RU2405170C1 - Radar station for successive range scanning with linear adjustment of duration of probing phase-shift keyed radio pulses - Google Patents

Abstract

FIELD: physics. ^ SUBSTANCE: radar station with space probing with phase-shift keyed signals includes a second code generator, a second phase modulator, a reception antenna, a high frequency amplifier, second and third mixers, first, second and third frequency doublers, a preamplifier, a low-pass filter, an audio frequency amplifier, headphones and a threshold unit. Use of new units and a code sequence with linearly varying duration of pulses connected in a certain way in the radar station lifts restrictions on detection range in the near zone, and also ensures successive range scanning and measurement of distance to low-speed and fixed ground targets. ^ EFFECT: lifting restrictions on detection range in the near zone, as well as successive range scanning and measurement of distance to low-speed and fixed ground targets. ^ 9 dwg

Description

The invention relates to the field of radar and can be used in the development of portable radar surveillance systems for the protection of ground objects.

Known radar station (radar) continuous radiation [Bakulev P.A., Stepin V.M. Methods and devices for moving targets selection. - M .: Radio and communication, 1986, p. 34], which contains a transmitting antenna, a series-connected radio frequency generator, a detector, a Doppler frequency filter and an indicator device, while the second input of the detector is connected to a receiving antenna.

A disadvantage of the known radar is the inability to detect and continuously monitor radar signals reflected from low-speed ground targets or targets with zero radial velocities located in the controlled area.

Known radar with sounding space linearly-frequency-modulated radio pulses [Belotserkovsky GB Basics of radar and radar devices. - M .: “Owls. Radio ”, 1985, 336 p., P. 67], which contains a serially connected synchronizer, a transmitter consisting of frequency and pulse modulators and microwave stages, while the inputs of the frequency and pulse modulators are connected to the transmitter input, and the outputs are connected to the corresponding inputs microwave stages whose output is connected to the output of the transmitter, an antenna switch and an antenna, the output of the antenna switch through a receiver consisting of a series-connected frequency converter, the input of which is connected to the input iemnika, intermediate frequency amplifier and video detector of a compression filter, whose output is connected to the receiver output, connected to the output device, a second input coupled to the second output of the synchronizer.

A disadvantage of radar with space-sensing by linear frequency-modulated radio pulses is the inability to detect and observe radar signals reflected from ground targets whose delay time is less than the duration of the emitted linear frequency-modulated (LFM) radio pulse.

The closest in technical essence to the proposed one is a radar with sounding space phase-shift radio pulses, described in [Belotserkovsky GB Basics of radar and radar devices. - M .: “Owls. Radio ", 1985, 336 S., p.72], adopted as a prototype.

Figure 1 shows the structural diagram of the radar device of the prototype, where it is indicated:

1 - synchronizer;

2 - code generator;

3 - output block;

4 - phase modulator;

4.1 and 4.2 - the first and second gated amplifiers;

5 - master oscillator;

6 - power amplifier;

7 - antenna;

8 - mixer;

9 - intermediate frequency amplifier (UPCH);

17 - antenna switch;

18 - matched filter;

19 is an optimal filter;

20 - video detector.

The prototype device contains a serially connected synchronizer 1, a code generator 2, a phase modulator 4, a power amplifier 6, an antenna switch 17, a mixer 8, an amplifier 9, a matched filter 18, an optimal filter 19, and a video detector 20, the output of which is connected to the first input of the output unit 3, the second input of which is connected to the second output of the synchronizer 1. The output-input of the antenna switch 17 is connected to the antenna 7. The second output of the code generator 2 is connected to the second input of the phase modulator 4, the third input of which is connected inen to the output of the master oscillator 5. Moreover, the phase modulator 4 consists of parallel-connected first 4.1 and second 4.2 gated amplifiers, the outputs of which are combined and are the output of the phase modulator 4, the first inputs of the gated amplifiers 4.1 and 4.2 are connected and are the third input of the phase modulator 4. The second the inputs of the first 4.1 and second 4.2 gated amplifiers are respectively the first and second inputs of the phase modulator 4.

