A Direction Finding System for Transient Signals

Currently deployed direction finders used with radio-tagged animals have proved to be of great value in the study of endangered species of wildlife. The automated collection of directional data, supplanting or supplementing individual researchers with hand-held instruments, has permitted major increases in research productivity. However, only one design of a suitable automated instrument exists on the market. It is available from only one source, in limited quantities, and is still in a developmental stage. The current users of this equipment experience much difficulty in achieving the results for which they originally hoped. The authors believe this equipment can eventually be improved in performance and reliability, but it will take much time and effort on the part of the researchers who use it in the field. It is possible to develop a much more capable instrument, based on more modern technical concepts. The resulting instrument should have higher accuracy and reliability, would employ a greatly simplified antenna system and thus be more portable, and, using mainly off-the-shelf components and widely used software, should be more reliable. A collateral benefit of this project would be development of an acoustical direction finder. The same principles apply to sound waves as to radio waves only the sensors utilize different physical principles. Existing microphones can be equipped with appropriate baffles to yield the requisite directional properties. The existing sound amplifiers, signal processing software, and data storage facilities can be used. The direction finding algorithms developed for the radio direction finder also can be used for the acoustical case. With the current state of development of digital signal processing techniques it is now possible to deploy electromagnetic and acoustical direction finders capable of enhanced abilities in the detection of transient signals and in determining their directions of arrival.