Tx Amplitude in USRP N210

GNU Radio
1

Hi,

I am trying to find out how to set the TX-amplitude parameter between
0-1,
which
is given as an option in USRP sink. My attempts
to find a clear explanation of
this parameter have all failed.

Also, I would like to understand how to
set the receive SNR in the source file?

As for the receive SNR, my guess would be
to solve the classic equation, which
involves estimating the noise figure,
transmitted power, gains of antennas etc.,
however it does not seem to me a very
realistic approach. How do you set this value?

I would appreciate anyone’s hints.

Best Regards,

Konstantinos

2

On 28/09/11 04:01 AM, Konstantinos wrote:

Hi,

I am trying to find out how to set the TX-amplitude parameter between 0-1,
which
is given as an option in USRP sink. My attempts
to find a clear explanation of
this parameter have all failed.

A UHD sink has a “Gain” parameter–is that what you’re talking about?
That parameter sets the
analog gain of the particular daughtercard in use. The final output
power produced by the
transmit side will be a product of the analog gain setting, and the
magnitude of the signals
coming from the Gnu Radio flow-graph. In UHD, it expects signals that
are normalized into
{-1.0,+1.0}, and UHD scales that into the range expected by the
particular hardware.

I would appreciate anyone’s hints.

Not sure what you mean by “set the receive SNR in the source file”. The
SNR is a property of a received
signal. It’s not something you “set” in the hardware, although
hardware/software settings can
certainly influence the received SNR.

–
Principal Investigator
Shirleys Bay Radio Astronomy Consortium

3

Thanks for your reply.

Please, let me re-write the previous questions.

Actually, I did not mean the Gain parameter in UHD. I meant the
TX_amplitude parameter (between 0 and 1) that is set in the
transmit_path.py. In this file it defines this parameter as the:
“digital amplitude sent to the USRP”.

Also, regarding the SNR. I meant to write the estimated SNR used to
guide the cyclic prefix synchronization, that is located in the
ofdm_receiver.py

Thank you and apologies for the mistake.

Best Regards,

Konstantinos