Frank H. Sanders

Abstract: When radiofrequency pulse envelopes are observed away from their fundamental frequency their shapes differ from those at their fundamental frequency. Off-fundamental pulse envelopes tend to exhibit spikes at their rising and falling edges with lower-amplitude energy between the spikes. This phenomenon, called the rabbit ears effect, is described in this NTIA Report. Examples of rabbit ears pulse envelopes are provided in a mathematical simulation and from measurements of off-fundamental pulse envelopes of two models of 5 GHz weather radars. Morphologies of rabbit ears pulses are examined. A method is provided for using this effect to determine the durations and bandwidths of chirped pulses in bandwidth-limited measurement systems. Implications for off-fundamental detection of pulsed signals for dynamic frequency selection (DFS) algorithms are considered.

Keywords: radar spectrum; chirped pulses; dynamic frequency selection (DFS); off-fundamental signal detection; pulsed radiofrequency (RF) signals; rabbit ears

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