[aprssig] differential corrections available to public(insome places)
Gerry Creager N5JXS
gerry.creager at tamu.edu
Mon Mar 14 22:23:29 CST 2005
Rich Garcia wrote:
> Initially that is what was tested and as Gerry stated back then we needed
> DGPS stations at 60 or so mile intervals
> for optimum coverage and accuracy. The other issue was 15 or so second
> updates were necessary and here for the 60
> mile range that would mean 3 or so hops that a) Adds time delays and b)
> saturates the channel (maybe not fully) but
> quite a bit when you think of one packet generating 2 others every 15
> seconds plus the traffic. Gerry...what would
> it be like now, how far would the correction be valid for ?
The multiple hops don't tend to screw up the corrections accuracy. If
the correction arrives late, it's ignored. Channel saturation is a
bigger feature. That said, if it can't be sent with a max of 2 hops,
it's probably out of date when received. Big tower, no digi's lots o'
power. You know... what we tell folks not to do.
Current algorithms should allow a more dispersed network. I'm not
comfortable generalizing beyond that: Too many different GPS systems of
varying ages, software/firmware releases, and manufacturers.
... deletia follows...
Gerry Creager -- gerry.creager at tamu.edu
Texas Mesonet -- AATLT, Texas A&M University
Cell: 979.229.5301 Office: 979.458.4020 FAX: 979.847.8578
Office: 903A Eller Bldg, TAMU, College Station, TX 77843
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