On Sun, 2010-10-03 at 15:30 +0200, Jorge Miguel wrote: > Hi all!, > > I am going to measure both parameters, noise figure and phase noise of > my USRP2+XCVR2450 transceiver. > After some reading about different methods of measuring them I have > some questions. > > Phase noise. > I read that in the lack of a Signal Source Analyzer (SSA) the most > spread method of measuring it is with the delay line technique. Is it > the right way to measure the phase noise in the USRP? Has anybody of > you done it before? >
I just measure a CW and do an fft. Results: See the following post: http://lists.gnu.org/archive/html/discuss-gnuradio/2010-03/msg00299.html > Noise figure. > The standard way of measuring it seems to be the Y-Method using a > noise source connected to the DUT and then measuring the output power > of the DUT when the noise source is on and off. However as I > understand it, in this case the USRP2 is not a two port device. It is > just a receiver. Is it valid to measure the USRP2 power with software? > (usrp2_fft.py for example, as I have read in another mailing list > posts) > What I do is to insert a CW with known power and then estimate the SNR. The NF can then be calculated from SNR = -174 + log10(BW) + Pin + NF, where SNR and NF are in dB, Pin in dBm and BW in Hz. The BW is the noise bandwidth. Roughly it is sample_freq/2. > What are the range of values I should expect to understand I have made > a good measurements? Look at the data-sheet of the MAX2829. Note that at high Pin your SNR will be dominated by the distortion and the NF will seem larger than in actually is. BR/ Per _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
