Originally Posted by Bad_Dude
Instead of spending the money for ERS paper, could the anti static bag does the same job? If you put any electronic device in the bag, for example a cell phone, no signal is found. Thus this could be b/c it shields everything.
What do you guys think?
If you believe in how the ERS paper works as a technology even if it still served as a shield it wouldn't do the same job.
Cell phones have a certain frequency range of interest that by nature is likely easy enough to shield from while say a neighbouring video card presents another set of issues at also maybe different power levels, and blocking reception isn't the same task as say the noise from the onboard regulators and amplifiers.
The idea of the chaotic fiber lay in the paper is that it randomizes the intercepted frequencies, and thusly information they contain.
There's nothing however stopping it from saturating and transmitting or reflecting as it's clearly a high impedance type shield so it's of limited use in itself and is probably better intended for a layered type shield to put its' scattering ability to work in minimizing reflections, so it's not that the paper is useless but the misuse of it might not have the expected effect.
Charge potential on it building up or modulated by noise of any source isn't prevented from coupling electrically, via static capacitive charge displacement means and it'll do it uncontrolled via the paper isolator and height/distance relation to the conductive areas of the various onboard components and planes.
The best use of it would be to use some conductive foil tape to direct the current flow inherent to these charges and direct them away into a low Z groundplane, closest to and directly at the ground connections of the PCI in order to avoid loops of any great area which could even transmit across the ground plane.
Best would be extending the foil shield fully and have it bonded at multiple points clear across the area of the soundcard, perhaps even wtih bypass caps from it to the ground plane near sources of interest.
That extent is however all an excerise in diminished returns because if you use a conventional soundcard for instance noise conducted from the power and ground rails are virtually what the card uses almost directly and typically only ever with marginal onboard regulation and sparse filtration so the noise is going to drive a transport through the frontdoor while you're worrying about the crickets entering the rear windows.
You'd probably see a truer improvement by locating the DSP chip power source and getting a 100uF or 220uF small form factor electrolytic to sit stably directly across it and use low components that wont' greatly respond to the constant mecanical vibration inside a case or also be excited mecanically by poorly regulated, noisy rails
.Edited by rollemup - 4/24/10 at 6:09am