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[aprssig] Weather Station Path/Rate Recommendations

djhuff at rockwellcollins.com djhuff at rockwellcollins.com
Tue Jan 20 21:46:29 UTC 2009


Just to add a couple observations.  I agree with Steve to always do 
constant weather rate.
1. Weather stations based on rapid change sounds hard. You have temp, 
rainfall, humidity, wind speed, wind direction, barometer, and maybe dew 
point.  Which one of those is important enough for change detection, or 
more correctly, how do you do change detection on 6 items easily.  What 
are the limits of rapid change?
2. Wind Direction is notorious for rapid changes,  I have seen the 
direction change 2 or 3 times in a minute.  That many packets based on 
change would be bad for the network.
3. Most weather stations use a data averaging routine,  the Lacrosse units 
I have used in the past were 5-7 minutes per update for wireless, and 4-5 
minutes per update wired.  Sending data any faster than about 5 minute 
intervals is just repeating old data & wasting APRS bandwidth.  MANY 
PEOPLE FORGET THAT. 
4. I have setup my weather station to use a faster rate of about 10 or 15 
minutes in the spring & summer, when severe weather strikes more often, 
then run it down to 20 minute update rates int the fall & winter when the 
weather settles down.  I recommend that similar idea for others doing 
weather on APRS. 
5. As for paths, I suggest that is a local thing to be worked out among 
the local APRS sysops.  Back when I lived in a fringe area at the very 
edge of radar coverage, the weather service specifically asked me to 
change my path to do a 3 hop path so my data was visible on the APRS 
station in the NWS office.    I got flack for it from people living way 
out of state, they sent me emails, and I just sent them a copy of the NWS 
email specifically asking for a change, that usually shut them up quickly.
6. You also need to differentiate APRS weather sent via RF versus weather 
sent ONLY to APRS-IS, many stations do 2 different rates.

David 




Steve Noskowicz <noskosteve at yahoo.com> 
Sent by: aprssig-bounces at tapr.org
01/20/2009 02:00 PM
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Re: [aprssig] Weather Station Path/Rate Recommendations






> 30 minutes is too slow for most situations. ...
> for other types of weather ...rates of five minutes are
> desired by many ...

Sounds obvious to me.  This suggests a Wx station "Smart Beacon" 
algorithm.  Wx condition change rate handled just like vehicle speed.

No change -> 30 min _or more_
Rapid change -> 5 min.

73, Steve, K9DCI
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