Re: RX amp required - NOT TX


"Jeff Liebermann" <jeffl@xxxxxxxxxx> wrote in message
news:7dfv86dm5m9hrlnnne26e31jqjpu6o3k42@xxxxxxxxxx
On Sun, 12 Sep 2010 01:54:13 +0100, "Gemma" <noreply@xxxxxxxxxxx>

Question: What problem are you trying to solve by adding an RX amp?
Reducing coax loss is a solution, not a problem that needs solving.
Are you having reliability, coverage, thruput, interference,
multipath, or other problems at your hotspots?

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

Argh. After typing out a somewhat verbose but numbers rich reply my PC
decided to reboot without warning - thankyou Avira, that was most kind.

To give a slightly more condensed answer :) :-

Reliability is not an issue for some users - eg: almost any Dell computer
seems to be able to get a reliable connection even if they see us around -70
dBm - On the other hand Advent / MSI computers can fail to make a decent
connection even if they see us with a strength of -50dBm.

Coverage is fine with some clients - again Dells, or any decent spec USB
devices - which tend to throw out a bit more power than some of the the
notebooks do.

Throughput is fine - is someone can connect to us, they often can pull data
as fast as we can hoover it out the cable connection to give them.

Interference - well there are no shortage of other users about - but it is
consistently the case that borderline users can always see us, but just
cannot shout back loud enough for us to hear them.

As for multipath, I am guessing with MIMO that ought not be a problem -
though I admit if it is, I am unaware of it.

The problems are largely solved if we disable the onboard AP and drive any
of the ubiqitti AP's from the public lan port. For some reason Ubiqitti
radios (especially the NS2) have a fantasically high sensitivity and while
fully appreciating your comments about saturation / SNR etc with over
amplifying, the sensitivity of the receivers on NS2 is I think in the order
of -95 to -97 dBm. Certainly they are the most effective units we have EVER
found when it comes to connecting weak clients (talking more about specific
applications over a distance here not hotspot)

http://www.ubnt.com/downloads/ns2_datasheet.pdf

To be honest, although I am not adverse to playing around with transceivers,
once they get into UHF (and high end of UHF too), it has gone way past my
skills to make neat cuts / connections etc on PCB's where an extra 1mm of
track in the wrong place can suddenly make the whole thing go downhill in
terms of performance.

Give me something working at a few Megs and I will tinker all day :)

I think I was just hoping someone would come back and say something like
"You need the RX+12 from whizzlec for about £25" - alas they didn't :) I
think the simplest answer is to stick with the NS2 solution. It seems
wasteful but it DOES work and it IS simple.

Thanks again though for your helpful and throughtful comments and
questions - I apologise for just giving a condensed version of my reply as
the figures I pulled from the Xirrus Wi-Fi inspector for example evaporated
with the reset and I am just a shade too tired to go outside and take
readings again now!

Kind Regards

Mark


.

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