  An improved method for Fluctuation Enhanced Sensing (FES) is introduced. We
enhanced the old binary fingerprinting method, where the fingerprint bit values
were +/- 1, by introducing ternary fingerprints utilizing a reference odor. In
the ternary method, the fingerprint bit values are -1, 0, and +1 where the 0
value stands for the situation where the slope of the spectrum is identical to
that of the reference odor. The application of the reference odor spectrum
makes the fingerprint relative to the reference. This feature increases the
information entropy of the fingerprints. The method is briefly illustrated by
sensing bacterial odor in cow manure isolates.
