[aprssig] Cool new sensor

[Scott Miller]

My money would be on the magnetometer for linearity and long-term 
stability, since you're just counting zero crossings over time.  You 
don't need to worry about offset, non-linearity, or drift.  Or the 
mounting position of the sensor.

And yeah, the fact that handheld anemometers are dirt cheap now is why I 
didn't bother with the phone thing.

Scott
N1VG

On 3/24/2015 8:39 PM, Steve Dimse wrote:
> On Mar 24, 2015, at 11:07 PM, Scott Miller <scott at opentrac.org> wrote:
>
>> If it's a multi-axis magnetometer, that would probably be a better way to measure wind speed than the accelerometer.
>>
> If it were on a rotating anemometer, the magnetometer would give you a rotation rate by comparing multiple readings to get a rate of change, but the accelerometer could give you direct readings of centrifugal force, as would the gyroscope, so those would get my vote.
>
> And yes, the magnetometer, accelerometer, and gyroscope are all three-axis.
>
>> I've been meaning to try 3D printing a clip-on cup anemometer holder for my phone.  The anemometers I've got have magnets to trip reed switches and could probably be picked up pretty easily by the phone's magnetometer.
>>
> Interesting idea! I'd guess it would matter where the magnetometer was in the phone. Of course, I have a $10 handheld that gives me the same data and is probably the same size to carry. Maybe in a pop-up case?
>
> Steve
>
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