Kerry.

EPE is a funny animal and in an absolute sense really means little and can be quite deceiving. Simply by looking at displays generally doesn't give the overall picture as many will only see what they want to see. The following are 3 receivers of the same make from different era's ranging from 1994 to 2002 (pre and post SA software versions), all recorded data and over the same 24 hour time frame, all Standard Positioning Service and effectively all different. GPS1 1994 95% accuracy 6.2m EPE Range 8.9m to 101.3m GPS2 1998 95% accuracy 4.8m EPE Range 2.8m to 6.4m GPS3 2002 95% accuracy 3.1m EPE range 3.3m to 6.5m Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Ltljon:.... According to the host they were pretty accurate. And how accurate might that have been? Cheers, Kerry. I never get lost everybody keeps telling me where to go

Global POSITIONING System and yet some critical uses of the system have nothing to do with positioning at all, simply timing. Then there's the atomic explosion dettectors. Very similar accuracy but all done in reverse. Wonder if Global Positioning System (GPS) will become a generic simplified name for navigation receivers or will there be some correctness. GLONASSr, GALILEOr as well as GPSr? Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Stu & Sarah:... and as people have said - how many times do you actually get 12 satellites? Has a little to do with one's location but in my part of the world, 12 sats 10.6% of the time, can see up to 14 some of the time but that's of academic interest only. No it's not normal or something one should expect and really doesn't mean all that much either but we do have an above normal constellation and if we ever get down do the level the standards are actually based around then some are going to be complaining long and hard but right now they are rather pampered and a little spoilt. If things ever get to the level the standards are based on then that might sort a few out. Cheers, Kerry. I never get lost everybody keeps telling me where to go

18 channels is a little overboard right now and if one could find any mention of GNSS then that might make some sense. But no mention of GNSS (GPS + Glonass) so cross that option of the list. Actually there's been some speculation that receiver channels would increase to 14 or maybe even 16 to account for the "feeling" that WAAS is pinching something useful, which it really isn't anyway. So maybe 18 is just as cheap as 14 or 16 or whatever. In a few year times probably even 24 channel receivers (which have been around for quite a few years) will be outdated if there's a GPS + Galileo + Glonass built. If this milestone is reached then there'll be something like about 80 satellites and even 24 channels will be obsolete. Cheers, Kerry. I never get lost everybody keeps telling me where to go

#35 & #47 are simply Garmin WAAS conventions based on NMEA standards. Some manufacturers simply display WAAS sats with a "W". It just so happens that there's only provision for 32 GPS satellites but what would happen if this was increased or other systems developed with more than 32 satellites in the constellation. GPS + Galileo + Glonass receivers (when ever they are built) could have access to over 70 satellites, what then? Might be a reason why Garin#35 is actually PRN122 and #47 is PRN134. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Well people, that's about all you can do with those, is guess. Frankly I wouldn't take a guess, might give someone a bum steer. Also presumeably (and that's a guess also) they would be North lat and West Long? Cheers, Kerry. I never get lost everybody keeps telling me where to go

Format? good question and really the only person who "really" knows is the person who actually wrote them like this. I suppose that's what a format requires, some formatting, an appropriate decimal point as required, if they're decimal minutes then the appropriate minutes sign ('), seconds then why not a seconds symbol ("). Got me buggered why people write so called position formats like that, what do they think people are, mind readers . Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by nyarlotep:Just a thought, but could that 1000+ mph reading have been the speed of the satellite .... .... As I understand, the satellites would be moving at around 1000 mph to keep geosynchronous orbit. Just a guess though. GPS Sats travel at around 4km/sec (~9000mph) and also aren't in a geosynchronous orbit otherwise the system simply wouldn't work. This is just one of those things, the other 5%. Cheers, Kerry. I never get lost everybody keeps telling me where to go

Leica has made GPSr's for more years than I'd like to remember, which particular unit are you referring. Just about all the receivers here a Leica but Leica really isn't into basic recreational type units. everybody keeps telling me where to go

quote:Originally posted by timberlane74 & pumpkin: GREAT difference is subjective, as well! Military GPSr's, accuaracy can be measured in centimeters v. meters for civies... "Military GPSr's accuracy measured in centimetres", another one of the myths and misconceptions. Quite frankly military PPS cm accuracy is rubbish and if you want to go into the details well that won't be a problem either. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by EScout:...To me, the accuracy of a GPSr is how close you are to a known place on earth, when you entered those coordinates as your waypoint. That's about what it is and anything that a GPS shows in any way shape or form doesn't even come close to the definition of accuracy what so ever. Some "official" definitions "Positioning accuracy: The statistical difference between position measurements and a surveyed benchmark for any point within the service volume over a specified time interval" "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 within acceptable error tolerances and with respect to an accepted coordinate system, such WGS84 Earth-centred, Earth-fixed coordinate system" EPE simply fails to meet those requirements. Cheers, Kerry. I never get lost everybody keeps telling me where to go

GPS accuracy is a statistic so it depends on what and how one defines as accuracy. Accuracy means different things to different people. A unit which can display/output to 4/1000' has the accuracy resolution capability of around 0.09m (~4 inches) and they can/will do that (maybe about 0.5% of the time) but that's not what one would call accuracy. There's no great difference (at all) in accuracy between typical handhelds and equiv military receivers. Cheers, Kerry. I never get lost everybody keeps telling me where to go

