Abstract: A spectrometer system includes a thermal light source for illuminating a sample, where the thermal light source includes a filament that emits light when heated. The system additionally includes a spectrograph for measuring a light spectrum from the sample and an electrical circuit for supplying electrical current to the filament to heat the filament and for controlling a resistance of the filament. The electrical circuit includes a power supply that supplies current to the filament, first electrical components that sense a current through the filament, second electrical components that sense a voltage drop across the filament, third electrical components that compare a ratio of the sensed voltage drop and the sensed current with a predetermined value, and fourth electrical components that control the current through the filament or the voltage drop across the filament to cause the ratio to equal substantially the predetermined value.

Abstract: Several techniques are provided for aiding in the discrimination of detected biological signals indicative of blood pressure from detected signals not indicative of blood pressure (e.g., noise). A threshold, based predominantly on a level of noise, is developed and used in the discrimination. A second threshold, based predominantly on levels of previously detected biological signals, is developed and additionally used to help discriminate the biological signals from noise. The biological signals are detected during a selected portion of a cardiac cycle, and additional signals detected outside of the selected portion of the cycle are applied to the detected signals. Another threshold may be developed based predominantly on a level of signals sensed by a transducer positioned to preferentially sense noise; the transducer is positioned so that the noise that it detects is related to noise that is detected during the detection of the biological signals.

Abstract: A stethoscope, operable in an acoustic or electronically augmented mode, is disclosed. In one electronically augmented mode of operation, the stethoscope simultaneously provides the listener with combined unmodified, familiar audible sounds and sounds which have been electronically augmented to bring them within the human auditory range. Additionally, a timing sound may be provided along with the unmodified, familiar audible sounds and electronically augmented sounds to assist the listener in determining when sounds occur in the heart cycle. The timing sound may be enabled in the acoustic mode of stethoscope operation so that the listener can place familiar audible sounds within the heart cycle.

Abstract: A threshold detector for detecting the recurrence of a respiration event by comparing a filtered respiration signal to an adjustable threshold level. The adjustable threshold level is maintained at a value sufficient to substantially prevent the detector from indicating that a respiration event has occurred due to residual cardiovascular artifact being present in the filtered respiration signal.

Abstract: Systems and methods are disclosd for detecting the recurrence of physiological functions. The disclosed systems and methods are especially adapted for detecting the recurrence of a patient's respiration from a signal representative of changes in the patient's thoracic volume, despite the presence of cardiovascular artifact in the signal. A cardiovascular artifact filter suppresses the artifacts in response to a signal, generated by a cardiotachometer, which varies as and is proportional to the fundamental frequency of each artifact.

Abstract: A telephone care system enables personnel monitoring an emergency response center to be reminded that help is still needed at a given location. The system includes a provision for sending a plurality of alarm messages, wherein one criterion for selection of the message being sent is whether a message was previously sent without the alarm state thereafter having been terminated. In a preferred embodiment, a communication system in accordance with the invention includes a provision for sending repetitively, after an initial alarm message, a message to the effect that "help is still needed" until the alarm state has been terminated.

Abstract: For suppressing cardiovascular artifact present in a respiration signal, a cardiovascular artifact filter suppresses artifacts in response to an output signal generated by a cardiotachometer. The output signal is proportional to the fundamental frequency of the cardiovascular artifact. Recurrence of respiration is determined by coupling the filter to a threshold detector. A minimum threshold level proportional to the maximum amplitude of the artifact is supplied to the detector for minimizing the false indication of respiration recurrence due to presence of an artifact in the respiration signal.

Abstract: The present invention provides a small portable radio transmitter unit which can be worn on the wrist or suspended from a neck chain to provide immediate access in the event of an emergency condition and without interfering with the normal day-to-day activities of the wearer. The unit is contained within a watertight housing having a resilient membrane depressible by finger pressure to actuate a button switch within the housing for actuation of the transmitter. The housing is vented to the atmosphere to provide equalization of internal and ambient pressure in a manner providing isolation from water or other liquid entry to thereby maintain a watertight enclosure.

Abstract: A system for selectively removing a recording means from a strip chart scale to avoid marking undesired data thereon.

Abstract: A system for coupling a plurality of physiological signals across an isolation barrier. A plurality of physiological signals received at a number of signal inputs on the isolated side of the barrier are sampled during separate time periods and coupled to the primary winding of a transformer. The direction of signal flow through the primary winding is reversed during each said period. A pair of serial pulses of opposed polarities are induced in the secondary winding for each sampled signal. The pairs of serial pulses induced in the secondary winding are reconverted to the plurality of physiological signals on the non-isolated side of the barrier.

Abstract: A system and method for selectively removing a recording means from a strip chart scale to avoid marking undesired data thereon.

Abstract: Circuitry for refinement of fetal heart signals from an ultrasonic (or other mechanical energy) transducer, featuring improved signal processing circuitry connected to the transducer to convert useful information-carrying energy in the transducer output into a refined electrical signal, and improved correlation circuitry for providing an output to a cardiotachometer.