FLEX-6000 Signature Series – Maestro User Guide
Page 50
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This unique architecture allows pulse removal with far less distortion than many traditional noise
blankers.
Given the wideband nature of this feature, the threshold slider controls an entire Panadapter, which
may have several Slice Receivers attached to it. This means that the WNB can positively impact not
only the audio of Slice Receivers, but also the panafall visual display. For convenience, the slider is
available in each Slice and each Panadapter. Adjusting any one of them adjusts an entire Panadapter,
and all related slider controls are updated. Enabling and disabling the WNB function is available
separately for each Panadapter.
When the WNB detects a significant change in signal level or bandwidth, it attempts to normalize the
slider value. During this time, blanking will be momentarily bypassed, and the WNB indicator in the
Panadapter will start to flash (blink). Once a suitable normalized slider range has been re-established,
the noise blanking action will resume, and the WNB indicator will return to a solid color.
It is possible for certain WNB level settings to cause distortion with certain types of signals. For
example, in the proximity of very large signals, noise may become worse with aggressive settings of
WNB. If this is the case, either lower the WNB level setting, or disable WNB on that Panadapter.
12.4 SLICE SPECIFIC NOISE BLANKER (NB)
The Slice Specific Noise Blanker (NB) is used to combat fast rise time pulse-type noise such as power
line hash and car ignitions, on an individual Slice Receiver basis. To enable the Noise Blanker, tap the
NB button in the Slice Receiver Menu, then adjust the threshold control for the best noise
suppression. In general, the default setting is adequate, but depending on the noise characteristics,
some adjustment can help. The NB Threshold control adjusts the level at which a sample is
considered to be impulse noise. The general rule of thumb for this adjustment is to use the lowest
level that is effective. For large impulse noise (meaning the noise floor jumps are large) a lower level
should be used. If the impulse noise is causing only small jumps in the noise floor, a higher level can
be used.
Unlike the Wideband Noise Blanker, the Slice Specific Noise Blanker algorithm considers only 24kHz
of the RF spectrum, centered on the Slice Receiver’s tuned frequency, not the entire SCU RF
spectrum, as is the case with WNB. The NB algorithm complements the WNB algorithm and may be
used with or without WNB. It may more effective than WNB, less effective or have no effect on
specific examples of impulse noise.
The Slice Specific Noise Blanker may be turned on or off and adjusted for each Slice Receiver.
12.5 NOISE REDUCTION (NR)
The Noise Reduction processor (NR) will reduce random (“white”) noise making signals more
readable which are buried in the noise. It is best to adjust the AGC threshold first, and then enable
the Noise Reduction.
The Noise Reduction algorithm uses a correlation based adaptive filter. Noise Reduction increases
correlation between input and output with the assumption that noise is uncorrelated and should be
canceled out. The threshold adjustment controls the adaptation rate of the filter, so in the case of
Noise Reduction, there will be very little audible change while adjusting the threshold unless the
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