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Re: TRACKING

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  • johansea
    Gday Nick The best thing i have found is every scope is different :-) That may not help you, but the fact is the tolerances in the drivetrains and gears of the
    Message 1 of 23 , Dec 1, 2011
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      Gday Nick

      The best thing i have found is every scope is different :-)
      That may not help you, but the fact is the tolerances in the
      drivetrains and gears of the Meade scopes means some will be
      good and some will be not so good.
      Currently, programs like PEMPro are your best bet to get a best fit model for an individual scope, but non periodic errors will still apply, no matter how good the "periodic" bits are.
      During playback, there are also other "timing" problems
      associated with how PEC corrections get applied,
      when mixed with constant guiding corrections.
      The TDM unit looks like it could eliminate a lot of this
      if it ran when PEC was off, but i'm not sure yet.
      I now believe there is actually a much better way to send guide adjusts for the LX200s, but if used in current firmwares, it wont work for "guided" PEC training, but would work with guiding during playback.
      I will post on this in a few days when i have looked at it a bit deeper.

      Andrew Johansen Melbourne Australia



      --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@...> wrote:
      >
      > Andrew, with all the work you've done on PEC, what have you been able to achieve in the way of corrected tracking error?
      >
      > Nick
      >
      > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
      > >
      > > Gday All
      > >
      > > I haven't read the full specs of the new V2 TDM unit, but it appears to drive the scope corrections via the autoguider port in the scope, NOT by direct access to the motors.
      > > As such, it is at the mercy of the LX200 processing routine timings
      > > as to when and how it gets applied,
      > > and how the scope restarts after guide corrections stop.
      > > The scope only checks the status of the ST4 pins 225x per second, so thats the best granularity you can get.
      > > As part of rewriting the PEC, i have been studying the way the motor control gets handled, and its messy.
      > > I'm not 100% sure how it would work with a TDM unit
      > > but i believe that as long as the system "constantly" sends guide commands, then it should track OK and PEC would be OFF.
      > > The reason for this is there appears to be a 1sec delay after any moves are received before the system actually reapplies the newly calculated base tracking rates.
      > > Thus, ( an i havent tested this yet ), if guide commands come in at a higher than 1 per second rate, the underlying tracking rates will get calculated "but not applied".
      > >
      > > In Polar, with PEC OFF, this isn't a problem, but with PEC ON,
      > > it may result in PEC not getting applied anyway.
      > > End guess, Guiding this way at 5Hz "should" work in the CPU end of the things, but not sure if there are any limits in the motor cards.
      > > I would need to set up a test rig to check that, and thats not something i can do in the next week or so.
      > >
      > >
      > > Andrew Johansen Melbourne Australia
      > >
      > >
      > >
      >
    • John
      Hi Dick Well there was a very positive review of the TDM in the October S&T when fitted to a Classic LX200 16in. The author was surprised it worked so well in
      Message 2 of 23 , Dec 1, 2011
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        Hi Dick
        Well there was a very positive review of the TDM in the October S&T when fitted to a Classic LX200 16in. The author was surprised it worked so well in the classic with its fixed X2 Guide Rate. So in theory at least it should work better with a GPS/ACF as apparently it is desirable to adjust the guide rate in the range 0.15X to 0.5X to optimise performance.
        It seems strange that none of the many members of this forum have fitted it and come forward with their experience. Of course in the S&T 16in model it could be fitted inside the base which removed one disadvantage.
        Will look forward to hearing the results of your tests in due course.
        Regards
        John
      • paizisn
        Andrew, I was hoping you would give us a number. What s the best PE you ve achieved? Nick
        Message 3 of 23 , Dec 1, 2011
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          Andrew, I was hoping you would give us a number. What's the best PE you've achieved?

