Warning 1073366012:Overflow detected in the Arb's FIR Filter. Output waveform was clipped. Reduce the Arb Pre Filter Gain to eliminate overflow.

[ilyak]

Hello:

This warning occurs while generating signals from PXI-5673 ARB.

Does anyone know what might be causing this warning and how to fix it? The help is a bit sparse about it.

It didn't occur before. I understand that perhaps the reducing Arb Pre Filter Gain can help. However, I'd like to know the root cause of this and, if the gain has to be changed, how to calculate this gain value.

Thank you,

-Ilya.

[Kyle_A.]

Hi Ilya,

Are you using the Fixed WiMAX Generation toolkit with your hardware?  This will help specify if I have a correct solution for you about this particular warning.  Did this warning occur on a particular VI?  Which version of RFSG are you using?

From the looks of things, there doesn't seem to be a calcuation that I have found yet on this property, but as the help documentation suggests it can be reduced from its default 0 dB to prevent overflow from occuring at the power level you are working with.  Finding out the information on the above questions will be helpful, thank you.

[ilyak]

Hi Kyle:

Oh, sorry about not providing this info.

1. I'm using NI-RFSG 1.6.3
2. WLANG 2.0.0

This is just WiFi generation, not WiMAX.

Regards,

-Ilya.

[Sastry]

Hi Ilya,

Can you tell me which example are you running? And what are the settings on the front panel?

Sastry

[ilyak]

Hi Sastry:

Sorry for the long delayed relply.

I've installed NI-RFSG 1.7 and upgraded the firmware in the generators. Still the same warning comes up.

I don't run any example. It's my own C++ code. However, you can see the attached SPY log.

-Ilya.

[Faraclas]

There is a property of the niRFSG that controls the Pre-filter gain.  In LabVIEW this property is labeled "Pre-filter Gain (db)".  By default, it is set to zero.  If you are seeing overflow, just drop this value in incriments of one until the error message goes away.  I typically use the default but in some cases have dropped the pre-filter gain by 1 or 2 dB.  Note that this is related to the gain of your baseband signal (IQ) and the final output power will not be affected once you correct the overflow.

[ilyak]

Hi Faraclas:

Yes, I can do this. But I was looking for some science behind setting the 'Pre-filter Gain', not just basically guessing.

-Ilya.