[aprssig] APRS Newbie - Overwhelmed

[Weston Bustraan]

Replies inline

On Sun, Jan 21, 2018 at 7:05 AM, Michael Barnes <barnmichael at gmail.com>
wrote:

> I am wanting to get into APRS and am rapidly getting overwhelmed. My
> intent is to have APRS in my vehicle to see stations around me and to allow
> my home station to track me. I have a Raspberry Pi with touchscreen and
> TNC-Pi connected to a Kenwood HT with external antenna for the truck. That
> station will run Xastir. Most of the home monitoring I am assuming can be
> done with a computer displaying aprs.fi.
>
> I guess the first thing I am looking for is an APRS for Dummies guide to
> help me get started. I'll need to figure out how to configure the mobile
> for reporting or beaconing or whatever it does.
>

For me personally, I find it easier to have a defined purpose in mind when
attempting to learn a new technology. So, to that end, what do you want to
get out of APRS? Do you just want to track your vehicle? Do you want to see
where other hams are? Do you want to use it to communicate? Is it for
emergency purposes?



>
> I'm also trying to make sense of aprs.fi. I see a ton of icons on the
> map, but I have no idea what they all are. I am especially confused by a
> large number of what seem to be non-ham entities on there. I am seeing fire
> lookout towers, tug boats and Navy ships, what looks to be home weather
> stations, aircraft, and others. Some of these show different identification
> than ham callsigns, including aircraft numbers, marine and commercial
> callsigns, and some kind of weather identifiers.
>

A couple notes on that:
 - aprs.fi displays position information from other services
<https://aprs.fi/page/faq> other than just what appears on general APRS-IS
network, such as AIS
<https://en.wikipedia.org/wiki/Automatic_identification_system> and CWOP
<http://wxqa.com/>

- In addition to direct beacons from ham stations, APRS also allows hams to
place objects on the map by beaconing an object or item packet. So, in the
case of a fire lookout tower, if it doesn't seem like there is a ham there
in person, it's likely that the ham is somewhere else, telling you that the
tower is there. If you are looking at the info for an object on aprs.fi, it
will say "APRS object" and also have a "Source callsign:" field that
displays the ham who sent it


>
> From what I can gather, APRS depends on a lot of digipeaters to receive
> data from mobile units and both relay that info to other users as well as
> upload the data to the aprs.fi system, presumably via the Internet. I'm
> trying to figure out how all that aspect functions as well.
>

Again, that really all depends on what you're using APRS for. It is
completely possible to use APRS without digipeaters and igates, but you
will only see the stations and objects in your vicinity that you can hear
directly over RF.

Digipeaters server to extend the area over which you can hear RF packets.
I-gates extend that range even further by sending and receiving packets
over the Internet instead of RF.

aprs.fi, while it's one of the best interfaces to APRS out there, is not
"the" APRS system; it is just a client, just like Xastir. These clients are
connected to the APRS-IS network <http://www.aprs-is.net/>, which is the
real Internet backbone of APRS. So, an I-gate, whose job is to get packets
to the Internet, is not connected to aprs.fi directly, but rather the
APRS-IS network.


>
> Following the digipeater info is, what about areas out of range of a digi?
> What are the procedures for putting a digi in place? Do folks have portable
> digis that can be deployed temporarily to serve a non-covered area for a
> specific event or emergency? Do all digis have to be connected to the
> Internet?
>

If there's not a digipeater where you need one, then, I believe the general
consensus is, by all means, go ahead and put one there. I would recommend,
though, that you read up on APRS routing before doing so, so that you know
how to configure properly whatever hardware or software you choose in order
to be a good citizen in the APRS network

Yes, for emergencies in non-covered areas, it's completely legitimate to
stand up a temporary digipeater. The CERT
<https://www.ready.gov/community-emergency-response-team> team that I
belong to has plans to do just that if we need the APRS beacons out in the
woods where there are no existing digipeaters.

No, digipeaters don't need to be connected to the Internet. In general, the
term "digipeater" usually refers to a station that relays packets via RF.
And then "I-gate" is used for ones that are connected to the Internet. Many
times they work together. So, if you stand up a mobile digipeater, which
transmits to a local digipeater, which transmits to an I-gate, the packet
that originated in a location with no Internet connectivity can still
appear on the Internet.


>
> As you can see, overwhelmed. I know this is a lot of questions. I probably
> have a lot more, but I don't know enough yet to know what the questions
> are. Thanks for your time in helping me get started.
>
> 73,
> Michael WA7SKG
>
>
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