[aprssig] Point-to-point telemetry addressing
steve at dimse.com
Fri Nov 24 18:15:01 CST 2006
What jumps out at me is the packet is really long. Do you really need
to add "Telemetry from East Homer, NY on 11/23/2006 at 11:11 PM" to
every packet? This doubles the packet length and greatly increases
the chance for collision. Though time delays do occur, they are quite
rare, and the time a packet is received at findU should be adequate
for your needs. findU is synced to a level 1 time server, whereas
since your cottage does not have internet, the computer is probably
not synced at all (there appears to be a consistant 80 second offset
now) so findU's time is probably much more accurate even including
Looking at the packets, you seem to get about 70-80% through, with a
shorter packet you will have even greater return.
You should also occasionally send a position packet so you will
appear on maps!
On Nov 24, 2006, at 6:58 PM, VE7GDH wrote:
> Michael W9IP wrote...
>> I'm trying to maintain a telemetry link with our cottage (W9IP-2)
>> about 35 km away.... There is a good APRS digipeater (K2AMB-3)
>> near W9IP-1 and another good one (KB2FAF-10) near W9IP-2...
>> W9IP-1's path to W9IP-2 would be
>> APRS,K2AMB-3,KB2FAF-10,W9IP-2 and that W9IP-2's path to
>> W9IP-1 would be APRS,KB2FAF-10,K2AMB-3,W9IP-1
>> However, neither of these appear to work. The only addressing that
>> seems to work is APRS,WIDE2-2, but that only works from time to
>> time, when the two WIDEs happen to be K2AMB-3 and KB2FAF-10.
>> I understand that I shouldn't expect 100% because of packet
>> but so far specific addressing is just not working at all. Any
> It doesn't really matter what the path from W9IP-1 to the cottage
> is. If the
> cottage is W9IP-2, I would try a path of WIDE2-2. However, you said
> that you
> were using APRS,WIDE2-2. That would only work if there was a digi that
> responded to the alias of APRS. I'm assuming that you're not using
> at W9IP-2. If you are, the "APRS" in the "unproto address" is
> really the
> destination. Everything after that is the path. Try changing W9IP-2
> so it
> uses a path of WIDE2-2. This will work with any WIDEn-N digi that
> hears it.
> If it so happens that you don't have a reliable path to a WIDEn-N
> digi, but
> there are home fill-in digis within earshot that respond to
> WIDE1-1, you
> could try WIDE1-1,WIDE2-1 instead. Would that make it to the IGate?
> If not,
> you could increase the path to WIDE1-1,WIDE2-2. Generally speaking,
> stations shouldn't have WIDE1-1 in their path. My suggestion is for
> ONLY if
> using WIDE1-1 will help you get to a WIDEn-N digi that would
> otherwise be a
> bit iffy to get to directly. Re-reading you message, you said there
> was a
> "good" digi near W9IP-2, so avoid using WIDE1-1 unless you really
> need to
> use it.
> The other possibility would be to use a specific path from W9IP-2
> instead of
> WIDE2-2. You could try KB2FAF-10,K2AMB-3 for the path from the
> cottage. Do
> not include W9IP-1 as part of the path. First, it would be wasteful of
> bandwidth by adding 7 bytes to every transmission, and it wouldn't
> be doing
> any good because you are trying to receive the telemetry at W9IP-1,
> digipeat it.
> The generic WIDE2-2 could spread out in multiple directions. By
> it to specific digipeaters, it would only propagate via the path
> that you
> specify. However, if either of those digis went QRT, no other digis
> would be
> used. I would probably go with the generic WIDE2-2.
> You are right. You cannot expect to receive every beacon from
> W9IP-2. All it
> takes is a packet collision for it to fail, or a burst of noise,
> etc. If W9IP-2 has good "ears" it will at least hold off
> transmitting when
> the frequency is already in use. There is always the "hidden
> that you can't do anything about, but if you have a decent antenna
> at W9IP-2
> and the squelch is set loose or wide open, it will have a better
> chance of
> knowing if the frequency is already in use. The danger of a loose
> squelch is
> that if anything changes (i.e. something causes it to go open) it
> could end
> up never transmitting. You are better off running with the squelch
> wide open
> with the TNC set for software carrier detect.
> Unless you are using UI-View at W9IP-2, get rid of the "APRS" in
> the unproto
> 73 es cul - Keith VE7GDH
> "I may be lost, but I know exactly where I am!"
> aprssig mailing list
> aprssig at lists.tapr.org
More information about the aprssig