Search Results

The Active Signal A SCOPE (or noise-immune stethoscope) is intended for medical diagnostic purposes only. It may be used for the detection and amplification of acoustic signals generated by physiologic activity in the body. In the presence of relatively mild ambient noise it is used in Acoustic Mode and functions as a passive electronic stethoscope to receive sounds produced by the heart, lungs, bowel and other internal organs. To retain audibility at higher sound levels it is switched to Doppler Mode where an audible tone is produced by the ultrasound frequency-shift caused by motion of the heart and lungs. It can be used on any person undergoing a physical assessment. It is not intended to be used for diagnosis and treatment by unlicensed, untrained, or unqualified medical persons.

Active Signal's stethoscope combats noise intrusion through use of two modes of operation depending on the intensity of background noise: 1. In the presence of relatively benign ambient noise (loud accident scenes, ambulances, emergency rooms, civilian Medevac helicopters, etc.) the device is configured as an amplified electronic stethoscope employing a passive piezoelectric sensor. Noise rejection is imparted by design of the piezoelectric element and mass of the housing. 2. When the ambient sound levels exceed the passive sensing limit, an active Doppler mode is engaged. This transposes the detection of vital physiological sounds from the audio frequency range (used by conventional or electronic stethoscopes) where physiological sounds typically overlap the background noise and hence are swamped out, to ultrasound which puts the measurement into an entirely different frequency band. DEVICE CONFIGURATION: The top section of the device is the battery compartment, which contains two 1.5V AA-cells. The device is held between the index and middle fingers, with the thumb free to operate a 4-button control panel shown at here. The bottom section contains the stethoscope sensors and signal-processing electronics. For operation as a passive amplified electronic stethoscope (Mode 1, above), a tall column of piezoelectric ceramic material is used as the sensing element contacting the center of the front face. At the top, this column is pressed against the stethoscope's casing. For the active ultrasound-Doppler mode of operation (Mode 2, above), two semicircle-shaped disks, made of piezoelectric material, are embedded in the sensor head, where one functions as a transmitting and the other as a receiving transducer. Details of the mounting geometry, the gap size between the discs and the gap orientation, and also the carrier frequency, determine the width of the sound beam and its penetration depth. A thumb-operated 4-button control panel allows the device to be turned on (press any mode button), the signal volume to be set (+ and - buttons in the horizontal plane), and the operating mode to be selected.