Ultrasonic distance measurement method based on software radio spread spectrum

Abstract

Based on the research on software radio and spread spectrum technology used in radar system, one method of spread spectrum method ultrasonic distance measurement based on software radio is proposed. An appropriate pseudo random number (PRN) is modulated and transmitted by ultrasonic sensor. The time of flight is calculated by using software radio technology. Receiving signals are normalized by band pass sampling filter and 1 bit normalization method. The phase difference between the sending signal and receiving signal is captured by digital matched filter (DMF). This method shortens the processing time and reduces FPGA resource. The system design is based on Aletra's quartus II software, and it fits to FPGA chip after logic synthesizing and placement routing. The timing simulation result in placement and routing is presented. According to PRN code capture principle in spread spectrum correspondence, digital matched filter based on 1 bit quantification technology is carried out. Comparing with traditional digital matched filter, this method reduces the FPGA resources consumption to 1/24 at least. The simulation testing results indicate that spread spectrum method ultrasonic distance measurement based on software radio is feasible.