SMD 989
– User Manual
Page 43 (105)
Configure Modulator - PRBS
The PRBS tab provides selection of the available PRBS (Pseudo Random Binary Sequence) test
signal available for use with either the SMD 910 or SMD 912(A) modulators.
PRBS (Pseudo Random Binary Sequence):
The PRBS feature provides a digital test signal
with known properties used for BERT (bit error rate testing) of satellite equipment or transmission
paths. Test signals used are a binary PN (Pseudo-Noise) signal known as a PN-23 or Inverted
PN-23.
PN23 Normal: A normal version of the Pseudo-Noise PN-23 test signal
PN 23 Inverted: An inverted version of the Pseudo-Noise PN-23 test signal
For BERT tests, the PRBS setting may be set to Enabled. When Enabled, the normal input signal
to the modulator is removed and replaced with the selected PN-23 or Inv PN-23 signal.
IMPORTANT: For normal or non-testing applications in which the input is to be used to
modulate the satellite IF or L-Band carrier output, the PRBS test signal must be set to
DISABLED.
Figure 36: PRBS Pseudo Random Binary Sequence
