[time-nuts] Weather/units question for European members

Mark Sims holrum at hotmail.com
Fri May 23 21:16:32 EDT 2014


I am building a weather sensor that includes a ultrasonic anemometer to measure wind speed, direction, and air temperature.  It uses 4 cheap ($1 each) HC-SR04 ultrasonic rangefinder modules that output a pulse width proportional to the time of flight of the sound signal  (topic is time nut related since  it simultaneously measures the speed of sound in 4 directions to a pretty good accuracy/resolution using a cheap-ass microprocessor - ATMEGA328 (like and Arduino)...  and does so without using any counter-timer channels).
Now the question...  I would like it to be able to output data in imperial or metric units.  In what units is the typical wind speed reported  (meters/sec,  km/hour, ?).   Also air pressure (millibars/hectopascals/pascals/?). 		 	   		  


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