Ferrite EMI Suppressor "Tubes" Over USB Signal Cables ?

Hello,
Regarding those Ferrite EMI Suppression "tubes" that are placed over signal wires to reduce noise, might someone please offer a bit on how
used, and how effective they are ?
I have a small SDR radio Dongle that is connected to my PC via a USB cable.
There appears to be a fair amount of noise being picked up on the radio that is being radiated/induced from the PC, I believe.
e.g., should they be placed over both ends of the USB cable, at both the PC and at the radio Dongle ends ? Or, only at one end ? Why ?
I'll experiment, of course, but would like to hear your opinions on first.
Any thoughts on this would be most appreciated.
Thanks, Bob
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I definitely recommend ferrite beads on your usb cable.
Is the SDR encased in a metal shield box? If not I'd highly recommend it too, since there will be many more sources of interference that just your PC. Shielding the USB cable will only remove once source of noise but shielding the SDR will protect you from all of them.
On 08/23/2014 11:29 AM, Bob wrote:

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Very effective, if the noise source is the cable (conducted noise rather than radiated noise). Of course the solution depends on the nature (frequency) of the noise.

If it's radiated noise, the ferrite is unlikely to help.

Guess. No one knows until you try. When this is done in product (or compliance) testing, that's what why do. Try everything. It might not work at all, again, depending on the nature of the interference.

That's really all you can do but it would be good to know exactly where he interference is coming from and why it's getting in.

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