[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Discuss-gnuradio] Changing Bandwidth USRP

From: Marcus Müller
Subject: Re: [Discuss-gnuradio] Changing Bandwidth USRP
Date: Fri, 04 Oct 2013 13:41:22 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9

This is a completely different problem, is it? Bandwidth is orthogonal to the 
concept of dynamic range and amplitude values.

Anyway, your FFT plot knows about complex samples; therefore, it displays dB relative to 
the numeric value of "1.0"; this has nothing to do with your input signal 
power. But since USRP/daughterboards tend to work linearly over most of their available 
power range, you can just add a multiply_const to your signal processing flowgraph and 
get your value.
The factor, however, depends on your ADC/daughterboard combination, on the gain you set 
for the RF frontend, a little bit on temperature, the tuner, the impedance matching of 
your RF input to the Daughterboard etc.  So if you already know what you're putting in, 
just use this as a reference and "calibrate" yourself.

Hope that helped clear things up,


On 10/04/2013 01:05 PM, Antmrt wrote:
Thanks Marcus, my problem is how to calibrate the scale on the FFT plot. e.g:
I'm feeding a signal of -30 dBm to the usrp and on the plot the value
becomes about -10 dBm

View this message in context: 
Sent from the GnuRadio mailing list archive at Nabble.com.

Discuss-gnuradio mailing list

reply via email to

[Prev in Thread] Current Thread [Next in Thread]