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tomojitakasu / RTKLIB

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GLONASS ephemeris conversion PZ-90 -> WGS84 #676

Open borax00 opened 2 years ago

borax00 commented 2 years ago

Hi,

I've been going through the libRTK source code. Where the GLONASS satellite-position is caluclated from the broadcast ephemeris, it seems to be missing the conversion from PZ-90 to WGS84 (per e.g. Section 3.1.3.2 of https://gssc.esa.int/navipedia/GNSS_Book/ESA_GNSS-Book_TM-23_Vol_I.pdf). Is this an omission or am I missing something?

yydgis commented 2 years ago

currently, PZ-90 closely matches WGS84/ITRF, just ignore the difference

On Thu, Jul 21, 2022 at 5:54 PM borax00 @.***> wrote:

Hi,

I've been going through the libRTK source code. Where the GLONASS satellite-position is caluclated from the broadcast ephemeris, it seems to be missing the conversion from PZ-90 to WGS84 (per e.g. Section 3.1.3.2 of https://gssc.esa.int/navipedia/GNSS_Book/ESA_GNSS-Book_TM-23_Vol_I.pdf). Is this an omission or am I missing something?

— Reply to this email directly, view it on GitHub https://github.com/tomojitakasu/RTKLIB/issues/676, or unsubscribe https://github.com/notifications/unsubscribe-auth/AD6QBI5HLZDTZIUXGC2H4MDVVHWKPANCNFSM54JPJX2A . You are receiving this because you are subscribed to this thread.Message ID: @.***>

tomojitakasu commented 2 years ago

The errors due to the coordinate systems' differfence, i.e. PZ90 (even as PZ90.02) and WGS84, are usually negligible compared to the errors of GLONASS broadcast ephemeris.

Refer the manual E.2.

https://www.rtklib.com/prog/manual_2.4.2.pdf

borax00 commented 2 years ago

Awesome, thanks for the reply.

Waley04 commented 2 years ago

Hi,

I've been going through the libRTK source code. Where the GLONASS satellite-position is caluclated from the broadcast ephemeris, it seems to be missing the conversion from PZ-90 to WGS84 (per e.g. Section 3.1.3.2 of https://gssc.esa.int/navipedia/GNSS_Book/ESA_GNSS-Book_TM-23_Vol_I.pdf). Is this an omission or am I missing something?

This error has a negligible effect on the solution.

Waley04 commented 2 years ago

I agree. Again, for the sake of positioning and navigation, the G2139 is coincident with ITRF14(or IGb14).