3
rd
Generation Rack-
Mount RDMS™
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Quasonix, Inc.
Figure 224: Advanced Settings Window, Best Channel Selector Checked
4.5.3.3.7 Time Aligner
The Time Aligner option is only available with the Combiner option enabled and set to On. The Time Aligner can
be disabled or enabled. When disabled, it remains Off and does not affect the combiner.
Clicking on the check box to enable the (combiner) time aligner, as shown in Figure 225, lets it determine when to
operate (with no user intervention).
Figure 225: Advanced Settings Window, Time Aligner Selection Checked
Maximal ratio combining can only achieve optimal performance if the Channel 1 and Channel 2 input signals are
accurately phase- and time-aligned. Traditionally, diversity combiners have performed phase alignment only, relying
on the telemetry system design to provide adequate time alignment.
However, there are cases in which time alignment cannot be easily guaranteed. Such cases include frequency
diversity and spatial diversity, where the propagation of transmit and receive paths for Channel 1 and Channel 2 may
be quite different through cables, equipment, and the air. As bit rates continue to increase, fixed latency differences
are magnified in relation to the bit period.
The Quasonix RDMS™ Combiner can perform both phase alignment and time alignment of the Channel 1 and
Channel 2 signals. The Time Aligner is capable of correcting up to ±1300 nanoseconds of time skew between
channels (about a quarter mile of free-space propagation). Similar to phase alignment, time alignment is dynamic,
accommodating changes in relative target antenna positions over time.
