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New Member

Very, very strange

I was testing two AP 350 on a clear (2,4Ghz radio free) track. The antennas used were two 24db grids made by "California Amplifier".

So, here are the results:

4 kms – 95 - 100%

7 kms – 70 –100%

9 kms – 0 – 0% !!!

Plain EIRP calculations or radio standards simply cannot explain this? I can only think of one thing – the Access Points have some integrated “range filter”. Any other suggestions? The anntena aligment was almost perfect on both locations.

I would gladly discuss that with a TAC engineer but I am located in Bulgaria and I am not quite familiar with contacting and talking to a TAC specialist.

4 REPLIES
New Member

Re: Very, very strange

802.11b isn't supposed to work over more than 1 mile (1.6Km). Getting 7Km (4.35 miles) is good.

By the way, if Bulgaria has the same EIRP restrictions as the U.S., you'd better have the Transmit power turned down to 50mW (17dBm) or less, or have a whole lot of coax before the antenna.

Matthew Wheeler

Blue Modal

New Member

Re: Very, very strange

Matthew, lots of thanks for the reply, but I will strongly disagree with you on that opinion.

First of all, there are at least 10 web pages in this site (cisco.com) where the maximum range of the 350 series APs/WGBridges is set to 30 miles @ 1Mbps!

And the "strange" thing here is that there is no way that 2 more kms can add such a decrease in the total EIRP calculations, so that no connection will be established.

Meanwhile, I have talked to a Cisco select partner wireless engineer and he told me that he thinks that only the Bridges (AIR-BR350-A-K9) are not manifactured with that "filter"...

Anyway... any opinions are still welcome...

New Member

Re: Very, very strange

There's a difference between what's *possible* and what's *supported*.

The 1 mile max AP-to-Client spec is common to many manufacturers, regardless of antenna type and power. The issue is the delay spread in the coding (which varies for different data rates), not just transmit power or receive sensitivity. Therefor, for anything beyond the manufacturer's spec, you are on your own to risk exceeding the delay spread.

The figues you got were not stated as EIRP (if they were, I would have expected them to be in dBm, not %). The client's ability to show signal strength is dependent on its ability to associate with the AP. Most likely, you lost your association somewhere between 7Km and 9Km.

So, you are correct that the signal strength did not fall off from 70% to 0% over the last 2Km, but the total distance was great enough that you were no longer able to associate and therefor showed no signal.

Not sure what 'filter' you are refering to.

Matthew Wheeler

Blue Modal

New Member

Re: Very, very strange

Thanks once again.

As for the EIRP - this % comes form the "Link Test" utility. I don't know if there is a way to have the actual dbm level through the AP stats.

Excuse my incompetence, but what does that delay spread in the coding means?

Once again thanks for your answers,

Tihomir

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