SU657365A1 - Signal frequency determining arrangement - Google Patents

Claims (2)

The invention relates to the field of radiolocation, radionavigation and communication, and can be used in signal carrier frequency determination circuits. A device for determining the frequency of signals, comprising a mixer, a local oscillator, a filter, a detector, a synchronizer and an indicator 1, is known. A disadvantage of this device is the presence of losses detection of signals and measurement of their frequencies in the process of reverse voltage modulation of the local oscillator and reverse stroke sweep indicators. The closest to this invention is a device for determining the frequency, signals, containing a main mixer connected in series, a bandpass filter, a dispersion delay line, a detector and an indicator, a main heterodyne, whose input is connected to the synchronizer output and to the second input of the indicator 2. A disadvantage of such a device is the presence of a loss in the probability of detecting signals (especially pulsed). The purpose of the invention is to capture the accuracy of the device. This is achieved by adding two keys to the proposed device for determining the frequency of the signals, the local oscillator and the mixer, the first input of which is connected to the output of the additional local oscillator, the second input of the additional mixer is connected to the output of the first key, the first input of which is connected to the output of the main local oscillator the first input of the second key, the output of which is connected to the second input of the main mixer and to the output of the additional mixer, while the second inputs of the keys are connected to the second and third you. odes synchronizer respectively. FIG. Figure 1 shows the structural electrical circuit of the device proposed; in fig. 2 - time diagrams that show his work. A device for determining the frequency of signals contains a main mixer 1, a band-pass filter 2, a dispersive delay line 3, a detector 4, a local oscillator 5, a synchronizer b, an indicator 7, an additional mixer 8, a key 9, an additional local oscillator 10, a key 11. In the device for determining the frequency signals, the mixer 1 output is connected to the input of the bandpass filter 2, the output of which is connected to the input of the dispersive delay line 3. The output of the dispersive delay line 3 is connected to the input of the detector 4, and the output of But the last is connected to one of the indicator inputs torus 7. One of the outputs of the synchronizer b is connected in parallel to the input of the local oscillator 5 and to the second input of the indicator 7. The output of the local oscillator 5 is connected in parallel to the first inputs of the first key 9 and the second key 11. The second output of the synchronizer b is connected to the second input of the first key 9, and the third to the second input of the second key 11. The output of the second key 11 is connected to one of the inputs of the second mixer 8, to the other input of which the output of the second heterodyne 10 is connected. The outputs of the second mixer 8 and the first key 9 are combined and connected to the second input mixer 1 Synchronizer 6 operates on a cigarette-saw saw-tooth voltage and and switching voltage Uj, U (Fig. 2a, b, e). From the first output of the Synchronizer 6, the voltage U is fed to the input of the local oscillator 5 for tuning the frequency of the latter and to the vertical deflecting system of the indicator 7. The horizontal deflecting system of the indicator 7 receives a sweeping voltage from the internal source of the indicator 7. Thus, on the screen indicator is formed raster, an approximate view of which is shown in FIG. 2nd. Voltage Oc „from the second output of the synchronizer b goes to the second input of the first key 9, and voltage Uj. from the third output of the synchronizer b - to the second output of the second key 11. The dependence of the frequency of the local oscillator signal fjem t time is shown in fig. 2d. The signal of the local oscillator is supplied to the first inputs of the first 9 and second q keys. If the positive pulses of the output voltages of the synchronizer Uj coincide; and the frequency-modulated heterodyne signal at the outputs of the keys 9 and 11 alternately appear frequency-modulated signals. The output voltage of the second switch is fed to the first input of the second mixer 8, the second input of which supplies the second local oscillator voltage with a constant carrier frequency equal to twice the average frequency of the passband of the dispersion delay line 3 fc, p Dependences the average frequency of the dispersion delay line sf and frequency The second local oscillator zemz ° time is shown in FIG. 2g solid thin lines. In the second mixer 8, the output voltage of the second switch is converted. The output voltage of the second mixer at a frequency f trans. (Fig. 2d) is summed up with the output voltage of the first key and goes to the second input of the mixer 1. In the same figure, the dotted line shows the bandwidth of the dispersive delay line and the analysis band of the input signals P. The thick thick lines show the dependences of the frequency of the input f and the converted f signals from the time. At the output of the mixer 1, the difference frequency signals are separated by a band-pass filter 2. At the same time, the intermediate frequency of the converted signal f CRF fc het and time intervals corresponding to odd half-periods of modulating voltage fcnp f Prevr, go- / with time intervals corresponding to even half-periods of modulating voltage. The signal from the output of the bandpass filter 2 is fed to the input of the dispersion delay line 3 (shortening filter). The compressed pulses from the output of the dispersive delay line 3 (Fig. 2e) are fed to the input of the detector 4. The output signals of the detector are fed to the control electrode of the electron-beam tube of the indicator 7 and are observed on its screen as luminous marks (Fig. 2e). The position of the brightness marks on the raster scan of the indicator is determined by the frequency of the input signal. Thus, due to the use of a symmetrical modulating voltage, a local oscillator and a deflecting voltage indicator, losses in the detection of signals and the accuracy of determining their frequencies are excluded. The latter is especially important when analyzing pulse signals, the reception time of which is unknown and when using cathode-ray tubes with a magnetic beam cut-off system in the indicators, where the return time of the beam is large. An apparatus for determining the frequency of signals comprising a main mixer connected in series, a band-pass filter, a dispersive delay line, a detector and an indicator, a main local oscillator whose input is connected to the output of the synchronizer and to the second input of the indicator increase the accuracy of the device, it additionally introduced two keys, the local oscillator and the mixer, the first input of which is connected to the output of the additional local oscillator, the second input of the additional mixer n to the output of the first key, the first input of which is connected to the output of the main local oscillator and the first input of the second key, the output of which is connected to the second input of the main mixer and to the output of the additional mixer, while the second inputs of the keys are connected to the second and third outputs of the synchronizer, respectively. 6 56 Sources of information taken into account in the examination 1. Momot EG Radio measurements, Gosenergoizdat, MgL., 1957, p. 354. 2. Radio engineering, t. 2 1, 10, 1966, p. 53.