Narrowband Filtering Effects on Frequency-Hopped Signals
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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This thesis explored a low complexity solution to remove follower, narrowband tone jamming signals which are randomly dispersed within the bandwidth of a hop without causing non-linear phase distortions in a frequency-hopping FH system. Forward and reverse processed narrow stopband, elliptical infinite impulse response IIR filters were designed and applied to known audio and digital data. Analysis focused on narrowband filtering one hop of a FH signal in the absence of noise. The results were compared with the output of equivalent finite impulse response FIR filters and equivalent forward processed 11k filters. This analysis demonstrates the effectiveness of forward and reverse narrow bandstop 11k filtering to eliminate unwanted tone jamming signals while preserving the phase of the received FH signal. These results also suggest that a FH system with narrow bandstop filtering can operate reliably in the presence of a high power tone jamming signal.
- Radiofrequency Wave Propagation