Pages 263-264
A 1Mbps spread spectrum (SS) radio unit has been developed for wireless communication. As a first step, the very weak intensity 300MHz carrier signals are transmitted with direct sequence (DS) spectrum-spreading. The received signals are despread by using a SAW matched filter with a locally deposited ZnO layer on the input IDT on a st-cut quartz substrate to reduce mismatch loss. For DPSK data time-sidelobe of the filter autocorrelation is reduced using a new 25 chip spreading code. Further a time-window threshold-gate is developed, enhancing the receiver sensitivity by 8dB. As a tryal application to moving-picture wireless-transmission, a prototype visual transceiver has been developed, receiving the moving pictures of 112 × 112pixels with 5 frames/s at a distance 10 to 20m from the transmitter.
