SU1100575A1 - Device for extracting signal carrier frequency - Google Patents

Abstract

A DEVICE FOR SELECTING A CARRIER OF A SIGNAL SIGNAL, containing a series-connected DC detector and amplifier and a series-connected first frequency converter, a narrow-band intermediate frequency path and a first amplitude comparator, the second input of which is connected to the output of the force; the DC bodies, the input of the first frequency converter and the detector input is connected to the device input, the output of the narrowband path is connected to the input of the second frequency converter, the output of which is through the filter with the output of the device, and the second inputs of the first and second frequency converters are connected to the output of a tunable local oscillator, to the control input of which the heterodyne frequency control unit is connected, in order to improve the accuracy of the selection of the carrier frequency, the output of the first frequency converter is connected series-connected unit for changing the period of the radio pulse following the second narrow-band intermediate frequency path, the second amplitude comparator and the element coincident, the output is connected to the input of the control unit ui frequency oscillator. (L the second inputs of the second amplitude comparator and the coincidence element are connected respectively to the output of the DC amplifier and to the output of the first amplitude comparator.

Description

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The invention relates to a measurement technique and is intended to isolate the carrier frequency of a periodic sequence of coherent broadcast pulses. A device with a search contains a voltage-controlled local oscillator, logic elements for setting the local oscillator tuning and frequency estimation 13 is known. The disadvantage of this device is the ambiguous stopping of the heterodyne rearrangement when receiving a periodic radio pulse sequence associated with the received signal spectrum discreteness Closest The technical essence and the achieved result to the proposed is the device) CPU of selection of the carrier frequency of the signal, containing tunable g heterodyne, frequency converter, a torus in SU vlipyyutc. input signal IM tunable heterodyne signal, narrowband intraday daily frequency with center frequency and, (consisting of narrowband filter and intermediate frequency amplifier frequency converter, which receives signals from the output of the narrowband intermediate frequency channel and output tunable heterodyne Filter connected to the output of this converter, from the combinations Cr- + lu-u, Vedadel frequency and; „,., w .. + ui tC2J .. A significant drawback of the known device is the impossibility of an unambiguous selection The carrier frequency of a nonmonochromatic input signal, in particular, a periodic sequence of coherent radio pulses, since during the rearrangement of the local oscillator, the stop signal can be obtained from any spectral component of the input signal exceeding the threshold: rotation. sequence of coherent radio pulses. The goal is achieved by the fact that in a device containing a series-connected detector and amplifier current and serially connected first frequency converter, narrow-band intermediate frequency path and first amplitude comparator, the second input of which is connected to the output of the amplified direct current current, the input of the first frequency converter and the detector input are connected to the input of the device, the output of the narrow-band path is connected to the input of the second frequency converter, the output of which is connected through a filter to the device Output, and the second inputs of the first and second frequency converters are connected to the output the local oscillator, to the control input of which the heterodyne frequency control unit is connected, sequentially connected to the output of the first frequency converter are connected a unit for changing the radio pulse following period, a second narrowband intermediate frequency path, a second amplitude comparator and a coincidence element whose output is connected to the input of the unit controlling the frequency of the local oscillator, the second inputs of the second amplitude comparator and the coincidence element are connected respectively to the output of the DC amplifier and Exit the first amplitude comparator. Fig, 1 shows the block diagram of the device; FIG. 2 shows an example of the implementation of a unit for changing the period of a radio pulse; Fig, 3 spectra of periodic sequences of coherent radio pulses. and timing charts; On, 4 time diagrams of the formation of a sequence of radio pulses with a modified period of following. The device contains a frequency converter JL, tunable local oscillator 2, intermediate frequency E and 3 intermediate frequencies 4, amplitude comparators 5 and 6, detector 7, DC amplifier 8, coincidence element 9, local oscillator frequency control unit 10 (unit 11 for the next period, second frequency converter 12 and filter 13; The unit for changing the period of the radio pulse includes an electronic switch 14 potentiometers 15 and a delay line 16. In a device for selecting a carrier frequency of a signal, sequentially The detector 7 and the DC amplifier 8 are connected, the first frequency converter 1, the intermediate frequency narrow-frequency path 3 and the first amplitude comparator 5 are connected in series, the second input of which is connected to the output of the DC amplifier, the input of the first frequency converter 1 and the detector input are connected to the input device, the output of the narrow-band path 3 is connected to the input of the second frequency converter 12, the output of which is connected through the filter 13 to the device output, and the second inputs of the first 1 and second 12 converters the frequencies are connected to the output of the tunable local oscillator 2, to the control input of which the LO frequency control unit 10 is connected, to the output of the first frequency