The coordinates listed on this site are dDD MM.mmm'. They are not seconds but decimal minutes. First you will need to check exactly what format your GPS is set to as you might be mistaking 2 decimal minutes for 2 seconds (depending). Forget the conversions, set your GPS to display dDD MM.mm' (if limited to 2 decimal minutes) and enter the site coordinates rounding off the last number in the decimal minutes. Cheers, Kerry. I never get lost everybody keeps telling me where to go

The GPS Standard Positioning Service volume specifications goes out to 3,000 kilometres. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by Jowe:-- I live near Tacoma, WA and I have yet to acquire a WAAS signal. Could we be too far north? Has anyone acquired a WAAS signal north of 47 deg.? It's not only the Lat but the Longitude that will affect things. At 47N 122W the Brazil Sat is at 5 deg and the Pacific Sat at 11 deg so things are marginal especially to the Sat over Brazil. Actually the further north and west one goes (like Alaska) the elevation gets better to Pacific West, so some parts of Alaska would have a better chance of reception than where you are. Just as long as there's some ground stations in Alaska to make it useful anyway. Cheers, Kerry. I never get lost everybody keeps telling me where to go

And after all those different times, nobody mentioned GPS Time, which is the time all GPS receivers base time on. GPS time equaled UTC time at Midnight Jan 5/6, 1980 and hasn't been changed since. The leap second difference is part of the Nav message, which allows a GPS to determine UTC time and then whatever time zone the user wants to work in. Since Dec 31, 1998 the leap second difference is 13 seconds. "Time" and "Timing" are two entirely different things to a GPS (receiver) and all the leap seconds do is correct to UTC time and do nothing as far as position determination is concerned. Cheers, Kerry. I never get lost everybody keeps telling me where to go

The Plugger (PLGR) was only a single frequency unit and if one looks back at the spec in 1998 the horizontal accuracy @95% was 22m, vertical 27.7m and time 100 nanoseconds. Back then similar SPS accuracy (with SA) was horizontal 100m, vertical 156m and time 340 nanoseconds. The current 95% SPS SIS spec of horizontal 13m, vertical 22m and time 40 nanoseconds, however these are Signal-In-Space parameters but still very competitive. The replacement for the PLGR is the DAGR, which is a dual freq receiver and handles real-time systems as well, which the PLGR simply couldn't. Cheers, Kerry. I never get lost everybody keeps telling me where to go

GPS is designed to provide positions "on or near the earth" "Near the earth" in GPS terms is low earth orbit vehicles like the space shuttle, which uses GPS. However there's no commercially available GPS that has this capability but they are made. Cheers, Kerry. I never get lost everybody keeps telling me where to go

quote:Originally posted by GEO*Trailblazer # 1:.... (Theory Only) the Satts are sending signals to the seperate recievers at the same time ,if the clocks are timed together precisely,this is better,but one second of time equals about 100 feet more or less,so if your clocks are not precisely timed you inherit errors .... of course they are timed together (within reason a few nanoseconds or three) as that's what atomic clocks on satellites do, especially the Block IIR's, keep things in time. Receiver clocks do nothing else but tell the time and that's only approx time, within a few seconds. As for 1 second in GPS terms well that's a bit more than 100 feet, 10 nanoseconds is about 3 metres so 1 second, what's that that's make it, sort of a little more than 100 feet Cheers, Kerry. I never get lost everybody keeps telling me where to go

NO I never get lost everybody keeps telling me where to go

Rocks, yes they're call mmountains and sometimes they get in the way. I never get lost everybody keeps telling me where to go

Have you got (or ever booted the PC with) a GPS connected to this PC? Cheers, Kerry. I never get lost everybody keeps telling me where to go

GALILEO doesn't really duplicate GPS as much as it will complement and be interoperable with it as well as being independent. Control of GALILEO will be performed by civil authorities and in that alone are some real possible problems in the future. Their is certainly a Commercial Service (encrypted service for fee), which is quite distinct from the Open Access Service, which is equivalent to the GPS Standard Positioning Service mass market applications. The GALILEO single frequency Open Service 95% accuracy is 15 metres Horizontal and 35 metres Vertical so for this overall more accurate tag some need to define things a little better. All these 1m claims with qualifying the accuracy is rather misleading. Galileo Dual freq accuracy (and Safety-of-life service) will be 4m Horz and 8m Vertical. GPS civil dual freq accuracy will reportedly be around the 1.5m mark. GALILEO frequencies are different to GPS and also different to GLONASS and similar with many of the made but never released GPS+GLONASS receivers there will not doubt be a GPS+GALILEO receiver, maybe even a GPS+GALILEO+GLONASS receiver if the Russians get their act into gear? Cheers, Kerry. I never get lost everybody keeps telling me where to go

If it takes as long to implement as it has taken to get this far then it's not going to happen any time real soon. Right from the start there has appeared this problem that there's too many countries with too many imbedded "commercial" interests and not all parties have been able to agree especially when it came down to the euro's. What is the saying about too many cooks? Cheers, Kerry. I never get lost everybody keeps telling me where to go