A.A. Sudakov, S.N. Zamuruev

Modern theory of radio circuit and signals describes very well linear filtration which reduces parasitic influence noise on signal. Before filtration signal goes through communication channel which includes transmitter, radio channel and receiver. At the channel output signal has linear frequency distortions and energy losses caused by unmatching of signal spectral density and channel transfer function. Energy losses include losses caused by not full frequency band using and losses caused by signal attenuation outside of frequency band. This work shows solutions for following tasks - minimization of linear frequency distortions and energy losses of signal in communication channel for it effective optimal processing. Solving of first task is keeping constancy module of channel transfer function at signal bandwidth. Simultaneously argument of channel transfer function should be zero or multiple to . Solving of second task that is keeping whole signal energy during it transfer through channel with well known but any shaped amplitude frequency characteristic is proportionality of module signal-s spectral density to module of channel transfer function. If channel of channel transfer function is unknown so for minimization of signal-s energy losses it necessary to provide constancy module of channel transfer function within signal bandwidth and keep it zero outside of signal bandwidth. It means that module of channel transfer function must be rectangular -shaped at any argument of channel transfer function. At the same time module of signal spectral density should be proportional module of channel transfer function. Method of UWB signal synthesis which is matched with communication channel directly goes from requirements proportionality of signal spectral density and module of channel transfer function. Method consists of applying of inverse Fourier transform to channel transfer function. Suggesting that rectangular -shaped amplitude frequency characteristic is most widely used transfer channel function and applies proposed synthesis method it is possible to conclude that signal which goes though communication channel with minimal energy losses is signal with sin(x)/x envelope. Energy efficiency of found UWB signal for 2.62 dB more compare with widely used signal with Gaussian envelope of spectral density. Theoretical spectral efficiency for this signal reaches 100% and at least for 5% more compare with UWB signals from literature. On base of proposed signal it is possible to build an infinite number of sequences for using in UWB communication systems with orthogonal time division multiplexing (OTDM).