SU1744469A2 - Indicating device - Google Patents

Abstract

The invention relates to a radio metering technique, namely to indicator devices, can be used to indicate rapidly changing processes, in particular for visual analysis, direction finding and recording of parameters of complex signals with combined linear frequency modulation and multiple phase shift keying. The purpose of the invention is to increase noise immunity and eliminate the ambiguity of the visual assessment of the main parameters of the detected signal, as well as expanding the functionality of the device. The indicator device contains a sweep generator for four CRTs, two receiving antennas, two broadband amplifiers, frequency detectors, differentiating circuits, mixers, intermediate frequency amplifiers, keys, frequency multipliers by eight, bandpass filters, frequency dividers by eight, multipliers, phase detector, filter low pass, control signal driver, controllable delay element, detector, delay element, search block, local oscillators, phase shifters of 90 °, reference voltage generator, corrective voltage l torus, threshold blocks. 6 Il. WITH

Description

The invention relates to a radio measuring technique, namely to indicator devices, and can be used to indicate rapidly changing processes, in particular for visual analysis, direction finding and recording parameters of complex signals with combined linear frequency modulation and multiple phase shift keying (chirp -MFMN), and is an improvement of the device according to ed. St. No. 1682788.

The aim of the invention is to improve noise immunity and display accuracy.

FIG. 1 shows a block diagram of the proposed device; in fig. 2 is a detector circuit: in FIG. 3 shows the possible waveforms in FIG. 4, a frequency diagram illustrating the formation of additional reception channels, FIG. 5 - phase method of direction finding of a radiation source of signals in one plane; in fig. 6 shows timing diagrams for devices that work.

The indicator device contains a generator 1 sweep, the first electron beam tube (CRT) 2, the first receiving antenna 3, the first broadband amplifier 4, frequency detector 5, differentiating circuits 6 and 7, mixer 8, the first amplifier 9 intermediate frequency, the first key 10, the first multiplier 11 frequencies by eight, the first band-pass filter 12, the first divider 13 frequencies by eight, the second band-pass filter 14, the multiplier 15, the third band-pass filter 16, the second mind VI

four

- O Yu

hO

a frequency cutter 17, a fourth band-pass filter 18, a second frequency divider 19 by eight, a fourth band-pass filter 20, a phase detector 21, a low-pass filter 22, a control signal driver 23, a controllable delay element 24, a detector 25, a delay element 26, a key 27, a search block 28, a local oscillator 29, a frequency detector 30, a phase shifter 31 of 90 °, a reference voltage generator 32, a second CRT 33, a third CRT 34.

The detector 25 (FIG. 2) contains input elements 35 and 36, a spectrum width meter 37, a frequency multiplier 38 by eight, a spectrum width meter 39, a comparison block 40 and a threshold block 41. A second receiving antenna 42 is coupled to the second wideband amplifier 43.

The device also contains the second local oscillator 44, mixer 45, intermediate frequency amplifier 46, multiplier 47. bandpass filter 48, correlator 49, threshold blocks 50-51, key 52, multiplier 53, band pass filter 54, phase shifter 55, key 56 and fourth CRT 57 .

The suppression of spurious signals (interference) received on additional channels is based on the use of two receiving channels, the frequencies of the local oscillators of which are separated by a double value of the intermediate frequency. This circumstance leads to a doubling of the number of additional reception channels (Fig. 4). In this case, a correlator is used to process the frequency-converted channel signals. The presence of two receiving channels provides the direction finding of the radiation source of signals by the phase method. To increase the direction finding, the dimensions of the measuring base d can be increased (Fig. 5). The resulting ambiguity in the reading of the angular coordinate flo is stopped by the correlation processing of the channel signals.

The indicator device operates as follows.

Viewing a given frequency range is carried out using search block 28, which periodically with a period of Tp synchronously tunes the frequencies of the local oscillators 29 and 44 according to the sawtooth law. Simultaneously the search block 28 generates a horizontal scan of the CRT 33. which is used as a frequency axis and corresponds to the span of a specified frequency range . The keys 10, 27, 52, and 56 are always locked in the initial state. The tuning frequency of the band-pass filters 48 and 54 is chosen equal to twice the intermediate frequency.

