[evlatests] WIDAR wobbles vs. time

[Vivek Dhawan]

Michael inflicted upon me 80 minutes of data taken at 40msec
integrations, 20GB, to look for changes in wobbles vs time, etc.

1. load data and index it in short scans - it makes subsequent
    tasks start quicker.

2. FRING on 10sec of data, zero rates, then apply to all data.

3. BPASS on 1min, apply to all.

4. Average up across band, plot phase/amp vs time.

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.

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.

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.

Heard enough? I have - see y'all tomorrow

Vivek.