Comtech EF Data CDM-570 - Manual (Page 111)

CDM-570/570L Satellite Modem with Optional IP Module Revision 12
Front Panel Operation MN/CDM570L.IOM
5–25
5.2.2.1.4.7 (CONFIG: Rx) Descram (Descrambling)
Descrambling: Default-On
IESS-315-On Off (◄ ►,ENT)
Use the
◄ ► arrow keys to select Default-On, IESS-315-On, or Off, and then press ENTER.
Note: While this submenu always displays the available options, the cursor will skip past an
unavailable choice.
Note the following:
Selection Description
Default-On The appropriate descrambler type is automatically selected
IESS-315-
On
This applies only when Turbo is installed and has been selected as the FEC type
Off No descrambling
The default descrambler types are:
Uncoded :
Viterbi, no framing:
Viterbi, EDMAC frame:
Viterbi + RS or TCM/RS:
TPC:
ITU V.35 (Intelsat variant)
ITU V.35 (Intelsat variant)
Comtech proprietary, frame synchronized
Per IESS-308, frame synchronized
Comtech proprietary, frame synchronized
5.2.2.1.4.8 (CONFIG: Rx) Buf (Buffer)
To edit the size, in bits, of the Plesiochronous/Doppler Buffer, use the ▲ ▼ arrow keys to select
+/- 128, 256, 512, 1024, 2048, 4096, 8192, 16384, or 32768 bits. Press ENTER when done.
Select Disabled to disable the Plesiochronous/Doppler Buffer. The receive clock is then derived
from the satellite signal, and is therefore subject to clock offsets relative to the local transmit clock.
This is due, in part, to the originating clock being slightly different from the local clock (a so-called
plesiochronous offset), and to the motion of the satellite (a Doppler offset).
Note the following:
Rx Buffer: Disabled (Loop
Timing Mode)(▲ ▼, ENTER)
If the IP Module is installed and the selected Data Interface is IP, the buffer is disabled by default
and this is the only valid selection.
When a value other than Disabled is selected, the Plesiochronous/Doppler buffer is enabled, and
set to the selected size as follows:
Rx Buffer: +/-32768 Bits
(13.1ms) (▲ ▼, ENTER)