[evlatests] L352 health report.

[Vivek Dhawan]

Hoping for a 1-liner, gentle reader? Dream on.

I loaded data from AS895, (Shepherd) April 06, UT 9:30-17:30 or so.
The setup was standard continuum X-band, one calibrator throughout.

I compared the interferometer phase to the L352 RTP meter readings,
and found that, with one possible exception (ant 24) the meters are
applied with the correct sign to improve the phase drifts.

I try to say 'meter' for the L352 phase @512 MHz, and 'phase' for the 
interferometer @ 8.45 GHz.

There are oddities of various types, related to the state of each of
the meters. Perhaps 24 is also a meter problem, but I could not tell.
Plots are attached for the curious (or merely bored).

Ant.                            Comment.

13: Meter is bad? it shows a steady linear slope. Unlike the rest,
     it is not tracking the diurnal temperature cycle (which makes an
     inverted V in the phases during this experiment.)

14: Meter reading is inverted - the phase slopes are doubled.

18: Not too bad, only a small residual slope. But the phase wrap
     in the meter at ~16:34 caused a jump of ~90deg which persisted
     for the last hour, and the phase slope changed sign there too,
     though the meter reading did not change slope.

24: Meter reading looks like 18's; (and -14's since 14 is inverted).
     I think 24's meter is correct. But the interferometer phases
     look inverted with respect to other EVLA antennas. It is as if
     24 is getting twice the correction it needs (or it is already
     flat before the L352 correction is applied.)

26: Meter very noisy - messes up the short-term phases when applied.
     But the sign is correct for long-term drift; and there is still
     a small slope left over, as there is on 18.

17 & 23: No meters. The uncorrected phases appear as expected, and
     look a lot like 13.

16 & 21 Dead - no fringes; no L352s either.

-----------------------------

Keith Morris wrote:

> There are now 5 L352s in service, all with Module ID.  The two eldest 
> units (13 and 14), which had been overwritten with incompatible 
> software, are now back in service, and producing data.
> 
> The current roster includes:
> 
> ea13-l352
> ea14-l352
> ea18-l352
> ea24-l352
> ea26-l352
> 
> ea26-l352 has a known bug, which results in occasional jumps.  I am 
> working to correct this.
> 
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