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GPS says my permanent observatory has moved???

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  • iandaus
    Dick Perhaps you can confirm what is going on here? In message 57214 Mike Sidonio identified that his Lat/Long as reported by his LX200GPS had changed for his
    Message 1 of 17 , Jun 1 2:34 AM
      Dick

      Perhaps you can confirm what is going on here?

      In message 57214 Mike Sidonio identified that his Lat/Long as
      reported by his LX200GPS had changed for his Canberra location. I
      chimed in that I too had noticed this effect (over 2km movement)
      after 1.6b in Canberra. It had been consistent in earlier and later
      versions.

      To follow this up I have done some more testing.

      With 1.6b and previous versions
      ===============================
      The LX200GPS display reports my location as
      35d 12m 05s S 149d 03m 34s E

      The :gp# command responds with these coordinates as do :Gt# and :Gg#

      This seems as it should be. No problem as both the GPS string and
      the Lx200 interpretation match. The displayed lat/long on the
      handbox agree with this result.

      With 1.7i and subsequent versions including 2.0i
      ================================================
      The LX200GPS display reports my location as
      35d 11m 55s S 149d 02m 26s E

      The :gp# command responds with
      GPRMC,131026,V,3512.0872,S,14903.5754,E,000.3,179.9,310504,,*12#
      Which provides the same lat/long as previous versions (this is good)

      HOWEVER the :Gt# and :Gg# commands respond with
      -35_11:55 (35d 11m 55s S)
      210_57:34 (149d 02m 26s E) (this is bad)

      The handbox display agrees with the :Gt# and :Gg# results.

      Hence the movement of the site location. Could this possibly be a
      bug in the software calculation, or can you see another reason for
      the difference? Does this show in the Northern/Western hemisphere?

      Having fun
      Ian
    • autostaretx
      ... Thanks for that, Ian... you re the first (and so far only) person to actually extract the GPS receiver string so that we can determine which version of
      Message 2 of 17 , Jun 1 8:27 AM
        --- In LX200GPS@yahoogroups.com, "iandaus" <idelaney@w...> wrote:

        > In message 57214 Mike Sidonio identified that his Lat/Long as
        > reported by his LX200GPS had changed for his Canberra location. I
        > chimed in that I too had noticed this effect (over 2km movement)
        > after 1.6b in Canberra. It had been consistent in earlier and later
        > versions.
        >
        > To follow this up I have done some more testing.
        >
        > With 1.6b and previous versions
        > ===============================
        > The LX200GPS display reports my location as
        > 35d 12m 05s S 149d 03m 34s E
        >
        > The :gp# command responds with these coordinates as do :Gt# and :Gg#
        >
        > This seems as it should be. No problem as both the GPS string and
        > the Lx200 interpretation match. The displayed lat/long on the
        > handbox agree with this result.
        >
        > With 1.7i and subsequent versions including 2.0i
        > ================================================
        > The LX200GPS display reports my location as
        > 35d 11m 55s S 149d 02m 26s E
        >
        > The :gp# command responds with
        > GPRMC,131026,V,3512.0872,S,14903.5754,E,000.3,179.9,310504,,*12#
        > Which provides the same lat/long as previous versions (this is good)
        >
        > HOWEVER the :Gt# and :Gg# commands respond with
        > -35_11:55 (35d 11m 55s S)
        > 210_57:34 (149d 02m 26s E) (this is bad)
        >
        > The handbox display agrees with the :Gt# and :Gg# results.
        >
        > Hence the movement of the site location. Could this possibly be a
        > bug in the software calculation, or can you see another reason for
        > the difference? Does this show in the Northern/Western hemisphere?

        Thanks for that, Ian... you're the first (and so far only)
        person to actually extract the GPS receiver string so that
        we can determine which version of firmware got it wrong.
        Likewise no one down there posted a comparison to a separate
        GPS unit (maybe it's the -receiver- which is wrong, and the
        Autostar's correcting for it? (shall i pull the other one?))

