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Re: [Discuss-gnuradio] Daughterboard

From: Tim Pozar
Subject: Re: [Discuss-gnuradio] Daughterboard
Date: Thu, 04 Mar 2010 16:55:42 -0800
User-agent: Thunderbird (Macintosh/20090812)

To echo what John sent.  There are provisions to do testing and very
limited radiation from "intentional radiators".  You can see them
outlined in Part 15 of the FCC Rules and Regulations...


Depending on the frequency/band you are going to use, there are levels
that you can operate under.  Typically, levels are rated in how many
microvolts per meter that is induced on an antenna that is X number of
meters away from the radiating device.

If you just want to test a product, it is better to bench test it using
a closed system with coax and attenuators to simulate free space loss.
This way you can be assure you are not leaking out RF energy that could
be causing interference, you can be assured that you are testing with
known RF levels to confirm receiver sensitivity and transmitter power
levels and you are shielded from outside interferences that could affect
your testing.

If you need to test in free space, depending on the band you are using,
you may be under Part 15 rules to produce very low levels of RF.
Anything beyond that would require, as John said, an Special Temporary
Authorization for an experimental license.  You can see some details at:


If you are going to be operating on a frequency that is already in use,
you will need to coordinate with that license holder and get permission
to use it.  You will need to demonstrate this to the FCC when applying
for your STA.  This is one of the reasons why the OpenBTS picked Black
Rock and Burning Man to test.  It gave them a rather isolated area with
that would be easier to coordinate with and a population to test with.

A brilliant move if I may say so.

If you want to get an STA, I suggest you work with a telecom attorney
that has some experience in this area as it will speed the process up
considerably.  The OpenBTS folks may be able to help.  I can point you
at lawyers in this area if you like.


on 3/4/10 3:28 PM John Gilmore said the following:
>> When we use any of the USRP daughterboard to transmit, do we need the
>> authorization? For example, FRX900 includes the cell phone bands in US. If
>> we use FRX900 to transmit, do we violate the FCC rule? Or, we could legally 
>> use any daughterboard on any band that falls in the frequency range of the
>> daughterboard?
> When the OpenBTS folks transmit in the cellphone bands, such as at
> Burning Man last year, they get an STA (Special Temporary
> Authorization) from the FCC.  They also get permission from the chief
> engineer of one of the incumbent cellular licensees in the area, to
> avoid interference with already-licensed traffic.
> I don't recommend proceeding without those precautions.
> I believe no license is needed to do bench testing with a dummy load
> that doesn't radiate beyond the tabletop.  Merely opening the metal
> cover of your PC probably causes more electromagnetic radiation than
> that.
>       John

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