Re: ALMA Science Software Requirements (SSR) -- Step 1

[mel wright 456 <wright@creek2.Berkeley.EDU>]

Robert,

	some info' for 1.2 phased array mode:

During VLBI runs for the last 4 years we have run a simple script which
is synchronized with the VLBI scans:

. PREOB - calibration: 
	- cross-correlation integrations with the usual phase switching
	- selfcal wrt refant
	- adjust LO phase offsets on-line to phase the array.

. MIDOB - vlbi recording
	- turn off phase switching (Walsh functions) except for refant
	- select un-shadowed antennas
	- phased array of un-shadowed antennas (sum IF's except for refant) 
	- local fringes of phased antennas wrt refant.

[ The original system design had a de-Walshing card, so that one could
do cross-correlation integrations with the usual phase switching AND
 have a phased sub array simultaneously, but this didn't work out
because of cross-talk, probably through the summing network back into
the correlator IF's ]

				Melvyn.