This paper proposes that approximate wavelet transform and time-frequency analysis can be used to detect moving targets with uniform velocities in straight lines. The approximatewavelet transform does not only find out velocities in the square terms in phases of target signals

but also preprocess signals to delete most of background clutters and noises for the time-frequencyanalysis. The time-frequency analysis can find out velocities in both linear and square terms ofphases of signals.