Hello!
I'm working on a house automation project, and i bought a anemometer to measure wind speed. Sadly, the only one i found in my country had no technical specs whatsoever, i only know it works through pulses, and i have a small diagram. I need to create a sketch to send through serial print the wind speed, where i do start?
I guess you don't have a second anemometer to gauge this device?
I would start by counting the pulses you get by turning the meter one complete revolution. Then measure the distance between the center of rotation (the axis) and the center of one of the caps at the end of the four arms. Given that the loss by friction is negligible you can calculate the wind speed with these numbers.
vs = np / ppr * al * π
where
vs: wind speed
np: measured pulses during one second
ppr: pulses per revolution
al: arm length
You can reorder that to get the wind speed after every pulse by measuring the time between two pulses.
Attach the anemometer with a pole to a vehicle, drive around on a day with no wind, and record the anemometer pulse rate for various speeds.
Calculate a calibration factor from the data. Why Calibrate? | Calibrating Sensors | Adafruit Learning System
pylon:
I guess you don't have a second anemometer to gauge this device?I would start by counting the pulses you get by turning the meter one complete revolution. Then measure the distance between the center of rotation (the axis) and the center of one of the caps at the end of the four arms. Given that the loss by friction is negligible you can calculate the wind speed with these numbers.
vs = np / ppr * al * π
where
vs: wind speed
np: measured pulses during one second
ppr: pulses per revolution
al: arm lengthYou can reorder that to get the wind speed after every pulse by measuring the time between two pulses.
yes i don't have another a second wind sensor, so i'll try this solution and i'll be reporting my results.
Regards!
jremington:
Attach the anemometer with a pole to a vehicle, drive around on a day with no wind, and record the anemometer pulse rate for various speeds.Calculate a calibration factor from the data. Why Calibrate? | Calibrating Sensors | Adafruit Learning System
it's an interesting option, but i'll try first the math related one, it's quite windy in my country.
Since arm length is the radius, that formula should be
vs = np / ppr * al * π * 2
Pete