          Nick

          --- In LX200GPS@yahoogroups.com, "johansea" <johansea@...> wrote:
          >
          > Gday Nick
          >
          > The best thing i have found is every scope is different :-)
          > That may not help you, but the fact is the tolerances in the
          > drivetrains and gears of the Meade scopes means some will be
          > good and some will be not so good.
          > Currently, programs like PEMPro are your best bet to get a best fit model for an individual scope, but non periodic errors will still apply, no matter how good the "periodic" bits are.
          > During playback, there are also other "timing" problems
          > associated with how PEC corrections get applied,
          > when mixed with constant guiding corrections.
          > The TDM unit looks like it could eliminate a lot of this
          > if it ran when PEC was off, but i'm not sure yet.
          > I now believe there is actually a much better way to send guide adjusts for the LX200s, but if used in current firmwares, it wont work for "guided" PEC training, but would work with guiding during playback.
          > I will post on this in a few days when i have looked at it a bit deeper.
          >
          > Andrew Johansen Melbourne Australia
          >
          >
          >
          > --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@> wrote:
          > >
          > > Andrew, with all the work you've done on PEC, what have you been able to achieve in the way of corrected tracking error?
          > >
          > > Nick
          > >
          > > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
          > > >
          > > > Gday All
          > > >
          > > > I haven't read the full specs of the new V2 TDM unit, but it appears to drive the scope corrections via the autoguider port in the scope, NOT by direct access to the motors.
          > > > As such, it is at the mercy of the LX200 processing routine timings
          > > > as to when and how it gets applied,
          > > > and how the scope restarts after guide corrections stop.
          > > > The scope only checks the status of the ST4 pins 225x per second, so thats the best granularity you can get.
          > > > As part of rewriting the PEC, i have been studying the way the motor control gets handled, and its messy.
          > > > I'm not 100% sure how it would work with a TDM unit
          > > > but i believe that as long as the system "constantly" sends guide commands, then it should track OK and PEC would be OFF.
          > > > The reason for this is there appears to be a 1sec delay after any moves are received before the system actually reapplies the newly calculated base tracking rates.
          > > > Thus, ( an i havent tested this yet ), if guide commands come in at a higher than 1 per second rate, the underlying tracking rates will get calculated "but not applied".
          > > >
          > > > In Polar, with PEC OFF, this isn't a problem, but with PEC ON,
          > > > it may result in PEC not getting applied anyway.
          > > > End guess, Guiding this way at 5Hz "should" work in the CPU end of the things, but not sure if there are any limits in the motor cards.
          > > > I would need to set up a test rig to check that, and thats not something i can do in the next week or so.
          > > >
          > > >
          > > > Andrew Johansen Melbourne Australia
          > > >
          > > >
          > > >
          > >
          >
        • johansea
          Gday Nick How long is a piece of string? You want a number well one of my old logs shows i had about 50arcsec pkpk PE in my scope and i got it down to about
          Message 4 of 23 , Dec 1, 2011
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            Gday Nick

            How long is a piece of string?
            You want a number
            well one of my old logs shows i had about 50arcsec pkpk
            PE in my scope and i got it down to about +/-4 at best
            >>but it wasnt consistent<<.
            Ie in some areas it played back well and in others it didnt. This is due to non periodic errors in the way the worm interacts with the wormwheel.
            I have seen some results where people
            with very large raw data ( say PE > 50 )
            can correct it down to say +/- 2arcsec
            There are others with small raw PE ( say < 25 )
            that cant get much better than +/-5.
            It all comes down to how smooth "and" consistent the raw PE is, not how big it is to begin with.

