RU2143707C1 - Phase direction finder - Google Patents

Abstract

FIELD: radiolocation and radio navigation. SUBSTANCE: phase direction finder has N antennas, N controlled phase inverters connected to outputs of antennas and high-frequency adder. Digital processor computes phase difference of signals for each required pair of antennas by assemblage of values of amplitude of summary signal envelope obtained from output of receiver of summary signal under various combinations of phase shifts in phase inverters established in sequence in the course of each working cycle of direction finder. EFFECT: invention can find use for phase direction finding of sources of narrow-band signals in plane or in space. 1 dwg

Description

 The invention relates to the field of radar and radio navigation, in particular to direction finders for determining the direction with measuring the phase shift of signals recorded from spaced antennas.

 Known phase direction finders, the action of which is based on the formation of vector sums of signals received by a pair of spaced antennas, with a phase shift by fixed angles that are multiples of π / 2. An estimate of the phase difference of the signals received by the antennas is determined by the amplitudes of the four parallel-generated vector sums of signals corresponding to the four values of the phase shift between the summed signals. Direction finders of this type are described, for example, in US patent N 3.631.491, NKI 343 / 113R, MKI G 01 S 3/46 and in French patent N 2.718.252, MKI G 01 S 3/04 (application N 9403665 from 29.03. 94).

 Closest to the claimed is the direction finding device described in French patent N 2.718.252. The known device contains N antennas, a shaper of four vector sums with high-frequency switches of inputs and outputs, a multi-channel receiver with envelope detectors and ADCs at the outputs of each channel, a digital processor. A disadvantage of the known device is the low accuracy, due to the spread and instability of the transfer characteristics of the phase-shifting and switching high-frequency elements, as well as the complexity of the construction scheme. An object of the invention is to increase accuracy.

(1)
где: i = 1, 2,... (M^N-1), M^N - текущий номер комбинаций фазовых сдвигов в фазовращателях, последовательно устанавливаемых в течение рабочего цикла;
(γ_m-γ_n)_i- разность фазовых сдвигов в фазовращателях m-ой, n-ой пары антенн;
x_i - отсчет с выхода АЦП приемника при i-ой комбинации фазовых сдвигов в фазовращателях.The solution to this problem is achieved by the fact that in the direction finding device containing N antennas and serially connected to the receiver with an envelope detector and an ADC at the output and a digital processor, N controlled discrete phase shifters with the number of positions on the phase shift M more than two and with a resolution of 2π / M, phase shifter control unit, high-frequency adder with N inputs, while controlled discrete phase shifters are connected respectively between the antenna outputs and the inputs of the high-frequency adder, the output of which connected to the receiver input, control inputs of the phase shifters respectively connected to N-output signal phase shifters control unit, the clock input coupled to an output of the digital processor clock signal, generating output signals of a phase difference measurement φ _{m, n} for each desired m-th, n-th pair antennas according to the algorithm:

(1)
where: i = 1, 2, ... (M ^N -1), M ^N - the current number of combinations of phase shifts in the phase shifters, sequentially set during the duty cycle;
(γ _m -γ _n ) _i is the difference in phase shifts in the phase shifters of the mth, nth pair of antennas;
x _i - readout from the output of the ADC receiver at the i-th combination of phase shifts in the phase shifters.

The work of the proposed direction finder is illustrated by a block diagram and a description of the principle of action. The block diagram indicates:
1 - antenna; 2 - controlled discrete phase shifter; 3 - phase shifter control unit; 4 - high-frequency adder; 5 - receiver with envelope detector and ADC at the output; 6 - digital processor.

 Controlled discrete phase shifters 2 are connected between the outputs of the antennas and, respectively, the inputs of the high-frequency adder 4. A receiver with an envelope detector and an ADC at the output 5 is connected between the output of the high-frequency adder 4 and the input of the digital processor 6. The first output of the digital processor 6 is the output of the measurement result. The second output of the digital processor 6 is the output of the synchronization signal and is connected to the input of the synchronization signal of the control unit 3. The outputs of the control unit 3 are connected to the control inputs of the controlled discrete phase shifters 2.

