Pressure drift

mcrossley · **Posted:** Tue Jan 17, 2012 5:14 pm

Oh dear, my pressure sensor has been giving a freaky absolute reading for some time, but putting a big offset in Cumulus.ini has been fine. But over the last couple of weeks it seems to have developed a drift against Rays Davis. I added 0.5hPa via the Cumulus calibration screen (so I do not have to stop/restart Cumulus) last Friday, now it looks like it is nearly 1hPa low again.

I've not seen other people reporting drift before, is it just my FO?

It's looking increasingly like I need to start saving for a Davis :cry:

dpmiller · **Posted:** Tue Jan 17, 2012 9:04 pm

console batteries good, contacts clean?

mcrossley · **Posted:** Tue Jan 17, 2012 9:26 pm

Thanks, but it runs off USB power 24x7

dpmiller · **Posted:** Wed Jan 18, 2012 7:24 am

might be worth putting a voltmeter on the 5v rail of the PC before condemning the console, then.

mcrossley · **Posted:** Wed Jan 18, 2012 9:02 am

It seems to be converging again now. The drift wasn't big this time, but I'll keep an eye on it.

Won't the console have a 3V internal voltage regulator though? In which case fluctuations in the USB 5V supply shouldn't matter.

MickinMoulden · **Posted:** Fri Jan 20, 2012 2:37 am

Hey Mark, I get the same. Probably every month I need to calibrate it in Cumulus. Around 1hPa every time. My station keeps reading lower and lower and have to add in Cumulus. I'm OK with that, but feel eventually it's going to die.

MickinMoulden · **Posted:** Sat Jan 21, 2012 4:49 am

Calibration was at +4.5hPa, have just added another 1.3hPa. I think I'll start noting when I apply these changes. :roll:

mcrossley · **Posted:** Sat Jan 21, 2012 9:25 am

Mine seems to have stabilised again after that 0.5hPa correction.

MickinMoulden · **Posted:** Sat Jan 21, 2012 9:51 am

It's never a sudden jump, it happens really slowly that you don't know it's happened until you do a check.

ScottVan · **Posted:** Sat Jan 21, 2012 2:08 pm

I've put the calibration offset into the console directly. It went haywire when my computer received a Windows update and it locked up and was dead for 2 days. Coincidence? Not sure. Fail over from USB power to batteries? Brand new Duracells that hardly ever been used - always plugged in to USB.

Tracks along nicely now with the local airport pressure.

Scott

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Pressure drift

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