        'Tis a pity it's the new one.

        Other than lightly perusing the (messy) code in the "convert
        GPS ddd.ddddd string to dd mm ss" routine, i really couldn't
        move until i had a southern GPS string to look at.
        My own location (if memroy serves, i'll recheck later) has
        -not- moved (i have an easy-to-remember lat/long), but neither
        have the clouds, so outdoor testing has been minimal.

        I've forwarded your note to Meade. (numbers demonstrating
        a problem get far better action)

        Anyone else willing to connect to their Autostar with
        Hyperterminal and type :gp#
        It's really quite painless. No patch required.
        And it'd still be nice to hear of a separate GPS receiver's
        confirmation/refutation of "old" vs. "new" location.

        have fun
        --dick
      • autostaretx
        ... Now that i m a little further awake (and have taken a reading with my own telescope)... Well, by inspection , yours is obviously wrong. Just looking at
        Message 3 of 17 , Jun 1 9:08 AM
          --- In LX200GPS@yahoogroups.com, "iandaus" <idelaney@w...> wrote:
          ...
          > With 1.6b and previous versions
          > ===============================
          > The LX200GPS display reports my location as
          > 35d 12m 05s S 149d 03m 34s E
          ...
          > With 1.7i and subsequent versions including 2.0i
          > ================================================
          > The LX200GPS display reports my location as
          > 35d 11m 55s S 149d 02m 26s E
          >
          > The :gp# command responds with
          > GPRMC,131026,V,3512.0872,S,14903.5754,E,000.3,179.9,310504,,*12#

          Now that i'm a little further awake (and have taken a reading
          with my own telescope)...

          Well, "by inspection", yours is obviously wrong.
          Just looking at the GPS "sentence" shows "14903."
          All they have to do is "split" that to 149 03,
          but they somehow have changed that three to a two.
          (i'm highly suspicious that the 34 seconds of your old
          reading is "complimentary" (around 60) to the 26 secs
          you're getting now. The same syndrome appears on your
          latitude's seconds, too.

          My own location has -not- changed:
          GPRMC,50439,A,4740.1024,N,12221.3449,W,0.2,324.7,60602,,,0E#
          still yields: 47 40' 06", 122 21' 21"
          (yes, the GPRMC is an old one)

          have fun
          --dick
        • autostaretx
          My -guess- is that they re subtracting the fractional (seconds) portion, rather than adding it, for southern and east-of-Greenwich (can a German or Japanese
          Message 4 of 17 , Jun 1 10:23 AM
            My -guess- is that they're subtracting the fractional
            (seconds) portion, rather than adding it, for southern
            and east-of-Greenwich (can a German or Japanese site
            confirm that their longitude did, or did not, "shift"?)

            I'd also guess that they get the latitude wrong
            in austral South America, but get the longitude correct.

            Either way, if my theory is correct, i should be able
            to patch it. If it's cloudy tonight (as forecast),
            i'll try (but it doesn't -really- matter, since it only
            shifts your location at most 2000 meters in each cardinal
            direction)

            have fun
            --dick
          • johansea
            Gday Dick ... The app i sent you the other day compares HBx to GPS string data returned on its front page. From memory the HBx and GPS have NEVER
            Message 5 of 17 , Jun 1 3:45 PM
              Gday Dick
              <..snip..>
              > Thanks for that, Ian... you're the first (and so far only)
              > person to actually extract the GPS receiver string so that
              > we can determine which version of firmware got it wrong.

              The app i sent you the other day compares HBx to GPS string data
              returned on its front page. From memory the HBx and GPS have NEVER
              agreed for my site ( which is why i displayed them ), but the errors
              were always constant ( and close ) so just assumed thats how it was.
              ( Ie Near enough is too good principle )
              Will do some more checks on that today if you want.

