RT3070 wireless adapter adjust tx power??

Cian

I think you should be able to work out that the manufacturer is not using english as a first language.

The descriptions are gramatically incorrect for a start.

Your calculations are based on solid reasoning , but the fact still remains that it has to be two way, so even if you were pumping 10kw out, the link wouldn't work.

just a minor note though ..

The next set of results are using some facts:

  i.  Most networks I can pickup have a rx sensitity between -53 to -79 dBm.  So lets pick a number in between: -71

  ii.  RX antenna - most corperate networks do not have 2dBm antenna gain  So I will say about 0.5 dBm for internal gain and such.

i      this is the Received signal strength at YOUR end.

II      See below. 3dBi gain isn't unreasonable. You are mixing terms. (dBm which is a measure of power, and gain which is in dB.)

The NZ Radio Spectrum Services has some info about maximum radiated (that includes antenna gain) at

http://www.rsm.govt.nz/cms/licensees/types-of-licence/general-user-licences/short-range-devices

I'm picking that the Australian equivalent is similar.

If you are interested in getting signal from a site, then you should be able to use a suitable device and directional antenna (Antenna gain is compared to a dipole radiating 360deg, and while you can get some gain from the design, its generally because its directional).

My setup uses a 800mW Ubquiti Bullet

http://www.gowifi.co.nz/wisp-client-radios/ubiquiti-bullet2hp-802.11b/g-800mw-outdoor-ap/bridge.html

24dBi Grid pack antenna

http://www.gowifi.co.nz/antennas/2.4-ghz/directional/2.4-ghz-24-dbi-die-cast-wireless-grid-antenna.html

The range to the site is 32km, and the Rx signal (at this end) is currently -64dBm (but drops to -74 if the hedge grows).

The site survey sees a few others, with a noise floor of -97dBm.

I think -81dBm Rx is a little low, and its quite feasible for the 'site' to use an antenna with 3dB gain. (3dBi)

Obviously with any frequency above about 50MHz its line of site, ie you need to see it.

2.4 GHz and lower will tend to bounce around off hard surfaces, but they don't really follow the earths curvature, so its approx 11mile (17km), unless you have some elevation.

Buildings and other materials will attenuate the signal, so careful placement is important.

regarding the USB.

5v at 500mA gives 2.5 watts.

I note a 500mW (27dBm) devices with 5dBi antenna is available as a USB device.

I think as Shabaz has indicated, that the 5800mW is the eirp (Effective Isotropic Radiated Power) ie the equivalent power required if you had a dipole...

I seem to recall some similar claims about audio power. The marketing department invented this peak power measurement, which of course is a mathmatically anomoly.

It made the speakers and amplifiers look great though.

Mark

So I guess that the end of the story is this:

DO NOT PUT 5800mW into the adapter!!!!  It Will Explode (or therabouts)!!!

Should I try it?  I know how to get rid of the software limits.

Hi Mike.

I have looked into EIRP and dicovered this:

http://en.wikipedia.org/wiki/Equivalent_isotropically_radiated_power

If you use the formula on the top of the page:  answer = P - L + G

If:

      Power (P) = 1000mW (30dBm)

     Loss (L)  = 1 dBm

     Gain (G) = 21 dBi

Then you end up with 58dBm total power.

Now what does the 5800mW (37.635dBm) relate to?

Cain

Common myth.

Power is consumed or used, not put in.

Bit like a loaded trailer on a car, it requires x amount of power to move it.

if you stick a 1000Hp car on the front the trailer still requires the same power to move it.

However they derived the figures it doesn't really matter.

Is the device working for you.?

Mark

It works great!  I was just interested in the accual power usage.

Thanks for all help!

YOU ARE GETTING THE ERROR BECAUSE YOUR COUNTRY SETTING ONLY ALLOW TXPOWER TO BE SET AT THAT LEVEL TO CHANGE TXPOWER YOU NEEED TODO AS FOLLOWS  iw reg set BO ..this change your setting to country Bolivia which allows higher txpower trannsmission .next do iwconfig wlan0 txpower 30 ..then iwconfig wlan0 now you should see that txpower is 30 dbm ..

zero dark wrote:

 

YOU ARE GETTING THE ERROR BECAUSE YOUR COUNTRY SETTING ONLY ALLOW TXPOWER TO BE SET AT THAT LEVEL TO CHANGE TXPOWER YOU NEEED TODO AS FOLLOWS  iw reg set BO ..this change your setting to country Bolivia which allows higher txpower trannsmission .next do iwconfig wlan0 txpower 30 ..then iwconfig wlan0 now you should see that txpower is 30 dbm ..

If you read the rest of the topic, you would understand that I have established this ages ago.  Please (as I can see you are new here) remember to read the whole topic before posting a reply in capital letters.

Last message:

From wallarug:

 

It works great!  I was just interested in the accual power usage.

 

Thanks for all help!

Thank you for your reply anyway.