Comtech EF Data cdm-570a - CONFIG: Rx) Buf (Buffer); CONFIG: Rx) Descram (Descrambling)

CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
Front Panel Operation 6–33 MN-CDM570A
6.3.2.4.8 (CONFIG: Rx) Descram (Descrambling)
IMPORTANT NOTE – All selections are always viewable. If a Hardware or FAST
option is either uninstalled or invalid, the cursor will skip past the unavailable
choice.
Descrambling: Default-On
IESS-315-On Off (◄ ►,ENT)
Use the
◄ ► arrow keys to select a parameter. Press ENTER.
Parameter
Description
Default-On
The appropriate scrambler type is automatically selected.
The default scrambler types are:
• Uncoded – ITU V.35 (Intelsat variant)
• Viterbi, no framing – ITU V.35 (Intelsat variant)
• Viterbi, EDMAC frame – Comtech proprietary, frame synchronized
• Viterbi +RS or TCM/RS – Per IESS-308, frame synchronized
• TPC – Comtech proprietary, frame synchronized
• 8-QAM TPC – ITU V.35 (Intelsat variant)
• VF or ULL – ITU V.35 (Intelsat variant)
• VF2S or VF2L – ITU V.35 (Intelsat variant)
Off
No scrambling
NOTE: In legacy CDM-570 Compatible mode, IESS-315 is not available for all FEC types.
However, in CDM-570A mode, IESS-315 is a permitted choice for all FEC types. When
IESS-315 is selected, the ITU V.35 scrambler specified in IESS-315 takes priority over all
“Default-On” scramblers and is used instead. Therefore, for many operating modes, the
two scrambler selections are redundant.
When using Carrier-in-Carrier, the IESS-315 (V.35) scrambler is the only permitted
choice.
6.3.2.4.9 (CONFIG: Rx) Buf (Buffer)
Rx Buffer: +/-32768 Bits
(13.1ms) (▲ ▼, ENTER)
When you select a value other than Disabled, this enables the Plesiochronous/Doppler Buffer,
set to its selected size as per the preceding example. The available size selections, in bits, are
(+/-)00128, 00256, 00512, 01024, 02048, 04096, 08192, 16384, or 32768.
While it is only possible to select the size in bits, the corresponding total buffer size displays in ms
(which varies in inverse proportion to the data rate).
Use the ▲▼arrow keys to select the desired bit size. Press ENTER.
The buffer’s input is the signal from the satellite, with any clock offsets and jitter.
The buffer’s output is derived from the local TRANSMIT clock. In this way, the receive data is
perfectly synchronous with this local clock.