Standard Features; Aupc; Software - Flash Upgrading - Comtech EF Data CDM-600L Installation And Operation Manual

CDM-600L Satellite Modem
Introduction
1.1

Standard Features

The CDM-600L provides a wealth of standard features which go far beyond the basic
requirements of the Intelsat specifications.
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Note: In EDMAC mode, an additional 5% overhead is combined with the traffic data,
(1.5% in Turbo BPSK modes, Turbo Rate 1/2 QPSK/OQPSK, and all data rates greater
than 2 Mbps) which permits Monitor & Control (M&C) information to be added
(transparently to the user), allowing access to the distant-end modem. This mode does not
require any additional cabling at either the local or distant-end modems - access to
EDMAC is via the standard M&C control port. Full M&C is possible, and importantly,
the on/off status of the carrier at the distant-end carrier can be controlled. In addition, for
firmware version 1.2.0 and higher, the proprietary D&I++ framing mode is available.
This combines Drop & Insert (D&I) operation with a similar EDMAC link and a 2.2%
overhead.
1.1.1

AUPC

An important innovation in the CDM-600L is the addition of Automatic Uplink Power
Control (AUPC). This feature enables the modem to automatically adjust its output
power to maintain the Eb/No of the remote end of the satellite link constant. This
provides protection against rain fading, a particularly severe problem with Ku-band links.
To accomplish this, either the EDMAC or D&I++ or ESC++ framing types may be used,
and the distant end modem constantly sends back information about the demodulator
Eb/No using reserved bytes in the overhead structure. Using the Eb/No, the local modem
then adjusts its output power, and hence, a closed-loop feedback system is created over
the satellite link.
A benefit of this AUPC feature is that the remote demodulator's Eb/No can be viewed
from the front panel display of the local modem.
1.1.2 Software – Flash Upgrading
The internal software is both powerful and flexible, permitting storage and retrieval of up
to 10 different modem configurations. The modem uses 'flash memory' technology
internally, and new firmware can be uploaded to the unit from an external PC. This
Low rate variable data rates – 2.4 kbps to 5.0 Mbps
Mid-rate variable data rates – 2.4 kbps to 10.0 Mbps
High-rate variable data rates – 2.4 kbps to 20.0 Mbps
Embedded Distant-end Monitor and Control (EDMAC) (see Note)
Asymmetric Loop Timing
Automatic Uplink Power Control (AUPC)
Software – Flash Upgrading
Modulation Types –BPSK, QPSK, and OQPSK
1:1 and 1:10 redundancy switches
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Revision 2
MN/CDM600L.IOM