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[aprssig] A wish for the next TM-D710A firmware update

Wes Johnston, AI4PX wes at ai4px.com
Tue May 20 02:52:48 UTC 2008


Hmmm... just a difference of opinion.   I wrote a program a few years ago to
emulate smart beaconing on my laptop.  It showed me when it wanted to beacon
and for what reason.  I drove around watching it and tweaking it to provide
a useful track but not qrm too much.... and so starts my explaination....

There seems to be much misunderstanding about how to optimize smart
beaconing.... and i'm sure there are many opinions... everyone has one,
right?

 Smart beaconing has three modes.... slow(time triggered) , meduim (turn
triggered), and fast (distance triggered)

For driving a car, I prefer the following behavors....

When I am parked beacon at a reduced rate.  This is time triggered.

When I _intentionally_ turn off a highway or main road I want a beacon to
mark my turn.... This is turn triggered.

Once I reach a speed that is too high to turn (let's say 45mph / 70kph ) , I
want a bread crumb every mile or two.  I do not want to corner peg the long
slow turns on the highway or interstate.  The home audience can figure out
on their own that there is no opportunity for me to exit the interstate on
that last long slow turn.  The most aggrivating is the slow S turn... the
road slowly veers to the left then back to the right.  If your tracker is
setup improperly, it will beacon twice 1/2 a mile apart.... not what we
want.

I tend to run fast beacon speed just below the lowest speed I "cruise" at on
the interstate or main highway.  If you set it too high (ie 90mph), smart
beaconing uses turns to trigger all the time.  You will never enter the
distance triggered mode.  As I said this is sometimes troublesome on long
sweeping turns on the interstate.

The long slow turn is also an issue when you don't quite break out of the
meduim speed mode and into fast speed beaconing... the turn threshold
narrows up as speed increases thus it will trigger on a 10° snake in the
road at 60mph , and won't trigger on a 45° turn in a parking lot (if the
turn slope setting is wrong).  Not to keep beating this horse, but you want
to set the turn min so that it triggers on huge turns when you are moving 5
to 10mph, but don't set the turnslope so aggressive that it narrows up too
quickly and triggers on 1 degree turns at 30mph. (exagerated to make a
point).

As I said, in my opinion, ideally you want to run turn triggered (medium
speed beacon mode) when you are a)moving, b)but at a speed that is slightly
below the speed you would cruise at.  At any speed that you don't consider
it safe to turn off the highway, make that your fast beacon speed.  Then
adjust the time to beacon every mile or two at that speed.

The thing to remember is that we want quality of positions above quantity.
Turn triggered beacons provide excellent info.  But we do not need to neatly
trace the exact contours of the interstate or that winding two lane road
from the suburbs into the city.  But it is nice to know which street I
turned down in a residential neighborhood when there are streets every 200
feet.

Wes

On Mon, May 19, 2008 at 10:02 PM, Rory Burke <rory at burke.ac> wrote:

> I'd like to see the High Speed parameter for SmartBeaconing increased from
> 70 to something higher - at least 90, and the Fast Rate increased to
> something like 300 seconds.  If you spend some time analyzing the
> SmartBeaconing algorithm you will find that the real beauty of it is that
> you can decided how far apart in distance traveled you want to send beacons.
>  But the High Speed limit defeats that thinking if it is lower than the
> highest speed you travel.  You see, once you reach the High Speed, the
> beacons always come at the Fast Rate.  That means that once you are
> exceeding the High Speed the distance traveled between beacons becomes
> longer and longer.  Here's an example:
>
> Low Speed = 2 mph
> High Speed = 60 mph
> Slow Rate = 30 minutes
> Fast Rate = 60 seconds
>
> You will send a beacon at one mile intervals once you exceed 2 mph until
> you reach 60 mph.  But if you are in one of those places where 75 mph is
> safe and legal, you'll be sending beacons at 1-1/4 mile intervals.
>
> Now take a look at this example:
>
> Low Speed = 2 mph
> High Speed = 90 mph
> Slow Rate = 30 minutes
> Fast Rate = 40 seconds
>
> In this example you will send a beacon at one mile intervals until you
> reach 90 mph;  a speed that is not normally safe or legal - at least in most
> places in the US.  In this case, you travel 1/8 mile for every 5 seconds of
> Fast Rate.  So, if you wanted your beacons 2 miles apart you'd select a Fast
> Rate of 80 seconds, and if you wanted 5 mile beacon spacing you'd select a
> Fast Rate of 200 seconds.  The distance traveled between beacons would not
> change from what you've set unless you exceed 90 mph.
>
> I am aware that most folks who use SmartBeaconing are still in the "how
> often am I sending a beacon" mindset rather than the "how far do I travel
> between beacons" mindset.  I believe that if folks would take a hard look a
> the algorithm, and read the SmartBeaconing description on the HamHUD web
> site they would see that the real intent is the "how far" mindset.  Please
> note that the third paragraph of the SmartBeaconing description has an
> error.  It omits the fact that if the High Speed threshold is exceeded, then
> the positions are sent at the Fast Rate no matter how much faster you
> travel.  Here's a link to the description:
>
> http://www.hamhud.net/hh2/smartbeacon.html
>
> These changes would take a fairly simple firmware tweak the next time
> there's an update.
>
> 73 - Rory - K5MBH
>
> rory at burke.ac     k5mbh at arrl.net
>
> Where am I now?
> http://map.findu.com/k5mbh-9
>
>
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>



-- 
Wes
---
Where there's silence, there is no Hope.
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