On the subject of research, it appears that we have a bit of a GPS accuracy advantage in North America.
This 2004 PDF explains 4 methods of correcting GPS data (and also 6 sources of error). http://www.fs.fed.us/t-d/pubs/pdfpubs/pdf04712307/pdf04712307dpi300.pdf The WAAS method is "currently" available only in North America, according to this 2013 PDF: http://www.benmeadows.com/refinfo/techfacts/techpdf/GPS_Accuracy_WAAS_300.pdf In this informative PF post, a user tells how he notices the accuracy improve after turning it on and it getting it's WAAS data. http://www.pentaxforums.com/forums/pentax-k-5/154128-pentax-o-gps1-gps-usa-availability-3.html#post1682886 I'm not sure yet how much time needs to go by for this to happen, but I haven't yet read the whole thread, and I can ask the poster questions directly if I still need to know after some further research. I think it would be interesting if there was a database of info where people could share their experiences with the O-GPS1 and provide answers to a particular set of questions: Camera & firmware being used Location where it was used (LAT/LONG). This would also tell us if they were in North America or not, obviously. Elevation of location. (ASIDE: This seems to be where "all GPS units exhibit a weakness" but I'm not sure why that is. According to this PDF, http://www.nasa.gov/centers/johnson/pdf/584738main_Wings-ch5c-pgs360-369.pdf the space shuttle created topographical data sets that can give the elevation for virtually any location. Perhaps it is just not built into the GPS system yet, or there is no method for the GPS to "look it up" and enter it into the calculations.) How many satellites did it pick up? (the more you are working off of, the more accurate your position) Did they perform the precise calibration (and method?) Did they remain at the exact same spot for all exposures (or did they pick up and move several meters away)? If they moved, did they repeat the precise calibration before taking more pictures? (I'm not sure how many meters one would have to move before you would have an error big enough to matter. Obviously the longer the focal length of the lens used, the more sensitive it will be to positioning errors. If i was better at math, I could probably easily determine what an arc-second of error is in feet/meters on the ground.) Anyway, if we could accumulate the answers to these questions (and probably a few more) we could separate the reasons for people having problems. I tend to think that it is most often USER error (that is, not using the tool properly or in an informed manner) but it is a bit sad that Pentax has not done a better documentation job on this product. I think it is the result of some incredibly creative out-of-the-box thinking/engineering and I think that if more people learned to use it as my french friend has, that the astrophotography community would sit up and take notice. On Fri, Sep 13, 2013 at 8:35 AM, Darren Addy <[email protected]> wrote: > Interesting Matthew. I had not heard that before. > > Pure conjecture on my part: Is it possible that this is what the unit > is doing that drains the batteries, even when "off"? > If so, it still probably couldn't get the data from inside the house. > I wonder if it would be a good idea to keep it on the dash of one's > car, so that it could access the GPS satellites all day, before a > session. Or perhaps have 4 batteries charged and leave it on in the > car the afternoon before a nighttime shoot (changing batteries to > fresh ones just before the shoot). At least it gives me some things to > research and think about. > > On Fri, Sep 13, 2013 at 7:51 AM, Matthew Hunt <[email protected]> wrote: >> On Thu, Sep 12, 2013 at 8:14 PM, Rob Studdert <[email protected]> >> wrote: >> >>> When it works it seems pretty good but it does take an extraordinarily >>> long time to lock sometimes (noticeable when the phone takes seconds) >>> and it's really touch on batteries too. >> >> Getting a fast GPS lock depends on having up-to-date ephemeris data, >> which is broadcast by the satellites. A phone is on pretty much all >> the time, so it should always have up-to-date ephemeris data. (Also, a >> phone could "cheat" by getting ephemeris data from cell towers or the >> Internet; I'm not sure if they do that or not.) The O-GPS1 is probably >> used less frequently, so it's likely not to have recent ephemeris data >> at startup. It might also forget its ephemeris data when the batteries >> are removed. Getting an initial fix without ephemeris data can take a >> lot longer. >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. > > > > -- > Nothing is sure but death and Pentaxes. -- Nothing is sure but death and Pentaxes. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
