[ntp:questions] IEEE 1588 (PTP) at the nanosecond level?

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Wed Mar 19 22:16:37 UTC 2014

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
>   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:
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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