Kerry.

quote:Originally posted by cache chasers:In the rescue of the 9 miners at Q-Creek . They used a GPS to determine where to drill the rescue shafts. GPS yes but the result was only ever going to be as good as the underground surveys, which relies on simply "old fashion" survey techniques and conventional instruments. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by PDOP's:.... The surveyors love it as it's impossible for the equipment to run down virtual stakes like they used to with the wooden kind. But surveyors know how to put things in perspective, unfortuneately Managers love it as they think they'll need a few less surveyors, fortuneatley things don't run themselves (some managers think so but) and machine operators still haven't quite cottoned onto this no stake idea. Cheers, Kerry. I never get lost everybody keeps telling me where to go

And another SVN45, launched March 31 will shortly show up as PRN21. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Even in the days of SA position solutions didn't jump from so many metres north to so many metres south etc (and still doesn't post SA) but continuously wandered along a continuous (but extremely unpredictable) path, which in other ways was also certainly not random. Selective Availability had some unique and interesting qualities. Averaging (over time) certainly can eliminate some of the unknown errors, spikes etc that occur, 95% of those errors generally occur within a 24 hour period and generally about 30 days to account for 100% of all errors. In the end it generally still comes down to an unknown as one really doesn't know (with certainty) what type of period one is in (without planning), especially over the short term. The 50-50 figures and background is outlined in the following Averaging Example and the followup Averaging Part II followed by the Effects of obstructions on Averaging Far more important these days is being at whatever location at the best time as time of day certainly matters more. Cheers, Kerry. I never get lost everybody keeps telling me where to go

That's one of the problems as the cache, although could be represented exactly with coordinates, isn't as the coordinates aren't exact. Apart from that there is absolutely no reason why a single (or short term set of) coordinates taken with a straight GPS couldn't be better than some of the augmented systems. There is a reduced chance of it occuring but that won't (and doesn't) stop it from occurring. The integrity of the result is generally what it's all about probably more so than the actual accuracy especially with recreational type receivers. As for Trimble Ground Stations (or any of the others dual freq real-time systems) these have limitations as well. Certainly cm type accuarcy but at a the expense of distance. Really every type of accuracy endeavour comes at some type of price or limitation. WAAS is hellinglish expensive considering the overall cost and the (small) ground footprint it covers compared to the GPS system proper. Since WAAS was concieved many things have changed which really knocked the edge of the "amount of improvement" that was going to be possible for the $$'s. That difference is now not so much accuracy but integrity and error conditions/warnings, which just about all recreational receivers don't (probably won't) support. The same Trimble type receivers that are capable of cm accuracy in real-time over limited distances can pull mm accuracy over much further distances (100's km's) but that comes with a "time" limitation, in that it takes time (sometimes hours, days) and being pro-processed it's not an imediate solution. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by sbukosky:Waypoint averaging is a function of the GPS where it takes a reading every few seconds and averages them thus increasing the accuracy of the end waypoint .... That is correct 50% of the time but incorrect the other 50% of the time. The thing is one doesn't generally know which 50% one ends up with. Cheers, Kerry. I never get lost everybody keeps telling me where to go

WAAS certainly hasn't been declared fully operational and I also believe that up until at least March 31 (started sometime back in Jan) there was some deliberate degradation (and possible outages) of the system (at times) for the purposes of testing. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Even a WAAS enabled receiver will not be the same as the next WAAS enabled receiver, that's simply the fact that GPS or WAAS or whatever is not an absolute measuring system. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Where it was taken (or where it wasn't) taken could easily be "confirmed" with a "visible" display, date/time and position would solve that, but as usual not the case. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Peregrine007:Most Garmin GPSr's call it "accuracy", while Magellans (and maybe others?) call it "Estimated Position Error", or "EPE". EPE is obviously a little more scientific-sounding name, but essentially it's the same thing. Either way, your GPSr is "accurate" to within 17 ft or whatever the number is, relative to a fixed point of known positioning. Ok "17 ft relative to a fixed point of known positioning" but in reality there is no fixed point to compare, so is that "accuracy"? Definition of "Positioning Accuracy" , represents how well the position solution conforms to "truth". "Truth" is defined to be any specified user location where the position is known. So how can EPE (as in being "estimated") be the same thing as accuracy, which by definition is a position of "truth", truth isn't an estimate. Cheers, Kerry. I never get lost everybody keeps telling me where to go

