Activity Feed › Discussion Forums › Strictly Surveying › Where to download Precise Ephemeris?
Where to download Precise Ephemeris?
Posted by totalsurv on October 26, 2019 at 7:24 amWhere would I be able to download precise/final ephemeris data files from and what format are they in? I had been using the import from internet feature on Topcon Tools but the feature is not working on the updated version of Magnet Tools.
Will a simple import of this file and normal processing be enough once downloaded?
totalsurv replied 4 years, 5 months ago 7 Members · 12 Replies- 12 Replies
See the IGS Access to Products page for a list of ftp servers hosting the orbit files.
It’s been awhile since I’ve done it, but generally when you download CORS data, from any station, the latest ephemeris data comes along with it.
- Posted by: @norman-oklahoma
It’s been awhile since I’ve done it, but generally when you download CORS data, from any station, the latest ephemeris data comes along with it.
I haven’t done it for awhile either, but as I recall you have to check the “include precise ephemeris” box (or IGS ephemeris).
Loyal
I’m using Magnet Tools v5.1.1.0 and it’s working. As Norman says, you should get to this page:
The search results list the precise epemeris links as ‘final’, there are gps only and gps+glonass versions. They are only available after 12-18 days according to the IGS web page. So if you’ve complied with that and it’s not working why not try Topcon support?
- Posted by: @artie-kay
I’m using Magnet Tools v5.1.1.0 and it’s working. As Norman says, you should get to this page:
The search results list the precise epemeris links as ‘final’, there are gps only and gps+glonass versions. They are only available after 12-18 days according to the IGS web page. So if you’ve complied with that and it’s not working why not try Topcon support?
I get to that page and when I select import files I get an error message. Have tried Topcon support and they said it will be addressed at next release but they can’t give a date for that. It works on Topcon Tools though.
As previously noted by Norman Oklahoma and Loyal, the US NGS “User Friendly CORS (UFC)” site allows retrieval of .SP3 files (best of the three IGS orbits types: ultra-rapid, rapid and precise) along with GPS data from a site in the CORS network. It does not appear that an orbit-only option is supported.
BTW, the UFC allows download of data in addition to GPS.
Also, my direct link for downloading GPS orbits from the IGS Central Bureau no longer works. I have not used it in a while but a cursory search couldn’t find them on the site.
Surprised at the reported Topcon reply to this issue.
HTH,
DMM
I use Leica Infinity, GNSS Manager of program allows to to download precise ephemeris or IGS data but if you use another program gnsscalendar.com is very usable website to download.
Thanks to all. Does the final ephemeris really add anything to the results in general? I rarely see any significant difference between the broadcast and final versions but the project I am on specifies it.
Baseline error over baseline length is proportional to SV error over distance to the SV. Given the current IGS orbit accuracies, the difference between the rapid and final only impacts very long baselines. For example: a 5cm orbit error with a 20 000 000 m distance to the SV yields a 2.54e-4 m baseline error on a 100 000 m baseline.
Note that the broadcast orbits accuracies are indicated to be at the one meter level. For the same baseline length this magnitude error results in a 5mm error.
I could express these values in feet but why would anyone ever want to do that.
- Posted by: @geeoddmike
Baseline error over baseline length is proportional to SV error over distance to the SV. Given the current IGS orbit accuracies, the difference between the rapid and final only impacts very long baselines. For example: a 5cm orbit error with a 20 000 000 m distance to the SV yields a 2.54e-4 m baseline error on a 100 000 m baseline.
Note that the broadcast orbits accuracies are indicated to be at the one meter level. For the same baseline length this magnitude error results in a 5mm error.
I could express these values in feet but why would anyone ever want to do that.
Very useful. Seems like there is very little difference between the rapid and final.
I agree on the limited benefit in standard baseline processing of waiting for the final precise ephemeris. I still find broadcast performance (and predicted ultra-rapid orbits) inadequate for my requirements. I see clock accuracies are now at the pico-second level. Important for precise point positioning apps like NASA??s APPS (Automated Precise Point Positioning). See: http://apps.gdgps.net/
- Posted by: @geeoddmike
Surprised at the reported Topcon reply to this issue.
Topcon have released an updated version of Magnet Tools with this issue fixed.
Log in to reply.