            Andrew Johansen Melbourne Australia

            --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@...> wrote:
            >
            > Andrew, I was hoping you would give us a number. What's the best PE you've achieved?
            >
            > Nick
            >
            > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
            > >
            > > Gday Nick
            > >
            > > The best thing i have found is every scope is different :-)
            > > That may not help you, but the fact is the tolerances in the
            > > drivetrains and gears of the Meade scopes means some will be
            > > good and some will be not so good.
            > > Currently, programs like PEMPro are your best bet to get a best fit model for an individual scope, but non periodic errors will still apply, no matter how good the "periodic" bits are.
            > > During playback, there are also other "timing" problems
            > > associated with how PEC corrections get applied,
            > > when mixed with constant guiding corrections.
            > > The TDM unit looks like it could eliminate a lot of this
            > > if it ran when PEC was off, but i'm not sure yet.
            > > I now believe there is actually a much better way to send guide adjusts for the LX200s, but if used in current firmwares, it wont work for "guided" PEC training, but would work with guiding during playback.
            > > I will post on this in a few days when i have looked at it a bit deeper.
            > >
            > > Andrew Johansen Melbourne Australia
            > >
            > >
            > >
            > > --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@> wrote:
            > > >
            > > > Andrew, with all the work you've done on PEC, what have you been able to achieve in the way of corrected tracking error?
            > > >
            > > > Nick
            > > >
            > > > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
            > > > >
            > > > > Gday All
            > > > >
            > > > > I haven't read the full specs of the new V2 TDM unit, but it appears to drive the scope corrections via the autoguider port in the scope, NOT by direct access to the motors.
            > > > > As such, it is at the mercy of the LX200 processing routine timings
            > > > > as to when and how it gets applied,
            > > > > and how the scope restarts after guide corrections stop.
            > > > > The scope only checks the status of the ST4 pins 225x per second, so thats the best granularity you can get.
            > > > > As part of rewriting the PEC, i have been studying the way the motor control gets handled, and its messy.
            > > > > I'm not 100% sure how it would work with a TDM unit
            > > > > but i believe that as long as the system "constantly" sends guide commands, then it should track OK and PEC would be OFF.
            > > > > The reason for this is there appears to be a 1sec delay after any moves are received before the system actually reapplies the newly calculated base tracking rates.
            > > > > Thus, ( an i havent tested this yet ), if guide commands come in at a higher than 1 per second rate, the underlying tracking rates will get calculated "but not applied".
            > > > >
            > > > > In Polar, with PEC OFF, this isn't a problem, but with PEC ON,
            > > > > it may result in PEC not getting applied anyway.
            > > > > End guess, Guiding this way at 5Hz "should" work in the CPU end of the things, but not sure if there are any limits in the motor cards.
            > > > > I would need to set up a test rig to check that, and thats not something i can do in the next week or so.
            > > > >
            > > > >
            > > > > Andrew Johansen Melbourne Australia
            > > > >
            > > > >
            > > > >
            > > >
            > >
            >
          • paizisn
            Thank you. That s just the info I was looking for.
            Message 5 of 23 , Dec 1, 2011
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              Thank you. That's just the info I was looking for.



              --- In LX200GPS@yahoogroups.com, "johansea" <johansea@...> wrote:
              >
              > Gday Nick
              >
              > How long is a piece of string?
              > You want a number
              > well one of my old logs shows i had about 50arcsec pkpk
              > PE in my scope and i got it down to about +/-4 at best
              > >>but it wasnt consistent<<.
              > Ie in some areas it played back well and in others it didnt. This is due to non periodic errors in the way the worm interacts with the wormwheel.
              > I have seen some results where people
              > with very large raw data ( say PE > 50 )
              > can correct it down to say +/- 2arcsec
              > There are others with small raw PE ( say < 25 )
              > that cant get much better than +/-5.
              > It all comes down to how smooth "and" consistent the raw PE is, not how big it is to begin with.
              >
              > Andrew Johansen Melbourne Australia
              >
              > --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@> wrote:
              > >
              > > Andrew, I was hoping you would give us a number. What's the best PE you've achieved?
              > >
              > > Nick
              > >
              > > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
              > > >
              > > > Gday Nick
              > > >
              > > > The best thing i have found is every scope is different :-)
              > > > That may not help you, but the fact is the tolerances in the
              > > > drivetrains and gears of the Meade scopes means some will be
              > > > good and some will be not so good.
              > > > Currently, programs like PEMPro are your best bet to get a best fit model for an individual scope, but non periodic errors will still apply, no matter how good the "periodic" bits are.
              > > > During playback, there are also other "timing" problems
              > > > associated with how PEC corrections get applied,
              > > > when mixed with constant guiding corrections.
              > > > The TDM unit looks like it could eliminate a lot of this
              > > > if it ran when PEC was off, but i'm not sure yet.
              > > > I now believe there is actually a much better way to send guide adjusts for the LX200s, but if used in current firmwares, it wont work for "guided" PEC training, but would work with guiding during playback.
              > > > I will post on this in a few days when i have looked at it a bit deeper.
              > > >
              > > > Andrew Johansen Melbourne Australia
              > > >
              > > >
              > > >
              > > > --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@> wrote:
              > > > >
              > > > > Andrew, with all the work you've done on PEC, what have you been able to achieve in the way of corrected tracking error?
              > > > >
              > > > > Nick
              > > > >
              > > > > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
              > > > > >
              > > > > > Gday All
              > > > > >
              > > > > > I haven't read the full specs of the new V2 TDM unit, but it appears to drive the scope corrections via the autoguider port in the scope, NOT by direct access to the motors.
              > > > > > As such, it is at the mercy of the LX200 processing routine timings
              > > > > > as to when and how it gets applied,
              > > > > > and how the scope restarts after guide corrections stop.
              > > > > > The scope only checks the status of the ST4 pins 225x per second, so thats the best granularity you can get.
              > > > > > As part of rewriting the PEC, i have been studying the way the motor control gets handled, and its messy.
              > > > > > I'm not 100% sure how it would work with a TDM unit
              > > > > > but i believe that as long as the system "constantly" sends guide commands, then it should track OK and PEC would be OFF.
              > > > > > The reason for this is there appears to be a 1sec delay after any moves are received before the system actually reapplies the newly calculated base tracking rates.
              > > > > > Thus, ( an i havent tested this yet ), if guide commands come in at a higher than 1 per second rate, the underlying tracking rates will get calculated "but not applied".
              > > > > >
              > > > > > In Polar, with PEC OFF, this isn't a problem, but with PEC ON,
              > > > > > it may result in PEC not getting applied anyway.
              > > > > > End guess, Guiding this way at 5Hz "should" work in the CPU end of the things, but not sure if there are any limits in the motor cards.
              > > > > > I would need to set up a test rig to check that, and thats not something i can do in the next week or so.
              > > > > >
              > > > > >
              > > > > > Andrew Johansen Melbourne Australia
              > > > > >
              > > > > >
              > > > > >
              > > > >
              > > >
              > >
              >
            • Jason Ware
              You guys are focusing way too much on the magnitude of the PE. We used to hand guide 120 PE drives before the days of PEC. If you are around 10 or below that
              Message 6 of 23 , Dec 2, 2011
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                You guys are focusing way too much on the magnitude of the PE. We used
                to hand guide 120" PE drives before the days of PEC.

