THANK YOU Andrew :-) Your reply to my question has enabled me to now understand the core concepts of APRS and cleared up the mystery I have been trying to unravel for quite some time!

Greetings, Nigel.

This will be a rather long and rambling treatise to cover your questions.

The important thing to know about APRS is that it was designed for local tactical information over low-bandwidth radio links, not global messaging over the Internet. The APRS-IS Internet backbone is a useful extension to APRS, but it is merely a cool extra feature; it is by no means an essential part of APRS.

As such, it is perfectly expected that APRS networks will be entirely on RF over a contiguous geographical region. For example, a local charity bicycle ride event I work covers about 4 counties and uses APRS entirely over RF on a non-standard frequency (partially because they don't want ambulance-chasing lawyers and mass-media reporters heading to any problems that might occur, but mostly so they don't have to wade through irrelevant [to them] users of APRS to find their information or lose their information due to channel congestion). This radio network has no Internet connection at all. Similarly, our county ARES group runs APRS weather stations all over the county to provide micro-climate data to county Emergency Management. It runs entirely over RF to get the data to the county offices, and then over their in-building intranet to get to their GIS systems from our co-located I-gate.

Similarly, there is no "global server" in APRS. Like almost every other mode in amateur radio, there is no central control managing the field stations, unlike, for example, cellular telephones managed by the regional central switching office that also controls the cell tower base stations. APRS is an arbitrary peer-to-peer network, rather than a star-topology hub-to-leaf-nodes network. Some people have implemented specific services on APRS (such as the ANSRVR, WHO-IS, and EMAIL-2 pseudo-stations), but they are just other callsign-identified arbitrary points on the network that just happen to be located on the Internet backbone so they can be reached globally.

An RF-only station can easily set up a service, but it would only be reachable by stations within RF contact (directly or via digipeater), or via a Tx I-gate from more distant locations. For example, the APRS QRU service is deliberately intended to be a local RF service, not an Internet service. It is intended that a local RF user can send a text message to QRU with an information request (ex.: RP2M to find a list of local 2-meter analog repeaters), and any nearby stations that support QRU service and have this information will respond. The local RF user initiating the request has no need for a QRU response from the opposite side of the globe (and such a response would be totally useless anyway).

Most of the information in APRS is collected directly from the originators, not from central servers. Referring to the bicycle event again, the consumers (both redundant Net Control stations) receive the position reports from each support vehicle mobile station directly or via digipeater; the data isn't routed through a global server on the Internet. As such, each local peer in the APRS network is not only capable of sending its traffic via undirected multicast to all nearby stations, but can hear all other nearby stations (and digipeater relays for more distant stations) directly and use the pieces of information it hears as it chooses without needing to get the data via some central gate-keeping (and Single Point Of Failure) server.

Note that I specifically designed my YAAC software to function in the "off the Internet" mode. That is why it carries its own local copy of the map data instead of downloading it constantly from an Internet server. Yes, it can connect to the APRS-IS Internet backbone and use some other Internet-based services, but it is fully capable of functioning without them (and most other APRS client programs are, too).

When you hear the term "digipeater", it refers exactly to the "parrot type simplex repeater" you asked about in your message, although they are somewhat smarter than a dumb relay so as to avoid unnecessary retransmissions of packets (see Bob Bruninga's explanation of the New-N paradigm for digipeating to understand why). There are many different implementations of digipeaters available, either using commercially manufactured TNCs with alternate firmware, to software TNCs with digipeater capabilities, to conventional TNCs with custom applications behind them to perform the digipeating operations. The only thing they have in common is having a radio transceiver attached to them. Of course, such automated relay stations require appropriate authorizations from your national governmental authority (what authorizations are required vary with the jurisdiction).

aprs.fi is an Internet-based consumer of APRS packet data. It does not produce anything back to the APRS network (not an APRS data source); rather, it is a data assembler, combining received historical APRS packet data with Google Maps and several other data sources to provide a composite display. But any good APRS client does the same job to some extent.

So, if you want to provide an APRS data "service", you need to define what that service is going to provide and how clients are going to ask for it (such as the WHO-IS service accepting a callsign as input and responding with the name, licensing jurisdiction, and license class of the callsign holder), and then have your APRS software be prepared to recognize service requests when they come in and answer them, just as the QRU service does. And it shouldn't matter what path your clients use to request the service, just as it doesn't matter on the Internet what kind of technology your Internet service provider used to link you to the rest of the Internet.

