Front Panel; Figure 3-1. Front Panel - Comtech EF Data CDM-710 Installation And Operation Manual

CDM-710 Broadcast Satellite Modem
Functional and Physical Description
An Rx carrier from the satellite is received by the demodulator and reverses the process
performed by the modulator. The demodulator has an FEC decoder that corrects errors incurred
during transmission to improve the integrity of the data delivered to the data interface. A
synthesizer in the demodulator is programmed to select the desired carrier from the transponder.
Physically the
3.1

Front Panel

The front panel (Figure 3-1) features a Vacuum Fluorescent Display (VFD), a keypad, and eight
LED indicators. The user enters data via the keypad, and messages are displayed on the VFD.
The LEDs indicate, in a summary fashion, the status of the unit.
The VFD is an active display showing 2 lines, each of 24 characters. It produces a blue light, the
brightness of which can be controlled by the user. It has greatly superior viewing characteristics
compared to a Liquid Crystal Display (LCD), and does not suffer problems of viewing angle or
contrast.
The keypad has six individual keyswitches, mounted directly behind a fully sealed membrane
overlay. They have a positive 'click' action, which provides the user with tactile feedback. These
six switches are identified as [ ], [ ], [ ], [ ] arrows, ENTER and CLEAR. There are seven
LEDs on the front panel. Refer to Chapter 5 for description of operation.
is comprised of several main card assemblies.
modem
The Data Interface card is a plug-in module that is readily installed or removed at
the rear of the unit.
Note: Power is turned off to remove or install the data interfaces.
The Framer Card receives signals from the data interface card and routes signals
to the FEC Encoder and Modulator. The microcontroller for the unit also resides
on the Framer Card and is the embedded controller for the entire
microcontrollers handles all of the monitor and control for unit including the
front panel keypad and display, the RS-232 and RS-485 2Wire / 4Wire remote
port and the 10/100 Ethernet port. Interface with the other the modules in the
modem is provided by the framer assembly.
The FEC Encoder card is a plug-in module that resides on the Framer card. It
generates the encoded stream used by the modulator card.
The Modulator card plugs into the framer card. It maps and spectrally shapes the
I&Q data for delivery to the IF interface.
The Demodulator card also plugs into the framer. It recovers the selected carrier,
performs error correction and delivers data stream to the framer card.

Figure 3-1. Front Panel

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. The
modem