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Monitoring myoelectric signals

  • US 4,213,466 A
  • Filed: 08/11/1978
  • Issued: 07/22/1980
  • Est. Priority Date: 08/11/1978
  • Status: Expired due to Term
First Claim
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1. In a neurological monitor for measuring the spectral variation in a myoelectric signal, said monitor being of the type includingan electrode suitable for contacting a living being and detecting said myoelectric signal,circuitry for processing said myoelectrical signal to provide a display signal representative of said spectral variation, said circuitry comprisingmeans for amplifying said myoelectric signal to provide an amplified signal,filter means for providing a filtered signal corresponding to a portion of said amplified signal having frequency components on one side of a variable cutoff frequency,means for comparing said filtered signal to a reference signal and providing a control signal that is dependent on the difference in magnitude between said filtered and reference signals,means for automatically varying said cutoff frequency in accordance with the value of said control signal,means for providing a display signal representitive of said spectral variation in said myoelectric signal, anda display driven by said display signal, for observing said spectral variation in said myoelectric signal,the improvement comprising an attenuator for receiving said amplified signal and producing said reference signal, the attenuation being selected to make the magnitudes of said reference and filtered signals equal when said cutoff frequency is set at a median frequency of said myoelectric signal,whereby said circuitry will tend to adjust said cutoff frequency to said median frequency.

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