Tx Baseband Processing - Radyne DMD2050 Operation Manual

DMD2050 Universal Satellite Modem Theory of Operation
Figure 3-4. DMD2050 Universal Satellite Modem Functional Block Diagram

3.1.3 Tx Baseband Processing

The Tx Data and Clock enters the Baseband Processor, passes through a Rate Adapting FIFO
and enters the Framer/Drop Processor. In Closed-Net Mode, the data passes through the framer
unaltered. In IDR, IBS, and D&I Modes, the framer adds the appropriate framing and ESC as
defined in IESS-308 and 309. In D&I Mode, the framer acquires the terrestrial framing structure,
E1 or T1, and synchronizes the Drop Processor. The Drop Processor extracts the desired time
slots from the terrestrial data stream and feeds these channels back to the framer. The framer
then places the 'dropped' terrestrial time slots into the desired satellite channel slots. The data is
then sent to the Reed-Solomon Encoder.
The Reed-Solomon Encoder, encodes the data into Reed-Solomon Blocks. The blocks are then
interleaved and synchronized to the frame pattern as defined by the selected specification (IESS-
308, IESS-309, DVB, etc.). After Reed-Solomon Encoding, the composite data and clock are
applied to the BB Loopback Circuit.
TM110 – Rev. 1.3 3-5