1.6Gb/s 16-level Superposed APSK MODEM with Baseband Signal Processing Coherent Demodulator

A 1.6Gb/s 16-level superposed APSK MODEM using newly developed baseband signal processing coherent demodulator is described. The MODEM has much improved performance characteristics while having much simplified configuration comparing with the already reported one. Jitter power of the recovered carrier is less than -36dB and required C1/N for BER of 10/sup -9/ is better than 25.4dB through the MODEM loop back test (BT = 1.35).