SU1354128A1 - Acoustical analyser of microwave radio signal spectrum - Google Patents

Abstract

This invention relates to optical information processing. The purpose of the invention is to increase the frequency resolution of an acousto-optic spectrum analyzer with parallel analysis of SBS radio signals. In an ultrasonic modulator (M) 4, light is excited by two longitudinal elastic waves propagating in one direction. As a result, longitudinal elastic waves of difference frequencies propagating in the same direction are generated in the sound pipe M 4. The amplitude of the latter is proportional to the amplitudes of the spectral components of the analyzed microwave radio signal. Light modulated by an elastic difference-frequency wave is focused by the integrating lens 7 on the recording device 8. Both inputs 5 and 6 M 4 are located on. one of his butt. In this case, the pump generator is the source 9 of a monochromatic signal with a frequency that coincides with one of the extreme frequencies of the analysis band, which greatly simplifies the instrumental implementation of the spectrum analyzer. 1 il. I (L 5 6 11 by 1C oo

Description

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This invention relates to optical information processing and is intended to analyze microwave radio signals.

The aim of the invention is to increase the frequency resolution of an acousto-optical spectrum analyzer with a parallel analysis of microwave radio signals.

The drawing shows a diagram of a spectrum analyzer.

Analyzer Contains consecutively located optically coupled coherent radiation source 1, collimating system consisting of lenses 2 and 3, ultrasonic light modulator 4 with two inputs 5 and 6, integrating lens 7, recording system 8 in the form of a line of photodetectors based on devices with charge coupling and pump generator 9. The analyzed signal is fed to one of the inputs 5 or 6 of the light modulator, the monochromatic signal from the pump generator is fed to the other input 6 or 5.

Spectrum analyzer works as follows.

In the modulator, two longitudinal elastic waves are excited, propagating in the same direction. As a result of the nonlinear interaction of these initial waves in the acoustic duct of the modulator, longitudinal elastic waves of difference frequencies are generated, propagating in the same direction, whose amplitude is proportional to the amplitudes of the spectral components of the analyzed radio signal.

If the analysis frequency band is, for example, 10% of the pump frequency, then the frequency of the difference elastic wave will be 10 times less, and its propagation length will be 100 times greater than that for the elastic wave corresponding to the signal being analyzed, how the attenuation of elastic waves is in quadratic dependence on frequency. For light modulation, the modulator aperture region is used, where only differential frequency waves are present.

To register the elastic waves of the difference waves generated in the sound duct

frequency ultrasonic light modulator is set at the Bragg angle

to the incident light flux. Light modulated by an elastic difference frequency wave is focused by integrating

with a recording lens 7 on a recording device 8. A linear photodetector based on charge-coupled devices is used as a recording system.

Increasing the frequency resolution in comparison with the known device is achieved by using the modulation of light by an elastic wave containing difference frequency components, which extends to a much greater distance from the piezoelectric transducer than the high frequency elastic wave of the signal being analyzed. Frequency resolution 5, calculated by the formula

S v / d

where V is the velocity of the longitudinal elastic waves in the sound pipe of the modulator; d - working optical aperture

modulator of the torus.

In this case, d 1p 1s D 1r is the propagation distance of the elastic wave of the difference frequency; (, is the largest propagation distance of the elastic wave of the analyzed signal

In addition, the number of resolvable points N of an acousto-optic spectrum analyzer also increases;

N where uf is the analyzer frequency band.

Thus, for a spectrum analyzer based on an ultrasonic light modulator with a lead molybdate suction line at a center frequency of the analyzed signal of 2 GHz and an analysis band of 200 MHz, the frequency resolution will be 73 KHz, and the number of resolvable points will be 2,750.

Claims (1)

The optical scheme of the spectrum analyzer contains a smaller number of lenses than the known optical scheme, and the use of a monochromatic signal generator for pumping greatly simplifies the instrumental implementation of the spectrum analyzer compared to the use of the chirp signal generator in the microwave range in a known device. These simplifications constitute an additional positive effect of the invention. Invention Formula Acousto-optical microwave spectrum analyzer containing optically coupled coherent source31354128 light source, a collimating system, an ultrasonic light modulator, an ultrasonic light modulator, distinguished by the fact that it is fixed with the possibility of being installed in order to increase the frequency resolution at an angle to the light beam, corresponding to the parallel diffraction of light by an elastic spectrum. analysis of microwave radio signals, both inputs of a difference frequency wave, an integrated ultrasonic light modulator, spreading a lens, a recording system placed on one of its ends, and a gene in the form of a linear photodetector on an oscillator. pitching is Nove source devices with CCD and w monochromatic signal with a frequency generator and a pump, the output of the koto- coinciding with one of the extreme cerned is connected to one of two inputs of the frequency band analysis.