DOC 6501_Release V
ATS-6501 Users Guide
45
to operate in timescale setting for at least 48 hours before changing the timescale steer interval or
time constant settings to longer times. The time constant can be increased by a factor of 10 every
48 hours until the time constant is 250000 using the timescale_steer_timeconstant command.
2.9 Setting the System Time Manually
The ATS-6501 is capable of operating without the GPS Receiver and maintains system time
through several methods
2.9.1 Force Time
The force_time command has several options and users have the flexibility of choosing the
method(s) that will work best based on installation and system architecture. Once the command
has been successfully completed NTP will lock to the new system time and the unit will enable
the outputs.
force_time default - snaps time to 01/01/2012 00:00:00.
force_time now - snaps time to the operating system's time, if possible.
force_time irig [year] - snaps time to the active irig input.
force_time <date-time> - snaps time to the specified time.
force_time <NTP server>- snaps time to that of a remote NTP server.
• Default – Sets the system time to 01 Jan 2012 00:00:00
• Now – Sets the system time to the operating systems time.
• IRIG – The system obtains the time from an IRIG Time source and sets the system time.
If the time code selected from the irig_input command does not provide the year the user
must specify the year on the command line.
• Date-Time – Allows the user to specify the date and time in the yyyy-mm-dd-hh:mm:ss
format
• NTP Server – The system obtains the time from an NTP Server and sets the system time.
Enter the IP address of the remote NTP Server.
If for any reason the system is unable to successfully set the system time it will report an error.
Note: The force_time command will not work unless the steer_source is set to manual.
2.9.2 Deterministic Phase Lock Loop (DPLL)
The ATS-6501 can recover time as well as align to an external source without having to use GPS.
The system time can be set manually or via an NTP Server. The Low Noise Synthesizer (LNS) in
system has the ability to have a deterministic phase acquisition to the LNS, to any 10 MHz
reference signal. The phase of the 10 MHz LNS output has a deterministic (nonzero, but the
same every time) phase relationship to the phase of the 10 MHz frequency reference, either the
internal Rb or external 10 MHz reference after the LNS PLL acquisition.
At a system level, this allows the ATS-6501 to use the 10 MHz external reference as the phase
reference for the system. The LNS makes phase measurements at a higher rate and with lower
noise against the 10 MHz reference input than it would otherwise be capable of doing with the
4393A Card (PPS TIC).
1. Set the ATS 6501 up as shown below:
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