USB noise measurement

QA401
1

Hello , I want to measure the noise of my computer usb 5v , How do i set up my QA401 and how to measure up to 100 khz ?

Thanks

2

Hi @fdracing, since the USB supply voltage is 5V, you can go directly into the QA401. The best option would probably be a scope probe in x1 mode, and a USB breakout board, and then connect the ground of the scope probe to the USB ground, and touch the tip to the 5V.

I did just that and measured the USB supply on a QA401 at -53.1 dBV (20 kHz BW, no weighting). This is a hub powered by a 5V wallwart.

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3

Thank you Matt

the usb from my recent computer is not that clean

usb noise
usb noise960×699 107 KB

gonna make some tweaks to clean that out :wink:

.