Performance of a SAW Tapped Delay Line in an Improved Synchronizing Circuit

The large time-bandwidth products realizable with the aid of surface acoustic wave (SAW) tapped delay lines facilitate the construction of accurate timing circuits which can be employed e.g. in the p-n signal synchronizing circuit of a spread spectrum system. The performance of such a timing circuit, which employs a 255 chip SAW tapped delay line and a circuit for detecting the maximum of the correlation peak, is investigated theoretically and the theoretical results are checked by experiment. It is found that the input signal level required for the timing circuit with differentiation to achieve a specified timing variance is less than that of a timing circuit without differentiation by about 3 dB. Furthermore, differentiation makes the timing circuit practically immune to changes of the threshold level.