Comtech EF Data CDM-625A - Manual (Page 48)

CDM-625A Advanced Satellite Modem MN-CDM625A
Introduction Revision 3
1–4
1.3 Features
1.3.1 Physical Description
The CDM-625A is constructed as a 1RU-high rack-mounting chassis, which can be free-standing
if desired. Handles at the front ease placement into and removal from a rack.
The CDM-625A modem chassis assembly (CEFD P/N PL-0021325 Standard AC Chassis or CEFD
P/N PL-0021327 Optional DC Chassis) is physically comprised of two main card assemblies:
• Baseband Framing Card (CEFD P/N PL-0021331 or PL-0021534). This first card includes all of
the interface circuits, the framer/de-framer, plesiochronous/Doppler buffer, Reed Solomon
outer codec, HDLC framer, Ethernet switch, and the main microcontroller.
• Modem Card (CEFD P/N PL-0021330). This second card is the modem itself. It performs all
signal processing functions of modulation, demodulation, and primary Forward Error
Correction.
1.3.2 Modem Compatibility
The CDM-625A is fully backwards-compatible with the Comtech EF Data CDM-625, CDM-500,
CDM-550, and CDM-550T modems. As an Open Network Modem, the CDM-625A is fully
compatible with modems from other manufacturers that are compliant with the IESS-
308/309/310/314 specifications. Note, however, that IESS-315 (VSAT Turbo) defines closed
network operation, and this therefore requires modems from the same manufacturer at both
ends of the link.
The unit is also fully backwards-compatible with the CDM-600 and CDM-600L modems (With the
exception of a lower data rate range of 18 kbps). The modem includes software emulation of
CDM-600 and CDM-600L.
1.3.3 Verification
The CDM-625A includes many test modes and loopbacks for rapid verification of the correct
functioning of the unit. Of particular note is the IF loopback, which permits you to perform a
quick diagnostic test without having to disturb external cabling. During the loopback, all of the
receive configuration parameters are temporarily changed to match those of the transmit side,
and an internal RF switch connects the modulator output to the demodulator input. When
normal operation is again selected, all of the previous values are restored.
1.3.4 Updating Modem Firmware
Chapter 4. UPDATING FIRMWARE
The CDM-625A stores its firmware internally in flash memory, which simplifies the firmware
updating process without having to open the modem. Firmware downloads are available via the