[evlatests] WIDAR wobbles vs. time

[Michael Rupen]

> 5. Wobbles seen mainly between ant 2, 18, 19, 28; regardless of
>    whether the delay and BPass are applied or not, so their
>    details are not crucial.

Would be interesting to try fringe-fitting every record to take out
the delay clunks, and to look for wobbles in the delays.

Are wobbles antenna- or baseline-based?  I.e., do they show up with
CLPLT/CAPLT and/or in CALIB solutions?


> 6. FRPLT (= Fringe rate plot, Fourier transform of phase vs. time)
>    of 1min of data was done every 10 min to see changes. The period
>    of the wobbles does change in come cases by a factor 2 over 80min.

Ooh, cool!  I want to see these plots!

I'd like to see the actual periods here at some point, for both
the phase and the amplitude.  Brent has some theories which depend on
the magnitude of the oscillation and its period vs. the fshift difference
and various other subtleties which I can't recall right now :}


Three other things to look at:
- wobble magnitude and period vs. subband
- wobble magnitude and period vs. channel within a subband
- check for wobbles in the auto-correlations (which you should have)

Hey, we all love rich data sets, right?


> 7. I need to relate the wobble period to the natural fringe rate,
>    not yet done.  Anyone have a handy program?


> 8. I did find a more curious thing: The amplitude wobbles may be
>    different from the phase wobbles on the same baseline! e.g.
>    Amp 8%, phase 5deg (all pk-pk) on ant 19-28
>    amp 1%, phase 8deg on 2-19.
>
>    Even more curious, the period of the amp wobbles (0.4 sec) is
>    half that of the phase wobbles on the same baseline (19-28).
>    In most of the cases seen, phase and amp have the same period.

We've seen this "frequency doubling" several times, without understanding 
it...nice to know it's in this big data set as well.



Let me know if you need help with this data set...I know it's huge,
and there's lots to look at...

              -- Michael