AP650 Power Levels

Hi all,
With the country code on a wireless switch set to United Kingdom, France or Germany I've just noticed that the maximum power level you can apply to an AP650 bgn radio is 11dBm (13mw).  Is this correct for our regulations?  I thought 20dBm/100mw should be the maximum?

I have a customer who has just installed a wireless network in a hospital, and is now finding they can't radiate more than 13mw per AP!

I haven't tried other EU countries, but the US country code allows me to set the power beyond these limits.
Chris Frazee
Hello Chris,       I see the

Hello Chris,
      I see the same thing for United Kingdom, Germany, and France in my lab using the RFS4K v4.2.1 and AP650. We used to have a regulatory document for each Country for 2.4GHz and 5.0GHz from the following URL: http://wileyprd.symbol.com/regulatory/index2.html

I performed a search on Power, from the above URL, and went to the AP650/EMC Approvals. The letter states that RF output power (EIRP) for 802.11bg should be 19.98dBm. We would need to check the SPR database to see if this is a known issue and/or obtain an updated Country regulatory list for 2.4GHz and 5.0GHz.

I would recommend that you get a support case generated, provide customer information, in order that tracking can be performed and possible SPR. I have attached the documents referenced from the regulatory site.

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Chris Devereux
Thanks Chris. My original

Thanks Chris.

My original test was with v4.2, then after posting, I read the release notes for v4.2.1 which mention regulatory corrections and now I can set the power to the dizzy heights of 13dBm (20mw)!  Still below what I believe they should be.

I will raise a case with emea support and report back here.

Chris
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Oliver Wolff
Chris and Chris, we in

Chris and Chris,

we in Germany have were playing around with this for a while.
You both are correct, 11dBm and / or 13 dBm both are little to low values.
But not 20 dBm but 15 dBm is the correct value:
Mathematically, the EIRP limit is +20, mimo gain = 3dB, internal antenna gain is 2dB so the tx power on paper should be
20-3-2=15dBm.
BR Oliver
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Oliver Wolff
Chris and Chris, we in

Chris and Chris,

we in Germany have were playing around with this for a while.
You both are correct, 11dBm and / or 13 dBm both are little to low values.
But not 20 dBm but 15 dBm is the correct value:
Mathematically, the EIRP limit is +20, mimo gain = 3dB, internal antenna gain is 2dB so the tx power on paper should be
20-3-2=15dBm.
BR Oliver
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Oliver Wolff
Chris and Chris, we in

Chris and Chris,

we in Germany have were playing around with this for a while.
You both are correct, 11dBm and / or 13 dBm both are little to low values.
But not 20 dBm but 15 dBm is the correct value:
Mathematically, the EIRP limit is +20, mimo gain = 3dB, internal antenna gain is 2dB so the tx power on paper should be
20-3-2=15dBm.
BR Oliver
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Chris Devereux
OK thanks Oliver, I believed

OK thanks Oliver, I believed you the first time you said it ;-)

However, the AP300 allows 20dBm and this also has some internal antenna gain. 
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John Plummer
Mathematically this is true,

Mathematically this is true, but what about the AP650 external or are we saying that the AP650 has a 13mw radio and have to make up the EIRP with antenna gain.

Chris is the 5Ghz radio setting up the same? I thought that we are allowed 200mw on the .11a


John.
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Chris Devereux
John, The a/n radio on the

John,
The a/n radio on the 650 allows configuration up to 19dBm, no higher, so that too appears to be wrong.
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Alona Gian
All, The internal antenna

All,

The internal antenna gain is taking into calculations and user will not be allowed to configure any power beyond regulatory maximum minus antenna gain. And that why you see lower allowed limits.

Alona
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Henrich Hofbauer
FYI, if you want to see the

FYI, if you want to see the regulatory values for a specific country, you can use following command:

RFS4000#show wireless regulatory ?
  WORD  Two letter ISO-3166 country code ("show wireless country-code-list" to
        see list of supported countries)
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Chris Devereux
That's a useful command,

That's a useful command, thanks but I don't buy the antenna gain explanation.

If I take the regulatory power values supplied by this command for the UAE and United Kingdom, they are both the same for 11bgn (20dBm).

If I set my country code to the UAE (ae) I am allowed to set the power of the AP up to 20dBm, so there are some inconsistencies here.
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Christopher Hinsz
Transmit Power in an 802.11n

Transmit Power in an 802.11n system is calculated for the entire system (with multiple transmitting antennas) and is not a simple 1:1 relationship between antenna power and system power as it was in an 802.11a/g system.  For example, an AP650 transmitting at 17dBm on two transmit chains has an effective system power of 20dBm.   Additionally Motorola in an effort to avoid confusion with configuration between internal and external antenna models as well as multiple chains of operation does NOT take antenna gain or number of transmit chains into account in our GUI.  The user is asked to input the desired TX power per transmit chain before antenna gain.  So, for a 3.5db antenna, the actual setting would need to be 3.5 less.  Taking all of this into account, and looking at the example above.  An AP650 targeting 20dBm system performance and intending to use 2 transmit chains with 3.5db antennas would need to be set for 17dBm – 3.5dB = 13.5dBm in the GUI.
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Thomas Frederiksen
Why does the AP7131 behave

Why does the AP7131 behave differently with regards to the configuration of the antenna gain?

Br. Thomas Frederiksen

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Christopher Hinsz
Remember that the AP-7131 is

Remember that the AP-7131 is a 3 transmitter system.  Double the transmit power (AP650) equates to +3dB.  Triple the transmit power equates to +4.7dB.  It's also important to take into account that the two platforms have different antenna defaults and configurations.
   CSH
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Henrich Hofbauer
Hello Chris, Following our

Hello Chris,

Following our call with Colruyt yesterday and looking at your explanation above, can you please confirm that this is correct?

The internal antenna peak gain for the 2.4GHz band AP650 is 2.0dBi
An AP650 targeting 20dBm system performance and intending to use 2 transmit chains with 2.0db antennas would need to be set for 17dBm – 2db = 15dBm in the GUI.

Thank you.
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Christopher Hinsz
Often the tolerance on the

Often the tolerance on the antenna and frequency response mean that the max possible gain can be higher, and we often make the decision to ensure regulatory limits are observed by giving some slight margin to the peak regulatory value.  In looking at the 2.4 response for the AP650 antenna, I see a few spots that look close to 2.5, but that's subjective.  As mentioned on the call, Vinh (in looking at the data) does believe that we can up the 13dB limit to 14dB, which takes us to 19dB plus margin for antenna spec margins.
   CSH
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