UHF Analog Driver/Transmitter/
Chapter 2, System Description,
Translator
Maintenance & Remote Control Connections
LX Series, Rev. 3
2-15
the transmitter. This condition is the
result of a fault that causes the firmware
to hold the IF Processor module in a
mute state.
Operate Mode with Mute Condition
The transmitter will remain in the
operate mode but will be placed in mute
when the following fault conditions
exists in the transmitter.
•
Upconverter is unlocked
•
Upconverter module is not present
•
IF Processor module is not present
•
Modulator (if present) is in
Aural/Visual Mute
Entering Operate Mode
Entering the operate mode can be
initiated a few different ways by the
transmitter control board. A list of the
actions that cause the operate mode to
be entered is given below:
•
A low on the Remote Transmitter
Operate line.
•
User selects "OPR" using switches
and menus of the front panel.
•
Receipt of an “Operate CMD” over
the serial interface.
There are several fault or interlock
conditions that may exist in the
transmitter that will prevent the
transmitter from entering the operate
mode. These conditions are:
•
Power Amplifier heat sink
temperature greater than 78°C.
•
Transmitter is Muted due to
conditions listed above.
•
Power Amplifier Interlock is high
indicating that the amplifier is not
installed.
Standby Mode
The standby mode in the transmitter
indicates that the output amplifier of the
transmitter is disabled.
Entering Standby Mode
Similar to the operate mode, the
standby mode is entered using various
means. These are:
•
A low on the Remote Transmitter
Stand-By line.
•
Depressing the “STB” key on
selected front panel menus.
•
Receipt of a “Standby CMD” over the
serial interface.
Auto Standby Mode
The FCC requires that certain
transmitters automatically switch to
standby operation on loss of video input.
The LX Series transmitter incorporates
this feature as a user configurable
setting. When Auto Stand-By on
modulation loss is selected in the set-up
menus, the transmitter temporarily
switches to standby after ten seconds of
modulation loss. When the modulated
signal as reported by the IF Processor
module is again present, the transmitter
automatically returns to Operate mode.
This feature is implemented in
transmitter software versions 1.4 and
above.
RF System Interlock
A RF System Interlock signal is provided
through TB30-5. When this signal's
circuit is completed to ground such as
through a wire between TB30-5 and
TB30-15, the transmitter is allowed to
operate. If this circuit is opened, the
transmitter switches to a Mute condition.
This circuit may be completed through
coax relay contacts and reject load
contact closures to assure the RF output
system is available to receive the
transmitter's output RF signal. This
feature is implemented in transmitter
software versions 1.4 and above.
