Comtech EF Data DMD2401/DMD2401L - Manual (Page 17)

Introduction DMD2401/DMD2401L/DMD2401 IBS/IDR Satellite Modem
1-2 TM065 – Rev. 3.3
The DMD2401 can track and acquire a carrier over a programmable range of ±1 kHz to ±42 kHz.
Acquisition times of less than 10 seconds are typical at data rates of 64 Kbps over a range of
± 25 kHz.
To facilitate link testing, the DMD2401 incorporates built-in ‘2047’ test pattern generators with
BER measurement capability. A user-selectable terrestrial and/or satellite loopback test capability
is also provided.
For applications requiring systems redundancy, multiple DMD2401 modems may be used with the
Radyne RCS11 1:1 Redundancy Switch or the RCS20 M:N (N < 9) Redundancy Switch. A full
range of industry-standard interfaces are available for the DMD2401, DMD2401L, and DMD2401
IBS/IDR. These include RS-232, V.35, RS-422/-449 and ITU G.703.
Available options for the DMD2401 includes a low data rate asynchronous serial overhead
channel for remote monitor and control. Additionally, a Sequential Codec is available for
applications requiring compatibility with existing systems.
Figure 1-1. DMD2401 Satellite Modem
1.1 DMD2401 Available Options
A wide range of options are available for the DMD2401 Satellite Modem. A brief description of
each follows:
1.1.1 Reed-Solomon Codec
The DMD2401 can be equipped with a Reed-Solomon outer codec with an interleaver as an
optional enhancement. The encoder and decoder are completely independent and meet IESS-
308/-309 Specifications. Once prepped, this option can be installed in the field by following an
upgrade procedure.
Note: Custom Reed-Solomon codes are also available.
1.1.2 Sequential Decoding
The DMD2401 can also be equipped with an optionally installed sequential decoder. The
DMD2401 must be prepped for this option in the factory. Once prepped, the option can be added
by installing a daughter card on an existing header. Sequential Encoding/Decoding can operate
with 1/2, 3/4, and 7/8 Rates up to data rates of 4.375 Mbps.
1.1.3 Asynchronous Overhead Channel
The DMD2401 can be equipped with optional asynchronous overhead channel capability. The
option can be added in the field by installing a single interface PC board. The overhead channel
is proportional to the data rate (Baud Rate is approximately 1/2000 of the Data Rate for Standard
IBS and up to a maximum of 19.2 Kbaud for IBS Async).