Design features and performance of a high speed TDMA demodulator

This paper describes the major design features used in a high-speed, burst-type TDMA demodulator, capable of supporting data rates up to 90MBS. The major features discused are as follows: burst to burst fast settling AGC Loop; a times four (X4) Carrier Recovery scheme with an AFC tracking loop and double filter/multiplier phase cancellation; I.F. half symbol delay/multiply Symbol Timing Recovery; baseband implementation of NYQUIST/matched filtering techniques; and a time-sampled, digital implementation of a COSTAS recovered carrier phasing loop. The actual performance characteristics of the demodulator design operating at 70MHZ I.F. frequency and a data rate of 48MBS are presented.