[aprssig] APRS on Rovers -- Pt 2
w2ev at yahoo.com
Thu Jan 17 05:58:30 CST 2008
My original "Pt 2" bounced due to my error. I'm resending it. I apologize for any malformatting that may occur. Yahoo web mail doesn't like cut-and-pastes from e-mails. -= Ev =-
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Thanks to a conversation with Mark (N2MH), a few other items came to
light that will help to maximize your contest-APRS effectiveness. These
apply only to APRS on 144.39 MHz because it deals with DIGIpeating, not
HamIM (which is simplex on 147.585 MHz and has none of these issues).
1. If you are using a TNC, do *not* set it up to be a DIGIpeater to
other stations for any reason or on any alias. The APRS frequency of
144.39 MHz is waaaaaaaaaaaaay too close to the SSB sub-band centered on
144.200 MHz and I'm betting that the self-QRM from your *own* APRS
station's ID will cause you fits...let alone the traffic caused by having it
2. When launching on APRS, use the path of "WIDE1-1,WIDE3-3". This
will provide you with 4-hops of DIGIpeating, which will be about what your
SSB/CW RF range will be during the contest (yes, this is a
generality). This is *different* than the suggested pathway of "WIDE1-1,WIDE2-2"
because there is a tactical need for it to be...but *only* for the VHF
contest this weekend. Do not leave your Rovers APRS configuration in
that state, after the contest.
3. Test your APRS ID QRM now, before the contest begins. Set your TX
interval to something that won't make your head explode as you have your
volume turned up on 144.200, trying to dig-out a weak one and it
kicks-in. Under no circumstances should your ID be any more frequent than
every 5-minutes. Even when travelling at 60MPH, that is a location
error of only 5-miles. Frankly, every 10 to 15 minutes is probably plenty.
The only risk that you'll assume by longer ID intervals is that you
won't show as having moved from your hilltop until it ID's again.
4. Lastly...remember that APRS is supposed to HELP. If you find that
the self-QRM is unbearable to your contest operation, SHUT IT OFF and
contest. Just remember to turn it on while travelling and not operating
so at least we know you're out there. :)
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