The search voltage generator 28 can be used as a search block 28.

Received signals with multiple

phase manipulation (chirp-MFMN) from the outputs of receiving antennas 3 and 42 through broadband amplifiers 4 and 43 are fed to the first inputs of mixers 8 and 45, respectively, to the second inputs of which from the outputs

LOs 29 and 44 are supplied with voltages of linearly varying frequencies.

At the outputs of mixers 8 and 45, voltage combinations are generated. Amplifiers 9 and 46 are energized.

intermediate (differential) frequencies that go to the two inputs of the correlator 49. The output of the correlator 49 produces a voltage proportional to the correlation function R (t}, which has one

main petal and several side lobes. At the same time, the level of side lobes is significantly less than the level of the main lobe. The threshold level in block 51 is chosen so that it does not exceed the random

interference. It is exceeded only at the maximum output voltage of the correlator 49, which corresponds to the main lobe of the correlation function R (r0).

Since the channel voltage is formed by the same signal received via the main channel (Fig. 4), there is a strong correlation link between them. The output voltage of the correlator 49 reaches the maximum value and

exceeds the threshold level in block 51. When the threshold level Unopi is exceeded in block 51, a constant control voltage is generated, which is fed to the control input of the key 52 and opens it.

At the same time, the voltage from the output of the intermediate frequency amplifier 9 through the public key 52 is fed to the input of the detector 25. At the output of the frequency multiplier 38, an oscillation is formed in which the phase

manipulation is already missing.

The width of the spectrum of the eighth harmonic signal is determined by the duration of the signal, while the width of the spectrum of the received signal is determined by the duration of its elementary premises, i.e.

spectrum of the eighth harmonic signal N times

less than the width of the input spectrum.

Therefore, when multiplying the frequency

Chirp-mfmn signal on eight of its spectrum

minimized N times. This circumstance makes it possible to detect the chirp-MFMN signal even when its input power is lower than the noise and interference power.

The width of the input signal spectrum is measured with a meter 37, and the width of the eighth harmonic spectrum of the signal is measured with a meter 39. The voltage from the outputs of the meter 37 and 39 of the spectrum width is transmitted to two comparison units 40. At the output of the comparison unit 40, a positive pulse is generated, which is fed to the output of the block 41, where it is compared with the threshold voltage. The latter is chosen so that this level does not exceed the random interference. The threshold voltage is exceeded only when the chirp-MFMN signal is detected. When the threshold voltage is exceeded in block 41, a constant voltage is generated, which is supplied to the control input of the search block 28, placed in the stop mode, on the input of the delay element 26, on the control inputs of the keys 10 and 27, opening them, and on the vertically deflecting plates of a CRT 33. From this point in time, the viewing of a specified frequency range and the search for signals is stopped for the time of visual analysis of the main parameters of the detected LFM-MFMN signal, which is determined by the delay time of the element 26. On the CRT screen 33 a pulse (frequency mark) is produced, the position of which on the horizontal scan uniquely determines the initial carrier frequency of the detected signal (Fig. 3a),

When the tuning of the local oscillators 29 and 44 is stopped by intermediate frequency amplifiers 9 and 46, the voltages from the output of the intermediate frequency amplifier 9 through the open key 10 are fed to the input of the frequency multiplier 11 by eight, the output of which is the voltage released by the band-pass filter 12 and arriving at the input of the divider 13 frequency by eight. At the output of the latter, a voltage is generated (Fig. 6c), which is a chirp signal at an intermediate frequency, is separated by a band-pass filter 14 and is fed to the input of the frequency detector 5. At the output of the latter, a video pulse is formed (Fig. 6d) corresponds to the law of linear frequency modulation.

This video impulse is fed to the input of the differentiating circuit 6, the output impulse (fig. 6e) of which is fed to the vertical deflection plates of the CRT 2 and to the input of the differentiating circuit 7. The output of the latter produces short polar impulses (fig. Ba). A positive short pulse closes the sweep generator 1. The molded sawtooth voltage (Fig. 6g) is used as a sweep voltage and is applied to horizontally deflecting plates of a CRT 2, on the screen of which a pulse is formed (Fig. 6e). The duration of this pulse is proportional to the duration of the received chirp-MFMN signal, the amplitude is proportional to speed frequency variations inside the pulse, and the area

0 waveforms - frequency deviation of the received chirp-MFMN signal.

