On Thu, Nov 24, 2011 at 6:46 PM, Marcus D. Leech <mle...@ripnet.com> wrote:
> ** > > Actually, I am not using any sinusoidal function in this measurement. So, > zero values are not valid I think. I am mostly using the noise signal so I > thought there must be a value. > Here is a sample of what I got. > > Any idea would be highly appreciated. > > 0.0001220703 -9.1552734375e-05 0.0001831055 -6.103515625e-05 > 9.1552734375e-05 0 0.0001220703 -0.0001220703 0.0001220703 -0.0001220703 > 6.103515625e-05 -3.0517578125e-05 0 -6.103515625e-05 0.0002441406 > -6.103515625e-05 0 -6.103515625e-05 0.0002746582 0 > > Those samples look fine. And remember that '0' doesn't mean that it has to be exactly 0; just a signal too small for the ADC to pick up of to have any of it's bits toggled, so it will be 0 when sampled. Tom > How is it that you can be a masters student in electrical engineering, > and *not* know that noise signals are simply the super-position > of a large series of sinusoidal (or near-sinusoidal) functions? Once > again, the ADCs in an SDR receiver are sampling a complex voltage. > That voltage may occupy any values between {-adc_resolution, > +adc_resolution}. In UHD, the ADC values are scaled (normalized) > into the range {-1.0, +1.0} to make things within the flow-graph > somewhat more general, and allow a certain amount of hardware > independance. > > In general, the samples of a noise source will be equally distributed > about 0, and in fact you can confirm this by calculating the > running-average of all your samples--they will tend to converge to 0 (in > practice, there will be a small amount of DC offset which > will cause this convergence to be not exactly at zero). > > But all this should be in course textbooks, etc. The folks here are > generally kind, and patient, but they can't hope to teach people entire > courses in electrical engineering, RF design, linear and non-linear > circuit theory, and digital signal processing. Although, those who > *do*, generally charge money for it, in one way or another. > > > -- > Marcus Leech > Principal Investigator > Shirleys Bay Radio Astronomy Consortiumhttp://www.sbrac.org > > > _______________________________________________ > Discuss-gnuradio mailing list > Discuss-gnuradio@gnu.org > https://lists.gnu.org/mailman/listinfo/discuss-gnuradio > >
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