Citation
Abstract
The capacity of noncoherent multifrequency shift keying (MFSK) systems that use a hard decision receiver is determined as a function of the predetection signalto-noise ratio (ST/N,). For any given predetection signal-to-noise ratio there is an optimum number of frequencies that maximize the system capacity. This optimum number decreases as the predetection signal-to-noise ratio decreases. However, it is shown here that this number is never less than 7. This means that binary frequency shift keying, a commonly used modulation technique at very low data rates, is suboptimum by at least 2.2 dB, compared to the performance obtainable with 7 signals. Similar results are obtained for the computational cut-off Room, when convolutional coding with sequential decoding is used over such an MFSK channel, These channels are expected to arise in planetary entry missions into thick atmospheres, such as those of Venus and Jupiter.
Details
- Volume
- XIII
- Published
- February 15, 1973
- Pages
- 82–91
- File Size
- 685.2 KB