2 K ₂ • V ₁ ² ;
K ₂ - transfer coefficient of phase detectors (phase discriminators).

It can be seen from the above relationships that the output voltages of the discriminators depend on the angles γ and β, however, due to the fact that the cosine is an even function, the signs of Uout ₁ (γ) and Uout ₁ (β) are independent of the side of the deviation. To eliminate this drawback, a phase shifter 9 is included in the measuring channel, which changes the phase of the harmonic signal U ₇ (t) by 90 ^° . In this case, the voltage mismatch at the output of the phase discriminators 10 and 26 are determined by the expressions:
Uout ₁ (γ) = V ₂ • sin (2π • d ₁ / λsinγ),
Uout ₂ (β) = V ₂ • sin (2π • d ₂ / λsinβ),
The above dependencies are usually called direction-finding characteristics (Fig.3,4).

Таким образом, крутизна характеристик определяется величинами отношения d₁/λ и d₂/λ. Увеличение баз d₁, d₂ и уменьшение длины волны λ повышают крутизну K_γ и K_β.
Однако при этом возрастает неоднозначность отсчета углов γ и β.
Крутизна характеристик определяет зоны нечувствительности 2γ_min, 2β_min при заданном значении шумов V_ш, (фиг.3,4).The steepness of the characteristics in the region of small angles γ and β, where the characteristics are almost linear, is equal to:

Thus, the steepness of the characteristics is determined by the ratio d ₁ / λ and d ₂ / λ. An increase in the bases d ₁ , d ₂ and a decrease in the wavelength λ increase the steepness of K _γ and K _β .
However, this increases the ambiguity of the reading of the angles γ and β.
The steepness of the characteristics determines the deadband 2γ _min , 2β _min at a given value of noise V _W (Fig.3,4).

которые фиксируются индикаторами 11 и 27.The number of ambiguity zones, i.e., regions where the phase differences Δφ ₁ and Δφ ₂ change by an amount equal to 2π, are determined by the relations:
n ₁ = 2d ₁ / λ,
n ₂ = 2d ₂ / λ.
For a unique reference, it is necessary to choose n ₁ = 1 and n ₂ = 1, i.e. choose measuring bases based on the following conditions:
d ₁ <λ / 2;
d ₂ <λ / 2.
At the output of the phase discriminators 10 and 26, the phase differences are determined:

which are fixed by indicators 11 and 27.

 This is how the phase scales for measuring the angular coordinates γ and β are formed: accurate, but ambiguous.

Voltages U ₄ (t) and U ₅ (t), U ₄ (t) and U ₆ (t) from the outputs of receivers 3 and 4, 3 and 23 simultaneously arrive at two inputs of the correlator 12 (28), consisting of block 13 ( 29) adjustable delay, multiplier 14 (30) and low-pass filter 15 (31). The correlation functions R ₁ (τ) and R ₂ (τ) obtained at the output of correlators 12 and 28, measured by measuring instruments 18 and 34, have a maximum at the value of the introduced adjustable delay:
τ ₁ = t ₂ -t ₁ ,
τ ₂ = t ₃ -t ₁ ,
where t ₁ , t _2, t ₃ - the travel time of the signal distances R ₁ , R ₂ , R ₃ from the radiation source to the first 1, second 2 and third 22 receiving antennas.

где τ₁, τ₂ - введенные задержки сигнала, соответствующие максимуму корреляционных функций R₁(τ) и R₂(τ).
Значения угловых координат γ и β фиксируются индикаторами 16 и 32. Так формируются временные шкалы отсчета угловых координат γ и β: грубые, но однозначные.The maximum values of R ₁ (τ) and R ₂ (τ) are supported by extreme regulators 17 and 33, acting on the second inputs of blocks 13 and 29 adjustable delays. The scales of blocks 13 and 29 of adjustable delays (angle indicators) are graded directly in the values of the angular coordinates γ and β of the radiation source of the FMN signal:

where τ ₁ , τ ₂ are the introduced signal delays corresponding to the maximum of the correlation functions R ₁ (τ) and R ₂ (τ).
The values of the angular coordinates γ and β are fixed by indicators 16 and 32. This is how the time scales for counting the angular coordinates γ and β are formed: rough, but unambiguous.