The prototype device operates as follows.

The carrier frequency signal of the master oscillator 5 through the third input of the phase modulator 4 is fed to the inputs of two gated amplifiers 4.1 and 4.2. The second inputs of the amplifiers 4.1 and 4.2 from the output of the code generator 2 receives a periodic sequence of pulses. Suppose that in the interval of the duration of an elementary (partial) video pulse with a code symbol “0”, a gated amplifier that does not create a phase shift is open, and in the interval with a code symbol “1”, a gated amplifier that shifts the signal phase by 180 ° (Δφ = π) .

Thus, at any given time interval, only one of the amplifiers 4.1 or 4.2 is in the open state. At the output of the phase modulator 4, a phase-shifted signal is generated. It goes to the input of the power amplifier 6, where it is amplified and fed through the antenna switch 17 to the input of the antenna 7. The emitted phase-shift signal, having reached the target, is reflected in the opposite direction and is received by the antenna 7, passes through the antenna switch 17, and goes to the mixer 8 (local oscillator not shown here). The phase-shifted signal converted to an intermediate frequency is fed to an amplifier of intermediate frequency 9. From the output of the amplifier 9 it is fed to the input of the matched filter 18. To ensure consistent filtering of the received signal, the passband of the matched filter 18 is consistent with the spectrum of the received code sequence. At the output of the matched filter 18, at the end of the code sequence, a single radio pulse is formed at an intermediate frequency with a duration equal to the duration of one partial radio pulse. The time-compressed radio pulse arrives at the optimal filter 19. The bandwidth of the optimal filter 19 is consistent with the spectrum of a single radio pulse. At the output of the optimal filter 19, a triangular pulse is formed with a peak value proportional to the amplitudes of the corresponding time pulses of the periodic code sequence. After detection in the video detector 20, the compressed pulse is supplied to the first input of the output unit 3, in which the post-detector signal processing and ranging are performed using the reference pulse from the second output of the synchronizer 1.

However, the prototype device does not allow the detection and observation of radar signals reflected from ground targets, the delay time of which is less than the duration of the emitted periodic phase-shift sequence, and there is no possibility of selection by range of signals reflected from stationary or low-speed ground targets from sounding signals reflected from underlying surface, the delay time of which exceeds the duration of the emitted pulsed phase-manipulated sequentially STI

Thus, the disadvantage of the prototype is the presence of restrictions on the detection range in the near field, as well as the lack of detection and continuous observation of radar signals reflected from stationary or low-speed ground targets in the conditions of interfering reflections from the underlying surface.

The objective of the proposed device is the removal of restrictions on the detection range in the near field, as well as providing a consistent overview of the range and measuring the distance to low-speed and stationary ground targets.

To solve the problem in a sequential range ranging radar with linear linear tuning of the duration of the sounding phase-shifted radio pulses, it contains a synchronizer, the first output of which is connected to the first input of the output unit, and the second output is connected to the input of the first code generator, the first and second outputs of which are connected respectively, with the first and second inputs of the first phase modulator, the third input of which is connected to the output of the master oscillator, connected in series According to the invention, a receiving antenna connected to the input of a high-frequency amplifier, the output of which is connected to the first input of the first mixer, the first frequency doubler, the pre-amplifier, the second frequency doubler, are introduced in series with the first mixer and the intermediate frequency amplifier, as well as the power amplifier and the transmitting antenna. and a second mixer, the output of which is connected to the input of a power amplifier, the output of which is connected to a transmitting antenna, a third mixer, a filter, connected in series p of low frequencies and an audio amplifier, the output of which is connected to the headphone, as well as a threshold unit, the input of which is connected to the output of the low-pass filter, and the output - to the second input of the output unit, designed to visually display the detection results and the distance from the reference point to targets, a third frequency doubler, the input of which is connected to the output of the pre-amplifier, and the output to the second input of the first mixer, the second code generator, the first and second outputs of which are connected respectively to the the second and second inputs of the second phase modulator, the output of which is connected to the second input of the third mixer, the first input of which is connected to the output of the intermediate frequency amplifier, in addition, the first input of the second code generator is connected to the second output of the synchronizer, and the second input to the third output of the first generator code, the output of the master oscillator is connected to the input of the first frequency doubler and the third input of the second phase modulator, the output of the first phase modulator is connected to the first input of the second frequency mixer, the signals at the outputs of the second code generator differ from the signals at the outputs of the first code generator by a constant change in delay, providing a consistent range overview.

