SU945799A2 - Spectrum analyzer - Google Patents

Description

(5) SPECTRUM ANALYZER

one

The invention relates to a measurement technique, namely to spectrum analyzers, and can be used in analyzing the spectrum of random vibration.

According to the main auth. No. a spectrum analyzer is known that contains a series-connected frequency converter, to which another input is connected to a frequency-modulated, Q-connected local oscillator controlled from a sawtooth generator, and an electromechanical filter, amplitude detector, vertical deflection amplifier, and electron-beam 15 tube, moreover, the second output of the sawtooth generator is connected via a horizontal deflection amplifier to a cathode ray tube, in which between the output of the electro-20 ro-mechanical f ltra and the input amplitude detector includes series connected second transformation. frequency receiver with auxiliary

a local oscillator, a bandpass filter, a third frequency converter with a tunable local oscillator, and a second electromechanical filter, the tunable local oscillator being coupled to the sawtooth generator ij. Essentially, this analyzer is designed as a triple frequency conversion unit with selective circuits at the output of each frequency converter, two of which form a narrowband filter, and an amplitude detector with an indicator.

However, when analyzing a random vibration, the presence of a known statistical error does not make it possible to fully realize the capabilities of the analyzer in terms of resolution, due to the resulting narrow band of the analyzing filter. In order to fully realize the capabilities of the analyzer in resolution, it is necessary to increase the analysis time. which significantly impairs the technical characteristics of the device as a whole. The purpose of the invention is to improve the measurement accuracy. This goal is achieved by the fact that the known spectrum analyzer is equipped with a multiplier of signals, an adder and N sinusoidal signal generators, the outputs of which are connected to the inputs of an adder, the output of which is connected to one input of the signal multiplier, the second input of which is connected to the output of the triple frequency conversion unit, and the output the signal multiplier is connected to the input of the amplitude detector.

FIG. 1 shows a block diagram of a device for analyzing random vibration when testing products; in fig. 2 - diagrams explaining the principles of operation of the device. The spectrum analyzer contains a triple frequency conversion unit, a multiplier of 2 signals, an amplitude detector 3, an indicator k, an adder 5, and a generator of a 6 sinusoidal signal la .. The analyzer works as follows. The signal under investigation (Fig. 20) is fed to block 1 of a triple frequency conversion, where, within the analysis band A, there is a sequential selection of the signal by a narrowband electoral system, from the output of which the signal goes to the first input of the signal multiplier 2 (Fig. 2 (and the input of the multiplier 2 receives the sum of the harmonics from the output of the sum of the torus 5, whose frequencies are selected with a offset shift (0ig. 2 g). Harmonics (Fig. 2fi). N generators 6 are produced. 2, at the output of the multiplier 2, a signal is obtained whose spectrum is expanded 2 N times as compared with the spectrum of the signal at the output of the narrowband system in the triple frequency conversion unit (Fig. In the signal spectrum at the output of the multiplier 2, there are no harmonic frequencies W | the balanced modulator on the basis of which multiplier 2 is made (harmonic frequency suppression is carried out), and only the signal generated near the frequencies of the harmonics of the narrow range of multiplier 2 remains at the amplitude detector 3 and further in 1 indicator (.

Taking into account the known ratio of a

Claims (1)

Since fj t is the linking error of the analysis with the analysis time and the frequency band of the analyzed frequencies, it can be seen that the expansion of the spectrum of the narrowband signal under study is 2 N times the current signal. The formation of narrowband signals is similar to the formation of sidebands with amplitude modulation of a harmonic signal by a narrowband process. Due to the linearity of the multiplier characteristic 2, amplitude modulation of harmonic signals with frequencies W by a narrowband process (Fig. 2.5} occurs independently of each other (superposition principle). C is the calculation of the onset between the output of unit 1 of a threefold frequency conversion and amplitude detector 3 of multiplier 2, the second input of which connected to the output of the adder 5, whose inputs are connected to the outputs of the N generators of the 6th sinusoidal signal, allows you to increase N times the accuracy of the analysis at a constant analysis time. High resolution The known ability of the known analyzer is also preserved due to the narrow band of analyzed frequencies in the triple frequency conversion unit. The economic effect of using the proposed spectrum analyzer is due to its technical advantages noted above. Formula of the invention Spectrum analyzer according to aut. No. 411384, characterized in that in order to improve measurement accuracy, it is equipped with a multiplier of signals, an adder and N generators of a sinusoidal signal, the outputs of which are connected to the inputs of an adder Whose output is connected to one input of multiplier signal, a second input coupled to the output of the triple frequency conversion, and the output signal of multiplier input connected to p amplitude detector. Sources of information taken into account during the examination 1. USSR author's certificate No. 4I384, cl. G 01 R 23/16, 1971 (prototype). ucJa (r ((d) c C 2 oJ iJH t i) n FC1.1