This paper studies the bit error rate (BER) performance of hybrid direct-sequence/slow-frequency-hopped Spread-Spectrum Multiple-Access (DS/SFH-SSMA) systems with noncoherent DPSK demodulation, employing predetection diversity (equal gain combining (EGC) in conjunction with interleaved channel coding operating through indoor radio multipath Rayleigh fading channels. Two interleaving techniques are considered: for the first interleaving technique, all bits of a codeword are transmitted during the same hop, whereas for the second interleaving technique, each bit of a codeword is transmitted during a different hop. It is shown in this paper that, in the absence of multi-access interference, both interleaving techniques yield the same BER performance; in the presence of multi-access interference, the second interleaving technique has a performance advantage over the first, and this advantage increases with increasing diversity order, error-correcting capability of the code and multi-access interference level.