RFL 9780 RFL Electronics Inc.
April 8, 2003 6-24 (973) 334-3100
If an under-voltage condition is detected by the power supply, the PWR_FAIL and/or POWERFAIL2
inputs to the 9780 Logic Module will be logic-low. This will generate a logic-low POWER signal to
prevent the LOW_SIGNAL_TRIP signal from going active for the period of the under-voltage
condition plus an additional 600 ms. The unblock trip output will effectively be blocked.
6.5.1.17 5 MS HOLD
The 5 ms hold circuit extends the LOW_SIGNAL_TRIP for an additional 5 ms. The extended logic-
high output signal, BLOCK_CHANNEL, is applied to AND1. The output of AND1, VALID_LOW, is
held low for the extended period. This prevents the unblock security timer from incrementing.
6.5.1.18 UNBLOCK TRIP RESTORE TIMER
Unblock trip restore timer is used to enable the unblock trip output after 50 ms of clear channel (a
logic-low LO SIG) or 50 ms of valid guard (a logic-high GUARD_RLY) output depending upon the
9780 Logic Module configuration. This circuit adds security by requiring a valid guard output or clear
channel before a trip can be generated.
If an abnormal condition causes LOGIC_ALM to go active following an unblock trip, the input to the
trip restore timer will be blocked until the abnormality ceases and the alarm drops out.
Once the 50 ms timer is satisfied, the logic-high UNBLOCK_CHANNEL signal will SET the SR Flip-
Flop. The logic-high output of the SR Flip-Flop is applied to AND1 allowing the unblock security timer
to monitor the LO SIG input. If significant channel loss occurs to satisfy the unblock security timer, a
valid low signal trip will occur.
6.5.2 TRANSMITTER LOGIC
The 9780 Logic Module accepts trip inputs and voice enable signals and uses them to generate control
signals for the transmitter module. It also contains a circuit that monitors the output of the power
amplifier module, and generates a transmitter fail (TX_FAIL) output.
6.5.2.1 TRIP INPUT CIRCUITS
The trip-input circuits accept trip inputs from solid-state input relays at the rear of the 9780 chassis and
passes them to the logic circuits.
In order for the 9780 to produce a valid trip command, a zero-volt signal must appear at one or both trip
inputs (edge connector pins B21 and C22) depending upon the configuration.
The first trip input accepts a signal applied to the TRIPIN_1 input (edge connector pin B21). An RC
network filters out any contact bounce. The output of this filter is applied to a Schmitt trigger. Its output
is passed on to the logic circuits.
The second trip input accepts a signal applied to the TRIPIN_2 input (edge connector pin C22). An RC
network filters out any contact bounce. The output of this filter is applied to a Schmitt trigger. Its
output is passed on to the logic circuits.
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