Product specifications

CDM-710 Broadcast Satellite Modem Revision 10
Functional and Physical Description MN/CDM710.IOM
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 modem is comprised of several main card assemblies.
• 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
modem. The
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.
3.2 Front Panel
Figure 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 of 24 characters each. It produces a blue light,
the brightness of which can be controlled by the user. Compared to a Liquid Crystal Display
(LCD), it has greatly superior viewing characteristics and does not suffer problems of viewing
angle or contrast.
The keypad has six individual key switches that have a positive ‘click’ action – this provides the
user with tactile feedback. The six key switches are identified as [↑], [↓], [→], [←] arrows,
ENTER and CLEAR. There are seven LEDs on the front panel. Refer to
Chapter 5. FRONT
PANEL OPERATION
for detailed information.
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