Modems
CDM-Qx Multi-Channel
Modem with DoubleTalk™
Carrier-in-Carrier™
INTRODUCTION
The CDM-Qx is the first 70/140 MHz modular multi-channel
satellite modem packaged in a single rack unit chassis.
The unit offers exceptional flexibility, redundancy,
integration, and performance with four configurable slots.
The unique architecture allows cost-effective deployment
of multiple modulators, demodulators or modems.
CDM-Qx also supports the DoubleTalk Carrier-in-Carrier
option, allowing it to transmit and receive in the same
transponder segment.
This flexible modem was designed with satellite
operators, service providers and enterprise users in
mind. It addresses common challenges encountered
when utilizing satellite communications, including:
• Requirement for increasing throughput of
point-to-point links without utilizing additional
transponder resources
• Need to expand networks with multiple modulators
and/or demodulators (asymmetrical links)
• Limited rack space
FEATURE ENHANCEMENTS
Enhancing the performance of the CDM-Qx is easy.
Additional features are added quickly on site, using
FAST access codes purchased from Comtech EF Data.
To enable these features, simply enter the code at the
front panel. Other features are added with a simple
module swap.
DOUBLETALK CARRIER-in-CARRIER
Designed for bandwidth compression, Carrier-in-Carrier
is based on Applied Signal Technology’s DoubleTalk™,
which uses “Adaptive Cancellation,” a patent pending
technology that allows full duplex satellite links to
transmit concurrently in the same segment of
transponder bandwidth.
Available as an option to the CDM-Qx, this added
dimension can result in a significant improvement in
satellite transponder utilization. When combined with
our advanced forward error correction and modulation
techniques, DoubleTalk Carrier-in-Carrier can deliver
unprecedented operating expense savings
FEATURES
• Optional DoubleTalk Carrier-in-Carrier allowing
Tx and Rx in the same transponder segment
• 50 to 90 and 100 to 180 MHz frequency range
• 128 kbps to 20 Mbps plus limited capability down to
32 kbps
• BPSK, QPSK, 8-PSK, 16-QAM operation
• Flexible configuration
• 1 or 2 modems
• Up to 4 modulators
• Up to 4 demodulators
• Any combination, four slots available
• Optional: Built In Redundancy
• 1:1 modem
• Up to 1:3 modulator
• Up to 1:3 demodulator
• RS-422, V.35, Sync RS-232, G.703 (E1/T1) Interfaces
• RS-232, RS-485 and TCP/IP for M&C remote control
• Viterbi 1/2, 3/4, and 7/8 (QPSK)
• Concatenated Reed Solomon, 2/3 8-PSK, 3/4 16QAM
• Optional: Turbo Product Coding, IESS-315 Compliant
• Asymmetric Loop Timing
• Common frequency reference for all modules
• Optional: High Stability Reference
• Optional: Redundant Power Supply
• Individual modulator output power control
• Interoperable with many Comtech EF Data satellite
modems: CDM-550T, 570, 570L, 600, 600L,
SDM-8000, 300A, and 300L3
TURBO PRODUCT CODING
The CDM-Qx offers optional 2
nd
generation Turbo
Product Codec (TPC). TPC simultaneously delivers
increased coding gain, lower decoding delay, and
significant bandwidth savings. The TPC provides:
• BPSK 21/44 and 5/16
• QPSK / OQPSK 21/44, 3/4, 7/8 and 17/18
• 8-PSK 2/3, 3/4, 7/8, and 17/18
• 16-QAM 3/4 and 7/8
REMOTE CONTROL
The operator may configure and monitor the modem
from the front panel, or through the remote M&C port.
M&C is via RS-232, RS-485 (2/4 wire) or TCP/IP.
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