Correction: SNR = 174 - log10(BW) + Pin - NF,
BR/ Per On Mon, 2010-10-04 at 09:29 +0200, Per Zetterberg wrote: > 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 _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