Figure 1 presents the structural diagram of the radar with sounding space phase-shift radio pulses of the prototype.

Figure 2 presents the structural diagram of the proposed radar sequential range review with restructuring according to the linear law of the duration of the probing phase-manipulated radio pulses.

Figure 3 presents the structural diagram of the first code generator.

Figure 4 presents the structural diagram of the second code generator.

Figure 5 presents a view of the law of change in the duration of the FM-LFM sequence, for example, at the first input of the phase modulator.

Figure 6 presents a view of the law of variation of the amplitude of the FM-LFM code sequence, for example, at the first input of the phase modulator.

Figure 7 presents a view of the law of phase change of the signal at the output of the phase modulator.

On Fig presents the spectrum of the received signal reflected from a stationary ground target (F _D = 0).

Figure 9 shows the spectra of the received signal reflected from a low-speed ground target (F _D ≠ 0).

The scheme of the proposed radar is shown in figure 2, where the following notation:

1 - synchronizer;

2.1 and 2.2 - the first and second code generators;

3 - output block;

4.1 and 4.2 - the first and second phase modulators;

5 - master oscillator;

6 - power amplifier;

7.1 and 7.2 - transmitting and receiving antennas;

8.1, 8.2 and 8.3 - the first, second and third mixers;

9 - intermediate frequency amplifier (UPCH);

10.1, 10.2 and 10.3 - the first, second and third frequency doublers;

11 - pre-amplifier;

12 - high frequency amplifier (UHF);

13 - low-pass filter (low-pass filter);

14 - amplifier audio frequencies;

15 - head phone;

16 is a threshold block.

The proposed device contains a synchronizer 1, the first output of which is connected to the first input of the output unit 3, and the second output to the first inputs of the first 2.1 and second 2.2 code generators. The first and second outputs of the first code generator 2.1 are connected respectively to the first and second inputs of the first modulator 4.1. The third output of the first code generator 2.1 is connected to the second input of the second code generator 2.2, the first and second outputs of which are connected respectively to the first and second inputs of the second phase modulator 4.2, the third input of which is connected to the third input of the first phase modulator 4.1, the output of the master generator 5 and the input the first frequency doubler 10.1, the output of which through the preamplifier 11 is connected to the inputs of the second 10.2 and third 10.3 frequency doublers. The output of the first phase modulator 4.1 through a series-connected second mixer 8.2 and a power amplifier 6 is connected to a transmitting antenna 7.1. In addition, the UHF 12 is connected in series, the first mixer 8.1 and the UHF 9, the output of which is connected to the first input of the third mixer 8.3, the second input of which is connected to the output of the second phase modulator 4.2, the output of the third mixer 8.3 is connected through the LPF 13 and the threshold block 16 is connected with the second input of the output unit 3. In this case, the output of the low-pass filter 13 through the audio amplifier 14 is connected to the headphone 15, the receiving antenna 7.2 is connected to the UHF 12.

The first code generator 2.1 is made according to the circuit shown in figure 3, which indicates:

2.1.1 - reference generator;

2.1.2 - linear frequency-modulated (LFM) generator;

2.1.3 and 2.1.4 - the first and second Schmidt triggers;

2.1.5 - block OR-NOT;

2.1.6 - block OR.

