Software Defined Radio Based Avalanche Beacon Receiver

Abstract

Annually, avalanches claim an average of 100 lives, and many more are injured. For victims buried by an avalanche, time is of the essence. If not rescued within 15 minutes, the victim only has a 10% probability of survival. Commonly, the people venturing into avalanche-prone areas equips avalanche beacons. These devices work as small radio transmitters transmitting a signal at 457 kHz once each second. Another avalanche beacon can then receive the signal and give the rescuer an indication of the buried victim’s direction and distance. In this thesis, I present a novel approach to automatically detect and measure the received power of a transmitting avalanche beacon. The approach uses a software-defined radio and a manually created antenna to sample radio signals. The created antenna is tuned to be optimal around 457 kHz. In addition to the hardware for sampling the radio spectrum, I present three algorithms for analyzing the received radio signal. The first algorithm performs the entire analysis in the time domain, the second algorithm works in the frequency domain, and the third algorithm utilizes both the frequency and time domains of the signal. The experiments show that the hardware and the algorithms can automatically detect a transmitting avalanche beacon from at least 20 meters away, possibly further