FlexRadio Systems FLEX-6000 Signature Series User Manual

FLEX-6000 Signature Series - SmartSDR for Windows Software User’s Guide
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13.3 WIDEBAND NOISE BLANKER (WNB)
The Wideband Noise Blanker (WNB) is used to combat fast rise time pulse-type noise such as power
line hash and car ignitions. To enable the Wideband Noise Blanker, click the WNB button, 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 WNB 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.
Large signals, both in the passband and around it, can result in distorted audio if the WNB threshold
control is set too high.
Since the Wideband Noise Blanker operates at the SCU level rather than at the Slice level easy
detection of wideband correlated noise pulses is possible. The algorithm employs an automatic slider
normalization function to make the WNB work consistently on different bandwidths and signal levels.
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 in the GUI controls an entire SCU,
which may have several Panadapters and/or slice receivers attached to it. For convenience, the slider
control is available in each slice and each Panadapter. Adjusting any one of them adjusts for an entire
SCU, and all related slider controls are updated. Enabling and disabling the WNB function is available
separately for each Panadapter. All Slices present on a Panadapter inherit the same value for the
WNB enable and level.
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.
13.4 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 a Slice Receiver basis. To enable the Noise Blanker, click the NB button,
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

FlexRadio Systems FLEX-6000 Signature Series Specifications

General

Brand	FlexRadio Systems
Model	FLEX-6000 Signature Series
Category	Transceiver
Language	English