The time domain and the characteristic spectrum of the frequency domain of output signals is obtained by extracting the high frequency weak signals with filtering wave technique.

Such key technologies are introduced as weak signal frequency acquisition,ultra-narrow phase-locked loop,side-band aided residual carrier loop,windowed loop technology,weighted IDF,SSME signal-to-noise estimation technology,varying loop bandwidth and varying window technique are emphasized.

Comparison of wavelet transform and Fourier transform in analyzing signal frequency;

The relation between signal frequency and measured velocity variation and the largest velocity variation,which can be responded by photomultiplier and digital oscilloscope in the VISAR application are discussed.

It is concluded that it is currently inadvisable to replace the generator rotational speed signal with the terminal voltage frequency signal as the PSS input state variable.

On the basis of the demand of manufacturing the checkout device,this paper analyzes the frequency signals of the aeroengine rotate speed and vibration,and then two signals of generating circuits are designed to simulate the corresponding signals.

to compose a frequency signal digital detection analysis device.