Comtech EF Data CDM-750, Инструкция по установке и эксплуатации

Страница: 97 / 300

CDM-750 Advanced High-Speed Trunking Modem Revision 2
Front Panel Operation MN-CDM750
5–21
•
The available frequency ranges are 50 ‐ 180 MHz, and 950 ‐ 2150 MHz (L ‐ Band).
•
The resolution is 100 Hz.
Press ENTER when done.
5.2.2.2.3 (CONFIG) Tx: Power
Output Power Level= –20.0 dBm
(
v
)
To configure the Tx Output Power Level: First, use the
W X
arrow keys to select a digit to edit, and
then use the
ST
arrow keys to change that digit. Note the following:
•
For Tx frequencies of 50 ‐ 180 MHz, the permitted level range is 0 to –25 dBm.
•
For 950 ‐ 2150 MHz (L ‐ Band), the range is 0 to –40 dBm.
Press ENTER when done.
5.2.2.2.4 (CONFIG) Tx: Frame
Tx Framing: Normal
DVB-S2 Framing Mode
(
v
)
Use the
ST
arrow keys to select Normal or Short Block , and then press ENTER . Note the
following:
•
With the default value of Normal is selected, the standard FECFRAME = 64,800 bits is
enabled.
•
If Short Block is selected, FECFRAME = 16,200 bits is enabled.
You should consider the use of Short Block Framing only when there is a
concern about data latency. See Figure C ‐ 4 Single Hop Latency in Appendix
C. ADAPTIVE CODING AND MODULATION (ACM) OPTION for an illustration
of how Normal and Short Block Framing affects overall system latency.
Short Block Framing will perform 0.2 db to 0.3 db worse in terms of
required Es/No for all ModCods. In all other circumstances, Normal Block
Framing should be used.