INNAME Main input file (name). INCLASS Main input file (class). INSEQ 0.0 9999.0 Main input file (seq. #). 0 => high INDISK 0.0 9.0 Disk unit #. 0 => any INVERS Input SN file version no. OUTVERS Output SN file version. BIF 0.0 16.0 First IF to use. 0=>1 EIF 0.0 16.0 Last IF to use. 0=>last TIMERANG Time Range is consider. SUBARRAY Subarray (default=1) FREQID Frequency ID (default=-1) OPTYPE 'DISP' -> fit dispersion and MB delay from SB delays else -> fit MB delay from SN table phases PRTLEV 0.0 10.0 Print fit results >=1 fits, 2=IF resids. APARM Editing parameters (1) = min SNR; def=5 (2) = max rate rms (deg) def = 50d (3) = max MBD rms (deg) def = 20d (4) = min. no. IFs. 0->all (5) = MBD Search range. 0 = ambiguity. <0. Use zero. (6) > 0 remove residual phase (7) > 0 keep bad data (8) DISP only >0 -> keep only dispersion, zero delay and phase (9) DISP only > 0 -> do NOT correct delay and phase for dispersion (10) DISP only, > 0 -> average DISP over R and L

MBDLY Type: Task Use: MBDLY fits multiband delays and, optionally, dispersion from the IF phases in an SN table produced by FRING or CALIB. The results are placed in another SN table. Adverbs: INNAME......Main file name (name). Standard defaults. INCLASS.....Main file name (class). Standard defaults. INSEQ.......Main file name (seq. #). 0 => highest INDISK......Disk drive # of image. 0 => any INVERS......Input extension file version #. OUTVERS.....Output extension file version #. 0=>make new BIF.........First IF to use. 0=> 1. Use to determine MBDLY for dual frequency SN table EIF.........Last IF to use. 0=> last. Use to determine MBDLY for dual frequency SN table. SUBARRAY....Subarray FREQID......Frequency ID (may need to set to 1) TIMERANG....Time range to consider OPTYPE......'DISP' -> use single-band delays to fit for a single multi-band delay plus dispersion for each record in the input SN table. else -> use the phases in each IF to fit for a multi-band delay PRTLEV......<= 1.0 -> show multiband fits. >= 2.0 -> show phase residuals for each IF Suggest using 2. APARM.......Editing control parameters: (1) is the minimum average SNR (WEIGHT in the SN table). 0 => 5. 0.01 lets everything by. (2) is the maximum acceptable rate scatter among the IFs in units of degrees over the integration period. The default is 50 degrees. (3) is the maximum acceptable rms residual phase of the IF phase residual in degrees. The default is 20 deg. (4) is the minimum number of IF's for a valid solution. The default is all. (5) is the search range (+/- value) for the MBD. Default (0) is the natural range and is equal to the least-common stepping frequency, but is often chosen too high. Try APARM(5)= 10 for DELZN work. If <0, then assume MBDLY = 0. This is useful for just averaging the phases over the IF's. (6) If =0, keep residual phase in data. This will leave the observed phase in the data after removing the multiband slope. Use with CL2HF. If =1, Remove residual phase from data. This will zero the observed phase. The phase inserted in the SN table is the average observed phase. Use this option for further imaging. (7) > 0 => pass "bad" data. Set this equal to 1 if you want to pass through 'bad' data previously blanked out by MBDLY. A zero or low quality code (5, 6, or 7) will be set by CL2HF. Useful for multiband observations when a source is detected in one band but not the other. (8) DISP only: If > 0, then write the dispersions in the output SN table but zero the phases and single-band delays. After CLCAL, you then run FRING over again on the dispersion-corrected data. This may produce a more reliable set of phases and SB delays. (9) DISP only: If > 0, do NOT correct the SB delays for the dispersion. Otherwise (if APARM(8) <= 0), the delays are corrected for having a dispersion now (10) DISP only: If > 0 average R and L fit dispersions before correcting phases and delays. NOTE - THE CALIBRATION ROUTINES ASSUME THAT THE R AND L DISPERSIONS ARE IDENTICAL.

