Launch site: SLC-40, Cape Canaveral Air Force Station, Florida
I read about it in the Air Force Times today. According to the article, "The new satellites are expected to provide location information that's three times more accurate than the current satellites."
Looks like it got delayed because of the high winds today.
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Stormy weather on Thursday shuts down 3rd launch attempt.
Paul in PA
I read an article where the whole contract for 32 new SV's was awarded.?ÿ Supposed to be in orbit by 2023 I think.
I read about it in the Air Force Times today. According to the article, "The new satellites are expected to provide location information that's three times more accurate than the current satellites."
So those who believe their mathematical solution over professional surveying experience in evidence and boundary will think they are three times better...
However, it'll be nice for reducing error ellipses in gps networks
At our last local surveyors sitdown, one member warned everyone else that he was in the process of upgrading all his GPS equipment with new software and installing new inhouse software that would enable his GPS system to out perform any other systems in use by everyone else.
I almost blew my veal parmesan all over the table.
First off, it will be more precise, not more accurate. Precision is a function of the equipment, no matter how precise, accuracy is beyond the scope of just equipment. Precision is improve by the fact that with 3 signals, the algorithms of, will have 3 comparisons, not just the 1 comparison from 2 signals. That does not make it 3 times better, more like 1.732 times. The newest signal is more powerful, which does not make it more precise, but does make it more likely you will get a solution. One will definitely be able to get a more precise signal in less time, so that is a benefit. No matter how more mathematically precise the receiver position is the survey accuracy does not get equivalently more accurate. Until the controlling CORS are similarly upgraded, the final benefits cannot be fully achieved.
The use of the third GPS signal is one way to improve precision, but precision can also be improved by utilizing combinations of the 3 other constellations.
Lastly do not use the language of the safety of life (airplane) issue which is comparing previously used L1 only to L1/L5 use. Their base consideration is plus/minus 1/2 a runway.
Paul in PA
3 signals gives 2 independent comparisons.?ÿ Given any 2 differences, the other difference is completely determined.
I would argue that an additional signal that has no systematic error but only random errors makes the result more accurate.?ÿ The improvement may be negligible small if other error sources outweigh it.?ÿ
Indeed many CORS have enough error in their assumed positions?ÿto limit overall accuracy.?ÿ That needs to be the next frontier of improvement when we adopt a 2022 datum that relies totally on them.
The L5 signal is orders of magnitude higher in amplitude. Is my signal to noise ratio improved by this, or is that a function of the difference between my L1/L2 ???
A stronger signal reduces the effect of interference and receiver noise, and may provide faster fixing, but with a modest amount of averaging the noise is not the largest contributor to error.?ÿ The iono/tropo propagation and any site multipath are probably more significant and are not improved by more signal strength.?ÿ Having an additional usable signal frequency does help with those aspects.
3 signals gives 2 independent comparisons.?ÿ Given any 2 differences, the other difference is completely determined.
Three signals give 3 comparisons. If you mathematically figure 2, yes you can difference for the third, but that does not necessarily mean it would exactly be the same value as using the full algorithm.
Paul in PA
"Standing down today due to strong upper level winds. Team is proceeding with the count until T-30 seconds for data collection. Next launch attempt is tomorrow at 8:51 a.m. EST, 13:51 UTC."
Satellite on its way! Great view of the launch from my driveway.
I have seen and felt live space launches before and they are a hoot.
I've been watching this one via SpaceX's webcast which is some fine viewing.?ÿ Great stuff!
Licensed Land Surveyor
Finger Lakes Region, Upstate New York
This new satellite has more fuel than ever before to extend it's lifetime. It will replace a satellite that has been up there for 21 years and with all it's new features testing is expected to take a year before it is activated. It may see 30 years of use. The launch cycle for all 22 # 3 models could be more than 10 years, so it may be that long before all the new benefits are seen on the ground.
I saw some explanation of the 3 times more accuracy statement. The signal received from the satellite will be 3 times more accurate and when enough are launched it will improve autonomous positioning. Our post processed and RTK positions will still be limited by the accuracy of base positions
Paul in PA
Question for Bill93:?ÿ You wrote something to the effect that the reference positions of the some of the CORS have a good bit of error in them.?ÿ
I am not quibbling with that statement or assertion.?ÿ But it begs the question:?ÿ when TN-DOT was bringing their RTN system on line, they wanted all of them to be CORS.?ÿ To have them accepted, TN-DOT had to submit 30 days of continuous 1-second data in order for NGS to certify them for stability etc.
I have made the statement, based purely on my logical inference, that CORS could be continuously monitored by post processing the data being uploaded every day.?ÿ I do not know that such reprocessing is being done but it seemed logical to me that at least some of that would be done for a variety of reasons.?ÿ If it is being done, why would any of the reference positions of the CORS be inaccurate??ÿ Does NGS not have the ability to monitor and update or decommission if warranted?
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NGS does a complete CORS network analysis of all 2000+ stations in a global solution every morning around 1ish.?ÿ The results are compared with the published values in North, East and Up.?ÿ From these data the agency computes short term (3 month) graphs for each station and computes each stations positional uncertainty (these are posted on the CORS datasheet web page).?ÿ The agency maintains a tolerance of .02 m in the horizontal and .04 m in the ellipsoid height for the NAD 83 (2011) values and .01 m horizontal and .02 m ellipsoid height in the ITRF08.?ÿ There certainly are a few stations that may be outside of those limits.?ÿ Regrettably NGS has a very small staff to manage and maintain the network - The entire agency is only about 200 people.?ÿ At this time they are (or will be when they get back to work) performing a complete reanalysis of all CORS in a project called REPRO2 - The data was supposed to be available for beta evaluation just around now.?ÿ Once completed there will be updated positions for all stations, greatly improved horizontal and vertical velocities and the integration of IGS14 to replace IGS08.?ÿ Most, if not all of the problem stations should be resolved with the final solution of this effort.
If you look at the CORS info on the NGS web site you can find graphs of each one day by day and some of them show north, east, and/or up deviations from the nominal position that are fairly consistent for weeks, sometimes in the range of 1 or 2 cm.
I could be wrong but I don't think those deviations are taken into account by OPUS.?ÿ Somebody eventually decides they are consistently out of tolerance (2 cm?) and updates the nominal values.
Edit: what Dave said.