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How to reduce the Audio Noise in various standalone instruments

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hussain1.bangalore

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Hello

I have one test station which has various stand alone instruments like Audio analyzer , spectrum analyzer . Oscilloscope , and other radio testing instruments .

Every time Audio test fails due to the signal interference. it would be great if any one refer me some good website for finding best filters to compensate this noise


Hussain
 

Try to use capacitors at the front-end of the receiver ..
 

Hello

Appreciate your response, the problem is we cannot use open capacitors etc we need some standard ready instruments like( Wruth electronics, etc) who provides solution for this kind of issues.

Hussain
 

Hi,

where does the noise come from?

Is it the EARTH connection? --> use one big common EARTH connection and connect each instrument in a star connection to it.
Is it influenced by the mains cables? --> filters in mains, Filters to a solid and common earth connection, isolating tranformers...
Is it influenced by air via electric or magnetic field? --> shielding
Or is it influenced by the signal connetions from DUT to instruments? --> isolating signal repeater, filters, isolating mains transformers....


Klaus
 

Hello Klaus

Thanks for your response,

We have Earth connections and all are connected to star connection to it and other filter on Power supply end.
Actually the test station is Automated test equipment & i have 3 such kind of station .. I am facing trouble with only one Test station.

there is the test by name Audio Droop which try's to measure the voltage below 0.1 VDC but reads 0.24 VDC and fails..

So i have tried using some filters on the input and output of the all standalone's (like audio analyser , spectrum analyser etc ) , But never worked :(


Hussain
 

Hi,

You say DC. I think with commonly used filters you cannot avoid DC.

Try to check whether it is a problem of your DC voltmeter or is there real DC on the DUT.

DC either comes from DC currents in GND lines ( check this if you disconnect one GND line of instrument after the other and check DC voltage)
or it is an effect of undersampling synchrounous (to sampling frequency) frequencies. This can be avoided with antialiasing filters.


Klaus
 

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