Operating Instructions
ProTelevision Technologies
PT 5780 DVB-T Modulator
Instruction Manual
Revision 3.11
4-32
alarm to warn the user that the (external) reference signal has been lost. Note, as before, there
is no automatic muting of the output signal, whilst the internal 10 MHz signal is in operation. A
short discontinuity in the output signal will occur when the instrument switches from the external
to internal frequency reference.
Once the external reference has been re-established the 10 MHz reference switches back to
the external source and the alarm is removed. The output signal is muted for 2 secs on
switching back to the external reference source, which is seen as a short discontinuity of the
output signal.
Using this reference setting in SFN will provide a system that continues operation in SFN in
case of loss of frequency reference. This may disturb some receivers located in transmitter
overlap regions, as a receiver may receive two non-synchronized SFN signals on the same
transmit frequency.
4.6
Fatal Alarms
There are a two possible “FATAL ALARM” messages that may be displayed by the modulator.
4.6.1
Modulator Board Controller Not Responding
If the modulator board stops responding, or does not respond during the start-up process, the
following window will be displayed:
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****** F A T A L E R R O R ******
=- BACK-END CONTROLLER NOT RESPONDING -=
----------------------------------------
The first line flashes. If the back-end controller starts responding or if the user presses the
“EXECUTE” button, the system automatically resets, and the system tries to recover.
4.6.2
Instrument Too Hot
Temperature sensors are mounted on the printed circuit boards; one on the master controller
board, two on the modulator board and one on the RF converter board.
Two alarm limits (lower and upper) are set for each sensor. On rising above a lower alarm level,
an alarm pending message is provided, with an indication to which temperature sensor is
causing this condition. If any of the board temperatures rise above their pre-defined upper limits,
the following display is shown (the first line flashes):
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****** F A T A L E R R O R ******
=- Temperature too high in Instrument -=
----------------------------------------
Local user access to the front panel controls is prohibited until the “EXECUTE” button is
pressed, which causes the system to automatically reset. At this point the system tries to
recover.
4.7
Error Handling and Codes
If any system errors arise, the alarm status display will list the alarm ID number to indicate the
source of the error. Please contact ProTelevision Technologies for advice.
Summary of Contents for PT 5780
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