On Apr 13, 2004, at 10:19 PM, <[EMAIL PROTECTED]> wrote:
Jim
I agree with you on a basic setup but if a system is engineered correctly, its very easy to have a balanced systems.
Note that the example I gave was about an AP with associated STAs. I assumed that the common case would be laptop/pda/phone like clients, unable (or unwilling) to support the 300/400mW cards, for a variety of reasons, including exposure limits. Therefore, the link will be greatly unbalanced.
The main benefit to a 300mW/400mW (soon) radio is a lower gain antenna thus a larger vertical beam width at the base station, this is NOT the best setup for all applications but it does add additional options to the WISP tool box.
Larger beamwidths invite more interference.
You've also missed my point. First a couple of assumtions:
1) antennas with gains greater than 30dBi are for our purposes, too large to be practical.
2) People will adhere the FCC rules, (even if they don't have the system certified with the antenna and pigtails they're using, but I digress.)
Check this out.
mW dBm max dBi ptmp max dBi ptp EIRP
1000.0 30.0 6.00 6.00 36.00
794.33 29.0 7.00 9.00 38.00
630.96 28.0 8.00 12.00 40.00
501.19 27.0 9.00 15.00 42.00
398.11 26.0 10.00 18.00 44.00
316.23 25.0 11.00 21.00 46.00
251.19 24.0 12.00 24.00 48.00
199.53 23.0 13.00 27.00 50.00
158.49 22.0 14.00 30.00 52.00
125.89 21.0 15.00
100.00 20.0 16.00
79.43 19.0 17.00
63.10 18.0 18.00
50.12 17.0 19.00
39.81 16.0 20.00
31.62 15.0 21.00
25.12 14.0 22.00
19.95 13.0 23.00
15.85 12.0 24.00
12.59 11.0 25.00
10.00 10.0 26.00
7.94 9.00 27.00
6.31 8.00 28.00
5.01 7.00 29.00
3.98 6.00 30.00
Note that when running ptp, the allowed EIRP is higher for the lower power card.
Also aesthetics comes in to play many times where a small, clean looking device unit is the only option, again the radio gain can be the difference between a link working or not.
#include <something about sacrificing performance for asthetics.h>
(and I do actually agree with you when it becomes the primary concern).
Some of this may be outside the decision of this list but there are valid reasons for these designs.
Actually, so far, it all seems to be on-topic to me.
Sincerely, Tony Morella Demarc Technology Group, A Wireless Solution Provider Office: 908-996-7995 Fax: 908-847-0202 http://www.demarctech.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Jim Thompson
Sent: Tuesday, April 13, 2004 8:02 PM
To: David Young
Cc: [EMAIL PROTECTED]
Subject: Re: [BAWUG] RE: 300mw?
On Apr 13, 2004, at 11:59 AM, David Young wrote:
On Tue, Apr 13, 2004 at 11:32:26AM -0700, Joel Jaeggli wrote:I thought the goal was to abuse the commans until is became unusable.
It sure seems so! It's really too bad, the money and mind-share that these high-power Prism cards get, when the 802.11 ASICs by Atheros, Realtek, and ADMtek are lots more versatile, and they provide *transmit power control* in one way or another.
The Prism cards will continue to become less of the equation with time.
The Prism 2/2.5 chipset just costs too much to make it into any real 'volume' product, and there are other 'high power' solutions
(on yes, Atheros and Realtek) chipsets, that, as David says, provide tx pwr ctl, as well as more interesting architectures for
software tricks, equivalent or better receivers, etc.
I'm not sure what the value of a 300 or 400mW AP is. The client almost certainly doesn't have that kind of tx power, so your link
won't be reciprocal. Perhaps the application is a 25dBm (300mW) bridge but this would be limited to about 18dBi of antenna gain,
and an additional dBi
of gain. Since you can run an additional 6dBi of gain (on each end)
with the lower power (23dBm) card, I would think that most people would employ the antenna, both for reasons of cost, as well as
better rejection of off-axis interferers.
obligatory disclosure: I sell a lot of high-power cards (as well as the other things mentioned here). Demarc is a competitor.
Jim
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