RU2010258C1 - Direction finder - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: direction finder has aerials 1 and 2, receivers 3 and 4, mixers 5 and 6, search unit 8, local oscillators 8 and 9, intermediate frequency amplifiers 10-14, amplitude detectors 15-17, keys 18-20, multipliers 21-24, narrow-band filter 25-28, phase-meters 29-31. EFFECT: expanded range of frequency search of signals without expansion of range of frequency retuning of local oscillators. 3 dwg

Description

 The invention relates to radio engineering and can be used for direction finding of radiation sources of phase-shift keyed (PSK) signals.

 Known devices for direction finding of radiation sources of signals are based on the use of three receiving channels, two of which are equipped with directional antennas, and the third is an omnidirectional antenna (see ed. St. USSR N 558584, G 01 S 3/40, 1973); two receiving channels with omnidirectional antennas (see Space trajectory measurements. - Edited by P. A. Agadzhanov et al. M.: Sov. Radio, 1969, p. 244, Fig. 7.2); an antenna having a cardiode or octal radiation pattern (see ed. St. N 164326, CL G 01 S 3/10, 1958); oscilloscope indicator (ed. St. N 375579, class G 01 R 25/00, 1971).

Of the known devices, the closest to the proposed one is the phase-direction-finder (Cosmic trajectory measurements. Edited by P. A. Agadzhanov et al. M.: Sov. Radio, 1969, p. 244, Fig. 7.2), which contains two antennas, two mixer, local oscillator, reference beat mixer, beat signal mixer and phase meter. The specified direction finder is built according to a superheterodyne circuit, which has an additional (mirror) receiving channel. This is due to the fact that the same value of the intermediate frequency f _pr can be obtained by receiving signals at two frequencies f _s and f _s , i.e.

f _ol = f _g - f _s and f _ol = f _s - f _g .

Therefore, if setting the frequency f _to take over the main receiving channel, along with it will take place and the mirror receiving channel, the frequency f _of which differs from the frequency f _s and 2f _straight and located symmetrically (mirror) relative to the local oscillator frequency f _r. The conversion on the mirror channel of the reception occurs with the same conversion coefficient K _ol as on the main channel of the reception. Therefore, it most significantly affects the selectivity and noise immunity of the direction finder. As a rule, an additional (mirror) receiving channel is suppressed by various technical means. However, from the point of view of expanding the range of frequency search for signals without expanding the range of frequency tuning of the local oscillator, it is advisable not to suppress, but to use an additional (mirror channel reception).

 The aim of the invention is to expand the range of frequency search for signals without expanding the range of frequency tuning of local oscillators.

 This goal is achieved by the fact that the search unit, the first, second, third, fourth and fifth amplifiers of intermediate frequency, the first, second and third amplitude detectors, the first, second and third keys, the third and fourth multipliers, the third and fourth narrow-band filters are introduced into the device , the second and third phaseometers, the inputs of the first and second local oscillators connected to the output of the search unit, the first amplifier of the intermediate frequency and the first key, the second input of which through the second amplitude amplifier is connected to the output of the fifth intermediate frequency amplifier, and the output is connected to the first input of the second multiplier, the second input of which is connected to the output of the fifth intermediate frequency amplifier, the second intermediate frequency amplifier, the second amplitude detector, the third key, and the second are connected in series to the output of the first mixer the input of which through the fifth intermediate frequency amplifier is connected to the output of the second mixer, the fourth multiplier, the second input of which is connected to the output of the second amplifier an intermediate frequency amplifier, a fourth narrow-band filter and a third phase meter, the second input of which is connected to the output of the first narrow-band filter, a fourth intermediate-frequency amplifier, a third amplitude detector, a second switch, the second input of which is connected to the output through a third intermediate-frequency amplifier, are connected in series to the output of the second mixer the first mixer, the third multiplier, the second input of which is connected to the output of the fourth intermediate frequency amplifier, the third narrow-band filter and the second zometr, a second input coupled to an output of the first notch filter.

 In FIG. 1 shows a structural diagram of the proposed device; in FIG. 2 and 3 are frequency and time diagrams explaining the operation of the device.

