APRS
I just want to let everyone know that this will be the last Newbie Tech Net until the new year. I’m going to take December off since it’s already a busy month for everyone, and it’s also a time when I get to take some holidays. I hope everyone doesn't mind the break in the schedule.
Also sometime in December I’m going to be notified about the times and dates of the CW training course that I’ve signed up for, it will run for January and February and my hope is that it won’t interfere with our Monday night net or the NORAC meetings. All I know right now is that it will be two evenings per week and will run for January and February. My fingers are crossed that I’ll be able to keep all of my evening commitments during those two months, but I won’t know until later in December.
So far I’ve done ten topics since starting this net in September and I would like to thanks those of you who have participated, we’ll see you again in the New Year.
APRS
APRS stands for the Automatic Packet Reporting System
"APRS was developed by Bob Bruninga, WB4APR in the 1980’s, as a real-time communications system for exchanging digital packet data." APRS is mostly known as a system for using radios, GPS and the Internet to transmit position data, and weather reports, as well as messages.
Bob Bruninga, is both an amateur radio operator and a senior research engineer at the United States Naval Academy, he implemented the earliest ancestor of APRS on an Apple II computer in 1982. This early version was used to map high frequency Navy position reports. The first use of APRS was in 1984, when Bruninga developed a more advanced version on a Commodore VIC-20 for reporting the position and status of horses in a 160 km endurance run.
During the next two years, Bruninga continued to develop the system, which he now called the Connection-less Emergency Traffic System (CETS). Following a series of FEMA exercises using CETS, the system was ported to the IBM Personal Computer. During the early 1990s, APRS (then known as the Automatic Position Reporting System) continued to evolve into its current form.
As GPS technology became more widely available, "Position" was replaced with "Packet" to better describe the more generic capabilities of the system and to emphasize its uses beyond mere position reporting.
GPS location data from your compatible radio or APRS device is sent out as a burst of data, the hope is that a nearby repeater with APRS also known as a digipeater, will hear and collect your data and forward it along to another repeater or an iGate. If your data is bounced to another repeater, then that repeater also forwards it along. Eventually your data will be bounced to an iGate, this is a device that transfers your RF data to the Internet. Once your location data reaches the Internet, it’s stored for about a week and anyone, including yourself can look-up your location and track your path.
Amateur Radio Operators can participate in APRS in a few ways.
1) You can just purchase an APRS compatible radio like a handheld or a mobile and configure it to report your APRS information. When you or your vehicle is traveling, your APRS data will be broadcast and available for query on the Internet. You may wish to track this info yourself, or show someone else how to find your APRS info online so they can track you. Imagine driving to see relatives in Calgary and giving them the website to follow your driving progress on, you could do that instead of relaying updates by cell phone or text every time that you reach an area with cell service.
Another way you can use APRS is you can setup most radios to also act as a Digipeater, this means that your radio is not only sending out your APRS data, but it’s also picking up the data of others with RF range and bouncing it out. If we use our previous scenario of the trip to Calgary there are places in the Rockies where no APRS repeater is within line of sight. With your vehicle acting as a mobile digipeater you might be within range of an APRS repeater, and you might also be picking up the date from other vehicles who are not in range of that same repeater. Their packets would not get through, without your vehicle helping move their data along.
And finally you can purchase an iGate or Digipeater and set it up at your QTH. You could become one more member of the APRS community who receives peoples APRS data and delivers it to the Internet. In this example my QTH here in Lumby could be an example. Maybe from my house APRS data couldn’t reach any nearby APRS digipeater or iGate. So I could set one up and act as the local relay station for APRS. Anyone traveling near Lumby could bounce their RF APRS data off my digipeater or iGate and get delivered to the Internet, filling a hole in the APRS service area around Lumby.
APRS, It’s easier today than it was in the past.
So if you were an Amateur 5-10 years ago or earlier, setting up APRS was a much trickier problem. It often involved multiple pieces of equipment, you would need a radio with a packet modem (a TNC) built in, or a radio and a separate TNC attached. You would need a separate dash mounted GPS as well that had it’s own antenna and support for exporting it’s data out to another devices. You would hook all this equipment together, figure out the setup of each piece of gear to work with another, and then you had APRS.
Nowadays, you buy a radio with APRS built in. Even in a tiny handheld, you’ll have the radio, packet TNC, and GPS all in the same radio. You add your callsign and SSID for APRS and you’re often good to go.
My first Kenwood handheld the TH-D72A that I bought 6 years ago, had APRS built right in.
