Two group hopscotch SPUDT application to data communication link

Group-type, single-phase unidirectional transducer (SPUDT) delay lines are discussed as utilized in SAW stabilized superregenerative receivers. The current production delay lines span the US and European commercial frequencies from 180 MHz to 928 MHz. Moreover, fundamental operating frequencies up to 1550 MHz are shown to be feasible. Typical operating characteristics are 150-μs group delay, less than 12-dB insertion loss, and triple transit suppression exceeding 45 dB. Two hopscotch delay line designs are presented in detail. One is a 315-MHz center frequency delay line and the other a 915-MHz delay line which are utilized in low-power receiver applications. The delay line characteristics which determine receiver performance are examined, including alignment for receiver set-on frequency, receiver sensitivity (-105 dBm), temperature stability, and maximum achievable data rate