The first code generator 2.1 contains a reference generator 2.1.1, the output of which is connected to the second input of the chirp of the generator 2.1.2, the output of which is connected to the inputs of the first 2.1.3 and second 2.1.4 Schmidt triggers, the outputs of which are connected respectively to the inputs of the OR-NOT block 2.1.5 and the OR block 2.1.6, the output of which is the first output of the code generator 2.1.1, the second output of which is the output of the OR block 2.1.6. In this case, the first input of the chirp generator 2.1.2 is the input of the first code generator 2.1, the output of the reference generator 2.1.1. - the third output of the code generator 2.1.1.

The second code generator 2.2 is made according to the circuit shown in figure 4, which indicates:

2.2.1 - R-S trigger;

2.2.2 - block And;

2.2.3 - pulse counter with a variable division ratio;

2.2.4 - chirp generator;

2.2.5 and 2.2.6 - the first and second Schmidt triggers;

2.2.7 - block OR-NOT;

2.2.8 - block OR.

The second code generator 2.2 contains a RS-connected trigger 2.2.1, an AND 2.2.2 block, a pulse counter 2.2.3, an LFM generator 2.2.4, a first Schmidt trigger 2.2.5 and an OR-NOT block, the output of which is the first output of the second generator code 2.2. The output of the pulse counter 2.2.3 is connected to the second RS input of the trigger 2.2.1, the first input of which is the first input of the code generator 2.2, the second input of which is connected to the second inputs of the AND 2.2.2 block and the chirp generator 2.2.4, the output of which is connected with the input of the second Schmidt trigger 2.2.6, the output of which is connected to the input of the OR block 2.2.8, the output of which is the second output of the 2.2 code generator.

The proposed radar operates as follows.

The oscillations of the first intermediate frequency f _{IF 1.0} from the output of the master oscillator 5 are fed to:

the third input of the first phase modulator 4.1;

the third input of the second phase modulator 4.2;

first frequency doubler 10.1 for generating a voltage with a frequency

f = 2 × f _{IF 1.0} .

In the phase modulator 4.1, the oscillations of the master oscillator 5 are amplified in one of two gated amplifiers. The gated amplifiers are controlled by amplitude-modulated video signals generated by the two-way limitation of the LFM oscillations in the code generator 2.1. The synchronization of the code generator 2.1 is carried out by video pulses coming from the first output of the synchronizer 1. The repetition period of these video pulses determines the duration of the LFM radio pulse T _M.

The type of laws for changing the duration and amplitude of the code is shown in FIG. 5 and FIG. 6, respectively. The code sequences of the pulses are gated by the phase modulator amplifiers so that in the time intervals with the code symbol "1" an amplifier is opened that does not create a phase shift (Δφ), and with the symbol "0", another amplifier is shifted that moves the phase by Δφ = π. At the output of the first phase modulator 4.1, a phase-manipulated signal with a change in the duration of partial pulses is generated according to a linear law. The form of the law of phase change of the signal at the output of the phase modulator 4.1 is shown in Fig.7.

The generated FM-LFM signal from the output of the first phase modulator 4.1 is fed to the first input of the second mixer 8.2 to generate a probing signal.

At the output of the first frequency doubler 10.1, a signal with a double frequency is formed. He through the preamplifier 11 enters the input:

a second frequency doubler 10.2 for generating a stand signal with a frequency f _P = 4 × f _{IF 1.0} ;

the third frequency doubler 10.3 for generating a signal of the first local oscillator with a frequency f _Г1 = 4 × f _ПЧ1.0 .

At the output of the second mixer 8.2, a continuous FM-LFM probing signal is generated with a frequency f _ЗС = 5 × f _ПЧ1.0 , which, after filtering and amplification in the power amplifier 6, is fed to the input of the transmitting antenna 7.1 for radiation in the direction to the ground target.

