Pulse-Position Modulation for Signal Identification
HARRY DIAMOND LABS ADELPHI MD
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The use of pulse position modulation PPM to code N signals has been investigated. The following three coding schemes were considered 1 identical pulse periods with synchronization, 2 distinct pulse periods without synchronization, and 3 position modulation of alternate pulses. The theoretical performance of these methods was considered with respect to the probability of overlapping signals, the average frequency of such overlaps, and the generation of false signals. This investigation was concerned primarily with performance limitations due to signal design rather than receiver characteristics thus, only the properties of the signal in an infinite signal- to-noise ratio thus, only the properties of the signal in an infinite signal- to-noise ratio environment were considered. The false signal was found to be nonexistent in coding method 1 and for each of the other two schemes, false signals were found to occur less frequently than pulse overlap. For any given set of parameters, the performance of each coding scheme as measured by the frequency of overlaps was found to be the same.