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[aprssig] Questions about paths

A.J. Farmer ajfarmer at spenet.com
Tue Sep 7 19:29:11 UTC 2004


I would say that running a RELAY is almost always never a bad thing.  The
same is true for receive only IGATEs (transmitting IGATEs that introduce
Internet traffic to RF are another matter).

I have a similar situation here.  The only difference is Digi coverage is
very good in this area, actually too good -causing a lot of QRM and
competition for network time with high AGL, high powered Digi's that are
broadcasting traffic from 150+ miles away.  At home, I can not get packets
to any digi's reliably when portable around the house with my TH-D7.  So, I
turned my home APRS station into a RELAY.  Now I can use my TH-D7 on the EL
power setting to conserve battery power and still get my packets reliably
into the network.  I am also assisting any nearby mobiles get their packets
in.  The footprint of my RELAY station is relatively small, so I should not
be adversely adding QRM to the network, just helping fill in a gap and
helping a portable low powered station.

I think if more stations would set up their home APRS stations as RELAYS,
coverage on 144.39 would increase dramatically without decreasing the
effectiveness of the network.  Even with the large Digi's in this area,
there are still a lot of "dead" zones that would benefit from modest home
based RELAYs.  In congested areas, we don't need more WIDEs, we need
coordination (which Bob preaches all the time) and RELAYs to fill in the
gaps.  Your location is a different matter - it sounds like you do not have
adequate WIDE coverage to begin with.  Every situation is a little
different, but I think that you really can't go wrong with setting up a
RELAY. 

I say go for it! 

73!

A.J. Farmer, AJ3U
http://www.aj3u.com


-----Original Message-----
From: aprssig-bounces at lists.tapr.org [mailto:aprssig-bounces at lists.tapr.org]
On Behalf Of Chris Kantarjiev
Sent: Tuesday, September 07, 2004 2:56 PM
To: aprssig at lists.tapr.org
Subject: Re: [aprssig] Questions about paths

> "Robert Bruninga" <bruninga at usna.edu> typed...

> You should not be digiing anyone
> unless you live on a very high hill and can serve the 
> community.  If you are diging otherwise, you are just adding
> QRM to everyone else..

This is a pretty blanket statement, admittedly from someone who Speaks
the Truth. I'm still very new to APRS, so let me tell you what I see
in two situations:

The first situation is at my home in Silicon Valley. I've been trying to
use a Pocket Tracker, which is pretty low power (about 250mW). It seems
to have a pretty tough time getting over the local noise floor, so I'm 
building up a more powerful tracker. But in the process of trying to
get it working, my observation is that it's a pretty long way from 
my neighborhood (zip 94306, 37.432/-122.153) to the nearest digi: 

http://www.findu.com/cgi-bin/near.cgi?call=KG6VYD

shows it about 7 miles away to the south, and nothing shows up to the
north in that listing. WC6O-3 seems to just RELAY; it has very little
HAAT.

So my temptation has been to install a TNC/radio in my garage and start
running a RELAY only digi; I've only got about 20ft HAAT, so it doesn't
seem to make much sense to claim to be WIDE. Once I have the setup
going, I'll try to contact a local repeater to transfer the gear
there - they could do a decent job of being WIDE, I think.

Am I wrong in this approach? I'm trying to fill in the digi network
for moderate powered trackers.

The second situation is at our mountain cabin, south of Yosemite
National Park. This is an environment with a lot less noise,
but it's mountainous and there are very few digis. A path of 
WIDE4-4 will usually get me to an igate.... 

http://www.findu.com/cgi-bin/near.cgi?lat=37.405&lon=-119.6242

The local repeater has good voice coverage, but no digi. The folks running
the closest digi (55 miles south, WA6YLB-3) are working on 
putting a digi to the north of me, in the Park proper. But there's
pretty much no coverage on the CA Hwy 41 corridor from Fresno up
to the park, mostly because of hill shadow. 

Again, my inclination has been to put a RELAY digi on my roof. I have
40-50 HAAT to the S/SE, with Hwy 41 to my N/NW above me. Once I
get it running, I would like to donate the hardware to the local
repeater in Oakhurst, which would be a really nice WIDE site.
There's a Forest Service lookout on top of an 8000' peak (Shuteye)
that would make a *great* WIDE site, if I can get some contacts
there (I think the folks putting the digi in the Park have
contacts with the FS - Shuteye isn't staffed year round, so it
will be ... interesting to keep a digi running there).

In general, digi coverage isn't very good in this part of the Sierra.
It seems we could use an igate closer; I don't have continuous
IP connectivity at the cabin or I'd put one in.

Back to my original question - is running RELAY in these situations
a bad thing?

Thanks,
chris

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