Cumulus Support

Hi
I think the pressure sensor on the WH model is in the base unit so if that is varying oddly something else must be going wrong assuming the room temperature is fairly constant.
Regards
Alan

apenwith wrote:Hi
I think the pressure sensor on the WH model is in the base unit so if that is varying oddly something else must be going wrong assuming the room temperature is fairly constant.
Regards
Alan

I don't think it is Alan as I'm sure somewhere I read that you have to compensate for height above sea level; could be wrong though.
Strange if it is in the base unit as it should track exactly with an Altimeter which is a foot from the base unit (and that will be temperature compensated) and it doesn't track that well.
Anyone know?
Mike.

P.S. Starting a new thread for the aspirated screen project to save hijacking this one.

Yes, the pressure sensor is definitely in the base unit (console).

steve wrote:Yes, the pressure sensor is definitely in the base unit (console).

Thanks Steve; that's very strange then, as it doesn't always track well with the Altimeter.
I can't believe that the Altimeter is off calibration.
Will have to do some more tests.
Mike.

You keep saying altimeter - If truly an altimeter:

"An altimeter cannot, however, be adjusted for variations in air temperature. Differences in temperature from the ISA model will, therefore, cause errors in indicated altitude."

Source: http://en.wikipedia.org/wiki/Altimeter

Now you know that your wx barometric sensor is in the base unit, and your altimeter is near enough the same location.

Try comparing the two pressure readings against INTERNAL temperature.

Old mercury barometers have to be temperature compensated, but I think electronic sensors either don't have that problem, or it's compensated for in firmware (I might be wrong !)

Thanks for the info. The altimeter is the aircraft type which has multiple revolutions.
It's situated 12" from the consul indoors where the temperature only varies by about 2 degrees at most so I don't think that is the problem. I've always though that these instruments will be one of the most accurate as it deadly important for aircraft (especially in the old days) and I bet they are temperature compensated. I'll keep an eye on it.
I also have situated an aneroid barometer, semi-pro one by Short and Mason, next to them to see how that tracks as well; that one's also temperature compensated.

I would think that digital sensors have to be calibrated in range and offset with the hardware on the board, but I doubt they will be temperature compensated in such cheap instruments as the WH1080. I dare say the very expensive WX stations will be though.

Mike.