Newcomers to APRS may have read the term SmartBeaconing but not yet considered how this feature can enhance the track display. This evening I made one of those meandering, punching holes-in-the-sky flights where we just tool around immersed in the incredible privilege of seeing the earth from our hand-built aircraft. After flying north of DCU and over my neighborhood in Athens, I wandered up past the Tennessee state line, descended to less than 1000' AGL and flew along the Elk River. Not only was the setting sun a magnificent spectacle, but the APRS path traced on the map nicely demonstrates the difference between standard, one-minute beacons and the tight turns that can be drawn when the SmartBeaconing algorithm kicks in. Here is the flight:
Smartbeaconing senses via the GPS data stream when the aircraft changes heading in a short period of time and begins drastically reducing the interval between beacons. It is first evident shortly after departure from 18 at DCU as the plane was flown in a 180 back to the north to downwind. It is next apparent shortly after overflying Ardmore as I crossed I-65, joined the Elk and began making tight turns to follow the course of the river. Notice how the beacon dots get very close together when the plane is making sharp turns, and when straight flight is resumed the beacons return to the standard 60 second interval. The multiple beacons in the turns allow the track to be drawn in a smooth arc on the map and results in a very accurate display of the plane's actual location during the flight. If Smartbeaconing was not available, the tight turns would not appear and the track would be drawn as a more or less straight line.
The software in the Micro-Trak 8000 (and Micro-Trak 300) is configurable to whatever sensitivity of Smartbeaconing the operator desires. The desire for smooth arcs on the map needs to be balanced against being courteous and not transmitting more beacons than necessary.
The portion of the flight following the river was flown in a valley (notice the depiction of terrain on the map) and no more than 800' AGL. The robust power of the MT 8000 was more than enough to flawlessly hit a digipeater 50 miles away even at such low altitude while maneuvering in tight turns. This is another case where the advantage of an external antenna (1/4 wave whip on belly of plane in my case) is aptly demonstrated.
SmartBeaconing 101
Linear Mode
