Reply by Phil Hobbs June 11, 20212021-06-11
boB wrote:
> On Sun, 6 Jun 2021 14:45:11 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> Phil Hobbs wrote: >>> (I posted this in comp.dsp a couple of weeks ago, but most of the actual >>> DSP people seem to have disappeared, so the discussion petered out >>> fairly fast.&nbsp; Trying again here.) >>> >>> >> Crap. Sorry! >>
> > Sorry about what ?
Posting the same thing here twice, when I intended the second one to go to sci.electronics.design.
> > It's an interesting project but my digital PLL skills are a bit > lacking. At least in software which is where I would like to be > better at. > > I do know about acquiring ECGs but only using diff amps. > > Might be a good question for the "dsprelated" forum along with > embeddedrelated and all that stuff.
Thanks. I pretty well keep to Usenet. Cheers Phil Hobbs
Reply by boB June 11, 20212021-06-11
On Sun, 6 Jun 2021 14:45:11 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>Phil Hobbs wrote: >> (I posted this in comp.dsp a couple of weeks ago, but most of the actual >> DSP people seem to have disappeared, so the discussion petered out >> fairly fast.&#2013266080; Trying again here.) >> >> >Crap. Sorry! > >Cheers > >Phil Hobbs
Sorry about what ? It's an interesting project but my digital PLL skills are a bit lacking. At least in software which is where I would like to be better at. I do know about acquiring ECGs but only using diff amps. Might be a good question for the "dsprelated" forum along with embeddedrelated and all that stuff. boB
Reply by Phil Hobbs June 6, 20212021-06-06
Phil Hobbs wrote:
> (I posted this in comp.dsp a couple of weeks ago, but most of the actual > DSP people seem to have disappeared, so the discussion petered out > fairly fast.&nbsp; Trying again here.) > >
Crap. Sorry! Cheers Phil Hobbs
Reply by Phil Hobbs June 6, 20212021-06-06
(I posted this in comp.dsp a couple of weeks ago, but most of the actual 
DSP people seem to have disappeared, so the discussion petered out 
fairly fast.  Trying again here.)

Hi, all,

Hoping there are still some DSP folks round here despite the evil Google 
ban. (But I repeat myself.)

I'm working on a completely noninvasive sensor for fetal blood oxygen, 
using optical sensing through the mom's abdomen.  It's a very low SNR 
measurement on account of all the attenuation.

The mom's heartbeat modulates her pulse-ox signal, which is much 
stronger than the fetus's on account of the scattering and absorption in 
maternal tissue.

The data are several time series.  The main issue is the variability of 
both pulses, which smear out the spectra and therefore knock the peak 
heights way down towards the noise.  There are weak multiplicative 
effects between maternal and fetal signals, as you'd expect.

What I'm looking to do is something like:

1. Use a digital PLL to find the time-dependent maternal pulse rate.

2. Resample the data accordingly, and notch out the first 5 or so mom 
harmonics.

3. Do the PLL thing on the fetal pulse, and signal average to pull out 
the average fetal pulse ox signal.

Extra credit: sometimes the baby's pulse can cross the first or second 
harmonic of the mom's, and it would be good to preserve both pulse 
shapes accurately.

Resampling a noisy signal isn't necessarily the most well-conditioned 
operation, so I'd welcome suggestions for just how to do this.

Thanks

Phil Hobbs

-- 
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com