Kerry.

quote:Originally posted by GEO*Trailblazer # 1:Todays Calibration Test.. (RTK) Real Time Kenetic GPS,Levica, against the E-Trex-RINO, WOW.....Theirs,DEG,MIN,SEC. 36-56-38.98853" 94-00-08.52483" elev. 1199.84' mine 36-56-39.0 94-00-08.5 elev. 1182.9',Accuracy (9')WASS Enabled, .01147" difference I'll let you do the math but that close enough for me..... One thing you need to do is at least get the terminology right RTK (Real Time Kinematic) and it's Leica not a Levica. Start referring to RTK as "Real Time Kenetic" and some will start to wonder. As for the accuracy, so what does it really mean? Dos it really mean anything or simply a case of coincidence. Cheers, Kerry. I never get lost everybody keeps telling me where to go

for the metric deficients, 2.5 cm (2.54cm actually) is one of your inches. But that idio aside his movement thing is quite daunting, really and it won't take 50 years to be a problem. In only a few years time one will have a dual freq handheld capable of less then 1.5m (that 4.92 feet for some) and places like Australia will have moved more than that since the time the reference frame was adopted. Even today some countries for high precision work are computing conversions on a weekly basis. 50 years time we might have to have a real-time dynamic datum and if we only knew where the centre of the earth was "exactly" everyday then that might be a good start. If this movement keeps up the mailman gunna's miss the slot Cheers, Kerry. I never get lost everybody keeps telling me where to go

The block IIA sats are designed to provide 180 days of operation without Control Segment contact. However over this time accuracy will slowly degrade. The current generation block IIR sats of which there are 8 in orbit (more to follow) are designed for 14 days non contact in standard mode and up to 180 days in autonmous navigation mode. In this auto mode direct communication between each of the block IIR's maintain system parameters. Apart from the main control centre at Schriver, there is also a backup Control centre away from Schriver that operates 4 times a year to ensure readiness as well as the pre-launch satellite check-out facility at Cape Canaveral that can act in a limited control role. Cheers, Kerry. I never get lost everybody keeps telling me where to go

NZGD2000 (New Zealand Geodetic Datum 2000) is their WGS84 compatible earth centred datum but probably a datum not found on too many GPSr's. WGS84 is equiv at this level for all intent and purposes. Most receivers support the old NZGD49 datum, which is approx 200 metres different. Cheers, Kerry. I never get lost everybody keeps telling me where to go

The only software is made by Garmin, sold by Garmin and completely controlled by Garmin. Cheers, Kerry. I never get lost everybody keeps telling me where to go

THIS SITE is a good place to start for coordinate systems. Some are easier to use (to those that find some strange) but generally all have a purpose. Aviation & Marine "generally" use a geodetic latitude/longitude in dDD MM.mmm format. Cheers, Kerry. I never get lost everybody keeps telling me where to go

It's WAAS enabled and this could be having some effect but lets hope that's not the excuse. Now based on the Cobra blub and the "Faster acquisition time" based on the 18 channels and the "Accelerated Satellite Acquisition Protocol" it's extremely slow. Cobra's performance spec is apprx 10 seconds (warm), 35 seconds (cold) and approx 50 seconds (first time). With all that big sounding technology, compared to other units that thing should start well under 60 seconds at any time. Cheers, Kerry. I never get lost everybody keeps telling me where to go

WAAS GEO Mode is now Normal and broadcasting type 2 message and not Type 0. I never get lost everybody keeps telling me where to go

quote:Originally posted by Wildbill34275:.... if i take up in a multi-story building will it be more accurate? No, what your seeing for a GPS height is basically norm regardless of the elevation. Elevation is around the 2 to two and half times less accurate than horizontal. SIS vertical accuracy specification is less than 22 metres (~72 feet) 95% of the time world average. Worst case is less than 77 metres (~250 feet) 95% of the time. Cheers, Kerry. I never get lost everybody keeps telling me where to go

That's about it, NMEA sentences just like them and straight simply text files. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Well WAAS was never designed to work in a forest, on a highway, in a town but more designed to work on aircraft, in the air free of obstructions and all that stuff. Still has limitations for aircraft use but now simply has the "official" approval to use it with properly "accredited" WAAS receivers. Like they've mentioned it has come at an immense cost and still not complete for the intended purpose and that purpose wasn't providing the system to half baked handhelds that simply don't support,can't support and probably never will support the system capabilities fully. WAAS is a bit like follow the leader but that's nothing new in the GPS field. The real bottleneck in the whole WAAS system is the vulnerability of loosing one of the inmarsats. That's actually going to cause some extreme problems. Really someone had to to something officially with WAAS as it simply has dragged on way to long with very little action. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by GEO*Trailblazer # 1:.... The Elevation Model is still under construction .... Honestly you really need to check the difference between a "Website under construction" and the significance to any Geoid model. If your not aware (and it's obvious your not) the latest Geoid model for the US is Geoid99, which is simply the latest in a string of previous Geoid models. As more data is collected then this will also be revised, just like it has done for the last umteen many years. Heaven help us if the geoid was still under "Construction". Every country has gone through revision of their Geoids and for the U.S you can find it HERE as GEOID99, uinder "construction" what crap. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:As for Lat/Lon changing with elevation, that is possible .... in practice it might but on paper that simply doesn't happen as the underlying coordinate system is nothing that really makes much sense to many. Take for example the points (in Earth Centred XYZ) X= 1353755.2815 Y= -5052283.4915 Z= 3637924.2670 X= 1353946.0924 Y= -5052995.6076 Z= 3638440.4858 Those coordinates mean things to the underlying workings of a GPS but to most of us they may as well be on the moon. What's the difference? purely only in the elevation. Both are 35 00' 00.0000"N, 75 00' 00.0000"W, the same horizontal point but the first is 100m and the other is 900 metres directly above it. In practice for sure there's some other influences but GPS coordinates are based on a formula that is a perfect model but the geoid creates some problems in determining orthometric heights from ellipsoid heights but that has little to do with being directly above or below some point. Cheers, Kerry. I never get lost everybody keeps telling me where to go

