Using Amplifiers w/.11b

[agent007]

Can anyone advise where to get information (perhaps a calculator of some sort) that would tell the ins and outs and how to's of using amps with .11b within FCC regs?

Thanks!!

[BER_vs_SNR]

Besides the PA (power amplifier) on the transmitting side and the LNA (low-noise amplifier) used on the receiving path of the RF section of any module (NIC or AP), both of which are integrated in the chipset at hand and therefore untouchable by the average person, can you be a little more specific as to what exactly it is that you are looking for, what type of amplifier you are talking about, so I can see if I can help you?

Or, have I misunderstood and you really do look for information about designing either one of these two integrated blocks?

Thanks.

[agent007]

My theory ( I know just enough to be dangerous) is that if I can mount an AP in a vehicle with a high gain antenna (8dbi) in repeater mode, I can extend the reach of an indoor WLAN. This way, whereever the vehicle is, the mobile client can hop to the vehicle, and then to the indoor LAN, instead of just trying to punch thru walls and glass with an .11b PC card. To get even further, I'm wondering if an amp can be used in conjunction with the repeater AP/antenna setup. Hope this clarifies :cool:

[jsicuran]

I used a Teletronics SmartAmp( 1watt) for experimenting on my rooftop stumbler project. It is a bi-directional amp. and Iwas able to pick up APs that I would not normally see without it. For my PtP testing it makes a differnece. However in general the noise ratio increases big time also. I know when using it I am violating fcc so I do not use it often for stumbling. I mostly use it for my ptp segment testing within fcc limits. I know YDI has calcs to use. Just becareful when using amps.


/JS

[agent007]

Hyperlink just told me that no amps are certified to work with Cisco radios........and thus they cannot sell me one. Bummer.

Is there a technical reason for this, or is it just that Cisco has no interest in amps?

I'm not interested in certification, I just want an amp that will work.

Thanks:D

[jsicuran]

Not FCC compliant/certified for a system.

That's the issue with amps for production work. Most of the time most wireless circuits are well designed to never need an amp.
But if you must:

As per the FCC for PtP your intentional radiator has a limit of 1watt and you can go over 4 watts eirp at the antenna. However for every 3dbi past the initial 6dbi of antenna gain you must reduce the power at the intentional radiator by 1db from the intitial +30dbm.

For PtMP it is a little simpler on the 2.4 and 5.8 upper you are allowed 1 watt at the intentional radiator and 4 watts of eirp past the antenna. For every 3dbi gain above the antenna's initial 6dbi of gain the power must be reduced by 3db below the intitial 30+dbm at the intentional radiator.

see

http://www.fcc.gov
I had a link to the part 15 but cannot find it at the moment.

Amps are great in a lab and testing, I must remember to not stand in front of my cantennas when using on, fried brain, like that made a differnece anyway.

regards

[engineerjeremy]

Amplifiers are only useful for eliminating cable loss. Amplifiers also amplify the noise as well as the signal. So you might extend your network, but you can degrade the preformance, omni + amp is that worset combination of the above. For a system to be certified the amp, radio, and antenna all must be certified together, not individually. You can run anything you would like. There are not any technical problems other than the issues I mentioned above and finding the correct pigtails for the various radios to the typical N styled connector for most omni's and sectors

[agent007]

Thanks for the responses and insights....

I'll just try without an amp to begin with and see if I can punch thru a wall of concrete with the repeater/5dbi omni setup. If that doesn't work, then I'll look at amps more seriously.

[jsicuran]

Originally posted by agent007
Thanks for the responses and insights....

I'll just try without an amp to begin with and see if I can punch thru a wall of concrete with the repeater/5dbi omni setup. If that doesn't work, then I'll look at amps more seriously.

try a directional.

[agent007]

I'm a glutton for punishment.......because of the application, I have to use an omni. The Cisco AP in repeater mode will be mounted in a vehicle.

Thank you sir, may I please have some more?

[oshea85]

a 1Watt bda with a 6 dbi antennae should work fine, and is legal as long as it's professionally installed (read part 15 again, guys). The requirement for FCC certification is on MARKETED systems. If it's not marketed that way, you don't need to get it certified, just make sure you comply with the power limits that are applicable to your situation.

[engineerjeremy]

So you can homebrew uncertified systems?