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

DaveH info at blackmountainforge.com
Sat May 24 01:55:18 UTC 2014

Hi Mark

I have been running an older Davis VantagePro station for the last fifteen
years.  It gives either miles per hour or meters per second.

Air pressure in either inches or millimeters of Mercury as well as

One note - wind direction is opposite from what you might think.  A West
wind blows to the East -- it is coming __from__ the West.

The project sounds like a fun hack -- I would be curious as to the
resolution you achieve with these modules.


> -----Original Message-----
> From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] On Behalf Of Mark Sims
> Sent: Friday, May 23, 2014 18:17
> To: time-nuts at febo.com
> Subject: [time-nuts] Weather/units question for European members
> 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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