Hi Guys,

I know that you can purchase "decoder" boards from Polar. Basically they do
the receiving and decoding and have a serial data output. The serial data
out transmits the current heart rate and some state information
approximately the same time as a heart beat.

I built a interface for a client of mine with these.. They were buying the
boards so I don't know much about them.

The boards have what looks like a packaged inductor (from Neosid - markings
"39k" and "N8". 7mm x 10mm x 4mm), some chip-on-board blobs which I'm
guessing are op-amps for signal processing and a Zilog micro to do the
decoding and a bunch of descreets..

Also be aware that some of the transmitters have a "coding" scheme that
allows several to be in proximity with out affecting each other too much.
I've no idea what this coding is.

I'm sure Polar's patent(s) would provide the details on how it all works.

Cheers,
Ash.

---
Ashley Roll
Digital Nemesis Pty Ltd
www.digitalnemesis.com
Mobile: +61 (0)417 705 718




> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Shawn Mulligan
> Sent: Tuesday, 7 January 2003 1:32 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [EE]: Sensing a simple AC Electromagnetic field
>
>
> M. Adam Davis wrote:
> >Anyone have a polar they could test the output of?
> >
>
> I had the same idea, and I actually tested the Polar unit
> last September, or so. I remember that the results were
> similar to yours, but I don't remember the exact frequency.
> I'll borrow my workmate's chest strap
> and retest in the next couple of days. I agree that you are
> looking at a LC circuit, with say a low power op amp, and
> low-pass filter, etc.

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