picking up HR from a transmitter, then inputting to computer

[andrew_h]

Hi - I have a project that I'm working out, but I'm struggling in a few
areas and so would appreciate any help possible.

I have a polar uncoded chest transmitter for HR - I know it outputs a
5Khz EF signal (weak), which is normally inductively coupled by the
watch, and then the HR is determined.

Anyway - I want to make a receiver where it could pick up this pulse
(and amplify it), count it per minute (obviosuly have some maximum
minutes) against another counter which kept track of the time. From
there it would be converted (ADC) and then sent to the computer through
USB or serial, and just the numbers themselves with some time reference
saved to a text file. I could then graph it myself in excel etc. The
text file would just have some sort of time reference (i.e. "1 72" -
where 1 is the minute count after recording, and 72 the heart rate -
where it has counted 72 pulses in the first minute).

I have found a circuit http://rick.mollprojects.com/hrm/ - which does
precisely the front end that I want... picks up the pulse, and
amplifies it. From there - I would need to convert using an ADC yes?
The idea from here is that it will then be sent to the computer,
through the USB or serial - I have read a 'silicon chip' article where
they have a USB module so data can be sent through that, after going
through the ADC. The problem from here is, how could I get it to save
the results of the counts to a text file?

AND...what would be the best way to 1) count the pulses for a minute,
then store this value, then repeat for the next minute - while 2)
having some time reference, like minutes after recording began.

Any help and ideas would be appreciated - I would really like to do
this!

 

[Bob]

Hi - I have a project that I'm working out, but I'm struggling in a few
areas and so would appreciate any help possible.

I have a polar uncoded chest transmitter for HR - I know it outputs a
5Khz EF signal (weak), which is normally inductively coupled by the
watch, and then the HR is determined.

Anyway - I want to make a receiver where it could pick up this pulse
(and amplify it), count it per minute (obviosuly have some maximum
minutes) against another counter which kept track of the time. From
there it would be converted (ADC) and then sent to the computer through
USB or serial, and just the numbers themselves with some time reference
saved to a text file. I could then graph it myself in excel etc. The
text file would just have some sort of time reference (i.e. "1 72" -
where 1 is the minute count after recording, and 72 the heart rate -
where it has counted 72 pulses in the first minute).

I have found a circuit http://rick.mollprojects.com/hrm/ - which does
precisely the front end that I want... picks up the pulse, and
amplifies it. From there - I would need to convert using an ADC yes?
The idea from here is that it will then be sent to the computer,
through the USB or serial - I have read a 'silicon chip' article where
they have a USB module so data can be sent through that, after going
through the ADC. The problem from here is, how could I get it to save
the results of the counts to a text file?

AND...what would be the best way to 1) count the pulses for a minute,
then store this value, then repeat for the next minute - while 2)
having some time reference, like minutes after recording began.

Any help and ideas would be appreciated - I would really like to do
this!

The most effective way to send and receive HR is with a CM connected to DV
or a PF. It's easy.

Hope this helps.

Bob

 

[andrew_h]

Hi Bob,

Can you expand those letters........ CM? DV? PF?

Soz...its not obvious what your referring to.

 

[Bob Masta]

Hi - I have a project that I'm working out, but I'm struggling in a few
areas and so would appreciate any help possible.

I have a polar uncoded chest transmitter for HR - I know it outputs a
5Khz EF signal (weak), which is normally inductively coupled by the
watch, and then the HR is determined.

Anyway - I want to make a receiver where it could pick up this pulse
(and amplify it), count it per minute (obviosuly have some maximum
minutes) against another counter which kept track of the time. From
there it would be converted (ADC) and then sent to the computer through
USB or serial, and just the numbers themselves with some time reference
saved to a text file. I could then graph it myself in excel etc. The
text file would just have some sort of time reference (i.e. "1 72" -
where 1 is the minute count after recording, and 72 the heart rate -
where it has counted 72 pulses in the first minute).

I have found a circuit http://rick.mollprojects.com/hrm/ - which does
precisely the front end that I want... picks up the pulse, and
amplifies it. From there - I would need to convert using an ADC yes?
The idea from here is that it will then be sent to the computer,
through the USB or serial - I have read a 'silicon chip' article where
they have a USB module so data can be sent through that, after going
through the ADC. The problem from here is, how could I get it to save
the results of the counts to a text file?

AND...what would be the best way to 1) count the pulses for a minute,
then store this value, then repeat for the next minute - while 2)
having some time reference, like minutes after recording began.

Any help and ideas would be appreciated - I would really like to do
this!

You may need an ADC, as long as you can get a pulse for each
individual heartbeat. All you need to do is count the pulses for
a minute, which can be done by the computer if you have
software skills. If you have even better software skills, you
can time the duration between individual beats and take the
reciprocal, giving a beat-by-beat heart rate readout rather
than making you wait for a whole minute to see what's happening.
However, this latter approach requires a real-time operating
system; if you are using Windows you'd need to write ring 0
drivers that can receive interrupt pulses and read a timer, etc.
Not for beginners. Or, if you have a Win9x or earlier system
you can put it into real-mode DOS and do the same thing
with an interrupt handler.

If you'd rather do more of this in hardware, you can have
a simple crystal clock and counter. Each pulse latches the
counter output to a buffer, then zeroes the count and
restarts counting. You then can read the buffered count
via a parallel port, or a serial port if you want to use a
parallel-to-serial converter. Either is fine for use with
Windows, since there is no critical timing needed by
the software.

Of course, you could also use a simple ramp circuit
instead of a counter, and sample the ramp on each
beat to get an analog voltage for an ADC. But then
you'd need an ADC, which is probably trickier than a
counter. (You can't easily use the ADC of a sound card,
since they only handle AC voltages.)

Best regards,


Bob Masta
dqatechATdaqartaDOTcom

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