(где с - скорость света) через усилитель высокой частоты 12 поступает на первый вход первого смесителя 8.1.FM-LFM signal reaches a target located at a distance R, is reflected from it, is received by the antenna 7.2. From the output of the receiving antenna 7.2 FM-LFM signal delayed by

(where c is the speed of light) through a high-frequency amplifier 12 enters the first input of the first mixer 8.1.

From the output of the first mixer 8.1, the received FM-LFM signal converted to the first intermediate frequency is fed to the intermediate-frequency amplifier 9 for filtering and amplification in amplitude. Then it goes to the first input of the third mixer 8.3.

. Поэтому на выходе второго фазового модулятора 4.2 образуется такой же сигнал, как и сигнал на выходе первого фазового модулятора 4.1, только задержанный на время

. Постоянное изменение задержки

обеспечивает последовательный обзор по дальности. Сигнал на выходе второго фазового модулятора 4.2 обеспечивает в третьем смесителе 8.3, поступая на второй вход, синхронно-фазовое детектирование принятого ФМ-ЛЧМ сигнала при

.By changing the division coefficient K _{D of the} pulse counter of the second LFM code generator, the signal generated by the LFM generator of the second code generator 2.2 differs from the LFM generator of the first code 2.1 generator of the LFM signal only by the delay value

. Therefore, at the output of the second phase modulator 4.2, the same signal is generated as the signal at the output of the first phase modulator 4.1, only delayed for a while

. Constant change in delay

provides consistent range coverage. The signal at the output of the second phase modulator 4.2 provides in the third mixer 8.3, arriving at the second input, synchronous-phase detection of the received FM-LFM signal at

.

The filter obtained at the output of the third mixer 8.3 signal is performed in the low-pass filter 13.

On Fig shows the spectrum of the received signal for the case when the Doppler frequency increment is zero (F _D = 0).

For the case of a moving target, when F _Д ≠ 0, the signal at the output of the low-pass filter 13 is shifted by the magnitude of the Doppler frequency increment (see Fig. 9).

The received low-frequency signal from the output of the filter 13 through the audio amplifier 14 is fed to the headphone 15 for listening, and through the threshold device 16 to the input of the output device 3 to display the detection results. The synchronization of the output device 3 is carried out by video pulses coming from the first output of the synchronizer 1.

The operator can classify targets (animals, a person, a group of people, wheeled and tracked vehicles, swimming equipment, noise) according to the characteristic sound coloring of the spectrum of the signal received by the headphone 15.

получим расстояние до цели

, поэтому цель будет отображаться на экране выходного блока 3 в виде пятна диаметром d_n на расстоянии D от точки отсчета:

где масштаб

зависит от максимального размера используемой части экрана D_m и максимальной дальности обзора R_m.Based on the above formulas

get the distance to the target

, therefore, the target will be displayed on the screen of the output unit 3 in the form of a spot with a diameter of d _n at a distance D from the reference point:

where is the scale

depends on the maximum size of the used part of the screen D _m and the maximum viewing range R _m .

, где ΔK_D - величина скачка коэффициента деления K_D при последовательном обзоре, а разрешающую способность экрана - по формулеThe range resolution with visual indication is [Finkelstein MI Basics of radar. Textbook for high schools. - M .: “Owls. Radio ”, 1973. - 496 p., Ill., P. 1.6.2]: δD = δD _nom + δD _e . Potential resolution can be found by the formula:

, where ΔK _D is the value of the jump of the division coefficient K _D during sequential review, and the resolution of the screen is given by the formula

.

.

It is known that the main role in the visual method of counting the range using scale lines of the electronic scale is played by interpolation errors, i.e. the mean square instrumental error of the range measurement during visual indication can be determined by the formula [M. Finkelstein Basics of radar. Textbook for high schools. - M .: “Owls. Radio ”, 1973. - 496 p., Ill., P. 1.7.41: σ _inst (D) ≈σ _int (D) ≈0.05k _m D _m , where k _m = 1 ÷ 2 depending on the scale of the range, D _m - the interval between the scale lines.

