Abstract: A low power pulse oximeter includes an input stage for amplifying a signal received from a light detector that is switchably connected to the power supply that powers the amplifier. The oximeter also includes an output stage with an LED driver circuit that is switchably connected to the power supply that powers the LED driver circuit. The input and output stages are switchably connected to the power supply when measurements need to be taken. When measurements do not need to be taken, they are switched off to reduce the power consumption of the oximeter.

Abstract: A digital telemetry transmitter for transmitting eight channels of diagnostic quality electrocardiographic data has input circuitry for receiving analog EKG signals originating at electrodes on the patient. The input circuitry includes a circuit for ascertaining the impedance of the electrode connection to the patient and to indicate an electrode fault. EKG signals from the input circuit are provided to a digital/analog converter for converting the analog signals into corresponding digital signals. The analog/digital converter may comprise an eight channel, 20-bit converter, sampling the input signals at a frequency of 10 KHz and providing a digital output signal having a frequency of 500 Hz. The output of the analog/digital converter is provided to a microprocessor control which provides a digital EKG modulating output signal. The output signal is periodically inverted to avoid stationarity in the transmitted data.

Abstract: An electrocardiographic patient lead cable apparatus comprises an elongated cable part and a connector. The cable part has a plurality of connecting wires with connectors for the electrodes. The connecting wires are joined together for varying portions of their length to form a flat common portion of the cable part. The common portion is connected at one end to the connector. The connecting wires separate from the common portion at the selected locations along the extension of the common part from the end connected to the connector to form relatively short separated connecting wires. The lead cable apparatus so formed facilitates correct connection of electrodes positioned at various locations on the body of the patient and reduces or eliminates tangling of the connecting wires. The connector is of compact, lightweight construction.

Abstract: An apparatus and method directed to an adaptive noise filtering arrangement. The arrangement has the ability to estimate a first set of data for a first time-dependent variable based upon at least two sets of data for two time-dependent variables related to the first time-dependent variable. Additionally, the arrangement has the ability to filter an actual set of data for the first time-dependent variable based upon the first set of data and the actual set of data. The estimated first set of data and filtered actual set of data can be printed or displayed in a graphical format for analysis.

Abstract: An apparatus and method directed to an adaptive noise filtering arrangement. The arrangement has the ability to estimate a first set of data for a first time-dependent variable based upon at least two sets of data for two time-dependent variables related to the first time-dependent variable. Additionally, the arrangement has the ability to filter an actual set of data for the first time-dependent variable based upon the first set of data and the actual set of data. The estimated first set of data and filtered actual set of data can be printed or displayed in a graphical format for analysis.

Abstract: Disclosed herein is a method and apparatus employing a D.C. drive motor and digital printhead for recording electrocardiographic data or other digital data on a chart at a constant time scale, regardless of temporary variations in the D.C. motor speed. A buffer memory stores sensed digital ECG data, and a data count register provides a count indicative of the amount of data stored. A pulse width register controls the width of long and short pulses generated by a motor driver for the selected paper speed. An experience count register has a count indicative of the relative number of long and short pulses generated. The original or current width of the pulses may be adjusted by the pulse width register, subject to the count of the experience count register, for controlling the speed of the D.C. drive motor. The motor speed is increased if the buffer memory is storing more than a preselected amount of data, and the motor speed is decreased if the buffer memory is storing less than a preselected amount of data.

Abstract: An analog-to-digital converter (ADC) controlled in a manner to increase its precision. The signal to be digitized is one input to an analog signal summing means whose output is the input to the ADC. A stepped or dither voltage signal is applied to the other summing means input during each analog signal sampling period of the ADC. The dither voltage steps are equal to the voltage equivalent of one ADC count plus 1/N where N is the number of steps per ADC count chosen to obtain a desired degree of precision in the digital signals that are output by the ADC. The dither voltage step that is combined with the current analog signal sample in the summing means amounts to displacing the sample in steps within each count of the ADC. The ADC converts each combined signal during a sampling interval to a succession of binary digital values which are summed.

Abstract: A waveform processor for processing waveforms of the ECG type from surface electrodes connected to the human body. Differential lead waveforms are sampled by a fast, high resolution A/D converter which are thereafter provided to a preprocessor where filtering and a reconstruction of the leads waveforms takes place. The waveforms are then detected, classified, and averaged to form composites of the X, Y, and Z terminal leads. Special filtering is used to detect the high frequency low amplitude features of the composite waveforms.

Abstract: A method and means for graphically recording electrocardiographic data reduces the amount of redundant data displayed so as to reduce the size of the electrocardiogram. However, arrhythmias and other aberrant ekg signal complexes are reproduced in context for diagnostic purposes. Typical or normal signal complexes received from the patient are used to establish an ekg signal complex pattern. In the absence of aberrant signal complexes, this pattern is recorded in lieu of the patient data at a speed which is less than the normal recording speed to form the electrocardiogram. One such pattern may be recorded for every 25 complexes in the patient data, thereby achieving the reduction in the size of electrocardiogram. When an aberrant signal complex occurs, it is entered in the electrocardiogram at the normal higher recording speed. For repetitiously occurring aberrant signal complexes, only certain occurrences of such aberrancies are entered in the electrocardiogram.