WastelandDoc & SensorBeast
WastelandDoc WastelandDoc
SensorBeast SensorBeast
WastelandDoc WastelandDoc
Hey, I’ve been cobbling together a low‑cost pulse‑oximeter for the field—just some scavenged LEDs and a photodiode. Think you could tweak the sensor math to pick up a faint pulse over the usual noise?
SensorBeast SensorBeast
SensorBeast: Sure thing, just slap a 1–5 Hz band‑pass filter on the raw photodiode output—most heart rates sit in that window. Then run a moving‑average window a few samples wide to smooth the ripple. If the signal still looks like static, try a lock‑in: multiply by a sine at the expected pulse frequency and low‑pass the product, that’ll pull out the hidden beat. Remember, the trick isn’t a fancy algorithm, it’s a clean, low‑pass, lock‑in combo. Good luck, and don’t forget to keep the LED steady; a wobbling light is just noise in disguise.
WastelandDoc WastelandDoc
Thanks for the rundown. I’ll start with the band‑pass and lock‑in combo—should clean up the jitter from the shaky LED. Keep a spare LED on hand in case the current one flickers. Let me know if the pulse stays stubborn after that.
SensorBeast SensorBeast
Sounds solid—just keep the LED brightness steady, and if the flicker’s still an issue, switch to a higher‑current, constant‑current driver. If the pulse still hides, try raising the lock‑in reference slightly; sometimes the heart is dancing just outside the assumed frequency. Let me know how it goes.
WastelandDoc WastelandDoc
Will do. First, lock down the driver, then tweak the reference a touch higher. I’ll give you an update when I have the pulse coming clean.
SensorBeast SensorBeast
Alright, keep the tweaking tight and keep that reference jitter‑free. I’ll be ready for the pulse confirmation.
WastelandDoc WastelandDoc
Got it, I’ll keep the settings tight and the reference steady. Will ping when the beat shows up.
SensorBeast SensorBeast
Good plan, keep an eye on the gain. Hit me back when the beat pops up.
WastelandDoc WastelandDoc
Will monitor the gain and ping you when the pulse comes through.
SensorBeast SensorBeast
Sounds good, just keep the noise floor low and the LED steady. Hit me back when you see it.
WastelandDoc WastelandDoc
Sure thing, I’ll keep the noise floor down and the LED steady. Will let you know when the beat shows up.
SensorBeast SensorBeast
All right, let me know when the signal starts singing. Good luck out there.