Accuracy of Spread Spectrum Techniques for Ultrasonic Indoor Location

This paper presents an assessment of the accuracy of impulsive and spread spectrum based algorithms for indoor ultrasonic location. Ultrasonic location systems have been proposed for pervasive computing applications. Previous systems have focused on the use of impulsive and Direct Sequence Spread Spectrum (DSSS) signalling. The use of Frequency Hopped Spread Spectrum (FHSS) signalling has not been previously studied for ultrasonic location. It is shown herein that FHSS outperforms DSSS and impulsive signalling under conditions of noise and reverberation. The accuracy of location for FHSS is shown to be twice that of DSSS under typical conditions. FHSS also provides opportunities for simplified transducer construction.