In this paper we address the problem of combatting combined interference in spreadspectrum communication links. We consider frequency-hopped spread-spectrum systems with M-ary FSK modulation and noncoherent demodulation which employ forward- error-control coding. The interference consists of partial-band noise jamming, nonselective Rician fading, other-user interference and thermal noise. The coding schemes which we analyze include: Reed-Solomon codes (with or without diversity and error-only, erasure-only or parallel erasure/error decoding), binary, nonbinary, and dual-k convolutional codes with and without side information (information about the state of the channel), and concatenated schemes (Reed-Solomon outer codes with either inner detection-only block codes or inner convolutional codes). In all cases we derive (i) the minimum signal-to-jammer energy ratio required to guarantee a desirable bit error rate as a function of RHO, the fraction of the band which is jammed, when the number of interfering users is fixed, and (ii) the maximum number of users that can be supported by the system as a function of RHO, when the signal-to-jammer energy ratio is fixed.