                If you are around 10" or below that is good enough. What matters is drive
                anomalies, tooth to tooth errors, drive roughness, etc.

                THE MEADE SCOPES ALL NEED TO BE FAST GUIDED. This is not
                a slam on the scopes. They use low cost gear trains and motors to, well,
                keep the cost low. There is a reason that "high end" mounts cost 2x what
                an entire Meade scope costs.

                I use an off axis guider, a Meade DSI pro II and maxim DL for guiding. I
                use 2" guide exposures, NO AO or TDM or magic dust and get SUB-ARC SECOND
                RMS tracking. Shoot 10 minute sub frames, reject about 20% and sigma
                combine.

                The only real problem I have is declination backlash and stiction. I overcome this
                with a slight misalignment and tweaking of the aggressiveness in Maxim DL.
                Declination balance is CRITICAL.

                Check my website for examples of what these wonderful imaging platforms
                can do.

                Here is my imaging train...

                http://galaxyphoto.com/jw_image_stack.jpg



                --
                -Jason Ware

                ---------------------------------------------------------
                VISIT MY ASTROPHOTOGRAPHY HOMEPAGE!!
                ASTRO IMAGES FOR DOWN-LOAD, TIPS, REPRINTS
                URL: http://www.galaxyphoto.com
                ---------------------------------------------------------
                My Other Hobby....High Power Rocketry
                URL: http://www.galaxyphoto.com/rockets.htm
                ----- Original Message -----
                From: paizisn
                To: LX200GPS@yahoogroups.com
                Sent: Thursday, December 01, 2011 12:51 PM
                Subject: [LX200GPS] Re: TRACKING



                Andrew, I was hoping you would give us a number. What's the best PE you've achieved?

