For a long time I thought that APRS was pretty much a solution to a nonexistent problem. It provides position tracking, but how many times can you follow your buddies around on a map before that gets boring? It uses a 1200 baud packet radio protocol, but most packet has been dead for years. The only exceptions are a few DX cluster nodes and some emcomm stuff. And even at that, 1200 baud is slow when most any gear can run 9600 now. So, what’s the attraction?
My thoughts changed after tracking a high altitude balloon. APRS really proved itself invaluable in this endeavor. We were able to not only copy direct packets from the balloon, but also see the beacon packets on aprs.fi using a smart phone when we were out of range. This made recovering the payload much easier–of critical importance when there’s the potential for a high altitude to travel outside of state lines and beyond.
At some point the location beacons stop getting reported to the APRS-IS network if it gets out of range of a digipeater. The last two times it was when the balloon was still 2-3000 feet up. This prompted me to examine how many digipeaters were in my local area. I live directly between two fairly large cities. Indianapolis and Lafayette both have wide area digipeaters but there aren’t any local digi’s in my area. Just one I-gate in Lebanon. I thought it might be nice to set one up. This should help provide coverage for local passing motorists and may be of help to the local ARES team in the future. Just last fall we had a destructive tornado come through my county only 10 miles away!
I’ve done a lot of reading on different ways to setup digi’s and I decided to purchase an older Kenwood TM-D700. This dual band data radio will operate APRS on one VFO and also VHF or UHF FM phone on the other VFO simultaneously. This is different than many dual banders that will operate phone on both bands, but not data and phone at the same time. The added benefit is that I now have a handy radio in the house for repeater/simplex operation. It was easy to setup the APRS features and get the packets beaconing. Then I enabled it to digipeat local WIDE1-1 packets and saved this config to one of the Programmable Memories. Phase two involved taking the digi to the next level. I downloaded
aprsisce/32 on my spare laptop. I had to make a couple changes to the xml file and then it would operate as a digi. Then I changed the 700 to run as a KISS TNC and connected it to the laptop. This proved simple once I found correct straight through F/F serial cable. The 700 still has an old school DB9 male serial port so I didn’t have to construct a special serial cable with a mini DIN connector like the newer TM-D710 requires. After making all these changes I saved the config to another Programmable Memory channel. Now my digi can operate stand alone or with the laptop. Using the laptop is nice since it shows all the activity in the area and also handles APRS messaging.