Calculus of the Power Spectral Density of Ultra Wide Band – Pulse Position Modulation Signals Coded with Totally Flipped Code
UWBPPM systems were noted to have a power spectral density (p.s.d.) consisting of a continuous portion and a line spectrum, which is composed of energy components placed at discrete frequencies. These components are the major source of interference to narrowband systems operating in the same frequency interval and deny harmless coexistence of UWBPPM and narrowband systems. A new code denoted as Totally Flipped Code (TFC) is applied to them in order to eliminate these discrete spectral components. The coded signal transports the information inside pulse position and will have the amplitude coded to generate a continuous p.s.d. We have designed the code and calculated the power spectral density of the coded signals. The power spectrum has no discrete components and its envelope is largely flat inside the bandwidth with a maximum at its center and a null at D.C. These characteristics make this code suited for implementation in the UWB systems based on PPMtype modulation as it assures a continuous spectrum and keeps PPM modulation performances.
Calculus of the Power Spectral Density of Ultra Wide Band – Pulse Position Modulation Signals Coded with Totally Flipped Code.

Calculus of the Power Spectral Density of Ultra Wide Band – Pulse Position Modulation Signals Coded with Totally Flipped Code.
Autori:
Tudor N.
Durnea
^{ [1]
}  Nicolae D.
Alexandru
^{ [1]
} ^{ [1]
} Gh. Asachi Technical University of Iaşi, Bd. Carol I, no 11, RO700506 Iaşi
Rezumat
UWBPPM systems were noted to have a power spectral density (p.s.d.) consisting of a continuous portion and a line spectrum, which is composed of energy components placed at discrete frequencies. These components are the major source of interference to narrowband systems operating in the same frequency interval and deny harmless coexistence of UWBPPM and narrowband systems. A new code denoted as Totally Flipped Code (TFC) is applied to them in order to eliminate these discrete spectral components. The coded signal transports the information inside pulse position and will have the amplitude coded to generate a continuous p.s.d. We have designed the code and calculated the power spectral density of the coded signals. The power spectrum has no discrete components and its envelope is largely flat inside the bandwidth with a maximum at its center and a null at D.C. These characteristics make this code suited for implementation in the UWB systems based on PPMtype modulation as it assures a continuous spectrum and keeps PPM modulation performances.
Cuvinte cheie:
Ultra Wide Band, Pulse Position Modulation, Totally Flipped Code, Power Spectral Density
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