"Accuracy" ? I didn't know there was too many receivers that actually reported "accuracy", some attempt to "Estimate" their "Position" "Error" but that's basically a little different to accuracy. The day the manufacturers actually provide some real information on the background behind these figures then one might be able to comment constructively, but they don't and they won't and they will remain just a (fairy) figure. In some respect the relative trend might mean mean something but even when Selective Availability was terminated just about all manufacturers were caught out as the displayed error was no where in line with the actual improvement in accuracy. When the software is simply changed to reflect an error figure ("accuracy"?) that appears to be more representative of the times, then it really doesn't say much for the integrity of the error value in the first place. Ah almost forgot, considering the world average system spec is less than 13m (~43 feet) @95% SIS then 17' is certainly well within spec. Cheers, Kerry. I never get lost everybody keeps telling me where to go

There's a saying that "They have the same basic parts and use the same signal. It is what they do with what they get that makes the difference" Much is made about antenna's and certainly all antenna's are not the same and neither is the way they work or how the user is maybe expecting them to work especially with reference to Correct Orientation Cheers, Kerry. I never get lost everybody keeps telling me where to go

As of April 1, there's 28 operational not including this new one. Also appears PRN17 has been "moved" in the past few days to a different plane/slot so that this new one can be put where PRN17 used to be (D3). Cheers, Kerry. I never get lost everybody keeps telling me where to go

Improve GPS accuracy, NO not really but every additional IIR is a refinement over older IIA's in many regards. The more satellites, better accuarcy thing is basically a myth as it ain't necessarily so. GPS IIR-9 (SVN 45) will actually "share" the same plane/slot (D3) as SVN#17. SVN 17 was the fifth block II Sat launched in Dec 1989 so is certainly getting on in years and a little past its design life. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Might be great signal strength but the geometry would probably be the other end of the scale and so would any integrity and accuracy. Depending on the time of day this type of occurance is possible but it's one of those instances in which the number of satellites means very little (the number of sats don't mean a great lot anyway) as they are all probably bunched in one small "window" of the sky. The geometry one would expect to be extremely weak and unreliable. Cheers, Kerry. I never get lost everybody keeps telling me where to go

The media at present appear to be a little out of control, everything has to be related to the war. But apart from that GPS IIR-9 was launched today after a brief delay and will be known as SVN 45, which will "share" D Plane, Slot 3 with SVN 17. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by BrianSnat:.... Garmin doesn't, so any averaging with a Garmin has to be done manually. The value of waypoint averaging is debatable however. Unfortuneately they do have some auto averaging (recent) software versions. Still waiting for an answer WHY! But yes waypoint averaging, now that's very debatable Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by EraSeek:.... Where is ''Here'' Kerry? A$'s as in Australian $'s Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Searching_ut:Is there a good site for that data Try searching for SOPAC (Scripps Orbit and Permanent Array Center) Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by The Face:.... I remember rushing out and getting my 45 the first DAY it was avilable in town here.I'm thinking it was around 250-300$ at the time,and worth every penny for me. A GPS45 here in 1994 was around A$1500 Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Johnny U-Boat:I heard a rumor that S/A is being turned back on this week from another geocacher. Is this true? Has anyone heard? I have a Magellen 315 - Any thoughts on how it would be affected if S/A is turned back on? Thanks!!!! Johnny, you've obviously been living in a vaccum, the blind leading the blind. Perhaps that makes 2 of you who can't read. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Wolf4dk:I have also heard that they where talking about turning off the WAAS on the sats because of the war .... Where did you "ACTUALLY" here that Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by The Face:Well, I have a Garmin GPS45 that must be 15 years old now thats still working fine .... The 45 was/is about 1994 vintage but if it was 15 years old then one would have paid a small fortune for it . Even when the 45 was released it was still a small fortune at the time compared to today. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by EraSeek:Till it is obsolete. even obsolete ones still work. I suppose if the manufacturers controlled the system (horrid thought) then "obsolete" would take on a whole new meaning . Aren't we lucky they don't Cheers, Kerry. I never get lost everybody keeps telling me where to go

Like any radio signal they can be easily tracked and the instructions on jammer use says "activate jammer then move quickly to a safer place" If one wants to attract (unwanted) attention then a jammer is an extremely good way to do it. Cheers, Kerry. I never get lost everybody keeps telling me where to go