Hi If the "signal" is actually 80 db below the noise, you will need a lot of cross correlation simply to find it at all. Your digitizers are going to have to be *very* good just to let you get that far in the first place.
Bob On Mar 20, 2011, at 6:36 PM, Magnus Danielson wrote: > On 03/20/2011 08:26 PM, Bruce Griffiths wrote: >> The beam from the interferometer/phased array can be swept over the sky >> by varying the phase shift between the elements during the data >> reduction process allowing high resolution imaging. >> Compensating for Earth rotation and consequent changes in the >> atmospheric delay are necessary. Differential phase shifts of a few tens >> of picosec are significant in the imaging process. >> The effect of atmospheric refraction has to be accounted for if accurate >> positions of the source relative to the Earth's surface are required. > > I would use cross-correlation between two (or more) antennas. The noise of > the individual antenna assembly would cancel out for sufficient correlation > length. That would help to boot-strap the direct correlation if not the FFTed > correlation will do. > > Long FFTs is cheap these days. > > Then again, the real VLBI people would beat me up for such naive approaches. > > Cheers, > Magnus > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
