Ungerboeck DPSK codes do not shape the signal spectrum
Rohit Ramesh · European Transactions on Telecommunications · 1995
Abstract We consider the power spectrum of trellis codes in conjunction with a differential encoder. We present a closed form expression for the power spectrum of PSK trellis codes that are subjected to differential encoding. Using this expression, we show that when the trellis code in question is defined by the Ungerboeck rules, the power spectrum of the resulting differentially encoded sequence is a constant; in other words, Ungerboeck DPSK codes do not shape the signal spectrum.