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A2537-002/01 February 2020
6-27
SEMCO Proprietary Information
Figure 6-39
illustrates AE selection using the remote GUI. The user clicks on the
Adaptive EQ
window
to
toggle
ON
as shown
.
Figure 6-39
AE Selection on Remote GUI
6.8.8
Low Density Parity Check (LDPC) FEC
FEC is a way of adding additional information to a transmitted bit stream in order to decrease the required
signal-to-noise ratio to the receiver for a given bit error rate. Low Density Parity Check (LDPC) is a block
code, which is a block of information bits with parity added in order to correct for errors in the information
bits. The “Low-Density” parity check matrix contains mostly 0’s and relatively few 1’s.
There are six different LDPC codes with different coding rates (rate 1/2, 2/3, 4/5) and information block
sizes (1024 and 4096). In the trade between transmission channel characteristics, bandwidth efficiency,
coding gain, and block size, all three rates and block sizes 1024 and 4096 are applicable.
In addition, the receiver provides for a selectable CCSDS and IRIG de-randomizer.
LDPC is only used with SOQPSK-TG modulation.
Figure 6-40 illustrates how to select the SOQPSK-LDPC demodulation format, rate, block size and de-
randomizer. (Front Panel display is
LDPC
which, when selected is SOQPSK-LDPC)
The operator pushes the
DEMOD MODE
button to access the
<
Ch1
> Demod Menu
display, uses the
UP
(2) and
DOWN
(8) arrows to scroll to
Mode
in blue, and then pushes
ENTER
or
SELECT
(5) to highlight
the
Mode
selection window in
bright magenta
. Using the
UP
(2) and
DOWN
(8) arrows, the operator
selects
LDPC
and then pushes
ENTER
or
SELECT
(5).
Using the horizontal
LEFT
(4) and
RIGHT
(6) arrows, the operator selects
<
Ch2
>
in the
Demod Menu
header bar. The operator then pushes
ENTER
or
SELECT
(5) to highlight the
Mode
selection window in
bright magenta
. Using the
UP
(2) and
DOWN
(8) arrows, the operator selects
LDPC
and then pushes
ENTER
or
SELECT
(5). Using the horizontal
LEFT
(4) and
RIGHT
(6) arrows again, the operator selects
<
Comb
>
in the
Demod Menu
header display bar and repeats the process for selecting Combiner
LDPC
.
Summary of Contents for RC100C-2
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