NMI provides the following precise time and frequency dissemination services:
Click here for information on our time and frequency standards, calibration services, research and the operation of radio clocks in Australia.
For further information email time@measurement.gov.au.
NMI's GPS time-transfer system offers a solution for time and frequency laboratories requiring a reliable and adaptable multi-channel strict common-view GPS receiver which generates data files formatted according to the standard CCTF specification. The system combines the reliability of a commercial GPS receiver engine with data-logging and processing software operating on a standard PC running under the Linux operating system. Features of the system are:
Reliability — more than 20 NMI GPS time-transfer systems are currently in operation. Most of these are in countries other than Australia and are virtually maintenance free.
Remote operation — the systems can be operated remotely, including data access, via a dialup or Internet connection.
Standard CCTF format data output — output from the receiver is processed and formatted following BIPM's standard for GPS time receiver software. A full description of this standard can be found in D.W. Allan and C. Thomas, Technical Directives for Standardisation of GPS Time Receiver Software, Metrologia 31, 69–79, 1994.
Extendable hardware — the systems can be expanded to include extra GPS receivers, other time signal receivers, distribution amplifiers, a built-in Rb frequency standard, and/or an uninterruptible power supply. By means of an NMI-developed 1 pps interface to the local time standard, the system can also be operated as a network-time protocol server.
Flexible and multiple GPS common-view schedules — raw timing data is collected for each visible satellite throughout the day and is processed to produce CCTF format data following the appropriate BIPM GPS common-view regional tracking schedule, and/or a schedule optimised for the particular time-transfer application.
GPS satellite clock monitoring software — software which processes the raw data to monitor the clocks of each visible satellite with respect to the local standard has also been developed.
The integrity of signals received from GPS satellites is monitored and recorded by GPS receiver systems at a number of locations in Australia and the Asia–Pacific.
Daily files of this data can be found at ftp://time.nmi.gov.au/pub/timedata/gps/APMP_data/GPS_Integrity/. Select the required location and the data file name format is MJD.html where MJD is the Modified Julian Day.
Daily values of UTC(AUS)–GPS time (as received at NMI Sydney) are calculated from overlapping two-day linearly fitted averages, and can be accessed from ftp://time.nmi.gov.au/pub/timedata/reports/. The file name format is nmlmm-yy.gps.
NMI maintains a number of network time protocol (NTP) servers which are referenced to UTC(AUS). To register for this service, email the following information to time@measurement.gov.au:
Privacy noteNMI collects contact information so we are able to notify users of changes to the service and inappropriate operation, e.g. by polling the servers at excessive rates (this has occurred several times through erroneous configuration and software or firmware bugs and has adversely affected the operation of our service to the detriment of other users).
NMI collects and maintains contact information in accordance with the principles and requirements of the Privacy Act 1988. This information is only used to contact authorised users of NTP services, and is subject to strict limits on disclosure under Principle 11 of the Privacy Act. It is maintained electronically in a secure database. Authorised users are entitled to review their own contact information as recorded by NMI. You can also raise any concerns with the Privacy Commissioner.
If you are unable to access our NTP servers because of network security concerns, we offer a telephone dialup service for synchronising computers which uses the automated computer time service (ACTS) protocol developed by NIST (USA). For more information go to http://www.nist.gov/physlab/div847/grp40/acts.cfm.
To ensure that you are notified of any changes to the service, please contact time@measurement.gov.au.
The telephone number for this service is 02 8467 3727. Currently this line is experiencing technical difficulties. For any urgent enquiries call 02 8467 3504.
NotesUsers outside Sydney are charged at STD rates.A phone call lasts about 30 seconds.The measured time difference are with respect to UTC(AUS) (not NIST as incorrectly described).
Daily values of UTC(AUS)–ABC TV-sync pulses are recorded and can be found in the first data column of the monthly reports of our clocks at ftp://time.nmi.gov.au/pub/timedata/reports/ (file name format nmlmm-yy.rep).