Program Update interval & GeniusBeaconing

Lynn Deffenbaugh


I've extended on the concept of SmartBeaconing (TM by the HamHud developers, google it to find out) and call it Genius Beaconing. You can configure the parameters via the Configuration dialog and clicking on the big Genius button. It offers the following parameters:

Min Time - Minimum time between beacons in seconds (driving a circle)
Max Time - Maximum time between beacons in minutes (sitting still)

Bearing Change - Beacon if bearing changes by this many degrees (or more)
Forecast Error - in 0.10 miles (see discussion below)
Max Distance - In 0.10 miles (see discussion below)

The last two parameters are what makes up my Genius Beaconing. APRSISCE keeps track of what was sent in the most recent beacon, particularly the speed and bearing component. If an outside observer was to extrapolate the last position by the speed and bearing for the time since the beacon, they would think you were somewhere. The local GPS knows where you actually are. When the difference between these two points is more than the Forecast Error, a beacon is generated. The forecast position is shown in the circle by that little red dot that moves outwards from the center. When it reaches the circle, the beacon is generated. This parameter will tend to generate beacons for slight turns that don't trigger the Bearing Change as well as generating beacons when your speed changes (faster or slower) by a substantial amount.

Because the forecast error won't generate beacons in steady non-turning motion, there's also the Max Distance parameter. Even if the forecast error is keeping pretty close to where you actually are, if you've traveled more than the Max Distance, a beacon will be generated anyway.

When you're sitting still, the Max Time applies. This is designed to be very long just to keep the system current while you're parked.

The Min Time is used to prevent lots of small changes (like driving in circles) from triggering a bunch of updates. APRSISCE will hold off any beacons for at least this time after a beacon was last sent. It shows this in one of the small red lines in the APRS OK box at the top center of the screen.

There are actually three small color bars at the bottom of the box above the top edge of the circle. These three bars show (not sure which is which right now, but if you watch them, you'll soon see which is which):

1) Time since last reception from APRS-IS. This extends from left to right until it reaches the configured Quiet Time maximum at which point APRSISCE will force a disconnect on the assumption that the connection has died in a non-detectable fashion. This is the bar that disappears the instant the stations list scrolls with a new update.

2) Transmit "Pressure". Given the different parameters that can trigger a beacon, APRSISCE shows this bar to give you an idea how long it will be until the next beacon. The line below APRS OK shows which parameter is reaching what percentage of threshold currently driving towards a beacon. This bar grows from left to right and disappears when a beacon is actually sent.

3) Min Time. This bar counts down from right to left as APRSISCE is enforcing the Min Time configuration. Even if the Pressure exceeds 100%, APRSISCE will not issue a beacon until this bar disappears to the left. This is the bar that appears suddenly red and then shrinks down through yellow to green until it disappears until the next beacon.

So, you can tweak the Max Time and Forecast/distance parameters to generate more beacons, but I'd encourage you to consider the effects on APRS-IS and what you're actually gaining by transmitting more frequently, especially if you are having your beacons gated to RF. Once you inform the observers that they can rely on your speed and bearing and elapsed time to place you within X (Forecast Error) miles of where you actually are, you probably don't need to beacon any faster.

The only parameter I sometimes think about decreasing is the Max Time to something like 10 minutes while parked instead of the 30 minutes that mine is currently set to (I don't remember what the defaults are).

Hopefully this answers your question and gives you what you need to know.

Lynn (D) - KJ4ERJ-12 - Watch my bike track tomorrow morning (hopefully)

David Shrum wrote:

Lynn KJ4ERJ,

Maybe I havent paid enough attention but Ill ask anyway, Im wondering if we (the user) can change the interval the program updates while we are using it. The reason I ask there has been a couple of times I was tracking a user (from my home computer) and noticed that it seem like there is a randomness to the updates; sometimes itll update 2 or 3 times within a short distance like when you would be slowing down for a turn or accelerating away from a turn but if you are on a mostly strait road it seems to take much longer for the updates. Im aware we can force an update but thats not what Im talking about.


Dave N8PU