SA.45s Chip-Scale Atomic Clock
SA.45s CSAC User Guide Revision D
27
Command:
!TA1221578499[CRLF]
Unit response:
TimeOfDay = 1221578499[CRLF]
Example (retard TOD by 3600 seconds = 1 hour):
Command:
!TD-3600[CRLF]
Unit response:
TimeOfDay = 1221574902[CRLF]
The TOD may be reported synchronous with the 1PPS output:
Example (retrieve TOD command):
Command:
!T?[CRLF]
Unit Response:
XXXX[CRLF]
where XXXX is the current TOD.
Note: This response does not occur until the next 1PPS output pulse.
When queried with the
command, the first character of TOD appears on RS232 within 20 ms of the
!T?
rising edge of the next 1PPS output pulse. Because this necessarily creates a delay of up to a second
between sending the
command and receiving a response from the CSAC, the host system must
!T?
allow for an RS232 receive timeout of at least 1000 ms when anticipating a response to the
!T?
command. For less critical timing applications, the TOD can be somewhat ambiguously parsed from the
standard telemetry string (see
"Telemetry (6 and ^)" (see page 20)
Note: The single-character is a shortcut for
.
T
!T?[CRLF]
3.4.3.9
Set 1PPS Phase Threshold for Discipline Status OK Check (m)
The 1PPS phase threshold (for discipline status OK check) when disciplining to an externally-supplied
1PPS reference source may be configured to provide optimal performance in a given application.
For applications with a long disciplining time constant and a noisier 1PPS reference (such as GPS), there
could be large variations in the reported 1PPS phase of a CSAC disciplined ok (checked through ADEV
measurement) but the phase threshold being set to a larger value ensures the DiscOK = 1 indication is
set correctly (see
"1PPS Disciplining" (see page 12)
For applications with a short disciplining time constant, the phase threshold can be set to a smaller
value. The range of 1PPS Phase Threshold for Discipline Status OK Check is 1 nanosecond to 10
9
nanoseconds (absolute values), with a default of 20 nanoseconds.
To set the phase threshold (for Discipline Status OK Check), the command has this format:
!mX[CRLF]
where X is the new phase threshold's magnitude/absolute value in nanoseconds.
Example (set 1PPS phase threshold for discipline status OK Check to ±20 nanoseconds):
Command:
!m20[CRLF]
Response:
20[CRLF]
To query the 1PPS phase threshold setting, without modifying the values, use the command
.
!m?
Example (query current 1PPS Phase Threshold setting):
Command:
!m?[CRLF]
Response:
20[CRLF]
Note: The single-character is a shortcut for
.
m
!m?[CRLF]
