Arrays of relaxation oscillators behave differently in the presence of
a non-uniformity of natural frequencies and/or coupling inputs than d
o arrays of phase oscillators coupled through phase differences. Phase
oscillators compensate for non-uniformities by creating phase differe
nces among the oscillators; relaxation oscillators coupled via ''fast
threshold modulation'' (FTM) can respond by changing wave forms while
leaving the fast jumps synchronous, For arrays of relaxation oscillato
rs including chains, this allows synchrony to be a solution, even thou
gh the oscillators have different amounts of inputs from other oscilla
tors; for phase-difference coupled oscillators in a chain, the generic
solution is a travelling wave. Relaxation oscillators coupled through
FTM also allow the encoding of patterns of oscillators into domains i
n which oscillators are in synchrony, with different domains in antiph
ase.