120-Mbit/s, 6 GHz On-Board Waveform Regenerator for Communications Satellites

A lightweight, low-power-consuming, differentially-coherent four-phase-shift-keyed (DQPSK) on-board waveform regenerator (OBWR) was developed for communications satellites in the 6 GHz up-link frequency band to process 120 Mb/s time-division multiple access (TDMA) signals. The most critical element in the design of the 6 GHz DQPSK-OBWR is the one-bit (16.67 nsec) delay line which was fabricated in a lightweight MIC configuration using barium-tetratitanate substrates to provide an RF-phase stability of less than ±l.5° over operating temperature variations of at least ±15°C. Using a ±35 MHz bandpass filter (see section 4) and for OBWR temperatures ranging from 10°C to 40°C, all the measured bit-error-rate performance characteristics are within 0.7 dB from theory.