  A system using a non-linear multi-swept sine wave system is described which
employs a multi-channel, multi-swept orthogonal waves, to separate channels and
make multiple, simultaneous online/offline CO2 measurements. An analytic
expression and systematic method for determining the orthogonal frequencies for
the unswept, linear swept and non-linear swept cases is presented. It is shown
that one may reduce sidelobes of the autocorrelation function while preserving
cross channel orthogonality, for thin cloud rejection.
