## Re: [tracker2] Smartbeaconing settings T2-135

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• ... Oooh, missed that little tid-bit before... I thought I read that it used km/h as the native units. This brings up 2 questions... (the second is a multipart
Message 1 of 18 , Jun 15, 2007
On 6/15/07, Scott Miller <scott@...> wrote:

> A quick note on the speed settings - as I think I've mentioned before, these are
> expressed in rather arbitrary units used internally in the tracker (32
> centimeters/second, if I recall).

Oooh, missed that little tid-bit before... I thought I read that it
used km/h as the native units.

This brings up 2 questions... (the second is a multipart question though)

1) Can you confirm the actual velocity?

2) Why use this as a unit, how is it derived, and would be easy to
tweak the value to match up to either km/h or mph?

> To convert from miles per hour, multiply by 1.397.
> To convert from kilometers per hour, multiply by 0.868.

Okay, that means if we want the high speed threshold to be 100 km/h
(60 mph) then we should enter 87 into the Tracker's high speed
parameter.

> I was trying to figure out a suitably efficient way to do the conversion in the
> tracker,
> It's not something that should be changed very often, and I don't want to take up
> a ton of space with unnecessary code.

Can you change 32 to 28 easily? That would make it line up fairly
closely to km/h. This really depends on the answers to question #2
above.

James
VE6SRV
• In light of my new found knowledge... So to set the unit up to the recommended settings on the APRS Wiki, use the commands SMARTBCON 7 87 1800 30 15 INTERVAL
Message 2 of 18 , Jun 15, 2007
In light of my new found knowledge...

So to set the unit up to the recommended settings on the APRS Wiki,
use the commands

SMARTBCON 7 87 1800 30 15
INTERVAL 180

This will set the OpenTracker low speed to 8 km/h (5 mph) and high
speed threshold to 100 km/h (62 mph).

James
VE6SRV
• I updated the manual and included the conversion factors and added a table. As for why they re used, it originally comes from the fact that the OpenTRAC
Message 3 of 18 , Jun 18, 2007
I updated the manual and included the conversion factors and added a table.

As for why they're used, it originally comes from the fact that the OpenTRAC protocol uses centimeters/second for speed, and that's how the OpenTracker stores the speed internally.  The profile switch and SmartBeaconing settings are 8-bit values, so it shifts the speed right by 5 bits (dividing it by 32) to give it a useful range of values.

It'll probably stay that way for now, since the Garmin binary protocol uses meters/second anyway.  There are actually a lot of these weird units in the configuration parameters, you just don't normally see them because the config program hides the conversions.

Scott

From: tracker2@yahoogroups.com [mailto:tracker2@yahoogroups.com] On Behalf Of James Ewen
Sent: Friday, June 15, 2007 5:59 PM
To: tracker2@yahoogroups.com
Subject: Re: [tracker2] Smartbeaconing settings T2-135

On 6/15/07, Scott Miller <scott@opentrac. org> wrote:

> A quick note on the speed settings - as I think I've mentioned before, these are
> expressed in rather arbitrary units used internally in the tracker (32
> centimeters/ second, if I recall).

Oooh, missed that little tid-bit before... I thought I read that it
used km/h as the native units.

This brings up 2 questions... (the second is a multipart question though)

1) Can you confirm the actual velocity?

2) Why use this as a unit, how is it derived, and would be easy to
tweak the value to match up to either km/h or mph?

> To convert from miles per hour, multiply by 1.397.
> To convert from kilometers per hour, multiply by 0.868.

Okay, that means if we want the high speed threshold to be 100 km/h
(60 mph) then we should enter 87 into the Tracker's high speed
parameter.

> I was trying to figure out a suitably efficient way to do the conversion in the
> tracker,
> It's not something that should be changed very often, and I don't want to take up
> a ton of space with unnecessary code.

Can you change 32 to 28 easily? That would make it line up fairly
closely to km/h. This really depends on the answers to question #2
above.

James
VE6SRV

• ... I figured as much with the 32 value in there. If it were simply a count you could stop early and come close to km/h. With the simple math derived from a
Message 4 of 18 , Jun 18, 2007
On 6/18/07, Scott Miller <scott@...> wrote:

> As for why they're used, it originally comes from the fact that the OpenTRAC
> protocol uses centimeters/second for speed, and that's how the OpenTracker
> stores the speed internally. The profile switch and SmartBeaconing settings are
> 8-bit values, so it shifts the speed right by 5 bits (dividing it by 32) to give it a
> useful range of values.

