Abstract: An oversampling pulse oximeter includes an analog to digital converter with a sampling rate sufficient to take multiple samples per source cycle. In one embodiment, a pulse oximeter (100) includes two mor more light sources (102) driven by light source drives (104) in response to drive signals from a digital signal processing unit (116). The source drives (104) may drive the sources (102) to produce a frequency division multiplex signal. The optical signals transmitted by the light sources (102) are transmitted through a patient's appendage (103) and impinge on a detector (106). The detector (106) provides an analog current signal representative of the received optical signals. An amplifier circuit (110) converts the analog current signal to an analog voltage signal in addition to performing a number of other functions. The amplifier circuit (110) outputs an analog voltage signal which is representative of the optical signals from the sources (102).

Abstract: A method of producing a diode drive current in an oximeter includes sensing at least a part of a current passing through the diode and converting the sensed current to a sensed voltage, inputting the sensed voltage to a feedback amplifier for stabilizing the current passing through the diode, and eliminating an offset voltage across inputs of the feedback amplifier. A pulse oximeter includes a diode for emitting light flashes, a feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier stabilizing a current passing through the diode, a nulling amplifier having inputs, a nulling capacitor, and an output, the nulling amplifier charging and discharging the feedback capacitor until the inputs of the feedback amplifier are at a same voltage. The operation may include synchronizing an elimination of input offset voltages of the feedback and nulling amplifiers with on or off state of diode current.

Abstract: A method of preparing a parametric speaker transducer for (i) generating sonic or subsonic audio output by propagating two frequencies having a difference in value equal to the desired sonic or subsonic audio output and (ii) decoupling the two frequencies to generate the desired audio output, the method comprising the steps of:

Abstract: An oximeter diode-driving device has a diode, a transistor operative to controllably connect current to the diode, a current sensing resistor that senses at least part of the current, a feedback amplifier operative to control the connecting of current by the transistor according to the current sensed by the current sensing resistor, and an inductor disposed in series with the current sensing resistor. A method of driving a current through the diode of an oximeter includes driving a current through the diode by connecting the current to the diode, controlling the connecting using a feedback type amplifier, the feedback type amplifier having a current source that uses a current-limiting resistor, and adding phase lead to a current passing through the current-limiting resistor.

Abstract: A method of producing a diode drive current in an oximeter includes sensing at least a part of a current passing through the diode and converting the sensed current to a sensed voltage, inputting the sensed voltage to a feedback amplifier for stabilizing the current passing through the diode, and eliminating an offset voltage across inputs of the feedback amplifier. A pulse oximeter includes a diode for emitting light flashes, a feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier stabilizing a current passing through the diode, a nulling amplifier having inputs, a nulling capacitor, and an output, the nulling amplifier charging and discharging the feedback capacitor until the inputs of the feedback amplifier are at a same voltage. The operation may include synchronizing an elimination of input offset voltages of the feedback and nulling amplifiers with on or off state of diode current.

Abstract: An oximeter diode-driving device has a diode, a transistor operative to controllably connect current to the diode, a current sensing resistor that senses at least part of the current, a feedback amplifier operative to control the connecting of current by the transistor according to the current sensed by the current sensing resistor, and an inductor disposed in series with the current sensing resistor. A method of driving a current through the diode of an oximeter includes driving a current through the diode by connecting the current to the diode, controlling the connecting using a feedback type amplifier, the feedback type amplifier having a current source that uses a current-limiting resistor, and adding phase lead to a current passing through the current-limiting resistor.

Abstract: An oximeter has an op-amp with a first input, a second input, and an output, the first input being directly connected to a reference voltage. A switch has an input connected to the output of the op-amp, and has a plurality of switch outputs. A transistor has a control input connected to one of the plurality of outputs, and has a current source terminal and a supply terminal. A diode is connected to the current source terminal of the transistor. The supply terminal of the transistor is connected both to the second input of the op-amp and to a second one of the plurality of switch outputs. The switch is thereby in a feedback loop of the op-amp, effecting a feedback-controlled switch for switching the diode on and off.

