Datum Systems PSM-500 - Page 81

PSM-500/500L/500LT SCPC Satellite Modem Operation
PSM-500/500L/500LT - Rev. 0.91
Page 3-21
Demodulator Parameter Detail
Representation
Type
Entry
Description
IF Eb/No Alm
2.0dB
Numeric 1.0 to 20.0 dBm in 0.1 dB
increments
A receive Eb/No level at or
below this level will produce
an alarm.
IF Low Level Alm
-65.5dBm
Numeric -26 to –85 dBm in 0.1 dB
increments. Dependent on
Bit Rate.
A receive carrier level at or
below this level will produce
an alarm.
IF Impedance
50 Ohm
Selection
0 = 50Ω, 1 = 75Ω
Receive IF impedance.
Data Bit Rate
2.100000Mbps
Numeric 1.200 to 20,000.000 kbps
in 1 bps resolution. Entered
in kbps to 1bps increments.
Modulator Bit Rate – The max
and min are determined by
settings and options.
Data FEC
Viterbi
Selection 0 = Viterbi,
1 = TPC Full
2 = TPC Short
3 = TPC (Legacy)
4 = TPC (CT)
TPC Decoder - Only available
if installed. Reed-Solomon is
enabled in R-S column.
Legacy in Rate ¾, 7/8 only.
CT compatibility Rate ¾ only.
Data FEC Option
Normal
Selection 0 = Normal,
1 = Swap C0/C1,
2 = Invert C1,
3 = Swap and Invert C1
FEC Optional Modes. May
change depending on FEC
options installed.
Data Code Rate
Rate 1/2
Selection 0 = ½, 1 = ¾, 2 = 5/6
3 = 7/8.
0 = 2/3 in 8PSK TCM
FEC Code Rate. The options
may change depending on
FEC installed and selected
R-S Mode
IESS-308
Selection 0 = Disabled,
1 = IESS-308
2 = IESS-309
5 = IESS Custom
Reed-Solomon column and
options only available if not
disabled. Entry is not shown
when TPC enabled.
»RS FEC (n)
126
Numeric In Custom Mode only:
Available n values
Read only in other modes
Block size
n = 22 to 255
»RS FEC (k)
112
Numeric In Custom Mode only:
Available k values
Read only in other modes
k = 20 to 253,
k must be 2 to 20 less than n
»RS FEC depth
4
Selection In Custom Mode only:
0 = 4, 1 = 8, 2 = 16
Read only in other modes
Interleave depth factor
Data Dif Decoder
Enabled
Not
Shown
0 = Disable, 1 = Enable Differential Encoder Not
shown or settable except in
special modes.