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Re: [tracker2] Smartbeaconing settings T2-135

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  • James Ewen
    ... 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
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      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
    • James Ewen
      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
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        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
      • 'Scott Miller'
        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
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          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

        • James Ewen
          ... 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
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            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
          • 'Scott Miller'
            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
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              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

            • Bob Burns W9RXR
              ... Where have you posted this revised manual? Bob...
              Message 6 of 18 , Jun 23, 2007
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                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...
              • Keri Morgret
                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
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                  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...
                • Keith VE7GDH
                  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
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                    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!"
                  • Bob Burns W9RXR
                    ... Thanks, Keith. That is a more current manual than the one I had. Bob...
                    Message 9 of 18 , Jun 23, 2007
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                      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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