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4.9 - Adjusting Squelch
In FM, AM, SAM and SSB demodulator modes, you can use SQL to force the audio output to zero when there is no signal. SdrDx offers both a noise detecting squelch and a signal level squelch for FM and AM, and a signal level squelch for SAM and SSB.
In noise mode, you will observe that usable AM and FM squelch levels are different; this is because the two demodulators present different noise characteristics. Note that squelch only works in AM and SAM mode when .
Signals below the yellow
line are squelched
When using the level-based squelch, in oscilloscope mode, observe the yellow "squelch line" that indicates where the squelch setting intercepts the signal level. A little playing with this, and you'll get very good at selecting the exact squelching effect you want. You can use the mouse-wheel or a left-click to adjust the squelch level when and the mouse is over the oscilloscope display.
allows stored memories to set squelch on recall; this in turn can enable smarter scanning, where one channel requires a stronger squelch than the next. The upshot is that you can scan a frequency with strong QRN right next to one with very quiet conditions, rather than having to set just one squelch level for the strongest noise.
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