A device and method of detecting and analyzing a vital field places an avalanche diode in the path of vital waves in the vital field. The vital waves interfere with the electron avalanche process in the avalanche diode. Control circuitry and an avalanche initiator cause electron avalanches at a known sampling frequency. The interference from the vital waves produces a beat frequency that is output from the avalanche diode. By adjusting the sampling rate by a known amount, a second beat frequency is produced and the beat frequency shift is used to determine the input frequency of the vital waves. The vital waves are very weak and produce frequencies into the terahertz range, so that the input frequency is undersampled by the device. Further, high sensitivity is required and a circuit design is implemented to maximize sensitivity while minimizing noise and other interference that is common to avalanche diode operation.
