N0RQ / N5SUE APRS solution
APRS is a registered TM of Bob Bruninga
Thanks to Pete, AE5PL, and Kirwin, N0XLR, who helped with APRS advice during various stages of this little learning endeavor.
First, I am not an expert on APRS by any stretch of the imagination. However, I did manage to get 1 fixed base station transmitting and receiving APRS, and 2 mobile trackers going successfully — and relatively inexpensively. Since those early endeavors, I’ve also set up 2 digipeaters and 2 I-gates as well (details here).
So here’s the notes….
First, the 2 mobile trackers. I went with “dumb” (no computer) mobile trackers — I can transmit location, but can’t receive anything, which is all I wanted. I got the TinyTrak3 – ~$30 as kit, ~$50 as assembled — found at the Byonics web site. Make sure to get the case if you don’t have one, as well as the gender changer / null modem adapter, so you can program your TT3 with your computer. The TT3 is a neat little device. Make sure to download the .pdf instructions before you buy it, so you know what you’re getting. It is relatively easy to get up and running. Also make sure to download the configuration software, which is pretty easy to use, and the instructions are good. eham.net has a review of the TT3. Soldering small things isn’t my forte, so I got the assembled version. One neat little feature in particular — it has a primary and a secondary configuration, which can easily be switched with an inexpensive switch. This is great for us — one side is programmed with my callsign, and the other is programmed with my wife’s. We have a switch up front in the car to make it easy to flip back and forth between the two. Other folks might use it to have different beacon comments, or use flip smart beaconing on or off… but that feature certainly is useful!
For a GPS receiver, I went with a “blind” (no display screen) GPS — the Deluo™ GPS for PC/Laptop (GM-305, Serial-RS-232). (Make sure to get the right one — not the one for USB!) [This model is no longer available, but there are others…] It is small (essentially the same size at the TT3 case!), inexpensive, and truly plug and play. The only thing you have to do to it is give it about 5vDC of power, as it wouldn’t like 13.8 volts very much! This can be done in a variety of ways, but my solution was to go down to the local Radio Shack and find a DC power converter — they have several models ($15 or so), so you just have to choose one with the right voltage output and amperage capability. Then a female PS-2 (round) connector was wired up to the RadShack DC converter — making sure to get the + and – on the right pins! The Deluo GPS has 2 connectors on it — one to plug into your TinyTrak3 (normally it would plug into a serial port on a laptop), and a PS-2 male (like a keyboard or mouse plug) to plug into a computer keyboard or mouse port, which gives the GPS its 5vDC of power. All you do is plug both things in, and it works.
There are other modern SERIAL GPS units that would work fine as well, as long as they have standard NMEA output.
You’ll need a cable to go from the TinyTrak3 to the radio — wired up like a Kantronics KPC-3+, I believe — depending on your radio, of course.
For a radio for the mobile trackers, we use a Yaesu FT-1500M unit (which have a data port, making it easy) in one vehicle, and a GE MVS commercial rig in the other.
Here is a picture of a GE MVS running APRS. The TT3 is receiving power from the MVS (tan serial cable on the left from the radio). The GPS (black serial cable) is plugged in on the other side of the TT3. (In this picture, the GPS was not powered up, thus no green LED on the TT3.)
For the home station I-GATE, it is another GE MVS, a Kantronics KPC-3 (eham review) and UI-View-32 software (eham review), running on an Dell GX620 desktop. Right now, we have it running on the “alt freq” (APRS alternate frequency) of 144.340 MHz, which is used a bit here in the busy DFW area.
APRS is both fun and practical, since Sue (N5SUE) and I (N0RQ) can track each other when the other person goes somewhere. Oh, and when one of our daugthers (licensed) uses the car, we know where they are, too!
If you need a good primer on GPS (not APRS), please see Radio Shack’s A Guild to GPS.
73, Dave, N0RQ