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

Rex rexa at sonic.net
Fri May 23 22:54:30 EDT 2014


I have a crappy Chinese-made handheld propeller anemometer. I'm not in 
Europe but FWIW the output can be selected as: m/s, km/h, ft/min, knots 
or mph. So, the first  two of those seem to be likely metric choices.

Your method sounds interesting. Would you be willing to share any 
details about how you are using the ultrasonic modules? Do they just 
point out into open space or is there something more involved?  Was 
there a reference that got you started on this idea?



On 5/23/2014 6:16 PM, Mark Sims wrote:
> 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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