SU907454A1 - Dispersion spectrum analyzer - Google Patents

Description

(5) DISPERSION SPECTRUM ANALYZER

I

The invention relates to radio engineering and can be used in radio electronic equipment for various purposes, including electrical measuring and radar technology.

Known dispersion analyzer containing the local oscillator, the dispersion delay line, mixers, filter, adder, reference oscillator and indicator 1.

The drawback of the device is the impossibility of analyzing the time-intersecting samples of the input signal.

Known dispersive spectrum analyzer, which contains a preselector, a mixer, a dispersive delay line, an indicator, an adder, a delay line with taps, a linear-frequency-modulated generator and a delay line 2.

The disadvantage of the analyzer is the low dynamic range.

The purpose of the invention is to expand the dynamic range.

This goal is achieved by the fact that a dispersion spectrum analyzer containing a series-connected preselector, a first mixer, a dispersive delay line, and an indicator, the first input of which is connected to the output of the reference oscillator through the delay line and the frequency multiplier, whose second output -modulated local oscillator, delay line with taps and an adder connected to the second input of the first mixer, equipped with

13 second mixer and the first and second filters, and the output of the dispersion delay line is connected to the second input of the indicator through serially connected second mixer

Claims (2)

20 and the first filter, the output of the adder is connected to the input of the delay line, the output of which through the second filter is connected to the second input of the second mixer. FIG. Figure 1 shows the structural scheme of the dispersion analyzer of the spectrum; in fig. 2 - timing diagrams The analyzer contains preselector 1 mixer 2, dispersion delay line 3, indicator k, adder 5, delay line 6 with taps, linear frequency modulated local oscillator 7 reference local oscillator 8, multiplier 9. delay line 10, first filter 11, second mixer 12, the second filter The analyzer works as follows. Through preselector 1, the signal U (t) under study (Fig. 2a) is fed to the input of the first-15GO mixer (for example, as a superposition of a series of sinusoidal oscillations). The analyzer uses the multiplication mode of oscillations of a linear-frequency-modulated local oscillator 7 consisting of a delay line 6 with taps and an adder 5. In this case, the second input of the first mixer is supplied M (in the case under consideration N equals 3) shifted relative to each other by T sequences of linear-frequency modulated radio pulses, the duration of which is Tf, the rate of change of frequency is dr, and the duty cycle is close to unity (Fig. 26). Due to the linear-frequency-modulated transform in the first mixer 2, a sequence of radio pulses is formed at its output, with a linearly time-varying carrier frequency. Each radio pulse sequence corresponds to one sample of the input signal. The rate of change of the oscillation frequency of the impulse response of the dispersion line 3 of the delay and the oscillations into which the harmonics of the input signal are converted have the same absolute values and opposite signs. Therefore, at the output of the dispersion delay line 3, a sequence of compressed pulses is formed, the total envelope of which corresponds to the spectrum of one of the samples of the input signal. In the analyzer, to combine the central frequencies of the compressed pulses at the output of the adder 5, non-overlapping sections of time are separated from a sequence of linear-frequency-modulated signals. This function is performed by the second (band-pass) filter 13, the bandwidth of which (A.f) is determined by the value of the product y-T | (3) (Fig. 2d). The sequence of radio pulses obtained at the output of the second filter 13 is fed to the second mixer 12 (Fig. 2d). 8, at the output of the second mixer, the central frequencies of the spectra of the compressed pulses are combined (Fig. 2c). Frequency-weight processing involves rounding the spectra of the compressed pulses using the first (weighting) filter 11. As a result, the level of side lobes of the compressed pulses decreases, and the dynamic range of the analyzer expands. Delay line 10 is used to delay a sequence of linear frequency modulated signals before being fed to the second mixer. 12 for a time equal to a constant delay in the dispersive delay line. The sweep of the indicator is triggered from the reference local oscillator 8 through frequency multiplier 3 and delay line 10. The accuracy of determining the frequency and therefore the accuracy of the spectral analysis depend on the timeliness of the start of the indicator. In order to coordinate the occurrence of squeezed pulses with the start of the indicator sweep, the same delay line 10 is used. In the case when a filter with a bell-shaped amplitude-frequency characteristic is used as the first filter, and the amplitude-frequency characteristic is dispersive, the delay line is rectangular, the expansion of the dynamic range depends on the rounding factor. The latter is determined by the ratio of the bandwidths of the dispersive delay line L. L. (Fig. 26) and the first (weighting) filter u.ff (Fig. 2c). LLZ At K equal to 2, the dynamic range of the analyzer is extended by 15–20 dB compared to the analyzer without weight processing and can reach values of the order of 30–35 dB. Thus, carrying out frequency and weight processing after a dispersive delay line with preliminary heterodyning in a limited frequency band allows expanding the dynamic range of a dispersive analyzer of a spectrum of signals. The invention of the Dispersion Spectrum Analyzer, which contains the first mixer connected in series, the first mixer, the dispersion delay line, and the indicator, the first input of which is connected to the output of the reference local oscillator via the delay line and the frequency multiplier, the second output of the local oscillator, delay line retreaded and the adder is connected to the second input of the first mixer, about tl and E FIG. 1 6 due to the fact that, in order to expand the dynamic range. it is equipped with a second mixer and a first and a side filter, with the output of the dispersion line connected to the second input of the indicator via serially connected second mixer and first filter, the output of the adder is connected to the input of the delay line, the output of which through the second filter is connected to the second input of the second mixer. Sources of information taken into account in the examination 1.Sharman Ya.D. Resolution and compression of signals. M., Soviet Radio, 197, p. 176-179. 2.Tverskoy V.I. Dispersion-time methods for measuring the spectra of radio signals. M., Soviet Radio, 197, p. 85. Dud MiwuBe Egv mt . "1 1- bytrka IMJ,) g- {6YS9P KO LUD bandwidth (f) t4Mmpa  V v y . J I I II-A44 well