11
AQM Series
Instruction Manual
Section 5 - Interactive Sequence Detail
5.1 QAM Mode
The AQM can be set to comply with the ITU-TJ-83 Annex A & Annex B specifications.
ITU-A - is used for DVB operation
ITU-B - is used for DigiCiper II operation
5.2 Encoder
The encoder selection is only used in ITU-A Mode. If set to ITU-B Mode, then the encoder shows NONe.
5.3 QAM
The QAM modulation type is user selectable. If the unit is set to ITU-B Mode, then only QAM 64 or 256
are available.
5.4 Alpha
The Alpha setting is used to set the roll-off factor. Settings are dependent on the Operation Mode.
The standard settings are as follows:
ITU-A - 15%
ITU-B - 18%
5.5 Interleaver
The Convolutional Interleaver is user selectable. Various choices are available depending on the Operation Mode. The
standard settings are as follows:
ITU-A - I 12, J17
ITU-B - I 128, J1
5.6 Baud Rate
The Baud Rate needs to be programmed based on the Input Data and QAM Mode used. The range is from 1 to 6.9
MBaud.
5.7 Input
The input Signal is fed to the module via the bNC connector on the rear panel. For normal operation, use ASi (Asynchronous
Serial Interface). The unit is also programmed with the ability to generate a PRBS (Pseudo Random Binary Sequence) test
signal. The PRBS signal is a polynomial sequence that is determined by the Input Selection choice. The following settings
are available.
PRBS 25M
PRBS 23
PRBS 15M
PRBS 15
These selections are also valuable if an Input ASI signal is not available. This can be helpful in balancing the Output Levels
of several units without the need for an Input ASI signal.
