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[Ham-80211] 2.4 GHz remote broadcast

Marlon K. Schafer ooe at odessaoffice.com
Sun Feb 18 04:57:23 UTC 2007


Oh boy, you want to cover the simple questions first eh?  hehehehe

answers inline:

----- Original Message ----- 
From: "kd4e" <kd4e at verizon.net>
To: "Marlon K. Schafer" <ooe at odessaoffice.com>
Cc: "TAPR Mailing List for Ham Radio Use of 802.11" 
<ham-80211 at lists.tapr.org>
Sent: Saturday, February 17, 2007 5:36 PM
Subject: Re: [Ham-80211] 2.4 GHz remote broadcast


> There is growing concern about congestion and
> competition for spectrum resources on 2.4.

For sure.  I've all but completely abandoned channel 6.  So 22 mhz of 
spectrum centered on 2441 or so are gone for all practical purposes.  Around 
50% of my installs for the last 6 to 12 months have included a home wireless 
router.  Out outdoor gear hears the local, or the next door neighbor, system 
at 20dB or more higher than my own ap's.  So by by channel 6 and most 
anything around it.

>
> I suppose it varies somewhat based on region and
> on one's specific locale.

Yeah, but even in the country it's a problem these days.

I can use 6 for backhaul if I run it at pretty high power levels (say a 20 
to 30 dB fade margin vs. my normal 10), but that only creates noise MILES 
past the end of my link.

>
> How would you compare the propagation, availability
> of surplus devices, and spectrum congestion across
> those bands, please?

Hmmm, propagation.  In which band?  Through what?

900mhz decent through trees and buildings.  But the 4 watt power limit still 
brings it to a dead stop after a couple of houses or a couple of dozen 
trees.  Half mile of dense trees I think is about all a data system will 
really work well for.  Naturally, the trees make all of the difference.....

2.4 can go through most walls in your house, but not the wire mesh or an in 
ceiling heating system.  Plaster and lath will also hurt distances in the 
home.  Low E windows are a brick wall for it, you're often better to shoot 
through a wall than a window.

5 gig, gotta see it to do it.

In all bands there are some newer technologies (ofdm, orthogonal frequency 
division multiplexing) that can recreate scattered bits of data into one 
good data packet where the old systems were just confused with all of the 
"echos".

5.2 and the new 5.4 ghz bands will be hard to use in long distance shots due 
to the hard eirp limit of 1 watt.

>
> Also, where do you see the challenges to each band
> in the near-term future?

Mostly congestion.  The technology and the rules have come together very 
nicely in the midst of a major spike in consumer demand.  The license owners 
have mostly sat on "their" spectrum and the wisps have jumped into the gap 
with both feet.

The technologies are doing a nice job of preventing a cb radio senario, but 
that'll only go so far.  As more spectrum opens up and the products get 
cheaper we will have more room to grow.

And, hopefully, the FCC will do a better job of policing the eirp cowboys in 
this band than they did in the cb band.  I think that the fact that there is 
soooo much life and business being run on unlicensed bands these days, it'll 
be much harder to ignore than it was in the past.

And trade groups like WISPA (www.wispa.org) are pushing for more rules 
compliance.  And, if the FCC will do a better job or enforcement (I've got a 
complaint in against a competitor for nearly 2 years now, with no real 
change in his operation other than to move his amps indoors where we can't 
see them anymore) we'll not complain but cheer.

that help at all?
marlon

>
>> We use 900mhz, 2.4ghz, 5.3ghz and 5.8ghz for our wisp.  Can I be of
>> any help in this thread? marlon
>>
>>> Some guys were giving a pretty close look at 5GHz.  Not sure what
>>> they concluded - there was some hope for some really high speed
>>> comms with minimal competition for spectrum.
>>>
>>>> Monday I noticed that a local TV station was doing a remote
>>>> broadcast from downtown.  What's interesting about this is that
>>>> much to my surprise this was done on 2.4 GHz analog.  I could see
>>>> it with a Wavecom Jr.  So for a few hours the 2.4 band was
>>>> trashed.  It started with a color test pattern a bit fuzzy as
>>>> they were apparently aiming the remote van's antenna towards Scrays 
>>>> hill, which I am in the path of.
>
>
>
> -- 
>
> Thanks! & 73, doc, KD4E
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Projects: http://ham-macguyver.bibleseven.com
> Personal: http://bibleseven.com
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 





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