Abstract: A photoplethysmographic system and method is provided to identify compatible sensors to monitors and/or for determining sensor attributes. The improved system includes a signal generation means for providing an interrogation signal, an identifying means coupled between a first and second sensor terminal operable to produce multiple outputs upon application of the interrogation signal in two modes of operation, and a processor to interpret the outputs. When the interrogation signal is applied to a sensor terminal in a first mode, a first output is obtained. Upon applying the same interrogation signal to the sensor terminal in a second mode, a second output is obtained. The first and second outputs may then be utilized by the processor comprising, for example, a photoplethysmographic monitor to yield enhanced sensor information. The disclosed method may be carried out utilizing the inventive photoplethysmographic system.

Abstract: A support device for an associated cover member includes a hub defining a bore adapted to receive a tip of an associated support pole. A shell projects radially outwardly from the hub. The shell defines an outer surface adapted to support an associated cover member. In use, the device is installed on a tip of a support pole so that an end portion of the tip projects through the support device. The projecting end portion of the pole tip is inserted into a grommet or eyelet of a cover to be supported. The pole is positioned so that the cover is supported on the outer surface of the shell. The device can have an overall frusto-conical shape.

Abstract: A photoplethysmographic system and method is provided to identify compatible sensors to monitors and/or for determining sensor attributes. The improved system includes a signal generation means for providing an interrogation signal, an identifying means coupled between a first and second sensor terminal operable to produce multiple outputs upon application of the interrogation signal in two modes of operation, and a processor to interpret the outputs. When the interrogation signal is applied to a sensor terminal in a first mode, a first output is obtained. Upon applying the same interrogation signal to the sensor terminal in a second mode, a second output is obtained. The first and second outputs may then be utilized by the processor comprising, for example, a photoplethysmographic monitor to yield enhanced sensor information. The disclosed method may be carried out utilizing the inventive photoplethysmographic system.

Abstract: A system and method of reducing cross talk in pulse oximetry signals that are attenuated by a patient tissue site are provided. In one embodiment, Red and IR LEDs of a pulse oximeter are separately excited (1010) and the respective Red and IR data vectors output by the detector are measured (1020). The Red and IR data vectors are normalized (1030) to unit length Red and IR data vectors. Red to IR and IR to Red cross talk vectors are computed (1040). The Red to IR cross talk vector may be computed as a vector having a length equal to the dot product of the normalized Red and IR data vectors with its direction being opposite that of the normalized IR data vector. The IR to Red cross talk vector may be computed as a vector having a length equal to the dot product of the normalized Red and IR data vectors with its direction being opposite that of the normalized Red data vector.

Abstract: A pulse oximeter (100) includes two or more light sources (102) for transmitting optical signals through an appendage (103) of patient. The sources (102) are operated to transmit code division multiplexed (CDM) signals. That is, the sources (102) are driven by drives (104) in response to signals from a digital processing unit (116) such that the sources (102) are modulated using different code sequences. The code sequences are preferably non-periodic and may be orthogonal to one another. The use of such CDM signals provides certain advantages related to noise reduction.

Abstract: Differential values, for use in blood oxygenation calculations, are determined based on multiple sample values for each channel of an oximetry system, each such value constituting a data point. In one implementation, each of these data points is defined by a sample window (220, 222 and 224), where the window includes, for example, 7-10 data points. That is, the data points within window (220, 222 or 224) are used to establish a differential value nominally associated with the data sample about which the window is centered. The differential value is calculated based on a mathematical model such as a weighted linear regression analysis. In this manner, output may be provided on a sample-by-sample basis while mitigating noise sensitivity.

