| 摘要 |
A surface acoustic wave (SAW) radar doppler shift detection system is provided by transmitting a modulation signal having an up-chirp component followed by a downchirp component from a dispersive array SAW assembly to a target, and then receiving the radar return from the target by a receiver which also employs a similar dispersive array assembly. Dispersive array assemblies are constructed with two in line dispersive arrays. The dispersive arrays of the transmitter is positioned relative to two input SAW transducers and two output SAW transducers such that a pulse signal supplied to the two input transducers results in an expanded signal of the output transducers. The expanded signal acts as a modulation signal which is multiplied by an RF and transmitted. The receiving array assembly detects the radar return signal, and, after it is multiplied down to the SAW frequency, compresses it. When the target is stationary relative to the transmitter and receiver platform, a single envelope will be detected which indicates that no doppler shift has occurred. When there is relative motion between the target and the platform, the spacing between two detected envelopes, and their relative shifts, is measured and utilized to provide an indication of the magnitude and direction of the doppler shift. The transducers of the array assembly are formed of hyperbolically shaped fingers to provide a wideband range of frequencies.
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