 The direction finder contains the first and second antennas 1 and 2, the first and second receivers 3 and 4, the first and second mixers 5 and 6, the search unit 7, the first and second local oscillators 8 and 9, the first, second, third, fourth and fifth amplifiers 10- 14 intermediate frequencies, the first, second and third amplitude detectors 15-17, the first, second and third switches 18-20, the first, second, third and fourth multipliers 21-24, the first, second, third and fourth narrow-band filters 25-28, the first, second and third phase meters 29-31.

 Moreover, the receiver 3, the mixer 5, the second input of which through the local oscillator 8 is connected to the output of the search unit 7, an intermediate frequency amplifier 10, a key 18, the second input of which is connected through the amplitude detector 15 to the output of the intermediate frequency amplifier 14, a multiplier are connected in series to the output of the antenna 1 22, the second input of which is connected to the output of the intermediate-frequency amplifier 14, a narrow-band filter 26 and a phase meter 29, the second input of which is connected through the multiplier 21 and the narrow-band filter 25 to the outputs of the goethe homelands 8 and 9, the output of the antenna 2 is connected in series to a receiver 4, a mixer 6, the second input of which through the local oscillator 9 is connected to the output of the search unit 7, an intermediate frequency amplifier 14, a key 20, the second input of which through an intermediate frequency amplifier 11 and the detector 16 is connected to the output of the mixer 5, a multiplier 24, the second input of which is connected to the output of the intermediate frequency amplifier 11, a narrow-band filter 28 and a phase meter 31, the second input of which is connected to the output of the narrow-band filter 25, to the output of the mixer 5, an intermediate frequency amplifier 12 is connected in series, a key 19, the second input of which is connected through an intermediate frequency amplifier 13 and an amplitude detector 17 to the output of the mixer 6, a multiplier 23, the second input of which is connected to the output of the intermediate frequency amplifier 13, a narrow-band filter 27 and a phase meter 30, the second input of which is connected to the output of the narrow-band filter 25.

 The direction finder works as follows.

Viewing predetermined range D _f by means of the search unit 7, which are periodically with period T _n sawtooth reconstructs synchronous oscillators 8 and 9. In the sawtooth generator or an electric motor can be used as a search unit 7. Keys 18, 19 and 20 in the initial state are always closed. From the outputs of antennas 1 and 2 through receivers 3 and 4, the received complex signals are received at the first inputs of mixers 5 and 6: for example, with phase shift keying (PSK):
u ₁ (t) = U _c cos [2π f _c t + φ _K (t) + φ ₁ ],
u ₂ (t) = U _c cos [2 π f _c t + φ _K (t) + φ ₂ ], 0 ≅ t ≅ T _with where U _c , f _c , T _c , φ ₁ , φ ₂ is the amplitude, carrier frequency, duration and initial phases of signals;
φ _K (t) is the manipulated component of the phase that displays the law of phase manipulation, and φ _K (t) = const for K τ _u <t <<(K + 1) τ _u , and can change stepwise at t = K τ _u , i.e., at the boundaries between elementary premises (K = 1, 2,..., N-1); τ _u , N is the duration and number of chips that make up the signal with a duration of T _s (T _s = N ˙ τ _u ).

- скорость изменения частот гетеродинов (скорость просмотра заданного диапазона частот).The second inputs of the mixers 5 and 6, respectively, from the outputs of the local oscillators 8 and 9 are energized
u _g1 (t) = U _g1 ˙ cos (2 π f _g1 t + π γ t ² + φ _g1 ),
u _g2 (t) = U _g2 ˙ cos (2 π f _g2 t + π γ t ² + φ _g2 ),
0 ≅ t ≅ T _n , where U _g1 , U _g2 , f _g1 , f _g2 , φ _g1 , φ _g2 , are the amplitudes, frequencies, and initial phases of the local oscillator voltages;
γ =

- rate of change of local oscillator frequencies (speed of viewing a given frequency range).

Moreover, the frequencies f _g1 and f _{g2 of the} local oscillators 8 and 9 are spaced twice the intermediate frequency
f _g2 - f _g1 = 2f _pr and selected symmetrical with respect to frequency f _{from the} main receiving channel
f _c - f _g1 = f _g2 -f _c = f _ol , which leads to the appearance of a second mirror channel at a frequency f _s2 (see Fig. 2).

The tuning frequency f _n1 and the passband Δ f _{1 of the} amplifiers 10, 12 and 14 of the intermediate frequency are selected as follows:
f _n1 = f _ave , Δ f ₁ = f _ave .

