Abstract: A method and system for determining the speed of sound in a fluidic medium by determining the travel time of an acoustical signal a predetermined distance in a fluidic medium by generating a cyclical reference signal of a predetermined frequency and transmitting a portion of the reference signal through the medium. The transmitted portion of the reference signal is received after travelling a predetermined distance in the fluidic medium. The cycles of the cyclical reference signal are counted during the period of time between the transmitting and receiving of the portion of the reference signal wherein the travel time of the portion of the reference signal, is the number of cycle counts divided by the frequency. The speed of the acoustical signal through the fluidic medium is a function of the path length divided by the travel time.

Abstract: A method of communicating with a remote precision transponder includes the step of transmitting first signals to the transponder. The first signals are received in the transponder, and second signals representative of the first signal are delayed therein for a precise time interval. After the precise time interval, third signals representative of the delayed second signals are transmitted from the transponder. Detailed embodiments of a transponder for performing these steps are also disclosed.