User's Manual

MODEL 2130 MARKER BEACON
Rev. A April, 2005 2-11
This document contains proprietary information and such information may not be disclosed to others for any
purposes without written permission from SELEX Sistemi Integrati Inc.
2.3.3 Local Control Unit (1A1) Simplified Theory of Operation
Refer to Figure 2-3. The Local Control Unit (LCU) controls the normal operation of the Marker Beacon. All operational
functions are performed by the LCU and are controlled by either front panel keyboard when in the local mode or by the
Remote Maintenance Subsystem (RMS) through the parallel interface. The LCU is controlled by the Portable
Maintenance Data Terminal (PMDT), Remote Control Status Unit (RCSU) or Remote Status Unit (RSU) through the RMS
for all remote operator intervention or by the RMS for automatic restart. The LCU receives the alarm outputs from the
installed Amplifier/ Monitor circuit card(s) and depending on the configuration of the system, uses the results of these
signals to determine alarm status. If an alarm is detected, the LCU shuts down the system currently radiating and
transfers to the standby system in accordance with the system configuration. The LCU also provides the ability to
disable monitors and bypass alarms as required by the operator.
The LCU provides +12V to the two possible synthesizer VCO circuits, the +12V to activate the transfer switch, and the
transmit enable clock to the installed Amplifier/ Monitors.
Status is reported by LED's visible to operator standing in front of the Marker, or through the RMS to the
PMDT/RCSU/RSU. An alarm shutdown is reported to the RMS as well as indicated by an audible alarm.
Figure 2-3 LCU Simplified Block Diagram
2.3.3.1 Local Control Unit (1A1) Block Diagram Theory
Refer to Figure 2-3.
2.3.3.1.1 DC to DC Converter
The LCU receives +12V from the two independent system power supplies and diode OR's the two sources to provide
input power to a DC to DC converter which supplies all required voltages for the LCU.
2.3.3.1.2 Power Fail Detectors
Each of the two independent +12V sources is monitored by a voltage comparator to monitor the health and availability of
power from each of the sources. These signals are used to determine voting logic for the alarm registers and are reported
back to the RMS via the parallel interface.