The tuning frequency f _n2 and the passband Δ f _{2 of} narrow-band filters 25-28 are selected as follows:
f _n2 = 2f _ave , Δ f ₂ = 1/2 f _ave .

The tuning frequency f _n3 and the passband Δ f _{3 of the} amplifiers 11 and 13 of the intermediate frequency are selected as follows:
f = 3f _{H3 Ave,} Δ f ₃ = f _ave
In mixers 5 and 6, the received signal is converted to the voltages of the following frequencies (see Fig. 3, a):
f _c1 = f _c - f _g1 - γ t = f _ol - γ t,
f _c2 = f _r2 + γt-f _c = f _ave + γ t, where the first index - the channel on which the signal is received;
the second index is the number of the local oscillator involved in the conversion of the carrier frequency of the received signal.

=

K₁·U_c·U

,
U

=

K₁·U_c·U

,
К₁ - коэффициент передачи смесителей,
f_пр = f_c - f_г1 = f_г2 - f_c - промежуточная частота,
φ_пр1 = φ₁ - φ_г1 , φ_пр2 = φ₂ - φ_г2.The amplifiers 10, 12, 14 of the intermediate frequency distinguish the following voltages:
u _pr1 (t) = U _pr1 ˙ cos [2 π f _pr t +
+ φ _to (t) - π γ t ² + φ _pr1 ],
u _pr2 (t) = U _pr2 ˙ cos [2 π f _pr t -
- φ _to (t) + π γ t ² - φ _CR2 ],
0 ≅ t ≅ T _c , where U

=

K ₁ · U _c · U

,
U

=

K ₁ · U _c · U

,
K ₁ - gear ratio of the mixers,
f _CR = f _c - f _g1 = f _g2 - f _c - intermediate frequency,
φ _pr1 = φ ₁ - φ _g1 , φ _pr2 = φ ₂ - φ _g2 .

K₂·U

U

,
К₂ - коэффициент передачи перемножителя
f_г2 - f_г1 = 2f_пр,
Δ φ_г = φ_г1 - φ_г2,
Δ φ₁ = φ₁ - φ₂ - фазовый сдвиг, определяющий направление на источник излучения ФМн сигнала.The voltage u _pr2 (t) from the output of the intermediate frequency amplifier 14 is fed to the input of the amplitude detector 15, where its envelope is allocated, which is fed to the control input of the key 18, opening it. In this case, the voltage u _pr1 (t) from the output of the intermediate frequency amplifier 10 is supplied to the first input of the multiplier 22, the second input of which is supplied with the voltage u _pr2 (t) from the output of the intermediate frequency amplifier 14. At the output of the multiplier 22, a harmonic voltage is generated
u _{3 (} t) = U ₃ ˙ cos (4 π f _pr t + Δ φ _g + Δ φ ₁ ),
0 ≅ t ≅ T _s , where U ₃ =

K ₂ · U

U

,
K ₂ - transmission coefficient of the multiplier
f _r2 - f _r1 = 2f _pr
Δ φ _g = φ _g1 - φ _g2 ,
Δ φ ₁ = φ ₁ - φ ₂ is the phase shift, which determines the direction of the PSK signal to the radiation source.

 This voltage is allocated by a narrow-band filter 26 and is supplied to the first input of the phasemeter 29.

K₂·U

U

.Voltages u _g1 (t) and u _g2 (t) from the outputs of the local oscillators 8 and 9 are fed to two inputs of the multiplier 21, at the output of which a harmonic voltage is generated
u ₄ (t) = U ₄ ˙ cos (4 π f _pr t + Δ φ _g ), where U ₄ =

K ₂ · U

U

.

sinβ, где d - расстояние между антеннами (измерительная база);
λ - длина волны;
β - угол прихода радиоволн.This voltage is allocated by a narrow-band filter 25 and is supplied to the second input of the phase meter 29. The latter determines the phase difference
Δφ ₁ = φ ₁ -φ ₂ = 2

sinβ, where d is the distance between the antennas (measuring base);
λ is the wavelength;
β is the angle of arrival of radio waves.

Therefore, if the PSK signals are received on the main channel at a frequency f _c , then the phase shift Δ φ ₁ , which determines the direction to the source of their radiation, is determined by a phase meter 29.

