FSK and DPSK Performance in a Mixture of CW Tone and Random Noise Interference

The bit error probability performance of both frequency-shift-keyed (FSK) and differential phase-shift-keyed (DPSK) binary systems are described when disturbed by an interference consisting of a mixture continuous wave (CW) tone and narrow-band random noise in addition to the usual broad-band thermal noise background. Performance of the two systems is shown to be identical with the exception that the equivalent DPSK performance occurs at 3 dB less signal-to-thermal-noise ratio. The combination of CW tone and noise interference severely degrades system performance under a broad range of conditions.