Ultra wide band FM: a constant envelope frequency domain approach

This paper presents a novel approach based upon wide-band FM techniques to generate a constant-envelope UWB signal whose bandwidth can be independently chosen from the data rate. Data is modulated on a sub-carrier using, for example, FSK techniques. The various users distinguish themselves by their sub-carrier frequency. Simultaneous demodulation of multiple FM signals having the same RF center frequency is possible when a linear FM demodulator, not preceded by any limiting devices, is used. Since the RF signal is not pulsed, no carrier synchronization (as in impulse radio) is required. Spectral roll-off of the UWBFM is steep allowing, for example, this system to co-exist with WLAN systems operating between 5 and 6 GHz.