The voltage u _pr1 (t) and u _pr2 (t) from the outputs of the amplifiers 12 and 14 of the intermediate frequency are respectively supplied to the first inputs of the switches 19 and 20. Since the passband Δ f _{3 of the} amplifiers 11 and 13 of the intermediate frequency frequency voltage u _pr1 (t) and u _pr2 (t) do not fall, then the keys 19 and 20 remain in the closed state.

=

K₁·U

U

;
U

=

K₁·U

U

;
f_пр = f_г1 - f_з1 - промежуточная частота;
φ_пр3 = φ₃ - φ_г1 , φ_пр = φ₄ - φ_г2.If PSK signals are received by the first image channel at frequency f _P1
u ₅ (t) = U _З1 ˙ cos [2 π f _З1 t + φ _K (t) + φ ₃ ],
u ₆ (t) = U _З1 ˙ cos [2 π f _З1 t + φ _K (t) + φ ₄ ],
0 ≅ t ≅ T _З1 , where U _З1 , f _З1 , T _З1 , φ ₃ , φ ₄ are the amplitude, carrier frequency, duration and initial phases of the signals, then in mixers 5 and 6 they are converted to voltages of the following frequencies (see Fig. . 3, b):
f ₁₁ = f _g1 + γ t - f _z1 = f _ol + γ t,
f ₁₂ = f _g2 + γ t - f _s1 = 3 f _pr + γ t; which fall into the passband Δ f ₁ and Δ f ₃ amplifiers 10, 12 and 13 of the intermediate frequency
u _pr3 (t) = U _pr3 ˙ cos [2 π f _pr t -
- φ _to (t) + π γ t ² - φ _CR3 ],
_WP4 u (t) = U _WP4 ˙ cos [π f 6 _ave t -
- φ _to (t) + π γ t ² - φ _CR4 ],
0 ≅ t ≅ T _z1 , where U

=

K ₁ · U

U

;
U

=

K ₁ · U

U

;
f _CR = f _g1 - f _Z1 - intermediate frequency;
_PR3 φ = φ ₃ - φ _r1, φ ₄ = φ _pr - φ _r2.

K₂·U

U

,
Δ φ₂ = φ₃ - φ₄.The voltage u _pr4 (t) from the output of the intermediate frequency amplifier 13 is fed to the input of the amplitude detector 17, where it is detected and fed to the control input of the switch 19, opening it. The voltage u _CR3 (t) from the output of the intermediate frequency amplifier 12 through the public key 19 is supplied to the first input of the multiplier 23, the second input of which is supplied voltage u _CR4 (t) from the output of the intermediate frequency amplifier 13. The output of the multiplier 23 produces a harmonic voltage
u ₇ (t) = U ₇ ˙ cos (4 π f _pr t + Δ φ _g + Δ φ ₂ ),
0 ≅ t ≅ T _s1 where U ₇ =

K ₂ · U

U

,
Δ φ ₂ = φ ₃ - φ ₄ .

This voltage is allocated by a narrow-band filter 27 and fed to the first input of the phase meter 30, to the second input of which a harmonic voltage u ₄ (t) is supplied from the output of the narrow-band filter 25. The latter measures the phase shift Δ φ ₂ = φ ₃ - φ ₄ , which determines the direction to the source radiation FMN signals received on the first mirror channel at a frequency f _S1 .

The voltage u _pr3 (t) from the output of the intermediate frequency amplifier 10 is supplied to the first input of the switch 18.

Since the voltage does not fall into the passband Δ f _{1 of the} intermediate frequency amplifier 14, the switch 18 remains in the closed state.

=

K₁·U

U

;
U

=

K₁·U

U

;
f_пр = f_з2 - f_г2 - промежуточная частота;
φ_пр5 = φ₅ - φ_г1 , φ_пр6 = φ₆ - φ_г2.If the PSK signals are received on the second mirror channel at a frequency f _s2
u ₈ (t) = U _З2 ˙ cos [2 π f _З2 t + φ _K (t) + φ ₅ ],
u ₉ (t) = U _З2 ˙ cos [2 π f _З2 t + φ _K (t) + φ ₆ ],
0 ≅ t ≅ T _З2 , where U _З2 , f _З2 , T _З2 , φ ₅ , φ ₆ are the amplitude, carrier frequency, duration and initial phases of the signals, then in mixers 5 and 6 they are converted to voltages of the following frequencies (see Fig. . 3, c):
f ₂₁ = f _z2 - f _g1 - γ t = 3 f _ol - γ t,
f ₂₂ = f _z2 - f _g2 - γ t = f _ol - γ t that fall into the passband Δ f _z and Δ f _{1 of the} amplifiers 11 and 14 of the intermediate frequency
u _pr5 (t) = U _pr5 ˙ cos [6 π f _pr t +
+ φ _to (t) - π γ t ² + φ _pr5 ],
u _pr6 (t) = U _pr6 ˙ cos [2 π f _pr t +
+ φ _to (t) - π γ t ² + φ _pr6 ],
0 ≅ t ≅ T _s2 , where U