                Nick

                --- In LX200GPS@yahoogroups.com, "johansea" <johansea@...> wrote:
                >
                > Gday Nick
                >
                > The best thing i have found is every scope is different :-)
                > That may not help you, but the fact is the tolerances in the
                > drivetrains and gears of the Meade scopes means some will be
                > good and some will be not so good.
                > Currently, programs like PEMPro are your best bet to get a best fit model for an individual scope, but non periodic errors will still apply, no matter how good the "periodic" bits are.
                > During playback, there are also other "timing" problems
                > associated with how PEC corrections get applied,
                > when mixed with constant guiding corrections.
                > The TDM unit looks like it could eliminate a lot of this
                > if it ran when PEC was off, but i'm not sure yet.
                > I now believe there is actually a much better way to send guide adjusts for the LX200s, but if used in current firmwares, it wont work for "guided" PEC training, but would work with guiding during playback.
                > I will post on this in a few days when i have looked at it a bit deeper.
                >
                > Andrew Johansen Melbourne Australia
                >
                >
                >
                > --- In LX200GPS@yahoogroups.com, "paizisn" <paizisn@> wrote:
                > >
                > > Andrew, with all the work you've done on PEC, what have you been able to achieve in the way of corrected tracking error?
                > >
                > > Nick
                > >
                > > --- In LX200GPS@yahoogroups.com, "johansea" <johansea@> wrote:
                > > >
                > > > Gday All
                > > >
                > > > I haven't read the full specs of the new V2 TDM unit, but it appears to drive the scope corrections via the autoguider port in the scope, NOT by direct access to the motors.
                > > > As such, it is at the mercy of the LX200 processing routine timings
                > > > as to when and how it gets applied,
                > > > and how the scope restarts after guide corrections stop.
                > > > The scope only checks the status of the ST4 pins 225x per second, so thats the best granularity you can get.
                > > > As part of rewriting the PEC, i have been studying the way the motor control gets handled, and its messy.
                > > > I'm not 100% sure how it would work with a TDM unit
                > > > but i believe that as long as the system "constantly" sends guide commands, then it should track OK and PEC would be OFF.
                > > > The reason for this is there appears to be a 1sec delay after any moves are received before the system actually reapplies the newly calculated base tracking rates.
                > > > Thus, ( an i havent tested this yet ), if guide commands come in at a higher than 1 per second rate, the underlying tracking rates will get calculated "but not applied".
                > > >
                > > > In Polar, with PEC OFF, this isn't a problem, but with PEC ON,
                > > > it may result in PEC not getting applied anyway.
                > > > End guess, Guiding this way at 5Hz "should" work in the CPU end of the things, but not sure if there are any limits in the motor cards.
                > > > I would need to set up a test rig to check that, and thats not something i can do in the next week or so.
                > > >
                > > >
                > > > Andrew Johansen Melbourne Australia
                > > >
                > > >
                > > >
                > >
                >





                [Non-text portions of this message have been removed]
              • paizisn
                Maybe so. I m on the steep end of the learning curve and appreciate any advice I can get. Nick P.
                Message 7 of 23 , Dec 2, 2011
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                  Maybe so. I'm on the steep end of the learning curve and appreciate any advice I can get.

                  Nick P.

                  --- In LX200GPS@yahoogroups.com, "Jason Ware" <jtw@...> wrote:
                  >
                  > You guys are focusing way too much on the magnitude of the PE.
                • johansea
                  Gday Jason ... Not me. ... Fully agree. Thats the point i have been trying to get across. ... Agree, but i think there are underlying bugs in the firmware here
                  Message 8 of 23 , Dec 2, 2011
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                    Gday Jason

                    --- In LX200GPS@yahoogroups.com, "Jason Ware" <jtw@...> wrote:
                    >
                    > You guys are focusing way too much on the magnitude of the PE.

                    Not me.

                    > What matters is drive
                    > anomalies, tooth to tooth errors, drive roughness, etc.

                    Fully agree. Thats the point i have been trying to get across.

                    > THE MEADE SCOPES ALL NEED TO BE FAST GUIDED.

                    Agree, but i think there are underlying bugs in the firmware here that means the results arent as good as they should be,
                    esp if PEC is ON and the guide rates are greater than 1Hz.

                    > The only real problem I have is declination backlash and stiction.

                    Can't help with the stiction, but there IS a bug in how the firmware applies DEC backlash, when polar.
                    Ie it only applies the high speed part part of it, and ignores the rest. This can leave it in no mans land.
                    I am testing a patch for that at present.

                    Andrew Johansen Melbourne Australia
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