In the years since, tiny handheld devices have hit the market that for about $100 bucks are a complete APRS solution with built in 10-12 hour battery pack inside. Search and Rescue groups often buy these for their members, hand them out upon deployment, and sit back and monitor the incoming APRS data from their members as they search.
Personal digipeaters and igates are also dropping in price and can be purchased for only a few hundred dollars, there are also fun and inexpensive ways to build these yourself using micro computers like Raspberry Pi’s or Beagle Bones. Even as a Amateur Radio Operator with Basic privileges you can setup your own digipeater or igate because they often run at very low power. And because they are all digital, your license will allow for it.
Now, unless you know of a local dead spot for which you feel a digipeater would be useful or there isn't an APRS digipeater for 60 or 80 kms then you may not need to go to that effort. Duplicate digipeaters with lots of overlapping range just add packet noise to the frequency.
Running an Igate however could be a very useful idea. In an urban environment they will pickup local packets that don't quite make it into the local digipeater. In the rural areas, even if there is another iGate within a hop or two, the redundancy is welcomed.
Setting Up APRS
When setting up APRS for your personal use you need to input your callsign into the device since it will need to beacon your callsign every 30 minutes or less, just like you would do as a live operator on voice. You will also assign your APRS an SSID, number.
On VHF in North America the APRS frequency is 144.390 MHz. In Europe it’s 144.800, and in Australia it’s 145.175. Keep in mind if your traveling outside of North America with an APRS enabled device you will need to change your frequency for that new region.
Since you can use APRS on multiple devices, the SSID’s help identify which device you are on. They go as follows.
Your callsign with no extra SSID information would be your only or primary APRS device.
Your callsign with a -1, -2, -3, or -4 at the end would be generic devices, or digipeaters
Your callsign with a -5 is used for other networks like D Star or cellphones. Yes you can install APRS software on your cell phone and use the phones built in GPS to send APRS data straight onto the Internet
-6 Special activity, Satellite ops, camping or 6 meters, etc
-7 Handhelds or other human portable
-8 Boats, sailboats, RV's or second main mobile
-9 Primary Mobile
-10 Internet, Igates, echo link, win link, AVRS, APRN, etc
-11 Balloons, aircraft, spacecraft, etc
-12 APRStt, DTMF, RFID, devices, one-way trackers*, etc
-13 Weather stations
-14 Truckers or generally full time drivers
-15 Generic additional station, digi, mobile, wx, etc
There are also APRS icons that you can configure, they include a person walking, a car, a truck, a plane, a semi-truck, you get the idea, the icons match the SSID categories so you can assign a SSID to your vehicle mobile, and then you can assign an icon of a car or truck to match.
Tracking APRS
When you want to track your APRS information you need go to an online to the website https://aprs.fi
Enter a callsign, and if you know the SSID number you can enter the dash and number as well to the end of the callsign. If you don’t know the dash and number for a particular persons callsign and device, jut enter the callsign and APRS.FI will show you other matches found with their SSIDS.
If you look me up on APRS-FI, you should see that I use VA7AEJ-5, -7, -9, -10, and -B. These SSID’s cover my phones, my handheld, my truck, and my D star hotspot.
Now when you enter that callsign info on APRS.FI the map on the website should jump to that persons location in the world, and like google maps you can zoom in, or zoom out, and move around the map on the screen and track their APRS location entries.
If you clear the search and just navigate to the Okanagan Valley on the map, you will see all APRS traffic from all sources.
You can filter the results you are seeing on the right side of screen where there are drop down menu to show the last 15 minutes all the way up to the last 7 days.
I encourage you to play around with the Show Last drop down menu options, as well as the Track Tail Length. Together these can show a colored line track on the map showing a moving APRS operator as they drive from point to point.
Also look for WX stations, these are weather stations and in the North Okanagan you should see one at the Vernon Yacht Club, and another in Lumby.
Zoom the map out to see the map between Vancouver and Seattle and you’ll be surprised at the amount of APRS data over the last day or so.
More About APRS
Read more about APRS online at aprs.org or many other sites created by hams.
Remember that APRS is not just about position reporting or just Amateur Radio.
While the map plotting is the most visible feature of APRS, the text messaging capabilities and local information distribution capabilities, combined with the robust network, should not be overlooked. One example is the New Jersey Office of Emergency Management which has an extensive network of APRS stations to allow text messaging between all of the county Emergency Operating Centers in the event of the failure of conventional communications.