Daniel D. McRae

Performance Evaluation of a New Modulation Technique

The performance of a new modulation technique which has been called mixed-base modulation (MBM) is presented. This technique provides significant performance advantages over other common modulation techniques for applications where both power and bandwidth are limited. Its performance for bandspreading factors of two relative to single-sideband is within 4 dB of the ultimate Shannon bounds. Most available techniques are very poor in this region. The viewpoint which allowed synthesis of this technique will be given before the basic approach and its performance are discussed. A section comparing the theoretical performance of MBM and that of other common techniques is followed by a discussion of some of the practical considerations.

Evaluation and optimization of data link protocols for HF data communication systems

The authors discuss channel behavior based on measured signal and noise variations. A simulation model is presented which replicates the observed variations. The results of applying the simulation model to three different data link protocols, including a new fast automatic link establishment (ALE) technique are discussed.<<ETX>>

A More General Approach to the Interpolation of Sampled Data by Realizable Filters

This paper derives an expression for root-mean-square (rms) interpolation error in a sampled data system employing lumpedparameter presampling and postsampling filters. The derivation for rms error employs basically a time-domain approach rather than the more usual frequency-domain approach. Plots of rms error versus sampling rate are given for first- through fourth-order Butterworth data using a Butterworth interpolation filter and no presampling filter. It is shown that using 100-percent duty cycle samples (rather than impulsive samples) can greatly improve the rms error.