easy mate, interpreting the FCC, the IRS and the US Constitution
shouldn't be that difficult
you see, a standard industrial spectrum analyzer, with proper input
attennuator settings, hooked up directly to the RF transmitter at the
connector will show exactly the TX power of the device. Simple as that!
now, suppose the measure of TX power is at the transmitting antenna,
then of course there's another setup and calculation for the spectrum
analyzer to do just that, but it begs the questions
1) how far away from the transmitter should the spectrum analyzer be
positioned? 0 feet? 1 feet? 3 feet? 10 feet? 10 miles?
2) what is the standard for the field-probing antenna? loop? yagi?
omni? what about its sensitivity?
3) if the probing antenna is to be right at the transmitting antenna,
then what part of the transmitting antenna should it touches? the head?
the tail? the middle? the center? the rim? at what angle?
sounds like the things only a clown would do in a circus, eh?
oh and why not buy at Fry's?..... like, the things you buy from the
store would fry themselves... or what?
just kidding
Jeff Liebermann wrote:
> bi241@scn.org hath wroth:
>
> >so the broadcom miniPCI driver says it's got 1300mW... but why 1300mW
> >and not 3100mW? well, i have another theory beside thinking garbage
> >values being returned..
>
> The garbage values theory was what the developers at Wi-Fi Hopper
> responded with when I bug reported the problem. I've seen the same
> bogus power report with other boards and drivers.
>
> >1300mW is about 31dBm!!! and i dont see why wifi cards cannot have
> >exactly that much of TX power. the FCC part 15 states that the limit
> >for 2.4GHz non-channel-hopping radios is 1000mW (or 30dBm) provided it
> >is attached to an antenna of 6dBi gain or less.... and for every 3dBi
> >increase in antenna gain, the TX power has to be reduced by 1dBm.
> >nothing further about the variations of radios+antennas
> >configuration...
>
> I don't want to get into interpreting FCC 15.247. The maximum power
> output is 1 watt. Unfortunatly, they don't say where they measure
> this 1 watt. It could be at the transmitter, or at the antenna. Hard
> to tell. The common interpretation is 1 watt maximum at the antenna
> with a 6dBi omni antenna. If you lower the gain of the antenna, you
> cannot increase the power output to compensate. It would have made
> much more sense for the FCC to specific EIRP (Effective isotropic
> reference radiated power).
>
> >but here comes the creative thinking.. from there, one may deductively
> >conclude that if the radio is permanently attached to a 3dbi antenna or
> >less, then its maximum TX power can be legally increased to 31dBi!!!
>
> No. Or at least no according to several testing labs that submit FCC
> Part 15 type certification reports. Nice try.
>
> Incidentally, if you really want high power in a laptop, see:
> <http://www.ubnt.com/products.php4>
>
> >i suspect that notebooks manufactures been doing this with their OEM
> >wifi cards, especially with those miniPCIs, to keep their customers
> >happy.... of course, those cards are not intended for desktop use,
> >obviously, never to be sold as a part of a "highpower wardriving kit",
> >or to be sold seperately at all, even if they are hard coded to a
> >specific channel within the 2.4GHz spectrum
>
> I like conspiracy theories but not this time. Linux utilities report
> the correct power output from the same cards that Windoze reports
> garbage.
>
> >the wireless networking section at Frys, compared to other sections,
> >has the most returned items from pissed off customer who bought
> >brand-name wifi devices that put out 30mW... lol
>
> That's one reason why I don't buy at Fry's.
>
> --
> Jeff Liebermann jeffl@comix.santa-cruz.ca.us
> 150 Felker St #D http://www.LearnByDestroying.com
> Santa Cruz CA 95060 http://802.11junk.com
> Skype: JeffLiebermann AE6KS 831-336-2558