Abstract: A system and method for locating patients in a hospital using M different frequency patient transmitters and N fixed location antennas within the hospital for receiving the patient signals. The received signals for each antenna are separated from the signals received by the other N-1 antennas, and the signal strength of each signal received by each antenna is measured. The received signal strength of each antenna is processed to determine which of the antennas received the strongest signals from each of the patient transmitters. Alternatively, the approximate location within the hospital of each operating patient transmitter is determined since the antennas are in fixed locations and the layout out of the hospital is known. In other embodiments, each of the antennas have a different modulation pattern to enable identification of which of the antennas receives which signals from the patient transmitters.

Abstract: A system for tracing uterine contraction is disclosed. The system comprises a probe and an electronics module. The electronics module includes a drive circuit and an output section having a frequency counter. The output section also includes a strip-chart recorder driven by a frequency-to-voltage converter. The probe includes an electro-mehanical transducer which is driven at resonance by the action of the drive circuit. When the probe contacts the abdomen of a pregnant subject, changes in the mechanical impedance of bodily tissue during a contraction affect the resonant frequency of the probe and thus the frequency output by the drive circuit. This frequency can be read directly from the frequency counter and recorded on the strip-chart so that contractions can be traced.

Abstract: A system for tracing uterine contraction is disclosed. The system comprises a probe and an electronics module. The electronics module includes a drive circuit and an output section having a frequency counter. The output section also includes a strip-chart recorder driven by a frequency-to-voltage converter. The probe includes an electro-mechanical transducer which is driven at resonance by the action of the drive circuit. When the probe contacts the abdomen of a pregnant subject, changes in the mechanical impedance of bodily tissue during a contraction affect the resonant frequency of the probe and thus the frequency output by the drive circuit. This frequency can be read directly from the frequency counter and recorded on the strip-chart so that contractions can be traced.

Abstract: An Intelligent Electrocardiogram System that solves the problem of faulty electrical connections between a patient and an ECG instrument is disclosed. The electrode employed by the invention comprises a disposable insulative pad and a snap connector that includes an LED anchored in the top central portion of the snap connector. Wires from the LED run into a lead that extend to an ECG instrument. An adhesive attached to the pad enables the electrode to be secured on the skin of a patient. The electrode includes a metal post embedded in the center of pad. The post protrudes up from the insulative pad through the connector side, which is the side opposite the side that touches the patient's skin. A spring contact surrounds the post and provides an electrical coupling to one of the wires inside the lead. The bottom portion of the post extends through and past a lower central surface of the pad that is capable of holding a volume of conductive jelly.

Abstract: Apparatus and method for representing slow motion of an oscillating heart by forming strobed images of the heart at a sequence of uniformly spaced times with controllable time interval lengths that are related to, but not identical to, the primary oscillation period T of the heart. The heart images may be formed at a sequence of times t=t.sub.0 +kMT.sub.h /N where t.sub.0 is an initial time, N is a positive integer, k=1,2, . . . , N-1 and M is a positive integer. Alternatively, the heart images may be formed at a sequence of times determined in part by the current oscillation cycle of the heart.

Abstract: Oxygen determination based on luminescence quenching of fluorescent dye is effected by using the frequency output of an offset-phase locked loop to calculate the time constant for the exponential decay of fluorescence. An offset phase angle between a periodic stimulus signal used to excite the dye and a response signal based on fluorescence detection is predetermined to optimize signal-to-noise ratio for a wide range of time constants. An offset-phase locked loop is used to vary the frequency of a periodic stimulus signal until the predetermined phase relationship is established. Where the stimulus and response signals are substantially sinusoidal, the offset phase angle is ideally about 49.3.degree., although substantially optimal performance is achieved using a more conveniently generated 45.degree.. The 45.degree. angle offset can also be used with a square-wave stimulus signal.

Abstract: A delay circuit comprising a plurality of cascaded saturating circuit elements is provided. The delay circuit may be incorporated in such circuits as modulators and demodulators to provide signal delay.

Abstract: A transversal filter is provided which includes a delay circuit comprising a plurality of cascaded saturating circuit elements. The delay circuit has a series of taps from which signals with varying delays are obtained. The obtained signals are combined to form filtered signal(s).

Abstract: A delay circuit comprising a plurality of cascaded saturating circuit elements is provided. The delay circuit may be incorporated in such circuits as modulators and demodulators to provide signal delay.

Abstract: A delay circuit for providing signal delay within an acoustic imaging system is provided. Reflected acoustic signals are transformed into electrical signals and are used to reproduce images of objects. Delay lines along the electrical signal path are used to focus the images compensating for asynchronism of electrical signals caused by variations in the length of acoustic signal paths.

Abstract: A circuit for detecting a Frequency Modulated (FM) signal is provided. An amplitude limited FM signal is propated through a delay circuit comprising a plurality of cascaded saturating inverters. A Boolean logic "Exclusive Or" (XOR) operation is performed between the FM signal before entering the delay circuit and after exiting the delay circuit.

Abstract: Output signals from a set of Faraday loops located in a common plane are combined selectively to simulate the output signals from a set of mutually orthogonal antennas. This arrangement and use of Faraday loops are especially suitable in a hospital environment for monitoring patients. Because of the availability of output signals from a set of equivalent orthogonal antennas, any danger of a gap in the monitoring of the patient is greatly minimized; the patient can be monitored regardless of the changing orientation of the patient with regards to the monitoring antennas.

Abstract: A spectrophotometer optical section is presented which employs a fine positioning beam director which corrects for any deflections of the output beam path and accurately positions the optical beam on the detector slit of the spectrograph. The detector slit is chosen to have a size slightly smaller than the size of the optical beam at the detector slit to have high slit throughput without introducing spurious absorption. The sample cells need not be rigidly mounted thereby enabling use of a sample cell and cell holder which allows quick, easy interchange of cells.

Abstract: A beam directing device is provided which employs one or more mirrors mounted on a single rotatable shaft. The orientation of the shaft controls the rotational orientation of these directing mirror(s) to direct the beam toward any of a number of sample or reference cells. Behind each cell is a cube corner which reflects the beam back to the directing mirror(s) for reflection toward the detector. In one embodiment, a shaft encoded senses the orientation of the shaft, the encoder output being servoed against a position signal to coarsely rotate the shaft in order to direct the beam to a sample cell and thence to a spectrograph slit. A pair of slit diodes detect the beam overlap on each side of the slit and their output is used to accurately position the beam on the slit to within one second of arc and correct for deviations in beam direction.