| Refid[27] | Clock Source |
|---|---|
| GOES | Geosynchronous Orbit Environment Satellite |
| GPS | Global Positioning System |
| GAL | Galileo Positioning System |
| PPS | Generic pulse-per-second |
| IRIG | Inter-Range Instrumentation Group |
| WWVB | LF Radio WWVB Fort Collins, Colorado 60 kHz |
| DCF | LF Radio DCF77 Mainflingen, DE 77.5 kHz |
| HBG | LF Radio HBG Prangins, HB 75 kHz (ceased operation) |
| MSF | LF Radio MSF Anthorn, UK 60 kHz |
| JJY | LF Radio JJY Fukushima, JP 40 kHz, Saga, JP 60 kHz |
| LORC | MF Radio Loran-C station, 100 |
| TDF | MF Radio Allouis, FR 162 kHz |
| CHU | HF Radio CHU Ottawa, Ontario |
| WWV | HF Radio WWV Fort Collins, Colorado |
| WWVH | HF Radio WWVH Kauai, Hawaii |
| NIST | NIST telephone modem |
| ACTS | NIST telephone modem |
| USNO | USNO telephone modem |
| PTB | German PTB time standard telephone modem |
| MRS | Multi Reference Sources |
| XFAC | Inter Face Association Changed (IP address changed or lost) |
| STEP | Step time change, the offset is less than the panic threshold (1000 s) but greater than the step threshold (125 ms) |
| GOOG | Unofficial Google Refid used by google NTP servers as time4.google.com |
Source de l’information
https://en.wikipedia.org/wiki/Network_Time_Protocol