40 Mhz SNOTEL WEATHER STATIONS!

Date: Thu, 4 Nov 1999 15:53:36 GMT
From: David Gordon 
To: vhfskip@onelist.com
Mailing-List: list vhfskip@onelist.com;
Subject: [vhfskip] RE: SNOTEL info...

From: David Gordon 

Hi there...here is a message sent to me about the SNOTEL network:
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Meteor communications was discovered by the military in the 1950's, but really 
didn't get off the ground until the Natural Resources Conservation Service 
(NRCS) began to explore what method was the most cost effective to use for 
automated weather stations to send their data back to a central point.  
Contractors began looking at the various technologies in early 1970.  They 
looked at line-of-site systems, satellite, and meteor burst.  The one that we 
choose was meteor burst. So, in 1975, the system began to take shape and in 
1976, the first SNOTEL data was transmitted using meteor burst communication.  
 
NRCS owns and operates two master stations which act as central receiving 
stations.  Only one is required, but because of the critical nature of the 
information that SNOTEL provides to it's users, two were installed for 
redundancy purposes.  Each master station is able to communicate with up to 
3,000 remote sites within a radius of 1,000 miles.  Once the master station 
receives the data, it is forwarded via landlines to Portland, OR and made 
available.  Currently, SNOTEL has over 650 remote sites in twelve western 
states.  SNOTEL uses two frequencies; 40.530 and 41.530 MHz.  Our output power 
from the master stations is around 1500 watts.  The remote sites transmit on 
41.530 MHz at about 100 watts.  The remote site transmitter is only on for about 
0.1 seconds.  The master station transmitters are always on and must establish 
the link between the master station and remote site.  Alaska has its own meteor 
burst master station and the data from it are delivered to Portland.
 
Using meteor burst communication was the cheapest method for us to use, plus it 
is totally under NRCS control.  If we want data, we don't have to wait for 3 to 
6 hours for the satellite (GOES) to acquire the remote sites data.  With meteor 
burst, we can reliably get hourly data from most geographic areas, where GOES 
needs to have a clear view toward the south.  That means that if we wanted to 
put a site down in a canyon where the southern skyline was obscured, we couldn't 
get data out using GOES, but can with meteor burst.
 
If you would like to access additional information, please visit our web site at 
 http://www.wcc.nrcs.usda.gov.  
 
I hope this helps, let me know if you have other questions, I would be happy to 
answer them.
 
We use two types of encoding, a 90 degree FSK for the first ~ 10 seconds of each 
minute then a 30 degrees FSK for the rest of the minute.  We do this to allow 
our two types of meteor burst radios to work.
 
From: "Garry Schaefer" 
 

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Hope this helps... good hunting!

-- David - KB4LCI
FM08 WV.
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