[time-nuts] simulation of interconnected clocks
Jim Lux
jimlux at earthlink.net
Sat Nov 30 22:29:58 EST 2013
On 11/30/13 5:33 PM, Hal Murray wrote:
>
> tvb at LeapSecond.com said:
>> Attached is frequency and ADEV of my heart beat for 10 hours.
>
> Neat. What did you use to collect the raw data?
>
>
There's a few Arduino/Sparkfun/Adafruit widgets out there that receive
the signals from off the shelf Polar heart rate monitors.
I had a grad student last summer build a box to log heart beats using
photoplethysmography (photocell sensing blood flow in fingertip). He
used a widget from one of the dealers that has the analog circuitry to
buffer the optical sensor.
If I were collecting it on a long term (many hours) basis, I'd go with
ECG based approaches (which is what the Polar sensors use), but with
stick on electrodes. Motion artifacts are a big problem.
Holter is the big name in commercial ECG loggers, but they're real
pricey (being FDA approved medical devices and all).
Microwave monitoring (radar) is a good "standoff" way to measure
heartbeats, but only works in fixed locations (e.g. I can set it up in
my office, in my car, or a room at home, and collect data, but it
doesn't work well when you're out walking around). If you get one of
those microwave Doppler door sensors at 10.5 or 24 GHz, you can get a
good heartbeat signal from them.
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