SU1747904A1 - Indication unit - Google Patents

Abstract

The invention relates to a radio metering technique, namely, indicator devices, and can be used for indication and rapidly changing processes, in particular, for visual analysis and recording of parameters of complex signals with combined linear frequency modulation and multiple phase modulation.

Description

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manipulation. The purpose of the invention is to improve noise immunity and selectivity. The indicator device includes a sweep generator 1, three tubes 2.33 and 34, a receiving antenna 3, a broadband amplifier 4, frequency detectors 5 and 30, differentiating circuits 6 and 7, mixers 8 and 43, amplifiers 9 and 44 intermediate frequencies, keys 10, 27 and 50, multipliers 11 and 17 frequencies by eight, band-pass filters 12,

The invention relates to a radio metering technique, namely to indicator devices, and can be used to indicate fast changing processes, in particular for visual analysis and recording of parameters of complex signals with combined linear frequency modulation and multiple phase shift keying (LFM-MPM) and var It is complementary to the main auth. No. 1682788.

The purpose of the invention is to increase the noise immunity and selectivity of the device by suppressing spurious signals (noise) received on the specular and combinational channels.

Figure 1 shows the structural diagram of the proposed device; figure 2 - structural scheme of the detector; on fig.Z - waveform view; Figures 4 and 5 are frequency and time diagrams explaining the operation of the device.

The indicator device contains a generator 1 sweep, the first electron beam tube (CRT) 2, receiving antenna 3, the first broadband amplifier 4, frequency detector 5, differentiating circuits 6 and 7, mixer 8, first intermediate frequency amplifier 9, first key 10, first multiplier 11 frequency by eight, the first band-pass filter 12, the first divider 13 frequencies, the second band-pass filter 14, the multiplier 15, the second band-pass filter 16, the second frequency multiplier 17 by eight, the third band-pass filter 18, the second frequency divider 19 by eight, fourth bandpass filter 20, first phase detector 21, fifth low frequency filter 22, control signal generator 23, first controllable delay element 24, detector 25, second delay element 26, second switch 27, search block 28, local oscillator 29, second frequency the detector 30, the first phase shifter 31 90 °,

14, 16, 18, 20 and 48, dividers 13 and 19 frequencies by eight, multipliers 15 and 47, phase detector 21, low-pass filter 22, control signal generator 23, controllable delay element 24, detector 25, delay element 26 , search block 28, heterodic 29, phase shifters 31. 42 and 45 by 90 °, reference voltage generator 32, adder 46, amplitude detector 29.5 Il.

reference voltage generator 32, second and third CRT VZ, 34, information input 35, reset input 36, first spectrum width meter 37, third frequency multiplier 38 by eight, second spectrum width meter 39, comparison block 40, threshold block 41, second phase shifter 42 at 90 °, second mixer 43, second intermediate frequency amplifier 44, third

phase shifter 45 at 90 °, adder 46, second multiplier 47, sixth band-pass filter 48, amplitude detector 49, third key 50, connected in a certain way.

The indicator device operates as follows.

Viewing the specified frequency range DF is carried out using search block 28, which periodically with a period T

reverses the frequency of the local oscillator according to the sawtooth law. At the same time, the search block 28 generates a horizontal scan of the CRT 33, which is used as a frequency axis and corresponds to the viewing band of a specified frequency range DF. Keys 10, 27, and 50 are always locked in their original state.

The signal from the output of the receiving antenna 3 through a broadband amplifier 4 is fed to the first inputs of the mixers 8, 43 and

multiplier 47. The second input of the mixer 8 from the first output of the local oscillator 29 is supplied with the voltage of a linearly varying frequency, which from the second output of the local oscillator 29 passes to the input of the phase shifter 42

by 90 °. The voltage generated at the output is applied to the second input of the mixer 43. At the outputs of the mixers 8 and 43, a combination voltage frequency is generated. Amplifiers 9 and 44 allocate intermediate frequency voltages that go to the two inputs of the adder 46 and then to the second input of the multiplier 47,

The tuning frequency of the bandpass filter 48 is chosen to be equal to the initial frequency of the secondary source. Therefore, the band-pass filter 48 allocates a voltage that, after detection in the amplitude detector 49, arrives at the control input of the switch 50 opening it. At the same time, the voltage from the output of the adder 46 through the public key 50 is supplied to the first inputs of the key 10, multiplier 15 and detector 25. At the input of multiplier 38, a frequency of eight detector 25, an oscillation is formed, in which phase shift keying is already absent.

