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Re: [aprssig] APRS in remote areas (fwd)



Satellite Ops in Alaska?

---------- Forwarded message ----------
Date: Sun, 15 Jun 2003 22:00:48 -0500
From: James Jefferson Jarvis <jj@aprsworld.net>
To: Bob Bruninga <bruninga@usna.edu>

While traveling in Alaska the summer of 2001 I observed that all of the
satellites are very easy to work, but there often isn't an IGATE in the
footprint of the satellite. I have logs where 100% of my packets were getting
digipeated by ISS, but never got to the internet. I don't know if is still
the case in 2003, but maybe we could find an Alaskan / Northern Canadian
stations to IGATE [PCsat, ISS, and any other UI digipeating satelites]...

-Jim KB0THN

On Sunday 15 June 2003 10:45 am, you wrote:
> I forward this to the SIG, because it is an important concept for
> distant travelers:
>
> ---------- Forwarded message ----------
> From: Bob Bruninga <bruninga@usna.edu>
>
> Someone said:
> > you can check my "Progress" as I trek to/through Alaska.
> > ...  I'm sending updates every 30 minutes.
>
> I dont know the details, but I would suggest that when an APRS traveler is
> not in full coverage of the APRS system that he should send his posit at
> least once every minute, if not more often.  Two vehicles passing at 60
> MPH only have about 2 minutes when they are within 5 miles simplex of each
> other.  Even beaconing at once every minute only gives you two or 3
> chances to be heard by the other station.
>
> With all the vagaries of propogation and other things that could cause the
> other station to not hear a single packet, the statistics of being heard
> with a once every 30 minute beacon are vanishingly small...
>
> In 30 minutes, two passing stations can be 60 miles apart.
>
> Dont worry about power either.  Transmitting every minute is insignificant
> as far as power is concerned.  The average current for a D700 for example
> just receiving is about 600 mA?  The AVERAGE current including
> transmitting at 50 watts one second once a minute only increases the
> current by 1/60th of 8 amps or about 130 mA.  Insignificant to the
> receiver power...
>
> Your best bet is to transmit via PCsat from midday to sunset.  After
> listening one day, you will hear PCsat on 144.39 and then if you remember
> that time, you can remember that PCsat comes over exactly 1/2 hour earlier
> every day and that there are passes 100 minutes before and 100 minutes
> after as well...  SO go to PCsat during those times.
>
> ALl the rest of the time, beacon away on 144.39 once a minuite in case you
> run into someone nearby on the ground...
>
> If you are in a populated area, run CTCSS-100 so you will hear otehr Voice
> Alert stations.  If you are in the wilderness change to normal squelch so
> that you will hear ANY packet station you may get near...  Hopefully, they
> also are beaconing once a minute to improve changes of finding each
> other...
>
> Just some thoughts...
>
> de WB4APR@amsat.org, Bob
>
> PCsat WEB  page     http://www.ew.usna.edu/~bruninga/pcsat.html
> ISS-APRS FAQ:       http://www.ew.usna.edu/~bruninga/iss-faq.html
> CUBESAT Designs     http://www.ew.usna.edu/~bruninga/cubesat.html
> APRS LIVE pages     http://www.ew.usna.edu/~bruninga/aprs.html
> APRS SATELLITES     http://www.ew.usna.edu/~bruninga/astars.html
> MIM/Mic-E/Mic-Lite  http://ssdl.stanford.edu/mims/
>
>
> ---
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