That's right Trailblazer CRAP. I tell you what about you get someone who is an authority to backup the crap and mindless talk you go on with. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Most likely do do with mask cut-off angles. Some receivers will use all satellites right down to the horizon (0 deg mask) and others can be as high as 10 degrees. Most receivers have fixed masks some can be user defined. All other things being equal (and not a lot between different GPS receivers are completely equal) the MLR appears to have a mask angle of a few degrees. In any event the low horizon satellites (rising or setting) generally introduce the most issues into the position solution. Really don't want them anyway so some manufacturers mask them out. Other manufacturers show right down to the horizon, which gives the impression their units are better 'cause they can see more satellites, not so. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by seventhings:One meter difference between NAD83 and WGS84 data is consistent with my experience using Garmin Vista. Quite frankly how the hell can a garmin Vista tell the difference is 1 metre between anything. Geez the URE in space is more than 1 metre an some try an convince themselves that handhelds have integrity of 1 metre, come on. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by shrdlu:.... "The Billion Dollar System" has cost at least twelve billion. ...and it's one of the best military tools ever built. I wish every twelve billion spent by the government was so beneficial. And every $$ worth it. WAAS so far 6 billion and for what? Bugga all and only covers a fraction of the world that GPS covers. .... and trailblazer# whatever don't talk so much crap quote:Most of the Coordinates are scaled.or adjusted to come close to what we might find out in the field also changing the elevation won't affect lat&long, Cartesian yes but not Lat&long, never seen so much misconception and rubbish. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by EraSeek:Estimated Position Error. How far of target you may or may not be 95% of the time, maybe. 95% Maybe? now I'd like to see that in writing, signed by any manufacturers chief trust me signerer, willing to guarantee it. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Well actually ALL GPS navigation info is in the past, simply can't be any other way. It basically shows where you've come from and not which way your heading (assuming your moving of course). The more a GPS unit has to do the more it can get behind. Many only have basic CPU and when that runs out of puff things can get a little further behind. Some might spec 1 second position updates but many simply spit the same position out over several seconds as it simply can't keep the processing power up during periods of high computational activity. Bit of a con really. High speed craft still rely on compass for direction. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Sissy-n-CR, not sure what you saw in that map, is there other info, can you explain. Cheers, Kerry. I never get lost everybody keeps telling me where to go

What that says is "The GPS data collected at the WAAS sites are unavailable for post-processing" .... and .... "WAAS correctors are still being transmitted." Two totally different sides of the WAAS ground stations. As all WAAS reference sites are Continuously Operation Reference Sites (CORS) and like many other sites all around the world data is normally available for post processing (in the past). It just says that data is not currently available not that WAAS is offline. Cheers, Kerry. I never get lost everybody keeps telling me where to go

There's more to WAAS than simply getting a lock, gee I get a WAAS lock here but accuracy is blown out of the water. Have a look at WAAS OPeration and follow the other links, everything you ever wanted to know about WAAS. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Dave54, I'm only too well aware of accuracy capabilities and it's not a case of believing in anything. As I mentioned accuracy means different things to different people and all accuracy is relative depending on how that accuracy is achieved. quote:but off-the-shelf Trimble GeoExplorer and Trimble Pro XRS consistently get sub meter accuracy here That statement is not totally correct, yes a Pro XRS can achieve sub-metre accuracy BUT only in real-time and generally only from a TRS and then it's all dependent on distance. And yes CM accuracy is possible but that's also time dependent, the more accuracy requires more time and again this is distance dependent. Other units are capable of sub millimetre but that really besides the point in this discussion about military type accuracy. What some have to realize that a PLGR in comparable mode is no more accurate than many commercial handhelds. Sure PLGR have some aumentation capabilities but so does a lot of other uinits, really need to compare apples to apples and accuracy to accuracy. One thing the PLGR can't do is post process but the DAGR will and being dual freq then that will have different accuracy capabilities again. In the real world any manufacturer who quotes SPS accuracy less than (better than) what the system specifications are really kidding themselves. Future performance can not be guarantted based on historical performance. Cheers, Kerry. I never get lost everybody keeps telling me where to go

That's basically the problem, the intersection of 2 (or more) circles. However one problem with using UTM is in/on and over (further than the overlap) zone boundaries, UTM basically totally useless then. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Certainly will. I never get lost everybody keeps telling me where to go