Thunderbolt Monitor Kit Manual v5.0.6
Page 5
3/8/2020
The contrast adjustment potentiometer (R6) has been adjusted for the standard 2x16
LCD display. There should be no need to change the setting unless a different display is
used or if the supply voltage is below 5.5V. Please note that VFD devices do not use the
contrast adjustment potentiometer or the backlight resistor R7.
Parameters displayed:
During normal operation, the kit displays the current time and date (in the selected
mode: GPS, UTC or Local) on the first line of the LCD. If a display with 20 characters is
used, the first line also displays the time mode. The second line displays the following
status information in sequence:
1. Disciplining mode
2. Disciplining activity
3. Receiver mode
4. GPS Decode status
5. Internal Thunderbolt temperature
6. DAC voltage
7. 10 MHz offset
8. External temperature (when enabled through the menu)
9. Critical Alarms, if any (see notes)
10. Minor Alarms, if any (see notes)
Notes:
If any Critical Alarm is present, the display of normal status information (items 1
through 8 in the list above) is suspended.
All Minor Alarms that are present are displayed on line 2 of the display at the end
of the sequence.
Details of the various modes reported by the Thunderbolt are described in the
Thunderbolt User’s Guide [6].
Alarm outputs:
The kit has two alarm outputs, one for the Critical (Major) alarms and one for the Minor
alarms. If a single indicator is preferred, the kit can be configured via the menu to
activate the Major alarm output for any alarm, Major or Minor. The kit can also be
configured via the menu to set a Minor alarm when a Leap Second is pending.
Time mode:
The kit can be configured to display GPS time, UTC time, Local time with DST, Local
Time without DST or Sidereal Time.
The difference between GPS time and UTC time is referred to as the “GPS Offset” or
sometimes the “UTC Offset”. As of December 2019, the GPS offset is 18 seconds. It
increases by one second typically every 18 to 24 months (Leap second events), on the
last day of June or December. The Thunderbolt receiver provides the current GPS offset
in its Primary Data Packet so the kit can decode it and there is normally no need to
worry about it, but the kit can be configured manually if preferred.
