[aprssig] smartbeacon fast rate

[Steve Bragg]

"Wes Johnston, AI4PX" <wes at kd4rdb.com> wrote:

> Nope... corner pegging is disabled when your speed is 
> highspeed...
> The pseudo code is missing the open curly bracket after the IF (speed
> > high_speed) line.... I'll see if I can dig around in the ham hud
> code and verify this though....
> This code says to me that if speed not 
> highspeed setting, set beacon
> rate based on speed/time, set the turn threshold and check for heading
> changes.

This isn't what I intended, and HamHUD II, the reference SmartBeaconing platform, isn't implemented this way.  The source code is available here:

http://www.hamhud.net/hh2/27004j_40mhz.zip

I have updated the SmartBeaconing page to reflect the HamHUD II code, and my intentions.

http://www.hamhud.net/hh2/smartbeacon.html

I wonder how many other platforms have implemented SmartBeaconing to disable corner-pegging at high speeds.  We truly need to create some kind of SmartBeaconing Working Group to iron out these kinds of misunderstandings.

Some may ask, "why corner-pegging at highway/interstate speeds?" SmartBeaconing is primarily about ensuring that dead reckoning works on mobile APRS trackers under changing conditions.  Corner-pegging provides an extra data point to a dead-reckoning APRS client when the mobile has the high-speed beacons set many miles apart.  Without this extra data point, dead-reckoning will fail on many interstate and federal highways, which have curves that change compass direction significantly in a short distance, at high speeds (for example, the West Virginia Turnpike).  

You might reply, "Yes, but you will know the direction when the next fast-speed beacon comes, and extra beacons cause QRM."  Fine.  Just set turn_slope to zero, and the turn threshold won't be adjusted for speed.  Now only corners that cross the fixed turn_min threshold will generate a corner beacon.   

Defaults are up to the implementer.  But please don't implement SmartBeaconing in a way that prevents highway corner-beaconing.

73,

Steve Bragg KA9MVA
SmartBeaconing co-author