Synchronous sampling phase and amplitude detection method and apparatus

A synchronous sampling phase and amplitude detection method and apparatus is described. An oscillator generates a signal at a particular frequency and then a frequency dividing circuit divides this signal frequency by a factor of four. This divided signal is transmitted via a transducer through a material and received by the same or another transducer. The received signal is then digitized. The received signal is next sampled at four times its frequency based on a reference signal from the oscillator and then characterized as a phasor. The phase and amplitude of the received signal are then calculated via trigonometric relationship of at least two samples separated by 90 degrees. The remaining samples are employed to reduce the noise equivalent bandwidth.