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Relay Contacts and Event Inputs
10.2.8
1 PPS Deviation
If the event capture channel is configured for 1 PPS Deviation (via Event/Deviation Setup Menu), the
readout will display the deviation of the 1 PPS input signal. In this case, the readout display will have the
format:
A 1 PPS XXXXX.XX
µ
S
SIGMA: XXXXX.XX
µ
S
Where: The top number is the mean (average) value of the most recent 16 records in the event buffer, and
represents the mean deviation (in microseconds) of the measured 1 PPS input signal compared to the GNSS
1 PPS signal. A negative number means the applied 1 PPS signal is early, and a positive number means it
is late.
The bottom number is the standard deviation (sigma) of the 16 sample values.
If there is no input, the the numerical value is displayed with dashes.
A 1 PPS
00.00
µ
S
SIGMA:
00.00
µ
S
A 1 PPS
--.--
µ
S
SIGMA:
--.--
µ
S
10.2.9
Clearing Records
There are three methods to clear event records: (1) using the utility software, (2) using the front panel keys,
and (3) using RS-232 commands. To clear the buffer from the front panel, press the TIMING key four times
and ENTER key twice. This will cause the display to issue the following prompt:
CLEAR EVENT?
YES = UP
NO = DOWN
To clear the event buffer from the utility software, click the Clear button, or go to Device menu and select
Clear. To clear events using RS-232 commands, type the CA command and the buffer will immediately be
cleared.
Clearing the 1 PPS Deviation Values
Using the Clear feature while in the 1 PPS deviation mode will effectively clear the buffer and start the
averaging process over again. Statistical mean and sigma will temporarily go to zero, begin to change more
rapidly, then settle down when the 16-value buffer fills after 16 seconds.
