[evlatests] Preliminary Wobble Report

[Brent Carlson]

Hi Rick,
>
>    For the third test (Brent's algorithm)
>
> No obvious wobbles are visible.  The phase wobble on 9 x 27, if 
> present, is less 1 degree pk-pk.  The amplitude wobble on 2x10 might 
> be present -- if so it is of much lower amplitude.
>    A Fourier analysis is needed for a most discerning judgment.
If there is no post-correlation residual sub-sample delay correction 
being done, depending on baseline length and integration time, I can 
imagine there being a percent or so amplitude oscillation, and a 
residual phase slope vs freq changing with each integration time, as the 
integration time beats with delay tracking, which could explain what you 
see. (The baseline-based coherence loss at the edge of the band due to 
22.5 deg phase excursion is ~2.5%, which is ~1% averaged over the sub-band.)

There's also the question as to whether the correlator chip integration 
time, for this test, was set to some odd ball number, or the standard 
200 or 250 usec.

--Brent