1 Development of a Programmable Ultrasonic Receiver Chris Allen

2 Outline Ultrasonic signals Ultrasonic receiver applications Ultrasonic receiver requirements Candidate component technologies

3 Ultrasonic signals Inaudible to humans Some animals and insects use ultrasonic signals for communication, navigation, hunting, etc. Humans use ultrasonic signals for structures testing, medical applications (imaging, flow measurement), industrial processes, and ranging/communication Compared to the speed of light, the speed of sound is very slow (6 orders of magnitude lower) 1-cm EM wavelength  30 GHz in air 1-cm acoustic wavelength  33 kHz in air

4 Ultrasonic receiver applications The availability of an ultrasonic receiver enables several applications Ultrasonic radar system (when used with an ultrasonic transmitter) Applications include distance measurement, wind speed measurement, target detection / identification / tracking, ultrasonic imaging Ultrasonic spectrum analyzer Applications include signal characterization/classification, propagation channel characterization, radiation pattern measurement, ambient noise measurement Ultrasonic communications Applications include wireless signal distribution (non line-of-sight), covert communications, communication through structures (walls, floors, pipes) Ultrasonic testing Non-destructive testing, industrial sensors

5 Ultrasonic receiver applications The motivations for development of this programmable ultrasonic receiver include: Development of an ultrasonic radar system Enables demonstration of various radar concepts for teaching/training Provides quick and low-cost evaluation of new radar concepts Development of an ultrasonic spectrum analyzer Useful for system characterization and troubleshooting Development of precision ultrasonic range measurement system Useful for avionics (formation flying UAVs) Development of a wind speed measurement system To measure the vertical wind component near a wind turbine which may increase its conversion efficiency

6 Ultrasonic receiver requirements Operating frequency range30 kHz to 50 kHz Signal bandwidth1 kHz to 20 kHz Dynamic range50 dB Number of channels4 Output formatUSB interface Final assemblycustom printed circuit board Size (max)2.25” x 4” x 0.625” (10 cm x 5.5 cm x 1.5 cm) Weight (max)80 g Power (max)5 100 mA, 500 mW

7 Candidate component technologies Transducer Knowles SPU04010HR5HMEMS microphone20 kHz to 80 kHz Amplifier Linear Tech LT1208hi-speed op amp45 MHz bandwidth Linear Tech LTC6910prog. gain amplifiers 11 MHz bandwidth Mixer Philips SA602Adouble-balanced mixer500 MHz f max Local oscillator Linear Tech LTC6903programmable oscillator1 kHz to 68 MHz input for external LO Processor Arduino Uno8-bit microcontroller5 V, 16 MHz Arduino Due32-bit ARM microcontroller 3.3 V, 84 MHz

8 Candidate receiver circuit diagram (only one channel shown)

Ultrasonic Tx board already developed 9