; SNREF ;--------------------------------------------------------------- ;! Chooses best reference antenna to minimize R-L differences ;# Task UV Calibration ;----------------------------------------------------------------------- ;; Copyright (C) 2012 ;; Associated Universities, Inc. Washington DC, USA. ;; ;; This program is free software; you can redistribute it and/or ;; modify it under the terms of the GNU General Public License as ;; published by the Free Software Foundation; either version 2 of ;; the License, or (at your option) any later version. ;; ;; This program is distributed in the hope that it will be useful, ;; but WITHOUT ANY WARRANTY; without even the implied warranty of ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ;; GNU General Public License for more details. ;; ;; You should have received a copy of the GNU General Public ;; License along with this program; if not, write to the Free ;; Software Foundation, Inc., 675 Massachusetts Ave, Cambridge, ;; MA 02139, USA. ;; ;; Correspondence concerning AIPS should be addressed as follows: ;; Internet email: aipsmail@nrao.edu. ;; Postal address: AIPS Project Office ;; National Radio Astronomy Observatory ;; 520 Edgemont Road ;; Charlottesville, VA 22903-2475 USA ;----------------------------------------------------------------------- SNREF LLLLLLLLLLLLUUUUUUUUUUUU CCCCCCCCCCCCCCCCCCCCCCCCCCCCC SNREF: Task to choose best reference for R-L phase difference INNAME UV data (name). INCLASS UV data (class). INSEQ 0.0 9999.0 UV data (seq. #). 0 => high INDISK 0.0 9.0 Disk unit #. 0 => any INEXT Input 'SN','CL' INVERS Input table file version no. SELBAND Bandwidth to plot (kHz) SELFREQ Frequency to plot (MHz) FREQID Freq. ID to plot, -1=>all SUBARRAY -1.0 Limit to subarray; <=0 -> 1 DOKEEP -1.0 1.0 > 0 => keep all "temporary" tables ---------------------------------------------------------------- SNREF Type: Task Use: Tries re-referencing an SN or CL table to see which reference antenna minimizes the R-L phase scatter. The task loops over all possible reference antennas copying the requested SN or CL table to a new version and re-referencing it. This re-referenced table is then read and the normalized gains in L are subracted from those in R and averaged in real and imaginary parts separately. The two rmses for each IF are added in quadrature and saved. After all possible reference antennas have been evaluated, the rmses are examined. The antenna with the lowest rms (averaged in quadrature over all IFs) is reported as are the lowest antennas in each IF. The rmses are then shown in detail. The output file will have 1 new SN or CL table if DOKEEP is false. If DOKEEP is true, it will have one for each of the possible reference antennas for your examination (with e.g. SNPLT). Adverbs: INNAME.....UV file name (name). Standard defaults. INCLASS....UV file name (class). Standard defaults. INSEQ......UV file name (seq. #). 0 => highest. INDISK.....Disk unit #. 0 => any. INEXT......'SN', or 'CL' table to be analyzed. INVERS.....Version number of table to analyze, 0=>highest no. SELBAND....Bandwidth of data to be selected. If more than one IF is present SELBAND is the width of the first IF required. Units = kHz. SELFREQ....Frequency of data to be selected. If more than one IF is present SELFREQ is the frequency of the first IF required. Units = MHz. FREQID.....Frequency identifier to select (you may determine which is applicable from the OPTYPE='SCAN' listing produced by LISTR). If either SELBAND or SELFREQ are set, their values overide that of FREQID. However, setting SELBAND and SELFREQ may result in an ambiguity. In that case, the task will request that you use FREQID. -1 => all, 0 => first SUBARRAY...Limit display to specific subarray. <= 0 -> 1. DOKEEP.....> 0 => keep all temporary SN/CL tables, else keep only the selected one. ----------------------------------------------------------------