An Investigation Of Spectral Properties Of PPM Signals Used In UWB Systems

The Ultra WideBand Pulse Position Modulation (UWB-PPM) systems are the most efficient implementations of the UWB systems based on impulses. They achieve a good quality of transmission by using a large bandwidth and small emitted energy. The deficiency of such systems is that they have a spectrum with energy concentrated at discrete points. These discrete frequency energy components generate interferences to narrowband systems operating in the same frequency interval, denying harmless coexistence. At the current date there is no complete formula for the power spectral density of the PPM signals which we could use to ascertain the size of this interference. We will present a method for the calculus of the PPM spectrum which will give an exact image of the signals´ power spectral density.