Data was taken for 100 minutes on 05sep02 with the IF connected to the downstairs noise source. 1.5625 Mhz bandwidth and 1024 channels were used. The plots show the size of the spike relative to Tsys. The spike is located at .78125 Mhz.
The correlator itself seems to be integrating ok. The expected rms is .00033 Tsys (actually it should be .00031 using 1/sqrt(b*tau*1.208)*1.04 which includes the true bin widths and the degradation from 9 level sampling). We measured an rms of .00035 using only a 2nd order polynomial fit to the baseline. Part of the extra rms is coming from the residual shape in the filters.
There is another spike at .3373 Mhz that is the same
in all 8 sbc. This implies that it is common to all sbc and both polarization's.
This means it must be coming from the common noise source. The center of
the IF band at the noise source is 750 Mhz and the plotted band has been
flipped so the frequency of the spike is 750 + 1.5625/2-.3373 = 750.444