Delta-sigma modulator for outputting analog representation of physiological signal
First Claim
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1. A method for operating a physiological monitor comprising:
- detecting an analog signal from a patient, wherein the analog signal comprises at least one modulated physiological waveform;
converting the analog signal into a digital signal;
demodulating the digital signal to produce at least two demodulated physiological signals;
applying at least one of the demodulated physiological signals to a delta-sigma modulator to provide at least one physiological waveform; and
filtering the at least one physiological waveform to provide a real-time analog filtered physiological waveform output, wherein the analog filtered physiological waveform is real-time relative to the time of detecting the analog signal from the patient to the time of providing the analog filtered physiological waveform output.
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Abstract
A method and apparatus for providing a substantially real-time representation of an analog representation of a physiological signal is provided. The waveform signal from the sensor is converted into digital form. A delta-sigma modulator is used as a simple Digital-to-analog Converter (DAC). The output can then be provided through a simple hardware filter to give an analog output signal in nearly real-time, which can be used for other instruments, synchronization, display, etc.
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Citations
19 Claims
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1. A method for operating a physiological monitor comprising:
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detecting an analog signal from a patient, wherein the analog signal comprises at least one modulated physiological waveform; converting the analog signal into a digital signal; demodulating the digital signal to produce at least two demodulated physiological signals; applying at least one of the demodulated physiological signals to a delta-sigma modulator to provide at least one physiological waveform; and filtering the at least one physiological waveform to provide a real-time analog filtered physiological waveform output, wherein the analog filtered physiological waveform is real-time relative to the time of detecting the analog signal from the patient to the time of providing the analog filtered physiological waveform output. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for operating an oximeter comprising:
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detecting an analog signal from a patient, wherein the analog signal comprises at least one pulse oximetry waveform; converting the analog signal into a digital signal; demodulating the digital signal to produce a red signal and an IR signal; applying one of the red signal and the IR signal to a software delta-sigma modulator, wherein the software delta sigma modulator is configured to provide a single bit, serial output; and filtering the single bit, serial output with a hardware filter to provide a real-time analog waveform output, wherein the analog waveform is real-time relative to the time of detecting the analog signal from the patient to the time of providing the analog filtered physiological waveform output. - View Dependent Claims (11, 12, 13)
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14. A physiological monitor apparatus comprising:
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an input configured to receive an analog signal from a patient, wherein the analog signal comprises a physiological waveform; an analog-to-digital converter configured to convert the analog signal into a digital form of the physiological waveform; a processor including a delta-sigma modulator configured to convert the digital form of the physiological waveform into an analog form of the physiological waveform, and wherein the delta-sigma modulator is configured to output the analog form of the physiological waveform; and a filter configured to receive and filter the analog form of the physiological waveform and to output a real-time waveform, wherein the real-time waveform is real-time relative to the time analog signal received from the patient to the time the real-time waveform is output. - View Dependent Claims (15, 16, 17)
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18. An oximeter apparatus comprising:
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an input configured to receive a signal, wherein the signal comprises a pulse oximetry waveform, and wherein the pulse oximetry waveform is representative of data gathered from a sensor coupled to a patient; an analog-to-digital converter configured to convert the pulse oximetry waveform into a digital form of the pulse oximetry waveform; a processor, comprising; a demodulator configured to separate the digital form of the pulse oximetry waveform into a red digital signal and an IR digital signal; and a software delta-sigma modulator configured to convert one of the red digital signal and the IR digital signal into an analog signal, wherein the analog signal is a serial, single bit output; a hardware RC filter configured to filter the serial, single bit output of the software delta-sigma modulator and to output a filtered signal in real-time, wherein the filtered signal is real-time relative to the time the input receives the signal to the time the filtered signal is output; and an output configured to provide the real-time filtered signal to a host. - View Dependent Claims (19)
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Specification