SBIR-STTR Award

Qualcomm, Inc. proposes to study the development of a digital UFH SATCOM modem capable of transmitting three times the information rate in a given channel bandwidth currently transmitted by conventional means. Over FLTSAR 25 khz channels typical current information rates are not greater than I6 kb/s, while the proposed system would transmit over the same bandwidth at up to 48 kb/s, with no greater increase in transmitted power (or link budget) than that required for the three-fold increase in data rate. The technique to be used is trellis coding with 8PSK and I6psk modulation. A unique coding technique which requires only modification of existing convolutional coders-viterbi decoders achieves this increased efficiency.

Satellite communications requires power efficient modulation and, often, bandwidth efficiency as well. This program will design, develop, fabricate, and test 2 modems that will allow transmission of 48 Kbps through a 25 KHz satellite channel. Current concepts in trellis coding have been adapted to more general convolutional codes and an encoding/decoding device has been developed on other programs. This device will be used in the modem, allowing the required processing to be performed efficiently. The result is a three fold increase in data rate with the same power requirement as the uncoded case.