I hope this helps explain APRS and remove some of the misconceptions about it being an Internet-dependent system (which it is not).

Andrew, KA2DDO
author of YAAC
________________________________________
From: [email protected] <[email protected]> on behalf of Nigel <zs6rn@...>
Sent: Sunday, January 12, 2020 3:43 AM
To: [email protected]
Subject: [yaac-users] Stand alone (no internet) field APRS 'service'

Hello from sunny South Africa :-)
Recently I posted a question on another APRS forum and unfortunately have received only one response and regrettably that reply has not fully answered my query (as an aside it was as a P.M. so it seems that none of the forum members willing to share their knowledge). Am now asking here (YAAC users) in the hope that someone will be able to respond so that I can better understand what is required for a stand alone APRS 'service'.

Advance apologies for showing my ignorance but I figure that if I do not ask the question, then I will remain in the dark regarding how APRS works overall...

1st my current understanding of 'how APRS works':
When using an APRS client e.g. APRSDroid, YAAC or similar, data packets are exchanged with a global server via the Internet via whatever transport medium is enabled e.g. RF and an IGate, Data via the cellular network or even audio from a recording (how I plan on experimenting <smile>) and then to the Internet or perhaps using an Internet connection at a home base.
These data packets convey the information necessary to enable the plotting of objects / stations / whatever on a map positioned according to the appropriate location co-ordinates derived via GPS or entered manually. Other traffic such as messaging is also carried by the data packets and the resulting 'text' displayed in the appropriate 'fields'.
So far so good (I hope).
Now the part I would like to better understand / specific question. What is / are the 'service(s)' being provided at the 'server' end of the APRS infrastructure e.g. and how can a 'standalone' (no internet available / required) service utilising only RF be facilitated so that LOCAL participants can track and be tracked using APRS features e.g. During a local event remote from cellular / data services.
I can visualise a scenario with there being an RF IGate assuming that there is some path to an Internet connection from said gateway, but if there is no Internet available and local tracking of resources and text messaging between stations is required?
Would a RF 'relay' of whatever received (a parrot type simplex 'repeater') provide desired functionality and if yes, what software could be used to implement (Linux preferred)?
Again my apologies for taking up bandwidth with what is probably considered something that is known by even the newest of newcomers to APRS, but I want to learn (and one day implement a portable standalone RF based APRS 'server') so hence the post and exposing my ignorance.
BIG thanks in advance for any and all feedback.
73 Nigel ZS6RN ex G8DEV

Hi, Gerold.

Thank you for your feedback. I was afraid of something like this, as Google is not the greatest translation dictionary in the world (not surprising, with the limited context it gets). I was never particularly fluent in sprecht Deutsch (two years in high school as a foreign language and then never using it again for 30+ years is not a good foundation), but I did the best I could. I would appreciate you reporting any corrections that need to be made, so I can fix the German translation file.

To change the display language in YAAC, you need to change the locale that YAAC is running in; the language is picked based on the operating system locale.

On Linux, it's easy. You can change the LANG environment variable from its default to en or en_US easily:

LANG=en_US java -jar YAAC.jar

On any platform, you can also override the locale for the Java virtual machine running YAAC with a Java system property:

java -Duser.language=en -jar YAAC.jar

But, please, tell me where I screwed up in the translations, so I can fix them.

Andrew, KA2DDO
author of YAAC

________________________________________
From: Gerold Kiesslich <gerold.kiesslich@...>
Sent: Saturday, January 11, 2020 7:51 AM
To: Andrew P.
Subject: Language in YAAC

Hi Andrew,

I have a question regarding the language adjustment in YAAC: I want to
change it from German back English, since the german terms are somehow
misleading. How can I do this?

Do I have to do a new installation?

73 gero DL5KLX

FYI, some newer Linux distributions have dropped ifconfig in favor of
ip. Some of the same output can be seen with:

ip address

73, Nate

--

"The optimist proclaims that we live in the best of all
possible worlds. The pessimist fears this is true."

Web:
Projects:
GPG fingerprint: 82D6 4F6B 0E67 CD41 F689 BBA6 FB2C 5130 D55A 8819

Greetings.

Yes, the aprsisserver plugin will more or less do what you want. All you need to do on the server-side instance of YAAC is add the plugin.

On the client side, you need to create a port of type APRS-IS and specify the host name as the IP address of your server system by typing it in (instead of picking a standard hostname from the list), and use the default port number 14580. Basically, the plugin on the "server" makes it act (sort of) like a Tier 2 backbone server (like the ones you would get with the noam.aprs2.net hostname), so other systems can connect to it the way they would connect to the Tier 2 backbone.

