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Hello Gordon,<br>
<br>
<div class="moz-cite-prefix">On 13/10/2014 20:45, Gordon Taylor
wrote:<br>
</div>
<blockquote
cite="mid:001401cfe6ca$6a0ea280$3e2be780$@thetaylorclub.com"
type="cite">
<pre wrap="">Thanks for the push Ian, I am well aware of theTT3 settings and thought I
had it all set up correctly. I changed a setting last weekend and now it
beacons at the correct interval when stationary. What setting was that you
may well ask.
I had the low speed value set at 0 in the smart beaconing settings.
Changing this to 2 and the tracker beacons every 900 seconds when stationary
which is correct.
I wonder if there is an issue with the algorithm or some other reason not to
use 0 for a slow speed setting. I see from the manual the algorithm has the
following line;
IF (speed <slow_speed)
beacon_rate = slow_rate
With a slow speed value of 0 it is not possible to get below this. Maybe
this is why</pre>
</blockquote>
It does depend on the implementation, but if it did literally what
is said above, then speed reported by the GPS will never be below
zero.<br>
<br>
Byon says in his manual:<br>
<br>
"<span style="font-family:
TT15Ct00;font-size:11pt;color:rgb(0,0,0);font-style:normal;font-variant:normal;">The
SmartBeaconing algorithm basically says that if the speed is
faster than the Fast Speed setting, position reports will<br>
<span style="font-family:
TT15Ct00;font-size:11pt;color:rgb(0,0,0);font-style:normal;font-variant:normal;">be
sent at the Fast Rate. If the speed is slower than then Slow
Speed, position reports will be sent at the Slow Rate. If<br>
<span style="font-family:
TT15Ct00;font-size:11pt;color:rgb(0,0,0);font-style:normal;font-variant:normal;">the
speed is in between, position reports will be scaled from the
Fast Rate. So if the speed is ½ of the Fast Speed, the<br>
<span style="font-family:
TT15Ct00;font-size:11pt;color:rgb(0,0,0);font-style:normal;font-variant:normal;">transmissions
will be sent at ½ the Fast Rate frequency (i.e., if the Fast
Rate was 90 seconds, it would send every 180<br>
<span style="font-family:
TT15Ct00;font-size:11pt;color:rgb(0,0,0);font-style:normal;font-variant:normal;">seconds.)
"<br>
<br>
</span></span></span></span></span>
<p><font face="Helvetica, Arial, sans-serif"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><span style="font-size: 11pt; color: rgb(0, 0, 0);
font-style: normal; font-variant: normal;"><span
style="font-size: 11pt; color: rgb(0, 0, 0); font-style:
normal; font-variant: normal;"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal;
font-variant: normal;"><span style="font-size: 11pt;
color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;">If I was the programmer asked to literally
implement this (even though it has issues), a
compliant approach would be<br>
if current speed < slow speed setting:<br>
use slow beacon period;<br>
else<br>
if current speed > high speed setting:<br>
use high speed beacon period;<br>
else<br>
period = high speed beacon period * high speed
setting / current speed.<br>
</span></span></span></span></span></font></p>
<p><font face="Helvetica, Arial, sans-serif"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><span style="font-size: 11pt; color: rgb(0, 0, 0);
font-style: normal; font-variant: normal;"><span
style="font-size: 11pt; color: rgb(0, 0, 0); font-style:
normal; font-variant: normal;"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal;
font-variant: normal;"><span style="font-size: 11pt;
color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><br>
The important thing here is the order or priority of
these ifs. Though you reported it never beaconed, it
just might have been an extremely long time.<br>
</span></span></span></span></span></font></p>
<p><font face="Helvetica, Arial, sans-serif"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><span style="font-size: 11pt; color: rgb(0, 0, 0);
font-style: normal; font-variant: normal;"><span
style="font-size: 11pt; color: rgb(0, 0, 0); font-style:
normal; font-variant: normal;"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal;
font-variant: normal;"><span style="font-size: 11pt;
color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;">Is the algorithm good? Well, the period vs
speed function is discontinuous but that is probably
of little consequence.<br>
</span></span></span></span></span></font></p>
<p><font face="Helvetica, Arial, sans-serif"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><span style="font-size: 11pt; color: rgb(0, 0, 0);
font-style: normal; font-variant: normal;"><span
style="font-size: 11pt; color: rgb(0, 0, 0); font-style:
normal; font-variant: normal;"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal;
font-variant: normal;"><span style="font-size: 11pt;
color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;">Is it a good implementation? Probably not...
but most things about APRS have shortcomings. Just
don't set the slow speed value to zero. Perhaps the
firmware and configuration program should enforce some
limits so users don't inadvertently disable the thing.<br>
</span></span></span></span></span></font></p>
<p><font face="Helvetica, Arial, sans-serif"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><span style="font-size: 11pt; color: rgb(0, 0, 0);
font-style: normal; font-variant: normal;"><span
style="font-size: 11pt; color: rgb(0, 0, 0); font-style:
normal; font-variant: normal;"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal;
font-variant: normal;"><span style="font-size: 11pt;
color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;">Save someone needing to comment, I know this
will be far deeper than most people might want to see,
but Gordon, they shouldn't stop you from understanding
why it probably did what it did.</span></span></span></span></span></font></p>
<p><font face="Helvetica, Arial, sans-serif"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><span style="font-size: 11pt; color: rgb(0, 0, 0);
font-style: normal; font-variant: normal;"><span
style="font-size: 11pt; color: rgb(0, 0, 0); font-style:
normal; font-variant: normal;"><span style="font-size:
11pt; color: rgb(0, 0, 0); font-style: normal;
font-variant: normal;"><span style="font-size: 11pt;
color: rgb(0, 0, 0); font-style: normal; font-variant:
normal;"><br>
73<br>
Owen</span></span></span></span></span></font></p>
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