[Xastir] Position rate question

[James Ewen]

> >  I running mobile in an 18-wheeler as KD5XB-11.  SmartBeaconing is enabled,
> >  and set for high speed of 240 MPH with a beacon rate at that speed of once
> >  every 75 seconds.  (I calculate that out to one position report every 5
> >  miles.)  When below the low speed threshold of 2 MPH, I should be getting a
> >  positinb report every 30 minutes.

When do you plan on getting your 18 wheeler up to 240 MPH? If you want
one position report every 5 miles at highway speed, why not set your
high speed to 60 MPH, and high rate to 300. When you exceed the high
speed, your beacon rate will not go less than 300 seconds. I guess you
will always beacon every 5 miles, where my settings beacon closer than
every 5 miles when exceeding the high speed rate.

Bring your low speed threshold up to about 5 MPH. This is most likely
the source of the numerous zero speed triggered reports.

> >       When I right-click on my own station and get station info, the list of
> >  recent packets received fills up really quickly with 0 MPH reports.  For
> >  instance, I've been sitting here in Shreveport for about 45 minutes, and the
> >  entire list is made up of 0 MPH reports.  I really expected to see only 1 or
> >  2.
> >
> >       So -- is this something I have mis-configured?  A bug?  Or am I
> >  interpreting this list incorrectly?

Probably a combination of the low speed threshold being set too low,
and possibly a logic problem in the programming.

> I, too, have had trouble with the smartbeaconing parameters.  A long
> time ago I saw exactly the same behavior you see, and disabled
> smartbeaconing at that time.
>
> Near as I can tell, somehow the random fluctuations of GPS fixes seem to
> allow Xastir to beacon very, very often when stationary if you don't set
> your smartbeaconing just so.  But I never spent any time figuring out why.

CornerPegging watches for changes in direction that exceed the
threshold. Random position changes due to GPS wandering look like you
are making changes in your direction of travel.

In the HamHUD, the first thing we look for is if the current speed is
lower than the low speed threshold. If it is, we set the beacon rate
to the low rate. We never look at any other parameters after that.
Changes in direction only get processed if we are exceeding the low
speed threshold.

Curt, since you are so intimate with the code, can you point me at the
relevant section of Xastir code that deals with SmartBeaconing and
CornerPegging? I'll have a look at it to see if how the logic is
processed.


In the mean time, there are a couple pages describing SmartBeaconing
and CornerPegging on the APRS Wiki...
http://info.aprs.net/wikka.php?wakka=SmartBeaconing

James
VE6SRV