For a visual assessment of the main parameters of the received signal, the frequency grid 5 is plotted on the CRT 2 screen.

The voltage (Fig. 6c) from the output of the bandpass filter 14 simultaneously arrives at the input of the controllable delay element 24, the output of which produces a voltage

0 which is fed to the second input of the multiplier 15, to the first input of which is received the received chirp-MFMN signal (Fig. 66) of the intermediate frequency from the output of the intermediate frequency amplifier 9 through

5 key 52. At the output of the multiplier 15, a beat voltage is generated (Fig. 3), which is the FMN signal at the beat frequency. The beat frequency is determined by the rate of change of the signal frequency.

0 and the delay value.

The voltage is separated by a band-pass filter 16 and the input of the frequency multiplier 17 is eight, which results in a harmonic oscillation.

5 The voltage is separated by a band-pass filter 18 and is fed to the input of a frequency divider 19 by eight, the output of which produces a voltage (Fig. 6i), which is a harmonic oscillation at the beat frequency. The voltage is separated by a bandpass filter 20 and is fed to the first input of the phase detector 21, to the second input of which voltage is supplied from the output of the generator 32 of the reference voltage.

If the indicated voltages differ from each other in frequency and phase, then a control voltage is formed at the output of the phase detector 21. The amplitude and variability of this voltage depend on the degree and direction of the beat frequency deviation from the frequency of the generator 32 of the reference voltage. The control voltage is extracted by the lowpass filter 22 and by means of the control driver 23

5, the signal acts on the control input of the controllable delay element 24 by varying the delay so that the beat frequency and the reference frequency are equal

To visually estimate the magnitude of the phase jumps and the multiplicity of phase manipulation of the received chirp-FMFN signal, CRT 34 is used with a circular scan, which is formed using the reference voltage generator 32, whose frequency is maintained at the same frequency as the beat frequency. The voltage (Fig. 6c) from the output of the band-pass filter 16 through the open key 27 is fed to the input of the frequency detector 30, the output of the band-pass filter 16 through the open key 27 is fed to the input of the frequency detector 30, at the output of which a sequence of short polarized pulses is formed (Fig 6k), the temporal position of which corresponds to the moments of an abrupt change in the phase of the signal (Fig. 6h).

The voltage from the output of the generator 32 of the reference voltage goes directly to the vertically deflecting plates, and through the phase shifter 31 by 90 ° to the horizontally deflecting plates of the CRT 34, forming a circular scan on its screen. The formed sequence of short bipolar pulses (Fig. 6k) from the output of the frequency detector 30 is fed to the modulating electrode of the CRT 34 and modulates its electron beam by brightness. On the screen of a CRT 34, an image is formed in the form of several bright points located on a circle (Fig. 36, c, d). The number of points determines the multiplicity m of phase shift manipulation, and the angular distance between them is equal to the magnitude of phase jumps of the received chirp-MFMN signal. If the frequencies are unequal, the velocity labels will move around the circumference with the difference frequency and the accuracy of the visual estimate of the multiplicity m of phase shift and the phase jumps of the received chirp-MFMN signal decreases sharply. A phase locked loop system is used to eliminate this.

The voltage from the output of the intermediate frequency amplifier 9 through the public key 52 simultaneously arrives at the first input of the multiplier 53, to the second input of which is supplied the voltage from the output of the intermediate frequency amplifier 46. At the output of the multiplier 53, a harmonic oscillation is formed, which is separated by a bandpass filter 54. The voltage from the outputs of the local oscillators 29 and 44 simultaneously goes to the two inputs of the multiplier 47, at the output of which a harmonic oscillation is formed, which is separated by a horizontal filter 49 and goes directly to the horizontal deviation plates, and

through a phase shifter 55 of 90 ° to the vertically deflecting plates of the CRT 57, forming a circular scan on its screen. To improve the accuracy of direction finding

The radiation source of the chirp-MFMN signals needs to increase the size of the measuring base. The resulting angular coordinate ambiguity is eliminated by correlation processing.

