2.2 Front Panel Controls and Indicators
5
2.2.1
Annunciator LED Definitions
Annunciator LED
Color
Purpose
Operate
Green
Clock Operating
Stabilized
Flashing Green
Clock Time stabilizing
Steady Green
Clock Time accurate
Unlocked
Red
Out-of-Lock when ON
Fault
Red
Internal fault when ON
Table 2.1: Annunciator LED Definitions
The four LED’s provide information about the operational status of the instrument. The Operate
and Stabilized LED’s are green and the Out-of-Lock and Fault LED’s are red. For normal operation,
with the clock locked and accurate, both green LED’s should be ON and both red LED’s should
be OFF. The following definitions apply to these indicators:
•
OPERATE
: Indicates that power is being supplied to the clock.
•
STABILIZED
: Flashes (ON-OFF, 1 second intervals) when clock time is stabilizing with
GPS. Is steady when the clock time is accurate.
•
OUT OF LOCK
: Illuminates when the clock has not yet synchronized, or has lost synchro-
nization, with the GPS.
•
FAULT
: Illuminates when an internal fault occurs. Faults are listed below.
Fault Indication
Definition
Out-of-Lock
GPS Receiver is not receiving satellite signals
Receiver Failure
Clock not communicating with GPS receiver
Antenna Short
Voltage (5 V) at antenna connector low (shorted)
Antenna Open
Open circuit condition at antenna (disconnected?)
Table 2.2: Fault Indications and Definitions
2.2.2
LCD Display
The Model 1094B contains a back-lit, liquid crystal display, which provides a 20-character by 2-
line readout that displays instrument time and date, geographical position, event data and status.
Using the lower set of keys, the readout is also used to display the current configuration of operation
parameters.
