On 2014-03-19 12:01, E-Mail Sent to this address will be added to the
BlackLists wrote:
Brian Inglis wrote:
Martin Burnicki wrote:
At the single nanosecond accuracy level it would also be
important to *which* local realizations UTC(k) you are referring,
UTC(NIST), UTC(USNO), UTC(PTB), ...
The source would need to provided by or calibrated against the ref,
at some cost!
Unless at that level you just call it UTC(GPS), UTC(LCL), or UTC(MB)!
Since you can get a e.g. Trimble
NTP Server GNSS GPS with 440 channels
GPS, Simultaneous L1 C/A, L2E, L2C, L5
Galileo, Simultaneous L1 BOC, E5A, E5B, E5AltBOC2
GLONASS, Simultaneous L1 C/A, L1 P, L2 C/A , L2 P, L3 CDMA
BeiDou, B1, B2
SBAS, Simultaneous L1 C/A, L5
QZSS, L1 C/A, L1 SAIF, L2C, L5, LEX
WAAS
EGNOS
MSAS
GAGAN,
SDCM,
OmniSTAR, L-Band VBS/XP/G2/HP
RTX, (Trimble WWC)
...
Which have four different UTC base sources,
the units must already do something to combine the results,
to approximate {calculate} UTC(TAI)?.
That's got two Maxwell 6 chips, so each does /only/ 220 channels.
As usual for Trimble, those are impressive, but no timing specs!
Each constellation has its own epoch, TAI or UTC time scale, and uncertainty:
http://www.navipedia.net/index.php/Time_References_in_GNSS
GLONASS uses UTC+03:00 (MSK before permanent DST added recently).
Their timing products still seem to be based on the Resolution SMT GG with
DOCXO in the Thunderbolt E GPSDO, and solve for time, given a fixed position.
--
Take care. Thanks, Brian Inglis
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