User's Manual

Model 1150A DVOR
Rev. - November, 2008
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.
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2.3.2.14.1.9
LCU Transfer Control State Machine #1 and #2 and Discrete Controls
The heart of the LCU is the two redundant transfer control state machines. These are configured by the RMS;
receive key commands from the front panel or from the RMS, and process alarms reported by the monitors after
being filtered by the Positive and Negative Alarm Registers. Once configured for on air, the state machines will
drive out the required signals to enable the transmit on clocks (1_TX_ON_CLK, 2_TX_ON_CLK), enable the +24V
power to the synthesizer VCO's (1_24VCO, 2_24VCO), and select the required system to be placed on the antenna
(1_+24ANT_SW, 2_+24ANT_SW).
With the redundant state machines, detection of an error assures that the system generating the error will be removed
from the air. The LCU transfers to the standby system if configured to do so either immediately for a hot Standby
system or after a 20 second delay for a cold Standby system. If further alarms are detected, the LCU transfer state
machines will shut the standby transmitter down and block any further transmission for a minimum of 20 seconds.
Restarts are under the control of the RMS.
The LCU transfer control state machines report status back to the RMS indicating the state of the state machines,
and any shutdowns that have occurred. The LEDs on the front panel reflect the current state of the state machines.
2.3.2.14.1.10
LED Control
Status is fed back to a local operator via the LED's on the front panel of the LCU. These reflect the state of the
transmitters and the various alarms as reported by the monitors.
2.3.2.14.1.11
Audible Alarm
If an alarm as reported by the monitors is detected that is not bypassed, the audible alarm is generated. The audible
alarm can be reset by pressing the Alarm Silence button on the front panel. In local mode, the audible alarm is
disabled.
2.3.2.14.1.12
Monitor Alarm Interface
In order to insure that a monitor alarm signal is communicated to the control logic, redundancy is incorporated into
the monitor alarm signals. Each alarm signal is sent as two signals, one active high and the other active low. In the
LCU, resistors are used to pull each of their signals to their active (alarm) state. This insures that an alarm condition
will be sensed if there is an open in either alarm line. If an alarm line is shorted to its inactive (non-alarm) state, the
other line will communicate an alarm condition. If the 1_INT_ALARM+ signal is disconnected, a resistor will pull
the input high resulting in an alarm condition being sent to the control logic in the EPLD U3. If the
1_INT_ALARM- signal is disconnected, a resistor will pull the input to a low logic level.
2.3.2.14.1.13
Station Control Logic
The station control logic is duplicated in both U1 and U3. The logic responds to local operator control through the
pushbutton switch inputs as well as remote control through the parallel interface. The local operator can perform the
following functions:
a. Specify which VOR transmitter is to be designated as main.
b. Turn either transmitter ON and connect it to the antenna.
c. Turn either transmitter ON and connect it to the load.
d. Turn either transmitter OFF.
e. Toggle the bypass state of either of the monitored signal sources (Integral, Standby).
f. Silence the aural alarm (until the next event causes it to sound).
g. Toggle the state of local control. When local control is set, input from the keypad is enabled.