channel signals. In this case, the maximum of the correlation function corresponds to the zone of a one-to-one reference of the angular coordinate D, i.e. the area where the phase difference varies within In. The output voltage of the correlator 49 will be maximum, only with R (ro) (TO. Where is the true bearing). In this case, the threshold level in the threshold block 50 is exceeded only at the maximum value of the correlation function R (TO), and therefore, at the maximum voltage, and does not exceed at the value m of the correlation function R (r) corresponding to the side lobes. When the threshold level is exceeded, a constant voltage is generated in the threshold unit 50, which is applied to the control input of the key 56, opening it. In this case, the harmonic voltage U4 (t) from the output of the bandpass filter 54 through

The open key 56 is supplied to the modulating electrode of the CRT 57. During the negative half period, the harmonic voltage of the CRT 57 is locked and only half of the circumference is visible.

The measured phase angle, which determines the direction to the radiation source of the signals, is counted as the angle between the dark part of the circle and the vertical straight line (Fig. A).

The delay time of delay element 26 is chosen such that it is possible to visually evaluate the main parameters of the received chirp-MFMN signal, observed

waveforms on CRT screens 2. 33, 34 and 57. After this time has elapsed, the voltage from the output of the delay element 26 is fed to the reset input 36 of the detector 25 (threshold unit 41) and resets its contents

on the hive value. In this case, the search block 28 is transferred to the rearrangement mode, and the keys 10 and 27 are closed, i.e. are transferred to their original states. From this point in time, view the specified

the frequency range and the search for chirp-MFMN signals continues.

If the next chirp-MFMN signal is detected, the operation of the device is similar.

The indicated operation of the device corresponds to the case of receiving signals on the main channel (FIG. 4).

If a false signal (interferer) is received on the first image channel, the intermediate frequency voltage is generated only at the output of the intermediate frequency amplifier 9. The output voltage of the correlator 49 is zero, the key 52 does not open, and a false signal (interferer) received via the first mirror channel at the frequency is suppressed.

If a spurious signal (noise) is received over the second image channel, then a voltage is generated at the output of intermediate frequency amplifier 46. The output voltage of the correlator 49 is also zero, the key 52 does not open, and the spurious signal (interference) received via the second image channel is suppressed.

For a similar reason, false signals (interference) received via other additional (combinational) channels are also suppressed.

If spurious signals (noise) are simultaneously received through the first and second mirror channels, then intermediate frequency voltages are generated at the outputs of intermediate frequency amplifiers 9 and 46. These voltages are applied to the two inputs of the correlator 49. However, the key 52 in this case also does not open. This is due to the fact that channel voltages are generated by different spurious signals (interference). Therefore, there is a weak correlation connection between them, the output voltage of the correlator 49 is not maximum and does not exceed the threshold voltage. Key 52 does not open and false signals (interference), simultaneously received by

the first and second mirror channels are suppressed.

Claims (1)

For a similar reason, spurious signals (interference) received simultaneously on the first and second combination channels, or on the third and fourth combination channels, or on any two additional channels are suppressed. The invention of the indicator device on the author. St. No. 1682788, characterized in that. in order to improve the noise immunity i / indication accuracy, a second receiving antenna, a second wideband amplifier, a second mixer, a second intermediate frequency amplifier, a second multiplier, a fifth band-pass filter, a third key and a fourth cathode ray modulating electrode are introduced into it; connected to the outputs of the first local oscillator, the second local oscillator, the second multiplier, the sixth band-pass filter, the second phase shifter and the vertical deflection plates of the fourth electr tron-ray tube connected in series to the output of the second intermediate frequency amplifier correlator and the first threshold unit, the output of which is connected to the second input of the third key, are connected in series to the output of the correlator to the second threshold unit and the fourth switch connected between the outputs of the first intermediate frequency amplifier and the input of the first multiplier, while the second input of the second multiplier is connected to the output of the first local oscillator, the output of the second local oscillator is connected to the second input of the second mixer, and the input of the second phase rotation is connected to horizontally deflecting plates of the fourth cathode ray tube. FIG. 2 OPMN  up U ar . . . , I tI f I 11) l) ig1 Os OG2 (JЈ2 2op kg kz fan Ym Fig l FIG. five 1 / H FIG 6