If you don't know what the IP address of your "server" system is, create a command prompt window on the "server" and type "ifconfig -a" (on a Linux system) or "ipconfig" (on a Microsoft Windows system). This should display your system's numeric IP address (a group of 4 numbers typically like 192.168.1.100, and the periods between them are important).

Hope this helps.

Andrew, KA2DDO
author of YAAC
________________________________________
From: [email protected] <[email protected]> on behalf of Rob Doar <robdoar@...>
Sent: Friday, January 10, 2020 6:08 PM
To: [email protected]
Subject: [yaac-users] aprsisserver help

I have YAAC set up on a raspberry pi, and I'd like to use YAAC on another machine to view the data. It looks like the aprsisserver plugin will achieve this. I've installed it but can't find any config options or information on how to connect the client machine to the server.

What am I missing?

Thanks!

I have YAAC set up on a raspberry pi, and I'd like to use YAAC on another machine to view the data. It looks like the?aprsisserver plugin will achieve this. I've installed it but can't find any config options or information on how to connect the client machine to the server.?

What am I missing?

Thanks!

next beta build#146 of YAAC ("Yet Another APRS Client"), created 2020-Jan-10

downloadable from
or

changes and updates include:
1. properly identify scope of Object/Item reports received over RF
by scanning the digipeater list for RFONLY and NOGATE aliases.
2. better calculate the transmit time for AX.25 frames for traffic
analysis.
3. fix infinite loop in processing OpenTRAC sequence number elements.
4. fix incorrect RF-transmitting station identification and tocall
for a Tx I-gate YAAC station.
5. log traffic forwarded by a Tx I-gate to the I-gate station as well
as to the originating station (i.e., how much local RF traffic is
the I-gate creating?).
6. fix bug where popup menus launched from the popup station information
window (launched by left-clicking or touchscreen touching a station
on the map) show selections suitable for a textual table display
rather than for a map.
7. minor optimizations to the OpenStreetMap PBF-format importer.
8. add built-in help to the Small Screen plugin.
9. add piped command support to the Sounds plugin in case the
text-to-speech synthesizer program needs its output piped to
another program to reach the correct sound card and speakers.

Thank you for the update, Andrew!? I have updated to build#145.? But I have two questions....

First, how does one enable (install?) the small screen plug-in.? I have one of those touch screens for my Raspberry Pi, and I am not familiar with YAAC plug ins.

Second, after I installed build#145, my maps disappeared.? I've been using OpenStreetMaps -- do I need to download a new set?

Thank you!

73, Jeff AL1Q

next beta build#145 of YAAC ("Yet Another APRS Client"), created 2020-Jan-07

downloadable from
or

changes and updates include:
1. expose some private components of the core YAAC graphical UI so they
could be re-used for the new Small Screen plugin.
2. make some of the popup menus alternatively have larger font sizes so
the menu choices can be selected more accurately with fat fingers on
a touchscreen.
3. fix a few pom.xml issues within the build structure.
4. Implement the first build of the Small Screen plugin.

The Small Screen plugin is designed to make YAAC more usable on systems
with low-resolution screens and/or touchscreens, such as the Raspberry Pi
with the 7-inch touchscreen connected to the DSI port. It uses a different
layout of the most useful of the YAAC screens (the map, raw packets table,
station/object list, text message table, and the GPS status dialog) in a
full-screen mode to take full advantage of what screen real-estate is
available instead of having it consumed by window manager overhead.
However, all of the other YAAC windows are still available for use.

Note that the sounds plugin may also be useful in mobile environments
using the Small Screen plugin. With the Raspberry Pi, sound effects could
be played through the Pi's default output-only hardware sound interface
with a small speaker, while other sound cards (such as the Tigertronics
SignaLink or NW Digital Radio DRAWS HAT) handle packet audio input/output.

On Mon, Jan 6, 2020 at 06:32 PM, James Ewen wrote:

There are no real mysteries in APRS, just answers that you have looked for yet.

?

So, the real problem is with the operators of BAMBAM and NICOLI, and YAAC is simply demonstrating the "Garbage In, Garbage Out" reality of computer technology. ?

Which clears up my concerns about BAMBAM -- I routinely see it "co-located" on YAAC with my digipeater (WA2WA), which is about 130 miles away. ?I had wondered what the issue was. ?The operator (KI7RUS, from the status text) should add the lat/lon to his beacon and edit the WIDE1-1 setting.

