CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
Front Panel Operation 6–28 MN-CDM570A
Buf 6.3.2.4.9
(Buffer) Select whether or not the Plesiochronous/Doppler buffer is used, and if so,
the size of that buffer.
Inv
(Inversion) Invert the sense of the received spectrum or the received baseband
data.
EbNo
6.3.2.4.1
1
b
0
Alarm threshold) Set the E
b
0
NOTE: This parameter is not available when VersaFEC ACM (IP-ACM) or
VersaFEC-2 ACM (V2-ACM) is selected.
SNR
6.3.2.4.1
2
(SNR) Used with VersaFEC ACM (IP-ACM) or VersaFEC-2 ACM (V2-ACM) modes
only. When either ACM mode is active, the CONFIG:Rx menu changes the EbNo
α
Rx Alpha Filter Rolloff Factor dictates how fast the spectral edges of the carrier
attenuate beyond the 3 dB bandwidth.
VERY IMPORTANT NOTE – The FEC type takes the highest configuration priority,
and the selection here depends on what, if any, optional plug-in codecs are
installed. The choice of FEC type then determines what demodulation types,
code rates, and data rates are available. The order of hierarchy is therefore:
FEC type (Highest) ► Demodulation type ► Code Rate ► Data Rate (Lowest)
When you change a parameter within this hierarchy, the other parameters may
become invalid. In this case, the firmware will change those other parameters to
ensure that the configuration remains valid at all times.
Example: Suppose you have selected Viterbi + Reed-Solomon, QPSK, Rate 1/2.
Then, you change the demodulation type from QPSK to 16-QAM. In this case,
Rate 1/2 is no longer a valid code rate, so it is automatically changed to the
nearest valid code rate (Rate 3/4).
6.3.2.4.1 (CONFIG: Rx) FEC (FEC Decoder Type)
RxFEC: Vit Vit-RS TCM-RS
TPC VF ULL VF2L VF2S Unc
With VersaFEC ACM (IP-ACM) mode active:
Rx FEC: Fixed VFEC (ACM)
With VersaFEC-2 ACM (V2-ACM) mode active, only VF2L or VF2S can be selected:
RxFEC: Vit Vit-RS TCM-RS
TPC VF ULL VF2L VF2S Unc
Use the
◄ ► arrow keys to select the FEC Decoder type. Press ENTER.
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