Wind Sensor usage and adjustment

Questions about Modern Device and JeeLabs Sensors
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Phugoid Floyd
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Joined: Tue Nov 25, 2014 4:46 pm

Wind Sensor usage and adjustment

Post by Phugoid Floyd » Tue Nov 25, 2014 4:51 pm

Hi,
I recently purchase the Wind Sensor (rev C) and is now experimenting with, basically using the provided Arduino sketch as written by Paul Badger. Observing the output (on a simple 4-digit LED didplay) while riding my bicycle which has a known-good speedometer for reference, I have noticed (what I conclude is) a significant sensitivity to the ambient air temperature. So I have a couple of questions:

-- Is there a straightforward way to adjust the sensor in order to get an accurate, or at least consistent output despite naturally varying air temperatures from one day to another?

-- About the zero wind adjustment: How does hardware calibration using the trimpot relate to tweaking the value of the sketch's constant "zeroWindAdjustment"? Is one method preferred before the other, or should both be used?

-- I believe this question has been asked before in the forum, but seen no answer yet: What orientation of the board (in relation to the air stream) is the "correct" or expected one, i.e. flat-on, or sideways left or right, or possibly even with the short side towards the wind?

Grateful for any tips!

// Martin

paul
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Joined: Mon May 12, 2008 4:19 pm

Re: Wind Sensor usage and adjustment

Post by paul » Sat Mar 07, 2015 11:36 am

Martyn,

You may have moved on to other things by now but I'll answer this to have it in the forum.


-- Is there a straightforward way to adjust the sensor in order to get an accurate, or at least consistent output despite naturally varying air temperatures from one day to another?

The sketch is supposed to do this somewhat, but there is room for it to be much tighter. There are a lot of tolerances in parts to consider. Please make sure you have a regulated 5 volts, because the output will vary greatly if the voltage changes much from 5.0 volts.

The direction of the airflow is measured facing the parts side of the sensor, so the wind vector is 90 degrees from the parts face of the sensor - facing directly into the sensor. It is fairly insensitive to wind angles from about -45 to + 45 degrees from the sensor but falls off about 30% with a wind vector parallel to the parts face (pcb) and then by 50% or more with wind coming from the backside (the backside of the pcb)

Hope this helps,

Paul

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