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The performance of a system utilizing a binary phase-shift keyed waveform transmitted over a frequency-selective, selective, slowly fading Nakagami channel with pulse-noise interference in addition to additive white Gaussian noise (AWGN) is examined. The underlying information bits are assumed to be convolutionally encoded prior to transmission over the channel, and the receiver is assumed to use soft decision Viterbi decoding with modified noise-normalization of the soft receiver output. Two types of modification are examined. In the first, the interference power present during a bit is multiplied by some factor prior to normalization, providing the means to determine the effect of either underestimating or overestimating the interference noise power on receiver performance. In the second, when interference power is determined to be present, the normalization factor is taken to be four or more times the noise power of AWGN alone, thus providing a deemphasis of bits that are affected by the pulse-noise interference that relies only on a measurement of the relative noise power instead of an exact measurement of the noise power for a particular bit. The performance obtained with both types of modified noise-normalization of the soft receiver output prior to decoding is compared with the performance obtained with a maximum-likelihood, soft decision receiver.