User Reference and Installation Guide
2-15
© 2006 Microwave Data Systems Inc.
All Rights Reserved.
MDS
Digital Radio
Series
05-4561A01, Rev. A
The ODU RF Up/Down Converter card provides the interface to the antenna. The transmit
section up-converts and amplifies the modulated Intermediate Frequency (IF) of 350 MHz from
the IF Processor and provides additional filtering. The receive section down converts the
received signal, provides additional filtering, and outputs an IF of 140 MHz to the IF Processor.
The 64-QAM Modem performs the modulation and demodulation of the payload and forward error
correction using advanced modulation and coding techniques. Using all-digital processing, the
64-QAM Modem uses robust modulation and forward error correction coding to minimize the
number of bit errors and optimize the radio and network performance. The 64-QAM Modem also
scrambles, descrambles and interleaves/de-interleaves the data stream in accordance with
Intelsat standards to ensure modulation efficiency and resilience to sustained burst errors. The
modulation will vary by application, data rate, and frequency spectrum. The highest order
modulation mode supported is 64 Quadrature Amplitude Modulation (QAM).
164H 161H
Table 2-5
summarizes the TCM/convolutional code rates for each modulation type supported by the MDS
Digital Radio Series.
Table 2-5. MDS Digital Radio Series TCM/Convolutional Code Rates
Modulation Type
Available Code
Rates
16-QAM
3/4, 7/8, 11/12
32-QAM
4/5, 9/10
64-QAM
5/6, 11/12
The major functions of the SDIDU
TM
can be summarized as follows:
•
I/O Processing – The SDIDU
TM
comes with a standard I/O capability that includes support for up to
16xT1/E1 and 2x100Base-TX user payloads, 2x100Base-TX for SNMP, and voice orderwire. In
addition, option cards for DS-3/E3/STS-1, 1-2 x STM-1/OC-3, and 4xDS-3/E3/STS-1 may be
added. The SDIDU
TM
architecture is flexible and allows for the addition of other I/O types in the
future.
•
Switch/Framing – The SDIDU
TM
includes an Ethernet Switch and a proprietary Framer that are
designed to support 1+1 protection switching, ring architecture routing, and overall network control
functions.
•
Network Processor – The SDIDU
TM
includes a Network Processor that performs SNMP and
Network Management functions.
•
Modem/IF – The SDIDU
TM
Modem performs forward-error-correction (FEC) encoding, PSK/QAM
modulation and demodulation, equalization, and FEC decoding functions. The IF chain provides a
350 MHz carrier, receives a 140 MHz carrier, processes OOK telemetry, and provides –48V
power. Two modems can be used for 1+1 protection or ring architectures.
•
Power Supply – The SDIDU
TM
power supply accepts
-
48 Vdc and supplies the SDIDU
TM
and ODU
with power. A second redundant power supply may be added as an optional module.
The Modem Processor and its associated RAM, ROM, and peripherals control the digital and analog
Modem operation. It also provides configuration and control for both the IF and I/O cards.
The
Summary of Contents for FOUR.9 Series
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