[evlatests] Y27 switched power signal, timing

[Barry Clark]

On 12/15/2012 10:35 AM, Walter Brisken wrote:
>
[snip]
>
> Unrelated to the search for hints in a possible timing offset problem
> the shape of the switched power signal comes out. The actual waveform
> differs from a pure square wave. The green trace on the plot is a binned
> version of the red trace. Both show that the first 30 ms after each
> transition there is a transient response. Probably of no consequence,
> though this differs from the nearly perfect square waves seen at the VLBA.
>
The switching occurs at each antenna on antenna time, which differs
by up to 100 us from VLA center time, so it will not be a clean
square wave on the sum.
>
[snip]
>
>
> Where to go from here? Since this timing test only demonstrates internal
> timing consistency within the VLA we still cannot exclude side-wide
> timing errors greater than 60 microseconds. Are there any ways to
> independently measure the VLA time to 10s of microsecond precision
> (e.g., comparison with GPS)?

Seems to me that the most likely place to look for fringes is in the
other sideband, or lost in frequency space.
>
>
> -Walter
>
>
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/evlatests