Codan MT-4E, Maintenance Manual

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MT-4E ANALOG & P25 DIGITAL RADIO SYSTEMS | MAINTENANCE GUIDE
Chapter 6: Additional Radio System Tests Page 61
RF Carrier Signal Levels on Links between Sites
When linking two radio systems together it is advantageous to test the RF signal strength between
the linked sites. A carrier signal level test can be performed by keying up the transmitter that links
to the radio site under test and measuring the RF carrier level at the receive antenna. Keying up the
transmitter at the other site can be done with a portable radio at your location, or by having someone
else key that link with a portable or base station. Measurement of the RF carrier level can be performed
by two diff erent methods.
The fi rst method to measure the RF carrier signal level is by connecting a switched RF attenuator
between the antenna port of the fi ltering equipment and the antenna as shown in Figure 6-4. Switch the
attenuator just until the receiver squelches and note the amount of attenuation. This is the fade margin
of the RF carrier signal on that link.
The second method to measure the RF carrier signal level is to measure the RSSI of the Receiver
(either by the voltage output on the System Regulator or the RSSI meter built into the Service section
of the RSS). Note the RSSI level, then connect a test set to the antenna port of the fi ltering equipment
and adjust the RF carrier level until the noted RSSI level is achieved. This is the received RF carrier
level on that link.
Figure 6-4: RF Carrier Level on Link Test
Portable
Repeater
Site B
Repeater
Site A
LINK ANTENNA
Switched Attenuator RF Carrier Signal
between Sites
LINK
ANTENNA
Filtering
Equipment
TRANSMITTER
CNTL
BUS
MIC RF OUT
A D
ANALOG
DIGITAL
NORM
OFF
KEY TX
MIC MODE
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
RECEIVER
NORM
SQ. DISABLE
OFF
CNTL
BUS
A D
RF N I
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
6 7
8
11
10
9
FUNCTION
12
REPEATER
CONTROL
RX B
TX B
RX A
TX A
PULL DOWN
TO REMOVE
9
5
3
7 11
15
9
13
3
7 11
15
SWITCH A SWITCH B
TRANSMITTER
CNTL
BUS
MIC RF OUT
A D
ANALOG
DIGITAL
NORM
OFF
KEY TX
MIC MODE
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
RECEIVER
NORM
SQ. DISABLE
OFF
CNTL
BUS
A D
RF N I
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
TRANSMITTER
CNTL
BUS
MIC RF OUT
A D
ANALOG
DIGITAL
NORM
OFF
KEY TX
MIC MODE
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
RECEIVER
NORM
SQ. DISABLE
OFF
CNTL
BUS
A D
RF N I
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
VOL
SYSTEM REGULATOR
METER
+
-
MADE IN CANADA
ON
OFF
SPKR
INT
EXT
EXT
SPKR
OFF
POWER
ON
2
1
5
4
3
6 7
8
11
10
9
FUNCTION
12
REPEATER
CONTROL
RX B
TX B
RX A
TX A
PULL DOWN
TO REMOVE
9
5
3
7 11
15
9
13
3
7 11
15
SWITCH A SWITCH B
TRANSMITTER
CNTL
BUS
MIC RF OUT
A D
ANALOG
DIGITAL
NORM
OFF
KEY TX
MIC MODE
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE
RECEIVER
NORM
SQ. DISABLE
OFF
CNTL
BUS
A D
RF N I
REF
IN
USB
FREQUENCY (MHz)
MADE IN CANADA
MODEL # CODE