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dgrimshire32
01-03-2003, 01:34 AM
This is the summary to my question about equipment used to calibrate EMG
systems. My original question follows and then the responses. Thanks to
all that responded.

I was just wondering what equipment people are using to calibrate EMG
systems before each use. Would a waveform generator work? What
frequency would you calibrate the system for? Would you pump in the
max amplitude the amplifier can handle? Should the equipment be
tracable to a national standard? Thanks for any help you can give.
I'll post a summary of replies.

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++

Please, try:
Whisper
EMG Test Set and Simulator
www.motion-labs.com
(1) (225) 272-7364

Best regards,
Wagner de Godoy
AACD - Brazil
++++++++++++++++++++++++++++++++++++++++++++++++++ ++

We use a special 'EMG source' the Whisper (Roessingh RRD,
The Netherlands). This gives a well defined artificial EMG, is
electrically floating and has options to measure 50/60 Hz common
mode interference.
For more routine use I had a battery powered sine generator, 100
Hz, 100 ÁV , but this is not commercially available.
A regular check-up, once a month, is indeed advisable. Hardly ever
the amplification shows changes, but a check on system integrity
and the possibility to calibrate the input ÁV's without relying on
error-prone gain factors, A/D gains, software bugs etc. etc. is
important.
Yours,

At Hof
Institute of Human Movement Sciences &
Laboratory of Human Movement Analysis AZG
University of Groningen
A. Deusinglaan 1, room 321
postal address:
PO Box 196
NL-9700 AD GRONINGEN
THE NETHERLANDS
Tel: (31) 50 363 2645
Fax: (31) 50 363 3150
e-mail: a.l.hof@med.rug.nl
http://www.ppsw.rug.nl/~ibw/
++++++++++++++++++++++++++++++++++++++++++++++

I use a calibrated signal generator (with valid calibration certificate) to
either test the full usable EMG frequency range and to test the HP and LP
filters (in our case: 10 Hz HP and 500 Hz LP).

Hope this helps,

Guy GOSSELIN, DC FCC, Senior Lecturer
Anglo-European College of Chiropractic
13-15, Parkwood Road, Bournemouth, Dorset, England, BH5 2DF
Tel: +44 (0)1202 436200 Fax: +44 (0)1202 436312
URL: http://www.aecc.ac.uk

Department of Medical Physics & Bioengineering
Southampton General Hospital
Tremona Road, Southampton, England, SO16 6YD
++++++++++++++++++++++++++++++++++++++++++++++++++ +++++++

I am not an EMG expert, but have done lots of related reading, and was
responsible for instrumentation calibration specifications and ISO
compliance in part of my previous life as an engineer.

The first question to ask yourself is what you are calibrating; an
instrument, or a system? The answer to this question will make your
decision about how to calibrate easier.

If you are calibrating the system, then this includes the subject/electrode
interface. For EMG information to be most useful, the system needs to
calibrated for each subject, for each electrode placement, for each
measurement session. Even if the electrode is left in place while the
subject takes a break then returns to continue the session, the calibration
should be repeated. This type of calibration cannot be traceable to a
national standard, but can be as simple as having the subject perform a
simple repeatable task.

If you are calibrating an instrument, then I'd suggest simply following the
instrument manufacturer's advice. And this would likely include using a
frequency generator covering the full range of frequencies and voltages
that the instrument is designed to handle.

Paul Ostic
MSc Candidate
Queen's University
Kingston ON Canada
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