              > Anyone else willing to connect to their Autostar with
              > Hyperterminal and type :gp#
              :gp# or :gps#? I'll try both, but never heard of :gp#

              Andrew Johansen Melbourne Australia
            • Simon Hanmer
              Hi all ... When I fire up my LX200-GPS 10 (permanently polar mounted; AutoStar 1.6b) in my garden shed observatory (GSO), I NEVER check the coordinates! I
              Message 6 of 17 , Jun 1 4:07 PM
                Hi all ...

                When I fire up my LX200-GPS 10" (permanently polar mounted; AutoStar 1.6b)
                in my garden shed observatory (GSO), I NEVER check the coordinates! I really
                have no idea if they change from night to night. The important thing is that
                the GoTo and pointing is accurate each and every night I get to observe
                (if only it were more frequent!). Bugs in calculations etc? Not that I
                notice.

                Question: do those of you who have noted GPS coordinate shifts also note
                pointing errors?

                If not ... continue to enjoy!

                If you do ... please tell us more

                Simon

                -------------------------------------------------------------
                Simon Hanmer
                Geological Survey of Canada, 601 Booth St, Ottawa, Ont., K1A 0E8
                Vox (613) 992-4704 : Fax 943-5318
                E-Mail (work) shanmer@...
                E-Mail (home) simon.hanmer@...

                http://www3.sympatico.ca/simon.hanmer/skh.html

                http://ottawa.rasc.ca/astronomy/geology/index.html

                From: "iandaus" <idelaney@...>
                Reply-To: LX200GPS@yahoogroups.com
                Date: Tue, 01 Jun 2004 09:34:39 -0000
                To: LX200GPS@yahoogroups.com
                Subject: [LX200GPS] GPS says my permanent observatory has moved???


                Dick

                Perhaps you can confirm what is going on here?

                In message 57214 Mike Sidonio identified that his Lat/Long as
                reported by his LX200GPS had changed for his Canberra location. I
                chimed in that I too had noticed this effect (over 2km movement)
                after 1.6b in Canberra. It had been consistent in earlier and later
                versions.

                To follow this up I have done some more testing.

                With 1.6b and previous versions
                ===============================
                The LX200GPS display reports my location as
                35d 12m 05s S 149d 03m 34s E

                The :gp# command responds with these coordinates as do :Gt# and :Gg#

                This seems as it should be. No problem as both the GPS string and
                the Lx200 interpretation match. The displayed lat/long on the
                handbox agree with this result.

                With 1.7i and subsequent versions including 2.0i
                ================================================
                The LX200GPS display reports my location as
                35d 11m 55s S 149d 02m 26s E

                The :gp# command responds with
                GPRMC,131026,V,3512.0872,S,14903.5754,E,000.3,179.9,310504,,*12#
                Which provides the same lat/long as previous versions (this is good)

                HOWEVER the :Gt# and :Gg# commands respond with
                -35_11:55 (35d 11m 55s S)
                210_57:34 (149d 02m 26s E) (this is bad)

                The handbox display agrees with the :Gt# and :Gg# results.

                Hence the movement of the site location. Could this possibly be a
                bug in the software calculation, or can you see another reason for
                the difference? Does this show in the Northern/Western hemisphere?

                Having fun
                Ian



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              • autostaretx
                ... Meade -says- :gps# in their document, but the parser -looks- for :gp# (and simply drops the s ) have fun --dick
                Message 7 of 17 , Jun 1 6:10 PM
                  --- In LX200GPS@yahoogroups.com, "johansea" <johansea@o...> wrote:
                  > > Anyone else willing to connect to their Autostar with
                  > > Hyperterminal and type :gp#
                  > :gp# or :gps#? I'll try both, but never heard of :gp#

                  Meade -says- ":gps#" in their document, but the parser
                  -looks- for ":gp#" (and simply drops the "s")

                  have fun
                  --dick
                • iandaus
                  Dick In the absence of a (second!) GPS unit I have had to resort to the manual map method. Assuming our Communications Authority have plotted the nearby Optus
                  Message 8 of 17 , Jun 1 10:53 PM
                    Dick

                    In the absence of a (second!) GPS unit I have had to resort to the
                    manual map method. Assuming our Communications Authority have
                    plotted the nearby Optus Cell Tower location correctly, applying the
                    map distance that I can measure .... yep the original coords are
                    correct, give or take a few seconds.

