An Experiment with Direct-Sequence Spread Spectrum and Differential Phase Shift Keying Modulation for Indoor, Wireless Communications.

Measurements have been made on an indoor, wireless communication system using direct-sequence spread spectrum and differential phase shift keying modulation. We describe the design and implementation of a transmitter and a receiver using a Surface Acoustic Wave (SAW) matched filter. The receiver performance is within 1 dB of the theoretical performance of a differential phase shift keying (DPSK) receiver in presence of additive white Gaussian noise. We also show receiver performance in a multipath fading indoor environment with multipath fade notches of up to 50 dB depth. The indoor channel multipath fading can be overcome by using an equal gain combiner. We further confirm the harsh nature of indoor mean power level attenuation. Also, we investigate the multiple access capability of the system by introducing an interfering transmitter with a different spread spectrum code sequence.