Essentially measuring scales measure the total phase differences:
ΔΦ ₁ = m + Δφ ₁ ,
ΔΦ ₂ = n + Δφ ₂ ,
where m, n are the number of complete cycles of the measured phase differences, determined by time scales;
Δφ ₁ , Δφ ₂ are the phase differences measured by phase scales (0≤Δφ ₁ ≤2π, 0≤Δφ ₂ ≤2π).
It should be noted that the location of the receiving antennas 1, 2, and 22 in the form of a geometric right angle, at the apex of which the first receiving antenna 1 of the measuring channel is located, is dictated by the ideology of direction finding of the FMN signal source in space.

The received FMN signal U ₄ (t) (Figs. 5, 6) from the output of the first receiver 3 simultaneously arrives at the input of the frequency detector 19, the output of which forms a sequence of short bipolar pulses (Fig. 5, d), the position of which on the time axis corresponds to the moments of abrupt phase change of the received FMN signal. The resulting short pulses are fed to the counting input of the trigger 20. Each incoming pulse transfers the trigger 20 to another stable state (trigger 20 has two stable states). At the same time, at the output of the trigger 20, an analog of the modulating code M (t) is generated (Fig. 5, a) in the forward M ₁ (t) (Fig. 5, e) or reverse M ₂ (t) (Fig. 5, e) codes . In this case, it does not matter, in the forward or reverse code, an analog of the modulating function (codes) is analyzed. This is because, by analyzing an analog of the modulating function M (t) extracted from the received FMN signal in the forward M ₁ (t) or inverse M ₂ (t) code, its parameters can be reliably estimated (the law of phase manipulation, duration τ _e and the number N of chips). The selection of an analog of the modulating function in the forward or reverse code depends on the initial state of the trigger 20. The selected analog of the modulating code is fixed by the registration unit 21, where the parameters of the received FMN signal are evaluated.

 Thus, the proposed phase direction finder in comparison with the base object and other devices of a similar purpose provides direction finding of the radiation source of the FMN signal in other planes and the assessment of its parameters. Thus, the functionality of the phase direction finder is expanded.

Claims (1)

A phase direction finder comprising a measurement and a first direction finding channel, wherein the measurement channel consists of a series of a first receiving antenna, a first receiver, a first multiplier, the second input of which is also connected to the output of the first receiver, the first narrow-band filter and a phase shifter 90 ^° , the first direction finding channel consists of a second receiver antenna, a second receiver, a second multiplier connected in series, the second input of which is also connected to the output of the second receiver, the second kopolosnogo filter, the first phase detector, a second input coupled to the first output of the phase shifter 90 ^o, and the first indicator of the series-connected to the output of a second receiver of the first variable delay unit, a second input thereof via a first extreme regulator connected to the output of the first lowpass filter, the third multiplier, the second input of which is connected to the output of the first receiver, the first low-pass filter and the first measuring device, while to the second output of the first control unit For the delay, a second indicator is connected, characterized in that it is equipped with a frequency detector, a trigger, a recording unit and a second direction-finding channel, consisting of a third receiver antenna, a third receiver, a fourth multiplier connected in series, the second input of which is also connected to the output of the third receiver, the third narrowband a filter, a second phase detector, the second input of which is connected to the second output of the phase shifter by 90 ^o , and a third indicator, from a series connected to the output of the third about the receiver of the second adjustable delay unit, the second input of which is connected through the second extreme regulator to the output of the second low-pass filter, the fifth multiplier, the second input of which is connected to the output of the first receiver, the second low-pass filter and the second measuring device, and to the second output of the adjustable delay unit a fourth indicator is connected, a frequency detector, a trigger and a recording unit are connected in series to the output of the first receiver, receiving antennas are placed in the form of a geometric right angle, at the apex of which is the first receiving antenna of the measuring channel, common to the receiving antennas of direction finding channels.

Images