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Noraxon telemyo problem

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  • Noraxon telemyo problem

    I'm using a Noraxon Telemyo telemetry unit and have been having a
    problem with the
    receiver shutting off during dynamic activities. I'm collecting from
    four muscles
    (anterior tibialis, medial gastrocnemius, vastus medialis, and lateral
    with a ground on the fibular head. The receiver is connected via a
    ribbon cable to
    an A-D board, with data sampled at 1200 Hz with EVA software (Motion
    Analysis Corp).
    We collect force plate, kinematic, and EMG data simultaneously. We were

    investigating the influence of ankle stirrup braces on EMG in subjects
    with a
    history of ankle sprain and had the subjects hopping sideways on the
    leg over a 6 inch high barricade. The signal recorded fine for 1-2
    seconds (1-2 hops),
    then the receiver would shut itself off. In reviewing the data that
    were recorded before the unit shut off, there was no apparent clipping
    or saturation of any of the channels (+/- 5 V range).

    Technical support at Noraxon suggested that I unplug the ribbon cable
    between the receiver and the A-D board, then do the movement while
    simply watching the bar graph display on the receiver. When I did this,
    the unit stayed on. As soon as I connected it back to the A-D board,
    the problem reappeared. If I had the subjects produce a maximum
    isometric contraction, there was no problem. It appears that the
    problem is some interaction between the dynamic nature of the hopping
    and the sampling characteristics of the A-D board, but I was not aware
    that a signal could get "backed up" like a drain when alot of data were
    being sampled.

    Has anyone else had this problem? Can anyone explain what's causing the
    problem and
    how I can get around it? Unfortunately, I am constrained in my sampling
    because the software will not allow me to sample at two different rates,
    and I need
    to sample the force plate at 1200 Hz.

    Thank you.
    Barbara Loitz-Ramage, PhD PT
    McCaig Centre for Joint Injury and Arthritis Research
    University of Calgary
    3330 Hospital Dr. NW
    Calgary, Alberta CANADA T2N 4N1
    voice (403)220-4327; FAX (403)270-0617; email

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