The Ham Farm - Packet Radio

APRS is a silent aspact of amateur radio in more ways than one. Non-verbal communications and the fact many hams don't delve into this interesting aspect of VHF communication.

APRS (Automatic Positioning Reporting System) was an outgrowth of packet radio. When GPS (Geographic Positioning System) systems made their way into civillian hands it was only a matter of time before amateurs were able to exploit the navigational nature of satelight positioning systems and put that technology to use on amateur radio bands.

The natural addition of position determination and then the capability of broadcasting that information over UHF/VHF and even HF ham bands created an interactive technology that, at 15 years old, in spite of Internet "instant communications" still isn't available to most non-hams or even most technically forward thinking commerical enterprises. Imagine: you hold in your hands, along with an entry level ham ticket, technolgy better than anything United Parcel Service can dish out!

With that capability comes some interesting applications and capabilities. Think about the possiblities APRS affords.

Community Events: With the appropriate software (Linux, MSOS, OSX, OS9 supported) vehicles outfitted with APRS can use "digital" VHF to transmit positioning to a central net control position. Imagine parades, races, and large social events with volunteers painted on a local or custom made map. Net control can follow those "rovers" and properly deploy resources at the approprate time.

Natural or National Disasters: APRS and more specifically, packet radio allows - when power is out and normal communications are down (include the Internet with that statement folks), packet radio allows users to send hospital lists, NTS messages, and other "data critical" information by "packet". And what's even more interesting is, like how the Internet works, information can be relayed from one remote radio operator to another - WITHOUT repeaters - important should power be out region wide.

Batteries in your handheld might be great, but if you can't use the repeater your effectiveness is limited to only a few miles. APRS and packet changes that by allowing users to relay through nearby radios messages to say, the local hospital where a ham station is manned and ready for emergency messages.

SKYWARN: Some counties and states in North Texas use APRS to effectively deploy storm spotters to key positions. Net control can overlay a weather map onto a street grid and send spotters to good observation positions. Net control can also assist spotters by giving their position and/or allowing spotters to see other spotter locations for location spacing. This greatly reduces spotter voice traffic by allowing net control to instantly know where all spotters are in the field.

Personal Use: Perhaps the most fun a ham can have is an "electronic tag" that states not only your location for other hams "on the move" but you can add other information about yourself to the transmitted packet information; such as the radio frequency you are monitoring (and PL tone if it's a repeater). Make contacts without ever breaking squelch on your radio.

So what do you need to make packet radio work?

In a "Back to the Future" moment - think back to about 1995. You probably connected to AOL or your ISP using a modem. That's the key to "hooking into" APRS.

Here's a list of what you need to get started:

1. Since our hobby is "audio" we'll need a modem to change digital computer signals to audio. TNC's are the modems. Some radios such as the Kenwood TS-2000, D700, and TH-7D already have TNC's built into their radios. Other radios like the Yaseu FT-8800/8900's have an access plug in the back of the radio to plug the TNC into. And if your radio doesn't have that an audio connection to your mike, speaker and PTT will make setup relatively painless.

2. You'll need an interface for the radio. This consists of a data patch cable. As mentioned above, this could be a data connector - usually an RS-232 computer based cable which runs to the GPS (more on that), a computer, and your radio.

3. An "interface device" such as a laptop computer (or tower type if you just plan to monitor 'at home'), to run packet software - although this part of it is optional! Palm assistants have also been pressed into service because of their small size.

4. Software. TNC devices can and do run without software. A "smart" TNC can perform packet relay, send and receive files, act as a digipeater, a bulletin board, and allow simultanious conversations with up to 10 other operators. Other functionality comes from such programs as UI-View, Xastir, and macAPRS which emulated TNC functions while providing additional functionality (such as adding your GPS system).

Connection is relatively easy. Rather than explaining in detail - the above illustration can best show the connection capabilities. The soldering and connection should be trivial for most itinerant ham operators. Check the internet for specfic information on radio connection. Some manufacturers provide "step by step" instructions on how to connect APRS devices to their radios.

Lastly, APRS provides an interesting and unexpected hobby I call "Ham Farms". What's that? Simply, with the appropriate PC, software, and TNC installed, you can watch where and what other hams are doing from the comfort of your home. Whether it be an event on a event APRS frequency or you simply want to watch the national APRS frequency (144.39Mhz), watch hams zig zag across the Dallas/Ft. Worth metroplex like that old "ant farm" you had before the ants died or escaped. Fortunately no hams have died directly from installing APRS so, I think, you are safe there. I've had some rather interesting QSO's with APRS fanatics. You will note, upon connection, our ARRL section chief Tom Blackwell N5GAR maintains a base station in Dallas. Myself, I run a base station in Lewisville and act as a digipeater most days.

Yes, you will have to dedicate a radio or, if you are running a dual/quad band VHF/UHF rig, a tuner, to the hobby. Some folks use their handitalkies as the transmitter, with a small mag-mount antenna. When they need their HT's they simply detach the hardware and antenna.

Check out the capabilities of this rather unique hobby. Other sites for additional information is as follows:

Getting started: http://www.choisser.com/packet/part01.html
Software (free and shareware): http://www.dxzone.com/catalog/Software/APRS/
Hardware (Tinytracker/TNC): http://www.byonics.com/tinytrak/