There has been some additional development of parts reported in “Multi-Modulator for Bandwidth-Efficient Communication” (NPO-40807), NASA Tech Briefs, Vol. 32, No. 6 (June 2009), page 34. The focus was on:
- The generation of M-order quadrature amplitude modulation (M-QAM) and octonary-phase-shift-keying, trellis-coded modulation (8PSK TCM),
- The use of square-root raised-cosine pulse-shaping filters,
- A parallel-processing architecture that enables low-speed [complementary metal oxide/semiconductor (CMOS)] circuitry to perform the coding, modulation, and pulse-shaping computations at a high rate; and
- Implementation of the architecture in a CMOS field-programmable gate array.