The spectral width of the eighth harmonic signal is N times smaller than the width of the input signal spectrum.

Therefore, when the frequency of the chirp-mfm signal is multiplied by eight, its spectrum is folded N times. This circumstance makes it possible to detect a 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, the width of the eighth harmonic spectrum is measured with a meter 39. Voltages proportional to the width of these spectra are fed from the outputs of the meters 37 and 39 to the two inputs of the comparison unit 40 and the output of the comparison unit 40 a positive pulse is generated, which is fed to the input of the threshold unit 41, where it is compared with the threshold voltage. The threshold voltage is chosen so that this level does not exceed random noise. The threshold voltage is exceeded only when a chirp-MFMn signal is detected. When the threshold voltage is exceeded, a constant voltage is generated in the threshold unit 41, which is applied to the control input of the search unit 28, switching it to the stop mode, to the input of the delay element 26, to the control inputs of the keys 10 and 27, opening them vertically - deflecting plates ELTZZ. From this point in time, the viewing of the specified frequency range and the search for the LFM-MFMS signals is stopped for the time of visual analysis of the main parameters of the detected signal, which is determined by the delay time of the delay element 26. At the same time, a pulse is formed on the screen of the CRT 33, the position of which on the horizontal scan uniquely determines the initial carrier frequency of the detecting chirp-MFM signal (Fig. 3a).

When the search block 28 is stopped, a voltage is formed at the output of the adder 46 (Fig. 56), which through public keys 50 and 10 enters the input of the 11-frequency multiplier by eight. At the output of frequency multiplier 11 by eight, a voltage is generated which is separated by a band-pass filter 12 and fed to the input of frequency divider 13 by eight. At the output of the latter, a voltage is formed (Fig. 5B), which is the chirp signal at the intermediate frequency and is separated by a band-pass filter 14. This voltage is fed to the input of the frequency detector 5, the output of which forms a video pulse (Fig. 5d), shape which corresponds to the law of linear frequency modulation. The specified video pulse from the output of the frequency detector 5 is fed to the input of the differentiating circuit 6, the output pulse (Fig. 5e) of which is fed to the vertical deflecting plates of the CRT 2 and to the input of the differentiating circuit 7. At the output of the differentiating circuit 7 short polarity pulses ( Fig.5e). Moreover, the positive short pulse is triggered, and the negative sweep generator 1 closes with a negative short pulse. The generated sawtooth voltage (Fig. 5g) is used as a sweep voltage and causes ShONTal Tbg5TOP tilt plates of a CRT 2 to fade. On the screen of a CRT 2 a pulse is generated (Fig. 5e), the duration of which is proportional to the duration of the received chirp-MFMN signal The amplitude is proportional to the rate of change of the frequency inside the pulse / and the area of the oscillogram is proportional to the frequency deviation of the received chirp-MFMn signal.

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

The voltage (Fig. 5b) from the output of the bandpass filter 14 is fed to the information input of the controllable delay element 24 and then to the second input of the multiplier 15, to the first input of which a voltage is applied (Fig. 5b) from the output of the switch 50. The multiplier 15 produces a beat voltage (Figure 5C), which is the QPSK signal at the beat frequency. Moreover, the beat frequency is determined by the rate of change of the signal frequency and the delay value,

The beat voltage is separated by a band-pass filter 16 and fed to the input of frequency multiplier 17 by eight, the output of which forms a harmonic oscillation allocated by the band-pass filter 18 and fed to the input of frequency divider 19 by eight, the output of which is a voltage (Fig.5i ), which is a harmonic oscillation at a frequency

a beat, allocated by the bandpass filter 20 and 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 generated at the output of the phase detector 21. Moreover, the amplitude and polarity of this voltage depend on the degree and direction of the beating frequency deviation from the frequency of the generator 32 of the reference voltage. The control voltage is extracted by the low-pass filter 22 and, using the control signal generator 23, acts on the control input of the controllable delay element 24 by varying the delay so that the beat frequency and the frequency of the reference voltage generator are equal.

