Comtech EF Data CDM-625A Installation And Operation Manual page 651

CDM-625A Advanced Satellite Modem
Appendix M
•
Latency for VersaFEC ACM at 100 ksps = 54 milliseconds
•
•
M.8 Configuring VersaFEC ACM in the CDM-625A
VersaFEC ACM requires the appropriate FAST code for the maximum operating
symbol rate.
Configuration is very straightforward from the CDM-625A front panel. For a detailed overview of
modem operations via the front panel, refer to Chapter 6. FRONT PANEL OPERATION. Follow
these steps to configure the CDM-625A for VersaFEC ACM operation:
Step Task
1 (SELECT) CONFIG: MODE
Set the Tx and Rx modes as IP-ACM.
2 (SELECT) CONFIG: TX  SYMB
Enter the desired transmit symbol rate. Note that
this is a fundamental departure from the way in
which the modem is typically configured.
3 (SELECT) CONFIG: TX  POWER
If Manual mode is selected, enter the desired
transmit output level. This will also be the Nominal
Power value if AUPC is selected.
If AUPC mode is selected, two additional choices
are presented – Mode/Range and Alarm Action,
as shown here:
In all case except MEO (which is a very unusual
mode) the mode is fixed at Normal. Enter the
maximum permitted power increase, between 0.0
and 9.9 dB.
You can chose to generate an alarm when the max
power or min ModCod has been reached, or not at
all. You can also chose what happens to Tx Power
when the remote demod unlocks. The choices are
Nominal Power, Max Power, or Hold.
(SELECT) CONFIG: RX  SYMB
4
Enter the desired receive symbol rate. Note that
asymmetric operation is supported – transmit and
receive symbol rates do not have to be equal.
For the example shown, the latency for a 16k block DVB-S2 ACM scheme is
approximately 7 times higher than VersaFEC ACM.
The latency for a 64k block DVB-S2 ACM scheme is approximately 25 times
higher than VersaFEC ACM.
The Transmit symbol rate is limited by the FAST code installed. There are three options:
• 37 ksps to 300 ksps
Front Panel VFD Mnemonic
Mode:Tx=IP-ACM:None Rx=IP-ACM:None
(422,V35,G703s,Audio,LVDS,HSSI,IP,ASI)
Tx-IF Freq Power FEC Mod Symb Scrambler
(Data 00192.000kbps, 00131.657ksps)()
TxSymbolRate = 01000.000 ksps (ACM Mode)
Data Invert=Off Clock Invert=Off
• 37 ksps to 1200 ksps
Output Power: Mode= Manual (Manual, AUPC)
Level= –20.0 dBm
Output Power: Mode= AUPC (Manual, AUPC)
Mode/range Alarm Action
AUPC-ACM Mode = Normal (Normal, +/- Track)
Max Permitted Power Increase: 3.0 dB ()
Tx Alarm: None (MaxPwr, MinMCod, None)
Rem Dmod Unlock Act=Nom Pwr(Nom, Max, Hold)
RxIF Freq FEC Demod Symb Descram Eq EbNo
(Data 02048.000kbps,02184.533ksps)()
RxSymbolRate = 01000.000 ksps (ACM Mode)
Data Invert=Off Clock Invert=Off
M–9
Revision 0
MN-CDM625A
()
• 37 ksps to 4100 ksps
()
()
()