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PostPosted: Fri Jun 06, 2003 8:46 pm
by recompiler1
These are just wild guesses but maybe to bounce the signal off the moon or a sattelite? I'm sure it requires FAR less power to do that but I guess it's nice to know you're allowed to.

PostPosted: Tue Jul 01, 2003 3:18 pm
by Novilio
Originally posted by sparafina
Hams can go up to 100 watts, but I'm not sure why anyone would. WiFi DXing to the moon?

Power limits on the amateur bands are not simple to describe: It depends on the band, on the mode (type of modulation) and the class of license you have. Entry-level licenses are allowed lower power than licenses with tougher testing requirements.

High power is useful on short waves for bouncing signals off the ionosphere and working the other side of the planet. I've used up to 200 watts between 1.8 and 30 MHz, but the more advanced license classes can use up to 2000 watts peak envelope power (PEP) on single sideband (SSB). It is a Part 97 legal requirement to use as little power as possible to establish and maintain communications, though there is a lot of stretching of that particular rule, which is pretty subjective in most people's eyes.

The amateur radio allocation on 2.4 GHz is relatively recent and not widely used, but the national ham radio organization (ARRL) has an initiative to "reclassify" stock Part 15 Wi-Fi gear for use under Part 97 by licensed amateurs. This initiative is called High-Speed Multimedia Radio. A very good intro can be found in the following article:

QST: High Speed Multimedia Radio

As for how much power amateurs can use in the 2.4 GHz spectrum, the answer is 1 watt without automatic power control (APC) and 100 watts with APC. APC is something found only on relatively expensive amps, but that's OK--at 2.4 GHz, powers above 1W represent a significant safety hazard, especially to the eyes. I personally don't use Wi-Fi gear with more than 100 mw out, and I'm careful with my bridging lashups, because the effective radiated power of a legal tight beam can approach 4W.

You can do a lot with "stock" Wi-Fi power levels. I talked to two older hams at the recent Colorado Springs hamfest who bridged a 28 mile path by using a pair of WUSB11 clients at the focus points of a couple of old 10-foot satellite receiver dishes.

Be clever before you jack up the power. Clever is always more fun than brute force!

--73--

--Novilio
(a ham for 30 years; currently holding call K7JPD)

PostPosted: Tue Jul 01, 2003 7:19 pm
by renderman
Originally posted by Novilio
Be clever before you jack up the power. Clever is always more fun than brute force!

--73--

--Novilio
(a ham for 30 years; currently holding call K7JPD)


Brute Force Vs Elegant solution : The eternal battle.

I personally prefer the elegant solution because it tends to be treated with more respect by others (like on this board). Just dumping more power/money into something is not as much fun as doing something on the small and/or cheap.

I'd also like one day to pro-create. As Novilio pointed out, playing with alot of high power gear just does'nt seem safe at the same frequencies as Microwave ovens that have some very ammusing warning labels on them about radiation exposure and your chances for procreating.

PostPosted: Tue Jul 01, 2003 7:50 pm
by sparafina
Originally posted by renderman
Brute Force Vs Elegant solution : The eternal battle.


I don't think that's really the case, its more about common sense. Kinda like the guys who dowse their charcoal with gasoline versus using one of those aluminum chimney things to start a barbecue. Some guys will do it just because they want to hear the giant "WHOOOM" when it ignites.

I always assume a person will RTFM and weigh out the options before trying a hare brained idea, like trying to broadcast via to what amounts to a microwave oven. Of course, I'm often wrong much to my amusement, I mean my chagrin.

As for power output versus distance, I always like to point out to people that GPS signals are significantly lower than WiFi, yet provide coverage around the world.