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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.consumers
Subject: Re: Info Wanted on Pulse Rate Gizmos
Message-ID: <674@kitty.UUCP>
Date: Mon, 30-Dec-85 15:43:48 EST
Article-I.D.: kitty.674
Posted: Mon Dec 30 15:43:48 1985
Date-Received: Wed, 1-Jan-86 02:38:56 EST
References: <594@ttidcb.UUCP>
Organization: Recognition Research Corp., Clarence, NY
Lines: 32

> I would like to buy (inexpensively if possible) a device for measuring and
> displaying my pulse rate while exercizing (e.g. using a rowing machine).
> Can anyone recommend a particular model?  DAK has a wrist watch type thing
> that supposedly does it - any comments?  A friend of mine has one which
> clips on to your ear and works moderately well but not perfectly, that's
> one of the reasons I'd like more information before rushing off to spend my
> 99 cents  (8-).

	The DAK unit works by taking an actual electrocardiogram (ECG) using
the wrist of one hand and the finger (touching the metal plate on the watch) of
the other hand as electrode points.  This is not as difficult as it may seem,
since the R-wave peak of the ECG signal measured under these conditions is
1 to 3 millivolts.
	The earlobe and finger units work on the principle of a plethysmograph
whereby an IR LED and phototransistor sense the actual volume expansion change
of the earlobe or finger with each heart beat.
	Movement of a plethysmograph sensor will easily cause measurement
errors, whereas ECG electrode movement is no where near as critical.
	I don't know of a consumer pulse rate device using an ECG other than
the above watch; this could be inconvenient since one has to move their finger
to the electrode plate on the watch each time for a measurement.  IF there were
a consumer ECG device using strap electrodes for each wrist, this would be best
of any method.
	If you don't mind an intermittent measurement, then the ECG watch may
be the best.

==>  Larry Lippman @ Recognition Research Corp., Clarence, New York        <==
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