[aprssig] smartbeacon fast rate

[Tom Russo]

On Fri, May 25, 2007 at 10:07:42AM -0400, we recorded a bogon-computron collision of the <mckeehan at mckeehan.homeip.net> flavor, containing:
> I picked the 60MPH for easy calculations :-)
> 
> I did not realize until I saw this note that corner pegging is disabled above
> the fast speed.

It isn't, at least not in Xastir.  Xastir disables corner pegging below the 
slow speed.

Above the high speed, the "min turn angle" is the turn threshold for corner
pegging.  Between high and low speeds, the turn threshold is adjusted by
the turn slope and speed (it is supposed to become less sensitive as speed
decreases, i.e. higher turn threshold).

It might be that other devices than xastir *do* disable corner pegging at
high speed, too.  On the hamhud site:

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

the pseudocode fragment shows corner pegging working at all speeds above
the low speed setting.  Xastir's implementation differs from this pseudo
code only in that bit about the turn threshold --- the pseudocode shows
turn_threshold always depending on speed, but xastir sets it to "turn_min"
when above high speed, and uses the formula in the pseudocode only when
between high and low speeds.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1 http://kevan.org/brain.cgi?DDTNM
"And, isn't sanity really just a one-trick pony anyway? I mean all you get is
 one trick, rational thinking, but when you're good and crazy, oooh, oooh,
 oooh, the sky is the limit!"  --- The Tick