sillyputty <(E-Mail Removed)> hath wroth:
>Been checking into the various, wok, steamer, etc DIY antennas (for
>ex. http://www.instructables.com/id/EQTRV35LX7EPUCHTJI/) and read that
>a USB wifi adapter is preferable over an internal wifi card, due to
>interference from HDs, fans, etc that could reduce the signal by 1/3.
>Any truth to this?
Sorta, kinda, maybe. There was a time when the major source of
receiver RFI (RF interference) was from the digital section of the
card itself. No need for an outside source of RFI when you can
generate it yourself. In the close confines of the typical laptop,
radiation from high power noise sources (RAM, CPU, power supplies),
directly to the card (not through the antenna) are a real problem.
However, internal noise sources have to be taken into perspective as
compared to external sources of interference, such as the neighbors
wi-fi system, microwave ovens, cordless phones, and such.
<http://wireless.wikia.com/wiki/Wi-Fi#Interference>
First, spread spectrum is VERY resistant to coherent sources of RFI
such as clock oscillators. There really are few broadband noise
sources inside computers (even with the "spread spectrum" option to
spray the CPU power over a wider area making it easier to pass FCC
Part 15). However, the outside sources, listed in the above URL are
literally thousands of time stronger than internal sources, despite
the differences in proximity. They're also broadband and sometimes
high power sources, which are difficult to deal with.
Therefore, I suggest you concentrate on the antenna design, in order
to keep the external interference sources out of your system and not
worry too much about internal sources. Of course there are some
laptops that have internal noise sources. Those can usually be
controlled adequately by on board (MiniPCI and PCMCIA) shielding.
--
Jeff Liebermann
(E-Mail Removed)
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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