CGGTTS
RINEX-Cli combines the
the RTK-rs position solver
and the CGGTTS library to
convert navigation PVT solutions to CGGTTS format.
CGGTTS is a file format specified by BIPM that describes a local clock behavior compared to a GNSS time scale and clocks embedded onboard satellites, usually from a unique constellation.
CGGTTS resolution has therefore the same requirements as SPP/PPP resolution.
The CGGTTS track solver has also a behavior that is very close to the position solver, considering this is the main part of the task.
Basically, anything possible in Position solving applies to CGGTTS solving.
CGGTTS is a method to compare two remote clocks to one another, by means of two remote SPP/PPP resolution against the same vehicles in sight.
This is a so called "Time Transfer" technique although it is more accurate to call this a clock comparison technique.
CGGTTS is specified so files can be exchanged and the comparison is directly made by comparing two CGGTTS files. This is the main reason why CGGTTS uses the UTC timescales, as opposed to anything we've dealt with so far.
CGGTTS measurements are scheduled along a table that is expressed in UTC and allows generating "synchronous" files, so each entry can be directly compared: no need for interpolation.
Our CGGTTS toolbox resepects this table by default, but that can also be customized.
Note that CGGTTS requires more computation than position solving, so it will always be slower than just solving positions.
--cggtts activates the special PVT solver and it can only be activated if -p is already activated.
Any other position solving options still apply, like customizing the default settings for example.
CGGTTS track resolution will generate one or more CGGTTS files.
Each file contains 24h of tracking so the total number of files to be generated depends on the time frame you have loaded.
In this section, we convert code based (SPP) PVT solutions into CGGTTS.
Although this is the "simplest" form of CGGTTS tracks formation, by injecting high quality data into this, we can already expect very good results.
rinex-cli \
-f test_resources/CRNX/V3/ESBC00DNK_R_20201770000_01D_30S_MO.crx.gz \
-f test_resources/NAV/V3/ESBC00DNK_R_20201770000_01D_MN.rnx.gz \
-f test_resources/SP3/GRG0MGXFIN_20201770000_01D_15M_ORB.SP3.gz \
-f test_resources/SP3/GRG0MGXFIN_20201760000_01D_15M_ORB.SP3.gz \
-P GPS \ # focus on GPS vehicles
-p --spp \ # force to SPP method
--cggtts # request CGGTTS track formation