Symmetricom Z3801A, User Manual

Page: 58 / 98

Chapter 3 Using the Receiver Status Screen
Receiver Status Screen Data
3-14 User Guide
FFOM (Frequency Figure of Merit) indicates the stability of the
Receiver’s 10 MHz output. The 10 MHz output is controlled by the
SmartClock’s Phase-Locked Loop (PLL). Thus, the FFOM value is
determined by monitoring the status of the PLL.
In the sample screen of Figure 3-6, the 0 indicates that the
SmartClock’s PLL is stabilized. The following table lists and defines
the FFOM values that could be displayed.
1PPS TI
indicates the difference (timing shift) between the SmartClock
1 PPS and the internal GPS 1 PPS signals.
HOLD THR
(holdover threshold) displays the user-entered time error
value.
ACQUISITION Section of the Status Screen
ACQUISITION Line
The
ACQUISITION
line in the screen summarizes the state of the
internal GPS Engine as indicated by the Tracking , Not Tracking , and
Position
areas of the screen.
If the Receiver Engine was considered to be synchronized to the GPS
signal, the [
GPS 1 PPS Valid
] message will appear at the end of the
ACQUISITION line. If the Receiver has not yet synchronized to GPS,
the [
GPS 1 PPS CLK Invalid
] message will be displayed.
FFOM Value Definition
0 PLL stabilized—10 MHz output within specification.
1 PLL stabilizing
2 PLL unlocked (holdover)—Initially the 10 MHz output
will be within specifications. However, when in holdover,
the 10 MHz output will eventually drift out of
specification.
3 PLL unlocked (not in holdover)—Do not use the output.