International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The relative anti-jam (AJ) performance of several diversity combiners are investigated. The modulation is 8-ary frequency-shift-keying (FSK), the demodulation process consists of energy detection of the eight frequency bins at each hop and the subsequent combining of detector outputs. Three combiners are considered : the linear combiner, where the detector outputs of each hop (corresponding to the same frequency bin) are summed without any processing; the self-normalized combiner, where the eight detector outputs of any particular hop are normalized so that they add to unity; and the max-normalized combiner, where the eight detector outputs of any hop are divided by the maximum value among those eight outputs. Results indicate that under worst-case tone jamming, the selfnormalized combiner performs the best, the max-normalized combiner second best, and the linear combiner performs the worst among the three.