R
R
M
M
A
A
S
S
-
-
1
1
2
2
0
0
A
A
l
l
a
a
r
r
m
m
12
Chapter 2
Technical Description
When ordering the RMAS-120, the transmitter unit must be specifically ordered
for work with different microwave frequency and amplifier configurations. The
standard alarm receiver has dual inputs for diversity microwave systems which
allow it to automatically adjust to the stronger AGC input in such systems.
2.2 Standard Transmitter
The standard RMAS-120-01 transmitter is capable of monitoring up to 2
microwave repeater amplifiers. For diversity and multi-channel applications, the
transmitter unit can be ordered to provide status information for up to 8
amplifiers.
See Figure 2.1
for a block diagram of the transmitter.
LED
DISPLAY
USER
CHECK
SWITCH
VCC
27
4
ANALOG
OPTO
ISOLATOR
TO USER
MULTIPLEXER
DIGITAL
INTERFACE
20 Committed
7 Uncommitted
MC
68HC711
Microcontroller
FILTER
AMPLIFIER
BALANCED
OUTPUT
4
27
2
6
Figure 2.1
RMAS-120 Standard Transmitter Block Diagram
Amplifier status is monitored through the use of current comparator circuit.
Generally, when there is a problem in an amplifier, the current drain for the
amplifier will either increase or decrease. An alarm will activate if the current
drain on any one of the amplifiers is significantly different from normal.
2.3 Alarm Descriptions
The alarms reported by the RMAS-120 are as follows:
The RF low power alarm is generated by comparing the RF level of the
carrier with the field-adjustable reference point (normally 5 dB below
nominal level). The standard transmitter can monitor up to 2 microwave
carriers. The optional transmitters can monitor up to eight microwave
carriers.
The battery major alarm is generated if the A (or B) battery voltage drops
below 11.5 V (12 V battery) or 23.0V (24 V battery).
The cabinet door alarm is provided for security monitoring.