Gregorian cal selection failure Nov17



    Most receivers have 2 diodes that can feed polA or polB. The possible selections are:

cal type
polA
polB
hcal
Diode1
Diode2
hcorcal
Diode1
Diode1
hxcal
Diode2
Diode1
h90cal
Diode2+90deg
diode2
lcal
Diode1 Diode2
lcorcal
Diode1 Diode1
lxcal
Diode2 Diode1
l90cal
Diode2+90deg Diode2

    Where H is the high cal and L is a lowcal  (an attenuator gets switched in).

The cal type selection failed on 13Nov17.  It was fixed on 05dec17 14:00 ast.

There are two bits that select the type of cal (and 1 more bit for the h/l cal).
The bits come from:
When a cal type request (eg corcal) is made, the request ends up going to all of the receivers at the same time.

The problem occurs if a receiver postamp chassis is powered off.

The cband wide postamp chassis was powered off 13Nov17 at 09:42 ast.

The problem was also seen in the daily tsys measurements:

I looked at the cal deflections for runs with polarization data (cross correlations between polA,polB)

A3119 mock spectrometer data (.ps) (.pdf)

I also looked at interim correlator data for x102 and A3172  (.ps) (.pdf)

Summary:

processing: x101/171205/lbwcarl_mock, lbwcarl_icor.pro



 home_~phil