Level detector noise
Application setup is dual oar singel channel ADC to DAC configuration on an 1701.
Noticed first on single band level detector a remaining, inaudible, noise at -30dB. Investigated further with multiband detector and this noise is in the lowest band. Proceeded to insert "digital silence" via swicth so I could select either external ADC input or tonegenerator. With tone generator selected and "off" the level indicator noise is gone. With ADC input selected and analog side shorted, noise is back level detector.
Also, using external spectrum analyzer on DAC output, the noise is not revealed.
Curious!
Thanks/Mike
The intended use of the level detector cells is basically to determine if the signal is present or absent. We never intended them to be used for detailed debugging.
The noise you see on the detector is not actually in the signal, but is a result of the way the level detector cell is calculating the signal level. Those algorithms are pretty outdated and do not have a very good dynamic range. We're hoping to update them soon.
In the meantime, I would suggest instead using one of these methods to check the signal level:
Brett
Thanks and link was very informative!
May benefit in finding its way to the help section of Sigma Studio.
Kind rgds/Mike
Hi,
This issue can be solved by placing a DC Block filter in front of the Level Detector (or in front of the whole project at the ADC), as shown here:
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