A Test Method for Noise Suppression Performance of Shortwave Radio Station

Abstract

The invention relates to a method for testing the squelch performance of a short-wave radio station. An interference signal is added to a single-tone modulated standard signal to form a dual-tone modulated signal. The squelch suppression ratio is defined as the ratio of the modulation degree of the speech audio modulation signal to the modulation degree of the interference audio modulation signal when the product is in a critical state of maintaining squelch. When this parameter is less than 3, it indicates that the squelch threshold is set too low, which may easily cause radio squelch failure in complex electromagnetic environments. When this parameter is greater than 3, it indicates that the squelch threshold is set too high, which may cause poor radio reception. The circuit makes the squelch suppression ratio equal to 3 to achieve the purpose of adjusting the squelch ability of the radio station. The invention can quantify the squelch test results, and proposes the squelch suppression ratio parameter to effectively repair the radio station.

Description

technical field

[0001] The invention relates to the field of testing short-wave radio stations, in particular to a method for testing the squelch performance of short-wave radio stations. Background technique

[0002] Shortwave radio stations generally use a frequency discriminator for demodulation. The frequency discriminator separates the effective signal from the background noise signal according to the signal input frequency. The frequency discriminator follows the parabolic distribution of the power spectrum of the output noise, and the square increases with the increase of the output frequency. Therefore, , when there is no useful input signal, it will output relatively large noise, and it is necessary to use a squelch circuit to process the noise. When there is no audio signal input or the signal is very weak, the output is cut off to keep the earphone quiet. For aircraft, the pilot communicates with the tower through the short-wave radio station. If there is no good ...

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