The height of the spike relative to the noise in the autocorrelations will depend on the spectral channel bandwidth (resolution) used.  But the comparison with the VLBA stations does indicate that it is excessive at GB and so will be adding more noise to the observations than necessary.

Cheers,

Craig

Jim Ulvestad wrote:

> Hi all,
>
> The phase cals for GBT in BU031D (2.3 GHz) on August 6
> are awfully strong relative to the system noise.  Peaks look
> like they're about 20% above the baseline noise level, when
> something like 5 or 6% should be a better level.  I'm
> attaching a plot of the autocorrelation bandpass that
> shows how high GBT phase cals are relative to those at
> the VLBA stations.
>
> Thanks,
>
> Jim