Comtec CDM-840 - Page 115

CDM-840 Remote Router MN-CDM840
Ethernet-based Remote Product Management Revision 3
6–33
The upper range of Data and Symbol Rate selection requires activation of the
TRANSMIT DATA RATE FAST option.
Select or enter the desired FEC Type, Tx Frequency, MODCOD, Tx Scrambler, Spectrum Invert,
and Carrier State settings. Click [Submit] to save. The valid operating range for each item in this
section is noted in parentheses:
• Data Rate (16 to 15343 kbps) – Enter The CDM-840 Tx Data Rate in kbps. Click [Submit] to
save.
When Adaptive Coding and Modulation (ACM) is set to Enable, the Data Rate is
set automatically. Manual configuration of Data Rate is disabled and the
appearance of the Data Rate section changes as follows:
• Symbol Rate (16 to 4500 ksps) – Enter The CDM-840 Tx Symbol Rate in ksps. Click [Submit]
to save.
• FEC Type – At present, VersaFEC is the sole available FEC type.
• Tx Frequency (950 to 2150 MHz) – Enter The CDM-840 Tx frequency in MHz.
• MODCOD (applicable only to CCM Mode) – Use the drop-down list to select the Modulation
type and FEC rate (MODCOD). The available selections are:
o
VersaFEC MODCOD 0 – BPSK 0.488
o
VersaFEC MODCOD 6 – 8-QAM 0.711
o
VersaFEC MODCOD 1 – QPSK 0.533
o
VersaFEC MODCOD 7 – 8-QAM 0.780
o
VersaFEC MODCOD 2 – QPSK 0.631
o
VersaFEC MODCOD 8 – 16-QAM 0.731
o
VersaFEC MODCOD 3 – QPSK 0.706
o
VersaFEC MODCOD 9 – 16-QAM 0.780
o
VersaFEC MODCOD 4 – QPSK 0.803
o
VersaFEC MODCOD 10 – 16-QAM 0.829
o
VersaFEC MODCOD 5 – 8-QAM 0.642
o
VersaFEC MODCOD 11 – 16-QAM 0.853
• Tx Scrambler – Use the drop-down list to select the Tx Scrambler as Off or Normal.
• Roll Off – The Tx Alpha Rolloff (α) dictates how fast the spectral edges of the carrier are
attenuated beyond the 3 dB bandwidth. With 20% rolloff the edge falls off more quickly
than with 25% and 35%.
Use the drop-down list to set the expected filter Tx Alpha Rolloff (α) of the carrier as 20%,
25%, or 35%. The default selection is 20%.
• Spectrum Invert – Use the drop-down list to select the Tx Spectrum Invert as Normal or Tx
Spectrum Inverted.