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Old 01-01-10, 02:29 PM
  #11  
mr_antares
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Originally Posted by bobzam
I also have a irregular heart beat and use an old Polar wrist model mounted on my handlebars but it needing a new battery which has to be replace by Polar.

So have been looking at upgrading to single computer unit.

I need to see my heart beats like the little heart symbol that flashes on my Polar. Looked a Cateye and it does not flash.

So Polar has a c100 that if I read the manual correctly, the outside of the symbol does show the actual heart beat.

Can anyone confirm this?

Bob
All of the Polar models work the same basic way. There is a simple EKG detection circuit in the transmitter that sends a "pulse" at 5 Khz each time it detects a heart beat. The watch unit (or the treadmill, etc) counts the pulses that arrive. All of the smarts on in the receiver, not the transmitter.

There's a good diagram of this in this patent: http://www.freepatentsonline.com/5632279.pdf (which describes the "coding" process that Polar uses)

Each time there is a pulse, the heart symbol will light up. In some Polar models, not all of the pulses are counted when they arrive at irregular intervals: this is intended to make the display more accurate in a noisy environment, and it also makes the device slightly more accurate for people with some arrhythmias.

Even so, you will still see a flash of the little heart symbol every time the sensor detects a heartbeat, even if that pulse is not counted in your heart rate display.

My experience was that this wasn't very effective: the heart rate numbers still went up and down irregularly. It was possible to get some sense of when I was working hard and when I wasn't, but doing any sort of "zone" training was out of the question.

Since all Polar transmitters use the same circuit (except that some of them code the pulse with an amplitude modulated signal), I would not expect that any of the Polar models to be any better or worse at counting your heartbeat. I tried a simple one and a fairly expensive one, and the results were very similar.
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