                    I like your diagnosis of Meade getting the sign wrong when adding
                    (ie accidentally subtracting) the seconds for S and E hemispheres.
                    We really need another set of coords to be sure but it sounds good.
                    This too would explain why while Mike and I both "moved" we didn't
                    move the same distance. Depending on your actual location you could
                    be out by 0 metres up to about 3.5 km (if seconds value was 0
                    varying up to 59) in NS and EW directions.

                    Tks for that

                    Having fun
                    Ian


                    --- In LX200GPS@yahoogroups.com, "autostaretx" <rseymour@w...> wrote:
                    > My -guess- is that they're subtracting the fractional
                    > (seconds) portion, rather than adding it, for southern
                    > and east-of-Greenwich (can a German or Japanese site
                    > confirm that their longitude did, or did not, "shift"?)
                    >
                    > I'd also guess that they get the latitude wrong
                    > in austral South America, but get the longitude correct.
                    >
                    > Either way, if my theory is correct, i should be able
                    > to patch it. If it's cloudy tonight (as forecast),
                    > i'll try (but it doesn't -really- matter, since it only
                    > shifts your location at most 2000 meters in each cardinal
                    > direction)
                    >
                    > have fun
                    > --dick
                  • autostaretx
                    ... Andrew supplied another set, AND i ve located where the 2.0i code gets it wrong... (they parse the ddd mm, then negate it if S outhern, =then= they simply
                    Message 9 of 17 , Jun 1 11:11 PM
                      --- In LX200GPS@yahoogroups.com, "iandaus" <idelaney@w...> wrote:
                      > Dick
                      >
                      > In the absence of a (second!) GPS unit I have had to resort to the
                      > manual map method. Assuming our Communications Authority have
                      > plotted the nearby Optus Cell Tower location correctly, applying the
                      > map distance that I can measure .... yep the original coords are
                      > correct, give or take a few seconds.
                      >
                      > I like your diagnosis of Meade getting the sign wrong when adding
                      > (ie accidentally subtracting) the seconds for S and E hemispheres.
                      > We really need another set of coords to be sure but it sounds good.

                      Andrew supplied another set, AND i've located where the
                      2.0i code gets it wrong... (they parse the ddd mm, then
                      negate it if "S"outhern, =then= they simply add the seconds.)

                      I'm trying to figure out how to patch it gracefully.
                      (i suspect that's not the only error)

                      have fun
                      --dick
                    • johansea
                      Gday Dick ... Considering Sth Hemi PEC is stuffed, Dec Backlash doesnt work and now the scope Location is wrong ( but only if yr Sth and/or East ),
                      Message 10 of 17 , Jun 2 2:08 AM
                        Gday Dick

                        <..snip..>
                        > Andrew supplied another set, AND i've located where the
                        > 2.0i code gets it wrong... (they parse the ddd mm, then
                        > negate it if "S"outhern, =then= they simply add the seconds.)
                        >
                        > I'm trying to figure out how to patch it gracefully.
                        > (i suspect that's not the only error)

                        Considering Sth Hemi PEC is stuffed, Dec Backlash doesnt work and
                        now the scope Location is wrong ( but only if yr Sth and/or East ),
                        maybe Meade will deem it time to issue a new version, and you wont
                        have to patch it. ( straight away that is :-), now where is that
                        parrot, i've got the nails )
                        Andrew Johansen Melbourne Australia
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