Direct RF modulation 256QAM microwave system

A 2 GHz common carrier system utilizing 256-QAM for high spectrum efficiency is described. A simplification in system design is accomplished by the use of direct RF modulation and demodulation rather than a more traditional IF (intermediate frequency) heterodyne approach. Technical considerations for this direct approach are discussed. The use of automatic power control results in reduced battery requirements, improved reliability, and easier frequency coordination. With inclusive M12 muldems, extensive error correction, and time domain equalization techniques, the radio system provides 12 DS1 (19 MBS) in a 3.5 MHz bandwidth.<
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