[evlatests] 3Bit utility scripts

[Barry Clark]

The samplers occasionally come up with the wrong number in the bit
selection slot.  This can be corrected by running the script
setBits.evla, in the widar script area.  You should run the script
only for antennas with the 3bit modules.

The T304 attenuators and equalizers can be set by including
something like the following near the beginning of your script:


myband = LoIfSetup('6GHz', 5500, 5000., 6500, 6600.)
myband.setWidarOffsetFreq(0.08, 0.08, 0.08, 0.08)
myband.getDownconverterAC().setDownconverterLevelControlMode(Downconverter.SETANDREMEMBER)
myband.setEqualizerServo(1)
subarray.setLoIfSetup(myband)

...

stt = array.time()
subarray.execute(stt+1.0/86400.0)
myband.setEqualizerServo(0)
subarray.setLoIfSetup(myband)
subarray.execute(stt+3.0/1440.0)
...


Notes:
a.)  This is currently available only in the EXECVER=test Executor.
Will be generally available at next install.
b.)  There is a bug which causes the highest numbered antenna not to
be set up.  (Under investigation.)
a.)  This doesn't work very fast because it keeps interacting with the
usual SETANDREMEMBER in an unfavorable fashion.  The 3 minutes above
seems adequate, but much less is not.  I'll fix that someday.