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Quant Asylum QA400 Problems
« on: November 19, 2016, 09:14:25 PM »
Consider the following QA400 SNR measurement:



It's not entirely clear to me how the SNR can only be 95.8dB if there are no peaks above -100dB.

What am I missing?

Note that this is actually not loopback. It's a THAT1206->THAT1646 board.

This is what loopback looks like:



And just for good measure here is with no stimulus:



So you can see what is harmonics of the stimulus and what is just system noise.

If you open each image in it's own tab you can switch between tabs and see exactly how each plot differs.

Ultimately I'm trying to see how good my THAT1206->THAT1646 board is.  It seems to me 96dB is pretty bad but I'm not entirely sure my test gear is working!


ruffrecords

Re: Quant Asylum QA400 Problems
« Reply #1 on: November 20, 2016, 06:44:28 AM »
It is because the noise if the rms sum of all the noise values  from 20Hz to 20KHz.

Cheers

Ian