Dear Casperites, I am trying to readout the cross correlation and auto correlation powers of signals input into the Roach, when it is programmed as a correlator, such as in the fourth tutorial <https://casper.berkeley.edu/wiki/Tutorial_Wideband_Pocket_Correlator>. In my setup, I am only using inputs from one of the ADCs, and so inputs "C" and "D" are unused; I use "A" and "B" only, and these can respectively be interpreted as a signal and reference beam of a holography setup.
My goal is to measure correlation as some value proportional to the square of electric fields, and I want to make sure I'm doing this correctly with the Roach. For example, for cross correlation, my goal is to measure <Ea* Eb>, where Ei is the electric field of the "i'th" input signal. Using the cross power calculation script <https://github.com/casper-astro/tutorials_devel/blob/master/tut4/poco_plot_cross.py> , 4 complex values (8 data points total, 4 real and 4 imaginary) are read from the roach, such as: 'dir_x0_%s_real' and 'dir_x0_%s_imag'. Two of these complex values go into an array called 'interleave_a', and the other two go into an array called 'interleave_b'. The value 'cross power' is then reported as 'numpy.abs(interleave_a)', but I do not understand this, because, first, I thought the output of that 'abs' function is going to have two elements in this case, or, second, that the cross power would only be the multiplication of two values, not 4. Would someone please be willing to explain the output of the roach, the 'interleave' arrays, and how precisely I can calculate <Ea*Eb>? Thank you all in advance for any help you are willing to provide! Sincerely, Alec -- You received this message because you are subscribed to the Google Groups "casper@lists.berkeley.edu" group. To unsubscribe from this group and stop receiving emails from it, send an email to casper+unsubscr...@lists.berkeley.edu. To post to this group, send email to casper@lists.berkeley.edu.