 Antennas are made in the form of weakly directed emitters, the beam pattern of which covers the expected range of bearing angles. Phase shifters are made on ferrites or on electronically controlled semiconductor diodes. The control unit is made on the basis of a binary register or counter with shapers of currents or voltages at the outputs of the bits.

The device operates in cycles consisting of consecutive clock cycles. In each i-th cycle of the operating cycle, the digital processor 6 issues a synchronization signal containing the number i of this cycle to the phase shifter control unit 3. The control unit 3 generates a combination of currents and voltages necessary for the installation in the controlled discrete phase shifters 2 of a certain combination of phase shifts corresponding to the number i of this cycle. After the end of the transient processes in the controlled phase shifters and in the receiver, the digital processor 6 reads the next i-th sample of the amplitude of the envelope of the signal x _i from the output of the receiver, remembers it and issues a synchronization signal containing the number of the new (i + 1) -th clock. After the end of all clock cycles, the total number of which is equal to the number of all possible combinations of phase shifter states, the digital processor calculates estimates of the signal phase differences for all required antenna pairs in accordance with algorithm (1).

 It is assumed that the measurement cycle time is significantly shorter than the amplitude correlation time of the signal.

(2)
При наличии необходимого набора известных величин γ_k,l= γ_k-γ_l выражения (2) образуют систему уравнений, которая может быть решена относительно неизвестных величин φ_k,l= φ_k-φ_l.
В предлагаемом устройстве используются M позиционные фазовращатели с дискретом по сдвигу фазы 2π/M, M - целое число больше двух. В каждом рабочем цикле производится установка всех возможных комбинаций состояний фазовращателей в N каналах. При указанных условиях решение системы уравнений вида (2) соответствует алгоритму (1), реализуемому цифровым процессором.The operation of the proposed device is based on using the dependence of the voltage x at the output of the quadratic envelope detector of the sum N of high-frequency signals on their amplitudes a _k , initial phases φ _k and on phase shifts γ _k in phase shifters. This dependence is described by the expression:

(2)
Given the necessary set of known values of γ _{k, l} = γ _k -γ _l, expressions (2) form a system of equations that can be solved with respect to unknown quantities φ _{k, l} = φ _k -φ _l .
The proposed device uses M positional phase shifters with a discrete phase shift of 2π / M, M is an integer greater than two. In each duty cycle, all possible combinations of phase shifter states are set in N channels. Under these conditions, the solution of a system of equations of the form (2) corresponds to the algorithm (1) implemented by a digital processor.

 Due to the symmetry of the input part of the proposed device, the effect of balanced suppression of the influence of amplitude and phase errors of phase shifters on the measurement result of the bearing is achieved.

 The proposed device can be used for phase direction finding sources of narrowband signals in the plane or in space.

Claims (1)

A phase direction finder containing N antennas and a series-connected receiver, with a bending detector and an ADC at the output, and a digital processor, characterized in that N controlled discrete phase shifters with the number of M phase positions greater than two and with a 2πM phase shift discrete are introduced into it, a phase shifter control unit, a high-frequency adder with N inputs, while controlled discrete phase shifters are included respectively between the antenna outputs and the inputs of the high-frequency adder, the output of which is connected to the receiver input, the control inputs of the phase shifters are connected respectively to the N outputs of the phase shifter control unit, the input of the synchronization signal of which is connected to the output of the synchronization signal of the digital processor, which generates the result of measuring the phase difference of the signals φ _{m, n} for each required mth, nth pair of direction finding antennas according to algorithm I

where i = 1,2, ... (M ^N -1);
M ^N - the current number of combinations of phase shifts in the phase shifters, sequentially set during the duty cycle;
(γ _m -γ _n ) is the difference in phase shifts in the phase shifters of the mth, nth pair of antennas;
X _i - countdown from the output of the ADC receiver at the i-th combination of phase shifts in the phase shifters.