I figured as much with the 32 value in there. If it were simply a
count you could stop early and come close to km/h. With the simple
math derived from a right shift operation, we'll learn to live with
it.

Thanks again Scott...

James
VE6SRV
• There s a lot of that base 2 integer math in there. The discriminator for the OT1+ is just a bunch of shifts and adds. The arctangent function uses floating
Message 5 of 18 , Jun 18, 2007
There's a lot of that base 2 integer math in there.  The discriminator for the OT1+ is just a bunch of shifts and adds.  The arctangent function uses floating point, but it still cheats with a lookup table and multisegment linear approximation.  Makes me wish I'd paid attention in math class.  Of course, when I wasn't paying attention in math class it was usually because I was sketching out embedded system designs in my notebook...

Anyway, it's these issues with unit conversion that have kept me from implementing the profile switch configuration in the command line interface.  Someday soon I'm going to  have to figure out how I want to do that.

Scott

From: tracker2@yahoogroups.com [mailto:tracker2@yahoogroups.com] On Behalf Of James Ewen
Sent: Monday, June 18, 2007 4:49 PM
To: tracker2@yahoogroups.com
Subject: Re: [tracker2] Smartbeaconing settings T2-135

On 6/18/07, Scott Miller <scott@opentrac. org> wrote:

> As for why they're used, it originally comes from the fact that the OpenTRAC
> protocol uses centimeters/ second for speed, and that's how the OpenTracker
> stores the speed internally. The profile switch and SmartBeaconing settings are
> 8-bit values, so it shifts the speed right by 5 bits (dividing it by 32) to give it a
> useful range of values.

I figured as much with the 32 value in there. If it were simply a
count you could stop early and come close to km/h. With the simple
math derived from a right shift operation, we'll learn to live with
it.

Thanks again Scott...

James
VE6SRV

• ... Where have you posted this revised manual? Bob...
Message 6 of 18 , Jun 23, 2007
At 03:11 PM 6/18/2007, 'Scott Miller' wrote:
>I updated the manual and included the conversion factors and added a table.

Where have you posted this revised manual?

Bob...
• I don t know where Scott posted it, but a FYI that he s been out of town without his computer for a couple of days. He ll be back later today, but might be a
Message 7 of 18 , Jun 23, 2007
I don't know where Scott posted it, but a FYI that he's been out of
town without his computer for a couple of days. He'll be back later
today, but might be a little buried in email. But it was worth it, if
I can speak for him -- readers in Silicon Valley will know what I'm
talking about when I saw we went over to the Geek Golden Triangle
area in Sunnyvale. Halted, Weird Stuff, Action Computers, Fry's, and
HRO. And missed a couple of other places only because they had already closed.

Have a great field day everyone.

Keri

At 09:18 AM 6/23/2007, you wrote:
>At 03:11 PM 6/18/2007, 'Scott Miller' wrote:
> >I updated the manual and included the conversion factors and added a table.
>
>Where have you posted this revised manual?
>
>Bob...
• Bob W9RXR wrote... ... Is it the T2-135 manual that you are looking for? Scott referred to a table and conversion factors which seem to appear in this manual.
Message 8 of 18 , Jun 23, 2007
Bob W9RXR wrote...

> Where have you posted this revised manual?

Is it the T2-135 manual that you are looking for? Scott referred to a table
and conversion factors which seem to appear in this manual.
www.n1vg.net/opentracker/t2-135_manual.pdf

73 es cul - Keith VE7GDH
--
"I may be lost, but I know exactly where I am!"
• ... Thanks, Keith. That is a more current manual than the one I had. Bob...
Message 9 of 18 , Jun 23, 2007
At 05:00 PM 6/23/2007, Keith VE7GDH wrote:

>Is it the T2-135 manual that you are looking for? Scott referred to
>a table and conversion factors which seem to appear in this manual.
>www.n1vg.net/opentracker/t2-135_manual.pdf

Thanks, Keith. That is a more current manual than the one I had.

Bob...
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