APRS (ham radio)

Automatic Packet Reporting System....

You're probably saying what is a Packet and what does this have to do with Jeeping? Hang with me for a minute..

A Packet is data and in the case of APRS it is speed, direction, altitude, location, and a message which typically states what frequency you are monitoring. This packet is transmitted via a 2 meter ham radio on 144.39 MHz, so you have to be a licensed amateur radio operator to use APRS.

Your data packet is transmitted from your 2m radio and can be received and decoded directly by another APRS users or it can be picked up by a digital repeater (digipeater or digi) and rebroadcast. If another digi is within range of the first one it will also rebroadcast your packet. Two hops is the generally accepted standard setting. If you have a full featured APRS set up (as opposed to just a simple/dumb tracker) you can view the other stations packet info and see them on a map.

A digipeater may also be an Internet Gateway (Igate) which then copies your packet info to the net for sites such as APRS.fi and OpenAPRS.net. These sites map you and your packets. This allows for your friends and family to see where you are on your wheeling adventures.

APRS can be used for more than just tracking. You can send messages to other APRS users (as long as they have a full featured APRS set up), you can send text messages, and short emails (both text and emails require that you be within range of an IGate). The APRS system also allows you to see who is around you, their distance from you, and their direction from you.... as the system was designed for situational awareness.

This type of system would be good for a trail run event where you could see what trail each group was on and where on the trail they were. It would also be good if you were in search and rescue. Others could see where you had been and if every S&R group had an APRS beacon you could see where everyone had been and make sure the area had been covered accordingly.

The system could also be helpful if you were wheeling and someone broke down or sustained an injury. Other radio operators (if you used your Ham radio to call for help) or rescue personnel could use APRS.fi to locate you and provide GPS coordinates.

The International Space Station has an APRS digipeater on board and it can be accessed using the same antenna on your vehicle as you would normally have for a mobile APRS set up, however 25+ watts would be advisable. This wouldn't be used for all your APRS needs, but could be utilized to get a message out if needed.

Hardware.. what do you need for an APRS set up.

You could take the easy way out and just download the APRS app for your phone (remember you have to be a licensed ham to use this) however this requires that you have a cell signal. If you want to go the RF route here is what you will need.

First off and most obvious, a radio. A radio that operates on the 2m band to be specific. There are some dual band radios that allow you to run APRS on one side and voice on the other, but most do not. Most dual band radios are dual receive but single transmit.
A dedicated single band (2 meter) radio would work fine. You can use a mobile or HT, the mobile would have more watts which may come in handy if you live in an area with sparsely placed digi-peaters. The radios that allow APRS and voice to be used at the same time also typically have the APRS hardware built in, these radios include the Kenwood TM-D710G (mobile), Yaesu FTM-400DR (mobile), Kenwood TH-D72A (HT) and Yaesu VX-8DR (HT).

GPS antenna/unit: If you want to have a dumb tracker where you just transmit your info and can not receive/look at other's info you will just need a GPS antenna. However if you want a full featured APRS set up with mapping capabilities you will want the GPS unit. The GPS unit provides the telemetry (location, speed, direction, etc) and well as mapping others info that is received. The most popular/sought after GPS unit is the Nuvi 350 though it is no longer in production it can be found used on Ebay. The Avmap Geosat 6 is an APRS specific GPS unit, but is pretty expensive. You may also use an Android tablet/smart phone with GPS and Bluetooth with a bluetooth TNC (see below).

You will also need a TNC or Terminal Node Controller. This device takes the digital info from the GPS and converts the digital info to audio tones to be transmitted by the radio and vise versa. Common TNCs are the Tiny Tracker and the Argent Date Open Tracker. These require the GPS be wired to them, and for them to be wired to the radio.

Another option is the Mobilinkd TNC that only connects to the radio with a wire, but connects to an Android tablet/smart phone via bluetooth, instead of a GPS unit. The phone/tablet would then need to have the APRSDroid loaded onto it. With this set up the radio/TNC can be hidden away under a seat or in a rear cubby and you would just have your phone/table on the dash with no cables running around the cab of the vehicle.

Lastly you would likely want an external antenna. If you are using an HT for APRS while hiking you could probably get away with a better HT antenna, however for mobile use you will want an external antenna.

I will also add that you can connect an Android smart phone directly to a

$19 Baofeng UV5R BAOFENG UV-5R Dual Band Two Way Radio (Black), 144-148MHz & 420-450MHz

Baofeng UV5R (perhaps other HTs as well though this is the one I see the most) without the TNC. This may work better for walking/hiking or if you have an extra phone to leave connected to the radio when mobile.

I currently run a Yaesu FTM-3100r with a Moblinkd tnc to my tablet or phone and it works quite well.

Let me know if you have any questions.

 

Here is what I see on my display.

 

Or this if I choose...

 

Here is a screenshot from one of my contacts through the ISS.

 

Propagation has been pretty good the last couple of days. I am in OKC and these are all the stations I have received in the last 2 days.

 

Pretty cool chit man.

 

im a ham not using aprs. its a great tool but most jeepers wont get a ham license and most aprs guys are not 4 wheelers.
this should be available for frs radio or even cb to be widespread for rescue, imo

 

Ham and APRS is slowly catching on with the offroad crowd. It's not for everyone and frankly a lot of the trash can stay on CB. Ham is a good tool to have though.

FRS and GMRS do allow digital communications though it is limited.
Not sure this would work well with CB for any kind of rescue though due to the lack of repeaters and minimal simplex distance. GMRS does allow repeaters but likely few if any in non metropolitan areas.

I would rather see GMRS replace CB for trail/convoy comms.

 

I have had 2 of those for about 4 years and one of them has spent the better part of those 4 years rolling around in the floorboard of my Jeep, still works fine.

Just be mindful of what frequencies you are operating on. And for what it's worth these radios aren't legal to operate, either the radio isn't type accepted and or the frequency requires a license.

 

Sounds like you did your homework, well done.
You might look at getting the Nagoya NA771 (I believe) antenna, it seems to be a popular upgrade though too long if you plan using it inside the vehicle in which case a mag mount may be the better option.

 

awww shucks!

I completely understand, just wanted to make sure you aren't disappointed and turned away from ham radio due to the lack luster performance of the stock rubber duck antenna. How you hold the radio in reference to your body or big melon (if you are like me) can have an effect on how the radio performs.

Hope all goes well though.

 

Should work better, I can't comment on distance as there are a number of factors that play into that such as terrain.
Play around with it and see what it can do and hopefully it will meet your expectations.
You might also look at the MURS frequencies, they allow 2 watts and are in the VHF spectrum.

 

Let me know how it goes.