Dave Hopkin Posted May 18, 2015 Share Posted May 18, 2015 Ok I have the altimeter/Vario fitted to a model and the Altitude displayed on the screen and spoken on a flick switch... Last time I was flying, I powered on and flew the altimeter vocals were telling me all sort of altitudes (from 13tf when it was on the grass - upto 460tf when the combined best guesses of the assembled throng was "about 200" Testing it at home, powered on, "reset Telemetry" on the TX and it reads0ft on the floor, carried upstairs leaving TX with long suffering (and not really amused) SHMBO - she reported then when I was upstairs holding the model right above my heads it read 13ft - my best guess for that would be 10ft for upstairs plus 6ft of me plus 2ft of my arm, which my befuddled brain tells me should be 18ft So have it is haunted or am I just an idiot? On second thoughts dont answer that! What am I doing wrong???? Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted May 18, 2015 Share Posted May 18, 2015 I know that most sensitive baro sensors are affected by light hitting them - make sure it's hidden away somewhere out of the sun Other than that, not sure. What make is it? Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 18, 2015 Author Share Posted May 18, 2015 Its the Frsky High Precision Vario **LINK** hooked up to a X8R RX and a Taranis TX In the model its inside the fus cavity under the wings so as much in the dark as I am!!!! Edited By Dave Hopkin on 18/05/2015 14:11:49 Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted May 18, 2015 Share Posted May 18, 2015 Ah right - I use that one too, and not had any problems! Electrical noise perhaps? Maybe try one of those little doughnuts around the signal wire, although having said that I bet it's a digital signal by that point, especially if you're plugged straight into the SPort. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 18, 2015 Author Share Posted May 18, 2015 The in house test was with the motor not running and yes its straight into the Sport on the RX (LiPo monitor isnt fitted) Quote Link to comment Share on other sites More sharing options...
andyh Posted May 18, 2015 Share Posted May 18, 2015 do you have a GPS sensor that you could compare it to? here's a graph of GPS & Vario Alt from my FrSky setup, which match up pretty well: it does rather sound like the calibration on your vario may be out a bit Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 18, 2015 Share Posted May 18, 2015 Those figures shouldn't be too much cause for concern, Dave. Atmospheric and temp changes, draughts, all contribute to a continuing slight variation in my Spekky altimeters and varios. They can vary by 3ft just sitting on the kitchen table for some minutes. I did run a test by putting a Spekky and an HK altimeter in the same glider and flew it to 750ft. Maximum difference in reading was no more than 5ft, so I would assume that they were both fairly accurate - at least as far as we need to be accurate: Pete Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 18, 2015 Author Share Posted May 18, 2015 @ andyH - nope not got a GPS to compare it too, just a tape measure! You mentioned the calibration might be a bit off - is there any calibration I should do or did you mean some factory calibration? Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 18, 2015 Share Posted May 18, 2015 Barometers are notoriously fickle devices. This plot below shows one on a quad: The baro is the wobbly line at the bottom. So what you say? Well the quad was sitting on my bench just being rocked from side to side gently at the time! They are definitely effected by large currents and warm air - so if they are near your power source, or in the cooling air stream from your ESC I'd definitely look to resite it. BEB Quote Link to comment Share on other sites More sharing options...
Pete B Posted May 18, 2015 Share Posted May 18, 2015 Dave's wife could well have been gently steaming at the time - that might not have done much for the air pressure in the house..... Pete Quote Link to comment Share on other sites More sharing options...
andyh Posted May 18, 2015 Share Posted May 18, 2015 Posted by Dave Hopkin on 18/05/2015 15:33:28: @ andyH - nope not got a GPS to compare it too, just a tape measure! You mentioned the calibration might be a bit off - is there any calibration I should do or did you mean some factory calibration? I meant factory calibration but, as others have said, even opening/closing a door in your house might throw out the reading Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 18, 2015 Author Share Posted May 18, 2015 Posted by Pete B - Moderator on 18/05/2015 15:41:16: Dave's wife could well have been gently steaming at the time - that might not have done much for the air pressure in the house..... Pete Pete, that's the normal atmospheric pressure in this house..... Quote Link to comment Share on other sites More sharing options...
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