Abstract: A hand-held, battery operated, Doppler ultrasound diagnostic device for use in obstetrical applications to, for example, measure fetal heartbeat, and vascular applications to, for example, measure blood flow and pressure, includes a cordless probe, a base unit, and an electric recharging stand. The probe detects the physical response signal being monitored through Doppler ultrasound techniques. The signal is used to frequency modulate a sine wave carrier signal which is transmitted by the probe and received by the base unit. The carrier signal frequency and wave form is chosen so as not to cause interference with other medical equipment that may be nearby. The base unit demodulates the carrier signal and retrieves the human response signal. The base unit displays the human response signal visually with an LED display and audibly with built in speakers. In addition, the base unit includes an output connectors which allow the human response signal to be recorded on a tape recorder or played through earphones.