converter 1 are connected in series the period changing unit 11 from the radio pulse unit, narrow-band intermittent frequency path 4, second amplitude section 6, the coincidence element 9, the output of which is connected to the local oscillator frequency control unit 10., the second inputs of the second amplitude comparator 6 and the coincidence elements 9 are connected respectively output amplifier 8 DC and you swing the first amplitude pa komparat 5. The device operates as follows. A periodic sequence of coherent for the pulses with the frequency of the current I1 and with the carrier frequency w, which is formed into the intermediate frequency, arrives at the input. i: using frequency converter 1 The amplitude spectrum of the signal at the output of frequency converter 1 is shown in fig. For, the signal from the output of the frequency converter enters the narrow-band path 3 of the intermediate frequency and the electronic switch 14 of the unit II for changing the tracking period. The electronic switch connects the first pulse to the first channel through which the signal passes without delay; the second to the second channel in which the delay is n in the horizontal 4tj, etc. The kth pulse passes through the kth. the channel with delay Xk-1) –Ds, after which the switch goes to position 1 and the switching cycle is repeated. Potentiometers 15 were inserted to equalize the transmission coefficients of the individual channels in order to obtain identical amplitudes of radio pulses at the output of block 11. As a result, a periodic sequence of radio pulses with a period of T 2 different from the T1 input signal and with a carrier frequency equal to frequency of input signals i) p, c. FIG. Figure 4 shows the timing diagrams of the formation of a sequence of radio pulses with a modified following frequency. The amplitude spectrum of this signal is shown in FIG. 36, In the composition of this spectrum, in addition to the non-actual frequency i%, the composition I was found, differing in frequency from the spectral component of the input cross section of FIG. This is the result of a parametric conversion of the signal in the device by varying the frequency of the following. Regarding the sequence of pulses (a bundle of radio pulses, the scheme of changing the tracking frequency is linear with variable parameters (parametric), since during the time of the burst the delay lines, i.e. change-parameters of the circuit. When rebuilding the heterodyne, narrowband paths 3 and 4 separate the spectral components from the original and modified (sequences;:;.. Radio pulses. Amplitude: cocharators 5 and 6 will operate on spectral patterns that exceed the threshold level detected by the detector. 7, operating at the peak detector mode, and the dc amplifier 8, the accuracy of setting the threshold level is not hard to apply, since the simultaneous operation of the comparators 5 and 6 will be. radio frequency pulses (at the carrier frequency), which is fixed by the coincidence block 9, the output signal of which arrives at the heterodyne frequency control unit 10 and stops the heterodynamic tuning. The heterogeneous frequency tuning rate is chosen from the condition that provides the ridges of the spectral components lower the difference between the frequencies of the initial and modified radio pulse sequences, which means that the carrier frequency of the coherent sequence is exactly the same radio pulses. With the help of frequency converter 12, the local oscillator signals and the intermediate frequency allocated by the narrow-strand path 3 are shifted. Filter 13 selects the combination wjwc. Thus, a monochromatic signal with a frequency equal to the carrier frequency of a periodic sequence of coherent radio pulses at the input is restored at the output of the device. , . . At a constant position of the switch 11, the proposed device, as well as the prototype, will restore the frequency of the monochromatic input signal. At the output of the device, the signal is present only in the presence of an input signal. For an arbitrarily long maintenance of the output signal, when the input signal is disconnected, it is necessary to connect an oscillator to the input of the frequency converter 12 with a frequency equal to the center frequency of the intermediate frequency narrowband drive. The proposed device allows the carrier frequency of a periodic sequence of coherent radio impulses to be restored with high accuracy without strict requirements for the channel transfer coefficients, which makes it possible to use it in systems operating with significant destabilizing factors without applying special stabilization measures, such as temperature control.

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Claims (1)

A SIGNAL CARRIER FREQUENCY ALLOCATION DEVICE, comprising a serially connected detector and a DC amplifier and serially connected a first frequency converter, a narrow-band intermediate frequency path AND a first amplitude comparator, the second input of which is connected to the output of the DC amplifier * the input of the first frequency converter and the detector input are connected to the input devices, the output of the narrow-band path is connected to the input of the second frequency converter, the output of which through the filter is connected to the output th device and the second input of the first and second inverters connected to the output of the tunable local oscillator, to the control input of which is connected a local oscillator frequency control unit, characterized i in that, in order to increase the accuracy of allocation of a carrier frequency to the output per-; of the frequency converter, the second narrow-band intermediate frequency path, the second amplitude comparator and the coincidence element; the output of which is connected to the input § (the local oscillator frequency control unit,, the second inputs of the second amplitude comparator and the coincidence element are connected respectively with the output of a DC amplifier and with the output of the first amplitude comparator. 'Η "*. About sl Cn