Comtech EF Data SDM-2020, Installation And Operation Manual

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Rev. 3 3–1
3
Chapter 3.
OPERATION
This chapter describes demodulator operation from the front panel and provides an
explanation of command functions.
For remote control operation information, refer to Appendix B.
3.1 Introduction
The SDM-2020 demodulator has three general modes of operation controlled by the
DVB Framing Type command in the Configuration Interface menu.
Refer to Table 3-1 for a description of the three modes.
Table 3-1. Mode Description
Mode Description
188 The demodulator receives a 204 byte satellite frame. The outgoing DVB/MPEG2 frame
consists of 1 sync byte (047 hex) and 187 bytes of data after the Reed-Solomon check bytes
(16 bytes) are removed.
204 The demodulator receives a 204 satellite frame consisting of 1 sync byte (047), plus 187
bytes of data and 16 bytes reserved for check bytes. The outgoing frame contains 204 bytes.
None (187) In this mode there is no outgoing frame structure. The demodulator receives a 204 byte
satellite frame and removes the 1 sync byte and 16 Reed-Solomon check bytes.
Note: The satellite frame is always 204 bytes, and the data format exiting the data interface
depends upon the type of interface and the configuration selected. Control functions and status
readings are accessible through the front panel keypad/LCD display, or the rear panel remote
port.