Comtech EF Data RCF6001 - Manual (Page 10)

Description RCF6001 Satellite Terminal
Page 1-2 TM082 - Rev. 1.0
The DMD2401 LB/ST operates at data rates up to 4.375 Mbps. Selection of any data rate is provided over
the range of 9.6 Kbps to 4.375 Mbps in 1 bps steps.
The DMD2401 LB/ST is designed to perform as both ends of a satellite Single Channel Per Carrier (SCPC)
link or as the VSAT remote site modem in a TDMA hub system. The Modulator and Demodulator operate
independently using BPSK or QPSK modulation in either SCPC or VSAT modes.
The DMD2401 LB/ST is programmable from the front panel. The program menu was specifically designed
for ease of use to quickly put the modem online and for any network changes. The modem also can be
monitored and controlled through the RS485 or RS232 serial control channel.
Available options for the DMD2401 LB/ST include a low data rate asynchronous serial overhead channel
for remote monitor and control. Additionally, a Reed-Solomon codec is available for applications requiring
Bit Error Rates of 10
-10 .
1.1 Applications
Following are just a few representative forms of satellite communications links and networks in which the
DMD2401 LB/ST modem may be used.
1.1.1 SCPC Point-to-Point Links
The most straightforward application for a satellite modem is to serve as the Data Communications
Equipment (DCE) for a point-to-point data link. When used in this mode, two modems located at two
different sites are tuned to complementary transmit and receive frequencies. Each direction of the
communications link may have the same or entirely different transmission parameters. In this application, it
is typical that the link is established and maintained on a continuous basis, although a special “on demand”
case is described later.
1.1.2 SCPC Point to Multi–Point Links in a Broadcast Application
A broadcast application might involve the necessity of sending continuous or intermittent data from one
source and “broadcasting” the information to many remote locations. For instance, constant pricing
information and updates may be sent by a central location to many store locations. There may be minor
return information from the remotes acknowledging receipt.
Another broadcast application could be transmitting background music from a central location to many
store sites. In this case, there would be no return path.
Figure 1-1. DMD2401 LB/ST Satellite Modem Front Panel