Companding is a procedure which can be used to smooth the effects of the fluctuating signal energy. The effect of the compressor in the transmitter is compensated with the expander in the receiver. PCA is an essential part in the lossy compression of the spectral images. In this paper we combine these two techniques to study the effect of companding in PCA compression of spectrum sets. Compressor is now applied as a preprocessing phase to spectrum sets. The experiments indicate that the low energy spectra are better reconstructed when the companding is applied. At the same time the overall reconstruction quality of the spectrum sets is slightly reduced.
['Arto Kaarna']
Companding and PCA compression of spectrum sets