Thanks for that explanation. ?

But I am puzzled about one matter concerning aprs.fi -- do you know if aprs.fi plots the position for BAMBAM using CWOP data? ?I ask because the FCC registered address for KI7RUS is in Vancouver, WA (no where near Goldendale). ?The CWOP database (http://wxqa.com/sss/search1.cgi?keyword=bambam) does have a lat/lon, which resolves to the same location shown on aprs.fi.

73, Jeff AL1Q?

Per another user's bug report, I have found and fixed the issue with the mini-webserver, as of build#144 (05-Jan-2020).

However, due to the internal design of the graphics code in the Java runtime, you need to be running in graphical mode to be able to generate the map images on the webserver, as they are copied from the map display in the graphical UI of YAAC.

Let me know if you still have issues with the blacklist using build#144 (05-Jan-2020).

Thank you Andrew!

--
Michael Cozzi
cozzicon@...
kd8tut@...
269-519-2389

开云体育

-- 
Created on and sent from a Unix like PC running and using free and open source software:

My station = WA7SKG in Dallas, OR
Digipeater = W7SRA about 20 miles SE of me, about 10 miles south of Salem, OR
Digipeater = NICOLI about 90 miles NW of me near Westport,OR
Digipeater = BAMBAM about 130 miles NE of me near Goldendale, WA
(These digipeaters show up in their proper locations on aprs.fi)

The NICOLI and BAMBAM digipeaters routinely show up with gray icons with red question marks in a small area about 2-3 miles radius of W7SRA digipeater.

Michael WA7SKG


Andrew P. wrote on 1/5/20 6:30 PM:

Hmmm... vicinity plotting can also work in the opposite direction to guesstimate the position of "stealth" digipeaters (those that do not transmit position reports of their own, and only meet their legal station identification regulations by UITRACE-inserting their callsign into digipeat paths). When a regular station's position report is digipeated by a "stealth" digipeater, YAAC attempts to approximate the position of the digipeater as being in the centroid of all the stations it has been heard to digipeat.

How do you know these digipeater positions are incorrect? How are you checking this?

Please provide some callsigns of the participating stations so others can help you interpret what is going on.

Andrew, KA2DDO
author of YAAC
________________________________________
From: [email protected] <[email protected]> on behalf of Michael WA7SKG <wa7skg@...>
Sent: Saturday, January 4, 2020 11:51 PM
To: [email protected]
Subject: Re: [yaac-users] Strange Position Reports

Still confused. The two items I see most are digipeaters. They show up
on my map near (varying in about a five mile radius) a local digi, but
one is actually 90 miles away and the other is 130 miles away with
significant terrain between them and the local digi. They are persistent
in that they move around a little bit, but are shown for days at a time
in the same area. I do have "vicinity plotting" turned off, yet they
still show up. They never show up in their actual locations.

I only have RF items on my map. Nothing from the Internet is displayed.

Just another of those APRS mysteries I guess.

Michael WA7SKG


Andrew P. wrote on 1/4/20 6:47 PM:

The question mark icon is for stations with unknown positions. A station
that sends a status message, telemetry, or positionless weather report
first (as far as your station newly listening is concerned) means that
YAAC doesn't know where to plot it or what its symbol is. So YAAC
guesses the station's location by assuming it's near its first
digipeater (assuming the digipeater's position report has been heard).
This feature is called "vicinity plotting".

Once YAAC hears an actual position report with an APRS symbol code from
the station, it will change the icon and move it to the correct location
on the map.

While the station's actual position is not known, and either it wasn't
digipeated and heard by an I-Gate whose position isn't known, or
digipeated by a digipeater whose position isn't known, the position
remains at latitude/longitude (0,0). The button on the map toolbar with
a big 0 on it will jump the map to that location.

Note that, if you don't like it, you can turn vicinity plotting off in
the expert-mode configuration dialog.

Hope this helps.

Andrew, KA2DDO
author of YAAC

-------- Original message --------
From: Michael WA7SKG <wa7skg@...>
Date: 1/4/20 15:36 (GMT-05:00)
To: [email protected]
Subject: [yaac-users] Strange Position Reports

I see periodic objects show up with the icon of a gray circle with a red
question mark. They are many miles from their actual location. Clicking
on the icon gives me a box of either seemingly garbage characters or
just a blank in the comments field. Many of these are fixed sites, so I
know the location is not correct. Some are mobile, but when I talk to
them later, they were never in the area.

What's up with that?

Michael WA7SKG