=

K ₁ · U

U

;
U

=

K ₁ · U

U

;
f _CR = f _C2 - f _g2 - intermediate frequency;
φ _pr5 = φ ₅ - φ _g1 , φ _pr6 = φ ₆ - φ _g2 .

K₂·U

U

,
Δ φ₃ = φ₅ - φ₆.The voltage u _pr5 (t) from the output of the intermediate frequency amplifier 11 is fed to the input of the amplitude detector 16, where it is detected and fed to the control input of the key 20, opening it. The voltage u _CR6 (t) from the output of the intermediate frequency amplifier 14 through the public key 20 is supplied to the first input of the multiplier 24, the second input of which is supplied voltage u _CR5 (t) from the output of the intermediate frequency amplifier 11. The output of the multiplier 24 produces a harmonic voltage
u ₁₀ (t) = U ₁₀ ˙ cos (4 π f _pr t + Δ φ _g + Δ φ ₃ ), where U ₁₀ =

K ₂ · U

U

,
Δ φ ₃ = φ ₅ - φ ₆ .

This voltage is allocated by a narrow-band filter 28 and fed to the first input of the phasemeter 31, the second input of which is supplied with a harmonic voltage u ₄ (t) from the output of the narrow-band filter 25. The latter measures the phase shift Δ φ ₃ = φ ₅ - φ ₆ , which determines the direction to the source radiation FMN signals received on the second mirror channel at a frequency f _z2 .

Thus, the proposed direction finder in comparison with the prototype provides an extension of three times the range of the frequency search for signals without expanding the range of tuning of local oscillators. This is achieved by using the first and second mirror receiving channels, which are formed due to the fact that the frequencies f _g1 and f _{g2 of the} local oscillators are spaced apart by a double value of the intermediate frequency
f _g2 - f _g1 = 2f _pr , selected symmetrical with respect to the frequency f of the main channel
f _c - f _g1 = f _g2 - f _c = f _ol and rebuild synchronously. (56) Space trajectory measurements. Ed. P.A. Agadzhanova and others M.: Sov. radio, 1969, p. 244, fig. 7.2.

Claims (1)

 Direction finder, containing two reception channels, each of which consists of a series-connected antenna, receiver and mixer, the second input of which is connected to the output of the local oscillator, as well as sequentially connected to the output of the first local oscillator, the first second, and the second to the other a filter and a first phase meter, the second input of which through the second narrow-band filter is connected to the output of the second narrow-band filter, characterized in that, in order to expand the range of the frequency search for signals fishing without expanding the frequency tuning range of the local oscillators, it contains the search unit, the first, second, third, fourth and fifth intermediate frequency amplifiers, the first, second and third amplitude detectors, the fourth, third and third, third and third, third and third narrow-band filters, second and third phase meters, with the inputs of the first and second heterodyne connected to the output of the search unit, the first intermediate frequency amplifier and the first key, the second input of which through the second amplitude detector is connected to the output of the fifth intermediate frequency amplifier, and the output is connected to the first input of the second intermediate frequency, the second input of which is connected to the output of the fifth intermediate frequency amplifier, the second intermediate frequency amplifier is connected to the output of the first mixer, the second the input of which through the fifth intermediate frequency amplifier is connected to the output of the second mixer, the fourth multiplier, the second input of which is connected to the output of the second amplifier of the exact frequency, the fourth narrow-band filter and the third phase meter, the second input of which is connected to the output of the first narrow-band filter, the fourth intermediate frequency amplifier, the third, the third, the fourth, and the third, third mixer, the third multiplier, the second input of which is connected to the output of the fourth intermediate frequency amplifier, the third narrow-band filter and the second phase meter, the second input of which one with the output of the first narrow-band filter.

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