4 MDS 4790/9790 Series I/O Guide MDS 05-3438A01, Rev. F
Figure 3. Typical Repeater and Polling-Remote Network
Simplex and Switched Carrier Operation
System-wide simplex operation is achieved by switching the master sta-
tion carrier on to transmit, then off to receive. The same frequency is
used for both transmit and receive.
Switched carrier, half-duplex mode works in the same way, except dif-
ferent frequencies are used for transmit and receive.
2.4 Features
Reliability is a hallmark of the MDS 4790/9790 design. The radio
employs a one-piece transceiver board which minimizes RF losses and
eliminates the need for inter-board cabling. This also allows easy
plug-in replacement if servicing is necessary.
In addition, the optional redundant version of the radio includes redun-
dant transceiver boards and power supply modules that automatically
activate if a failure in either of the transceiver boards or power supplies
occurs. This ensures continued operation in the event of most trans-
ceiver board failures.
The following list highlights many of the radio’s key features. For a full
listing of specifications, refer to Section 10.1, Technical Specifications,
beginning on Page 97.
–
I
DIAG
13.
8
VD
C
PWR
+
–
HOST SYSTEM
REMOTE RADIO
RTU
RTU
RTU
RTU
–
IDIAG
13
.8 VDC
PWR
+
–
–
IDI
A
G
1
3
.
8
V
D
C
P
W
R
+
–
–
I
DIAG
13.8
V
D
C
P
WR
+ –
–
I
D
IA
G
13.
8 VD
C
PWR
+
–
RTU
CONTINUOUSLY
KEYED
REMOTE RADIO
REMOTE RADIO
REMOTE RADIO
REMOTE RADIO
POLLING REMOTE
REPEATER
HALF-DUPLEX
SWITCHED CARRIER
TX HIGH
RX LOW
TX LOW
RX HIGH
TX LOW
RX HIGH
TX LOW
RX HIG