Dante Inovonics 552, Installation & User Manual, Page: 36 / 60

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When implemented with a traditional analog oscilloscope, the
XY display resembles a ‘connect-the-dots’ image of the so-
named children’s activity. The 552 and most digital ‘scopes
can optionally show either Lines or Points . The Points option
presents a more artistic ‘constellation’ as seen in the example.
In this case Points and Persistence were both engaged to also in-
dicate the short-term trend of the stereo image.
FM AND HD1 ALIGNMENT
We’ve discussed how the 552 can correlate level differences be-
tween the analog-FM and digital HD1 programs, but the HD Ra-
dio system also requires very tight time alignment between the
two program channels as well. The 552 is able to correlate this
metric and can even display a history of timing offset to aid in
tracking-down a diversity-delay problem.
Specs
at-a-Glance
The top of the FM/HD1 Alignment Webpage shows the current
time and level alignment information in-brief.
Timing error is shown by the number of 44.1kHz samples.
Both Inst. Alignment (instantaneous) and Avg. Alignment (averaged)
values are given. You’ll also find the
Peak Level
of the HD1 au-
dio program, and the HD1 program audio Loudness with re-
spect to the loudness of the analog-FM program.
The
Status bar tells whether the HD1 is leading or lagging the FM ,
and again by how many
samples
, plus whether the audio
Phase
between the programs is Normal or Inverted .
Alignment
Time Studies
The upper part of the screen plots both the instantaneous and
average program delay error against time. A
Confidence
plot is
included, which is an overall measure of how well correlated
the FM and HD1 signals are in terms of both time and level
alignment. A negative
Confidence
measurement indicates out-
of-phase audio.
In this image, HD lags
FM between 5 and 6
samples. The offset
may be presented ei-
ther in the number of
samples or in milli-
seconds per the
Delay
Units:
setting at the
bottom of the screen.