Temperature-Invariant Pulse-Compression Using Saw Devices

The hyperbolic f.m. chirp signal is derived and is shown to possess compression performance invariant to temperature differences between surface-acoustic-wave expansion and compression filters. The compressed output approximates to a sin x/x envelope, and the use of sidelobe weighting techniques is considered. Choice of signal parameters to minimise range/temperature ambiguity is indicated, and a constant-amplitude form of the signal is shown to possess similar properties. The similarities between the Doppler and temperature transformation suggest an up-conversion technique that would yield compression performance invariant to both temperature and Doppler shifts for very wideband signals. Such a system is postulated and shown to have other advantages.