Abstract: An oversampling pulse oximeter includes an analog to digital converter with a sampling rate sufficient to take multiple samples per source cycle. In one embodiment, a pulse oximeter (100) includes two mor more light sources (102) driven by light source drives (104) in response to drive signals from a digital signal processing unit (116). The source drives (104) may drive the sources (102) to produce a frequency division multiplex signal. The optical signals transmitted by the light sources (102) are transmitted through a patient's appendage (103) and impinge on a detector (106). The detector (106) provides an analog current signal representative of the received optical signals. An amplifier circuit (110) converts the analog current signal to an analog voltage signal in addition to performing a number of other functions. The amplifier circuit (110) outputs an analog voltage signal which is representative of the optical signals from the sources (102).

Abstract: An aircraft has a fuselage that defines an interior cabin and an exterior; a first housing located along one side of the fuselage exterior; a second housing located along the second side of the fuselage exterior; and an active vibration control system for limiting fuselage vibration, the vibration control system comprising a plurality of sensors located in the cabin; a controller in signal receiving relation with the sensor means; first actuator means located in the first housing and second actuator means located in the second housing and wherein the actuator means are in signal receiving relation with the controller.

Abstract: An oversampling pulse oximeter includes an analog to digital converter with a sampling rate sufficient to take multiple samples per source cycle. In one embodiment, a pulse oximeter (100) includes two mor more light sources (102) driven by light source drives (104) in response to drive signals from a digital signal processing unit (116). The source drives (104) may drive the sources (102) to produce a frequency division multiplex signal. The optical signals transmitted by the light sources (102) are transmitted through a patient's appendage (103) and impinge on a detector (106). The detector (106) provides an analog current signal representative of the received optical signals. An amplifier circuit (110) converts the analog current signal to an analog voltage signal in addition to performing a number of other functions. The amplifier circuit (110) outputs an analog voltage signal which is representative of the optical signals from the sources (102).

Abstract: A system for providing an improved DC and low frequency signal rejection in a photoplethysmographic measurement instrument is disclosed. The system is used in a measurement instrument which includes at least two signal sources (106, 108) for transmitting light signals at least at two wavelengths through a tissue of a test subject and a detector (112) for converting light signals transmitted through the tissue into a detector output signal. The system includes a DC restoration (114) which removes DC and low frequency signal components from the detector output signal prior to amplification thereof so as to avoid saturating amplified output signal with the low frequency signal component. The DC restoration (114) is configured to continuously remove low frequency signal component from the detector signal during dark intervals when the signal sources are deactivated, as well as during light intervals when one of the signal sources is activated.

Abstract: An improved method and apparatus is disclosed for use in frequency division multiplexed spectrophotometric systems. In photoplethysmographic applications the invention provides for the modulation of a plurality of light sources at different frequencies and in accordance with a predetermined phase relationship. Light from the sources that is transmitted through a tissue under test is detected at a detector. A composite signal indicative of the intensity of light received at the detector is demodulated based on the different modulation frequencies and predetermined phase relationship to obtain signal portions corresponding with each of the light sources. Modulation and demodulation are synchronized during each measurement period. The modulation waveforms used to modulate the light sources and corresponding demodulation waveforms used to demultiplex the composite signal are symmetrically timed about a center point for each of the measurement periods.

Abstract: A vibration-damped machine and method including beam being capable of gross movements in space relative to a stationary frame, means including a motor for causing the beam's gross movements; the gross movements tending to induce vibration into the beam, sensors for providing a signal representative of the induced beam vibration, an linear-acting inertial actuator mounted to the beam, and control means for receiving the signal and generating an output signal to actively drive the linear-acting inertial actuator at the appropriate phase, frequency and magnitude to damp induced beam vibrations. Embodiments of the vibration-damped machine are illustrated for a gantry robot, a horizontal machining center, an adhesive dispenser and a pivoting robot. The linear-acting inertial actuator is preferably controlled according to an inertial damping control method where the actuator is forced to behave as a damper attached to ground.