| For the advantage of extremely low power spectral densities, excellent immunity to interference from other radio systems, exceptional multipath immunity, capable of high bandwidth, multi-channel performance and high system capacity, UWB technology has aroused much attentions. More and more institutes and company are investing in this field. The UWB communication technology is new exploration of radio spectrum, and this will develop new fields of time-domain spectrum.This paper is part of "The technology of ultra-short pulse communications", one topic of certain Advance Research in the 10n Five-year Plan from the military. This work is in charge of solving its source and channel characteristics. This work ensures communicational reliability is achieved. We investigate and research thoroughly the time and spectral characteristics of the ultra-short pulse used in the UWB communications. For its wideband we calculate the signal's Power Spectrum Density (PSD), giving foundations for solving the potential interference it may cause to other communication systems. For indoor, outdoor and free space circumstance, we establish the channel models. For indoor and outdoor conditions, we establish Gaussian channel; corresponding free space conditions, Poisson channel model. Using ITM models we simulate the characteristics of the transmitting pulse in the free channel. From derivation we attain some useful expressions between the measured parameters and calculations. Through computer simulation and calculation, the results have shown our analysis valid, reliable and trustworthy. At last, some original tentative ideas and new hopes are brought up. |
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