We present the design and performance of a high speed MSK modem that i
ncorporates digital heterodyne processing. A novel table look-up proce
dure for direct IF/RF modulation, based on a suitable maximal-length s
hift register sequence, is described. High performance, linear phase,
low-complexity mixing and filtering in the receiver is achieved using
multirate IFIR filters, where the shaping filter may possibly be Mth-b
and. The configuration of the IFIR filters is chosen based on the carr
ier frequency and the filtering requirements.