tx power levels

pirateoftheairwaves · ‎11-27-2007

it was kinda surprising to learn that WLC expresses tx power as 1,2,3,4,5,6.

anyone knows what is the equivalent of these levels in dBm?

the autonomous 1230 has the tx power levels as max, 100, 50, 30, 20, 10, 5

is the comparison below correct?

wlc <--> 1200

1 <--> max

2 <--> 100

3 <--> 50

4 <--> 30

5 <--> 20

6 <--> 10

7 <--> 5

what is the exact value of the 'max' level?

thanks!

Richard Atkin · ‎11-27-2007

You've got the right idea with 1 being highest, and power decresing along the way. There's about 3dB difference between each integer, however the actual dB value varies for each setup.

The reason they're not fixed is because the WLC considers the region the network is in (EIRP laws) and antenna gain.

So,

Power Setting 1 = max power (Considering local laws and antenna gain)

Power Setting 2 = Power Setting 1 minus 3dB

Power Setting 3 = Power Setting 1 minus 6dB

Power Setting 4 = Power Setting 1 minus 9dB

and so on...

kfarrington · ‎06-24-2008

Good Question. I have fallen foul of this.

So with the following

Controller Radio Output Power

Tx Power Settings 802.11b/g (dBm) 802.11a (dBm)

1 (maximum) 17 17

2 14 14

3 11 11

4 8 8

5 5 5

6 2 2

7 -1 -1

8 - -

I have a couple of question:

How many milliwats is this does this equate to?

Is it 50, 25, 12, 6, 3, 1.5, 0.75 ?

Just used this tool but want to make sure this is correct?

http://www.aubraux.com/design/dbm-to-milli-watts-calculator.php

Also, what is power level 8? I dont have this on my controller?

Many thx,

Ken

Scott Fella · ‎06-24-2008

You can use the tool, just make sure what the db is first. 2.4GHz is 20dbi which is 100mW, 5GHz UNI-II and UNI-III is 17dbi which is around 25mw. UNI-I is 11dbi max which is 12.5mW.

So when youare at the max dbi and mw, every drop is half like mentioned above.

-Scott
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kfarrington · ‎06-24-2008

Hi Fella,

Why do you say 2.4Ghz is 20dbi, that is only for certain regions right?

Sorry am i missing sommat here? I got the table from the following url?

http://www.cisco.com/en/US/docs/wireless/access_point/channels/lwapp/reference/guide/1240_chp.html

Please can you clarify mate?

Many thx as always :)

Ken

Scott Fella · ‎06-24-2008

That is for US (-A). You see under B, the table shows 20dbi. Under G the table shows 17dbi. Figure 5-2 & 5-3 under -A you should be looking at if you are in the US.

-Scott
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kfarrington · ‎06-24-2008

Thx for the clarificaion mate.

We are in E band (us limey's) cheers :)

Thx

Ken

kfarrington · ‎06-24-2008

Thx for the clarificaion mate.

We are in E band (us limey's) cheers :)

Thx

Ken