Hello Swapna, The SNR in wireless channel cannot be measured but it can be "estimated". One way to do that for constant envelope modulation such as PSK is by measuring the variance in the received signal envelope. Ideally you should receive a constant stable envelope of your signal. However, due to the noise in the channel (assuming WGN channel, which is normally the assumption for the famous theoretical waterfall plots for BER vs SNR) you can find a relation between the variance in the envelope and SNR.
To get the exact relation I suggest you to look at the last chapter of Optical Bit Error Rate: An Estimation Methodology by Stamatios<http://search.barnesandnoble.com/booksearch/results.asp?ATH=Stamatios+V%2E+Kartalopoulos> V. Kartalopoulos<http://search.barnesandnoble.com/booksearch/results.asp?ATH=Stamatios+V%2E+Kartalopoulos> I hope that helps. Good luck! Kind regards, Yahia Tachwali ________________________________ From: discuss-gnuradio-bounces+ytachwali=ou....@gnu.org [discuss-gnuradio-bounces+ytachwali=ou....@gnu.org] On Behalf Of Swapna Raj [swapna.ra...@gmail.com] Sent: Thursday, February 12, 2009 8:57 AM To: Discuss-gnuradio@gnu.org Subject: [Discuss-gnuradio] Measuring SNR Hi, I am trying to implement a particular channel coding technique as part of my work(Master's Thesis). I need to test this technique in a fading channel. But since I have no control over the channel I cannot quantify channel condition.I need SNR to analyze the performance of the coding technique.The only solution i thought was to inject noise at source and ensure that transmission.But this is more like a simulation. I would like to know if there are better ways to do this. My second question is more related to Python programming. I need to run a series of scripts one after the other in my work.Though these scripts work fine independently. I get an error when I use os.popen(). In most cases I do not want the control to return back to the calling script.Could any one suggest what is the best way to do this, or atleast a reference? Thanks Swapna
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