SMD 989
– User Manual
Page 38 (105)
Description:
Determines whether the spectrum is inverted or normal.
Note:
When the SMD 920 L-Band option is installed, the default spectral inversion is
inverted as the upconverter will invert. Setting the output to Inverted will give a normal
output from the upconverter. This is shown in the RF Output status for Spectral Inversion.
Alpha Filter Rolloff
-
0.35
-
0.25
-
0.20
-
0.15
-
0.10
-
0.05
Description:
The filter rolloff is known as the Alpha
coefficient (α). The smaller the α, the
less bandwidth will be required on the satellite.
Rate Adaptation
(Only available in DVB-S2 single mode)
-
Disable
-
Enable
Description:
When set to enable a rate adaption is applied to the DVB-S2.mode. When
disabled the rate adaptation is not active. Rate adaptation forces the modulator to add or
remove null packets and re-stamp PCRs in order to match TS bitrate to the modulation
payload rate. Disabling rate adaptation is desirable where the input TS must be
preserved through the transmission chain. In such use cases, it is expected that the input
TS bitrate is fairly consistent and the payload mismatch can be resolved by occasionally
inserting a dummy frame instead.
PL Scramble Code
(Physical Layer Scrambling is only available in DVB-S2 or DVB-S2X
single modes)
Description:
This is used to specify a randomized scrambling sequence applied to each
PL frame and initiated at the end of each PL header. Scrambling randomizes band
energy dispersion and allow
s for a “signature” when may provide association to a satellite
operator or satellite. The complex code relates to an “n” value defined by an entry of
0 to
262 141.
PRBS Enable/Disable
A pseudo random binary sequence test signal is available for
testing. When Enabled the PRBS replaces the normal input modulation feeding the
modulator. Select Disabled for normal output applications. See the PRBS section of this
manual for added information.
PRBS:
(Only available in DVB-S2 Modes)
-
Enable
-
Disable