System, method, and device is presented for generating and processing tissue-monitoring signals. An emitting driver is operable to control, upon receipt of at least one emitted signal, an optical emitter to emit at least one emitted signal. A processor is coupled to the at least one optical emitter and operable to execute instructions to generate the at least one emitted signal. At least one photodetector is operable to detect one or more photons transmitted through tissue and to convert the detected photons into a detected signal. A hardware processing sequence is coupled to the photodetector and processor. The hardware processing sequence is operable to filter and condition the detected signal. The processor is operable to execute instructions to demodulate the at least one emitted signal and the detected signal.