[time-nuts] Off topic project sort of heart rate monitor NEEDBEATS PRE MINUTE TO ANALOG VOLTAGE
tmiller at skylinenet.net
Tue Feb 19 20:34:52 EST 2013
You can buy it for $8 COTS.
You clean up the QRS waveform with a one-shot then integrate to get rate.
----- Original Message -----
From: "Bob Camp" <lists at rtty.us>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Tuesday, February 19, 2013 8:23 PM
Subject: Re: [time-nuts] Off topic project sort of heart rate monitor
NEEDBEATS PRE MINUTE TO ANALOG VOLTAGE
The first layer to the onion is that the ECG signal is a bit complex.
There's also likely to be a bit of this and that on it.
How about taking the output of the instrument amp into the A/D port on a
cheap PIC? That would let you do some AGC and dynamic filtering. At even a
modest sample rate (say 10 KHz) the heart rate could be worked out in
software. I think I'd run a PWM out and drive an analog meter with it.
The nice thing about keeping it simple is being able to run it off a 9 volt
battery. That takes care of a *lot* of issues.
On Feb 19, 2013, at 7:58 PM, Paul Cianciolo <paulc at snet.net> wrote:
> Hello Folks,
> I am working on a project intended to convert an analog ECG signal to a
> voltage proportional the heart rate,
> The actual electrodes instrumentation amp is pretty much working fine so
> no worries there.
> The problem is, and here is where the relationship to time nut comes in.
> The signal output from the instrumentation amplifiers will be at a rate of
> approx 60 BPM or pulses, up to perhaps 90 BPM.
> The purpose of this apparatus is to print a rolling chart on the screen of
> a computer of heart BPM and then try different technicues of meditaion
> and calming technicues to lower my heart rate for short periods of time.
> My first tthought was a frequency to voltage IC like the LM2907 or the
> 2917 but I get the impresiion from the data sheets that these chips will
> not work at these very low 1 Hz applications,
> Then I thought maybe one of the frequecy counters could be configured as a
> rate meter and output a proportional voltage I need.
> No luck here either.
> Te latter components seem tobe somewhat time relatedand that is why I
> posted here.\\
> Thank you for reading this and for any suggestions you folks might offer.
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