Thus, the introduction of new blocks and a code sequence with a linearly variable duration of samples into the radar with space sensing by phase-manipulated radio pulses removes restrictions on the detection range in the near field, as well as provides a consistent range overview and distance measurement to low-speed and stationary ground targets, located in a controlled area.

To implement a technical solution, standard industrial equipment can be used. So, for example, the reference generator 2.1.1 is a generator with quartz stabilization, made, for example, on a chip of the K564LN2 series [V.N. Veniaminov, O.N. Lebedev, A.I. Miroshnichenko. Chips and their application: Ref. allowance. - 3rd ed., Revised. and add. - M.: Radio and Communications, 1989, 240 pp., P. 210, Fig. 7.10d].

The LFM generators 2.1.2 and 2.2.4 are, for example, a circuit of a digital synthesizer of the LFM signal [Kochemasov VN, Belov LA, Okoneshnikov VS Signal generation with linear frequency modulation. - M.: Radio and Communications, 1983. - 192 p., Ill., P. 55, Fig. 4.12].

Mixers 8.1, 8.2, 8.3 are, for example, diode frequency converters made according to the balanced circuit [M.S. Shumilin, V. B. Kozyrev, V. A. Vlasov. Design of transistor cascades of transmitters. Textbook for technical schools. - M.: Radio and Communications, 1987. - 320 p.: Ill., P. 178, Fig. 2.77].

The “OR” blocks 2.1.6 and 2.2.8 can be performed on the 530LL1 chip, the “OR-NOT” blocks 2.1.5 and 2.2.7 on the 530LE1 chip, the “AND” 2.2.2 blocks on the 1533LI chip, RS trigger 2.2 .1 - on the 1533TP2 chip, Schmidt triggers 2.1.3, 2.1.4, 2.2.5 and 2.2.6 - on the 133TL1 chips, the pulse counter with a variable division ratio 2.2.3 - on the 133IE8 chip [Perelman BL, Shevelev IN AND. Domestic microcircuits and foreign analogues. Directory. - M .: "Scientific and Technical Center Mikrotekh", 2000 - 375 pp., Ill., Items 1.1, 1.3, 1.5].

Claims (1)

A sequential range radar station (RLS) with linear linear tuning of the duration of the sounding phase-manipulated radio pulses, containing a synchronizer, the first output of which is connected to the first input of the output unit, and the second output is to the input of the first code generator, the first and second outputs of which are connected respectively to the first and second inputs of the first phase modulator, the third input of which is connected to the output of the master oscillator, the first mixer is connected in series and amplifies intermediate frequency, as well as a power amplifier and a transmitting antenna, characterized in that a receiving antenna is connected to the input of the high-frequency amplifier, the output of which is connected to the first input of the first mixer, the first frequency doubler, the preliminary amplifier, the second frequency doubler and the second a mixer, the output of which is connected to the input of a power amplifier, the output of which is connected to a transmitting antenna, a third mixer, a low-pass filter, and an amplifier Vukovyh frequencies, the output of which is connected to the headphone, as well as a threshold unit, the input of which is connected to the output of the low-pass filter, and the output - to the second input of the output unit, designed to visually display the detection results and the distance from the reference point to the target, the third frequency doubler the input of which is connected to the output of the pre-amplifier, and the output to the second input of the first mixer, the second code generator, the first and second outputs of which are connected respectively to the first and second inputs of the second a basic modulator, the output of which is connected to the second input of the third mixer, the first input of which is connected to the output of the intermediate frequency amplifier, in addition, the first input of the second code generator is connected to the second output of the synchronizer, and the second input is connected to the third output of the first code generator, the output of the master oscillator connected to the input of the first frequency doubler and the third input of the second phase modulator, the output of the first phase modulator is connected to the first input of the second frequency mixer, while the signals at the outputs The second code generator differs from the signals at the outputs of the first code generator by a constant change in delay, providing a consistent range overview.

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