• Capacity of Noncoherent MFSK Channels

      Bar-David,I.; Butman, S. A.; Klass, M. J.; Levitt, B. K.; Lyon, R. F.; Jet Propulsion Laboratory (International Foundation for Telemetering, 1974-10)
      This article computes the capacity of a noncoherent multifrequency-shift-keying channel as a function of the number of orthogonal signals, M, and the predetection signal-to-noise ratio, ST/N₀, for three basic receiver types; these are hard decision, unquantized (optimum), and quantized (soft decision). Computational cutoff rates for sequential decoding are also computed.
    • Performance of Noncoherent MFSK Channels with Coding

      Butman, S. A.; Lyon, R. F.; California Institute of Technology (International Foundation for Telemetering, 1974-10)
      Computer simulation of data transmission over a noncoherent channel with predetection signal-to-noise ratio ST/N₀ = 1 shows that convolutional coding can reduce the energy requirement by 4.5 dB at a bit error rate of 0.001. The effects of receiver quantization and choice of number of tones are analyzed; nearly optimum performance is attained with eight quantization levels and sixteen tones at ST/N₀ = 1. The effects of changing ST/N₀ are also analyzed; for lower ST/N₀, accurate extrapolations can be made from the data, but for higher ST/N₀ the results are more complicated. These analyses will be useful in designing telemetry systems when coherence is limited by turbulence in the signal propagation medium or oscillator instability.