Forum: GNU Radio what will be the real transmit power in Watt when we change the tx-amplitude in software

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Bill S. (Guest)
on 2008-11-13 01:56
(Received via mailing list)
Hello, everyone!

I am working on the benchmark_tx.py file, I know the transmit power for
RXF2400 is 50mW. But is this number corresponding to the option
-tx-amplitude setting to the default value 12000? If it is, i could
calculate the real tx power after i changed the tx-amplitude parameter.

Another interesting question is that in receive_path.py file, there is a
parameter called threshold to control the process of carrier sensing,
but that parameter is in dB and the default value is set to 30dB! Does
it mean the real threshold value is set to 1000 Watt?  That would be too
great! It is impossible! If it were not in Watt, is it in mW? I am
confused, could anyone tell me a little bit about this unit definition
in USRP?

Thanks a lot!

Bill
Brian P. (Guest)
on 2008-11-13 02:09
(Received via mailing list)
On Wed, Nov 12, 2008 at 6:55 PM, Bill S.
<removed_email_address@domain.invalid> wrote:
> Hello, everyone!
>
> I am working on the benchmark_tx.py file, I know the transmit power for
> RXF2400 is 50mW. But is this number corresponding to the option
> -tx-amplitude setting to the default value 12000? If it is, i could
> calculate the real tx power after i changed the tx-amplitude parameter.

Assuming a linear amplifier, the power of your modulated signal is
equal to its magnitude squared.

> Another interesting question is that in receive_path.py file, there is a
> parameter called threshold to control the process of carrier sensing, but
> that parameter is in dB and the default value is set to 30dB! Does it mean
> the real threshold value is set to 1000 Watt?  That would be too great! It
> is impossible! If it were not in Watt, is it in mW? I am confused, could
> anyone tell me a little bit about this unit definition in USRP?

It really refers to the dynamic range captured at the ADC.

Please refer to this:

    http://www.dsprelated.com/showmessage/36164/1.php

Brian
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