PROGRAM: MBDLY DOCUMENTOR: Ed Fomalont 95.03.08, rev 06.05.21 RELATED PROGRAMS: FRING, CALIB, DELZN, CLCAL, PCCOR, SNCOR PURPOSE New method added May, 2015: OPTYPE = 'DISP'. Use MBDLY in this mode on an SN table written by FRING in which a separate delay is found for each IF (spectral window). It uses the delays found by FRING to solve the equation SBdelay = MBdelay - Dispersion * lambda * lambda by least-squares. The task writes the MBdelay, and Disp in the appropriate columns of the output SN table. By default, the task will correct the SBdelay by adding Disp*(Vlite/freq)^2 leaving the delays as SB delays and the phases by subtracting Disp*Vlite+lambda. ************************* Comments below apply to all other values of OPTYPE: FRING and CALIB determine the value of the antenna-based phase for each IF for a specified solution interval. The results are placed in an SN table. The program MBDLY then reads this SN table (INVERS) to determine the best phase slope through the residual phases of the specified IF's. The results are put in a new SN table (OUTVERS). This delay over all of the IF's is called the Multi-band delay or the Group delay and it is often used in geodetic/astrometric experiments. The advantage is that the Group delay is not subject to lobe ambiguities associated with the phase. The group delays obtained from MBDLY can be put into DELZN to determine the residual atmosphere and clock residuals for each antenna, as a function of time. The peculiar phase constants for each IF must be determined and removed before MBDLY can calculate the phase slope. The peculiar phases can be obtained by using PCCOR and choosing an appropriate time range for a good calibrator. Another method is called the 'manual phase calibration'. Here you run FRING on a short segment of data (less than a minute) for a strong source with a complete set of data to obtain the Single-band delay, rate and phase. It is recommended to zero the rates (using SNCOR) unless the rates are persistently large for an antenna. Apply the solution to the entire data base using CLCAL. This will line-up the IF phases and define the multiband delay to zero for all antennas during the period of the short segment of data used in FRING. The relative IF phases should then be relatively stable so that the residual IF phases for any other source (strong and without too much structure) should be linear with frequency. MBDLY finds this phase/frequency slope. The Multiband delays can also obtained directly from FRING with APARM(5)=2.0. However, this procedure has been found somewhat unreliable so it is best to use FRING with APARM(5)=0 and then MBDLY. Since the phases are sampled at a few discrete IF frequencies, the best slope is ambiguous by an amount (1000/DF) nsec, where DF is the basic IF frequency spacing (MHz). For example, if the IF spacings are 0, 80, 140, 400 MHz (above a reference value), then DF is 20 MHz. The ambiguity spacing of the MBDLY is then 50 nsec and this is what is used if APARM(5)=0. However, it is best to use as small a MBD spacing as possible, and no more than 10 nsec is recommended for most DELZN observations. For astrometric/geodetic experiments, the results in the SN table produced by MBDLY are interpolated into the CL table using CLCAL. Then, the task CL2HF calculates relevant astrometric quantities needed for the Calc/Solve software and places these results in an HF extension file. Finally the task HF2SV translates the HF data into something that can be read into Calc/Solve. See instructions associated with these two tasks. Adverbs: BIF........The begining and EIF........The ending IF to use for the solution. Experiments with simultaneous S/X bands are common. It is recommended to separate the two frequencies and reduce separately. TIMERANG...The time range of the input SN table to process. 0 means take everything. PRTLEV.....Use 1 for most executions. The output will list some information about the fits, including the rms phase residual. If PRTLEV=2, the residual phase error for each IF is listed underneath each line. This offset should be less than a few degress for a reasonable fit. APARM..... Editting control parameters. Any SN table entry that exceeds one or more of the following criteria, will have a blanked multiband delay written in the output. (1) Minimum SNR. The default is an SNR of >5. This is reasonable. To include all data, let APARM(1) = 0.01 (2) Maximum rate rms. This is the maximum phase scatter over the integration time which is caused by the scatter in the rate solutions for the IF's. The default is 50 degrees. This could be set to 10 degrees for good data. This option removes source solutions which have significantly different phase rates amongst the processed IF's. It is a good indication of bad data or too weak of a source. (3) Maximum multi-band delay rms. The maximum phase scatter in the IF's after the removal of the best MBD. The default is 20 degrees. This could be set to 7 degrees for good data. Use PRTLEV=2 if there are problems here. (4) Minimum number of IFs. This is defaulted to all IFs otherwise no solution is given. This can be decreased even to 2 IF's as long as the phase difference between the two IF's is less than 180 deg. (5) The MBD Search Range. The default is the natural ambituity range which is equal to the inverse of the 'unit' spacing in the frequency set. For example, if the four IF relative frequencies are 0, 70, 385, 490 MHz, then the unit frequency sampling is 35 MHz, or 28.6 nsec which is the default. For frequencies which are not commensurate, APARM(5) should be set to a reasonable range. For example for most DELZN runs, APARM(5)=10 should be sufficiently wide. If APARM(5)<0, then assume MBDLY is zero and just average phases in IF's. This is useful for getting the average phase over all of the IF's for a weak source. (6) Unused now: formerly controlled whether residual phases were zeroed or not. They are now passed unchanged. (7) > 0 => pass "bad" data. Set this equal to 1 if you want to pass through 'bad' data previously blanked out by MBDLY. A zero or low quality code (5, 6, or 7) will be set by CL2HF. Useful for multiband observations, when a source is detected in one band but not the other.