For a visual assessment of the magnitude of the phase jumps and the multiplicity of phase manipulation of the received chirp-MFMS signal, a CRT 34 is used, performed with a circular scan. In this case, a circular sweep is formed using a reference voltage generator 32, the frequency of which is maintained equal to the beat frequency using a phase locked loop system.

The voltage (fig. Bz) from 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 (fig. Bq) is formed whose temporal position corresponds to the moments of a discontinuous change in the phase of the signal (fig. Bz ).

The voltage from the output of the generator 32 of the reference voltage goes directly to the vertical deflection plates, and through the phase shifter 31 by 90 ° to the horizontal deflecting plates of the CRT 34, forming a circular sweep on its screen. The sequence of opposite-polarity pulses (fig. Bk) from the output of the frequency detector 30 is supplied to the modulating electrode of the CRT 34, providing modulation of its electron beam in brightness. In this case, an image is formed on the screen of a CRT 34 in the form of several bright points located around the circumference (Fig. 3b, cd). The number of points determines the multiplicity of phase manipulation, and the angular distance between them is equal to the magnitude of the phase jumps of the received signal. If the frequencies are unequal, the velocity labels will move around the circle with the difference frequency, and the reliability of the visual evaluation of the multiplicity of manipulation and the magnitude of the phase jumps of the received signal decreases. A phase locked loop system is used to eliminate this.

Delay time of delay element 26

is chosen so that it is possible to visually assess the main parameters of the detected chirp-MFMn signal, observed waveforms on CRT screens 2, 33 and 34.

0 After this time has elapsed, the voltage from the output of the delay element 26 is fed to the reset input of the detector 25 and resets its contents to zero. In this case, the search block 28 is transferred to the mode

5 adjustment, and the keys 10 and 27 are closed, i.e. are transferred to their initial states. From this point on, the review of the specified frequency range DF and the search for the chirp-MFMS signals continues.

0 In case of detection of the next chirp-MFM-H signal, the device operates in the same way.

The operation of the device described corresponds to the case of receiving signals on the main channel at a frequency (figure 4). If a false signal (interferer) is received in the image channel, then the amplifiers 9 and 44 of the intermediate frequency separate the voltages supplied to the two inputs of the adder 46,

0 which are compensated at its output. Therefore, the spurious signal (noise) received over the image channel is suppressed. If a false signal is received by

5, the first combinational channel, the amplifiers 9 and 44 of the intermediate frequency, separate the voltages applied to the two inputs of the adder 46, which are compensated at its output. Consequently false

0, the signal received on the first combination channel is suppressed,

If a false signal is received through the second combinational channel, amplifiers 9 and 44 of the intermediate frequency extract the voltages that go to the two inputs of the adder 46. The output of which is the voltage applied to the second input of the multiplier 47, to the first input of which served by

0 a false signal from the output of the amplifier 4. At the output of the multiplier 47, a voltage is generated that does not fall into the passband of the bandpass filter 48. The key 50 does not open and the false signal is suppressed.

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Claims (1)

Invention Formula Indicator device auth. No 1682788, characterized in that, with to increase noise immunity and selectivity by suppressing false signals received on the specular and combination channels, a second phase shifter, a second mixer, a second intermediate frequency amplifier, and a third phase rotator, a second multiplier, a sixth band filter, and an amplitude detector, are injected in it, the first intermediate frequency amplifier is connected to the first multiply $ .0 s eight CRC  ° ° PG Lem through the entered and sequentially connected adder and the third key, while the second input of the adder is connected to the output of the second phase shifter, and its output to the first input of the second multiplier, the second input of which is connected to the output of the wideband amplifier and the second input of the second mixer, and the amplitude output the detector is connected to the second input of the third key. Fig 2 -e-0 f  V -, - 3 Cjnp Cjnp g Fig 5