Mark-5 VLBI Analysis Software Calc/Solve


What is Calc/Solve?

Mark-5 VLBI Analysis Software Calc/Solve is a set of programs for analyzing very long baseline interferometry observations made under astrometric and geodetic programs. It allows

Calc/Solve is a part of the complex of programs which support scheduling, operating, processing, archiving and analysis of geodetic VLBI experiments:

  1. sked/drudg software for scheduling VLBI observations;

  2. Field system software for control antenna and data acquisition terminal during the experiment;

  3. Correlator hardware and software processes the tapes with recorded signals and computes arrays of complex cross-correlation function.

  4. Haystack Observatory Post-processing System processes these arrays, finds fringes and calculates 5 VLBI observables for each scan, for each processed baseline: narrow-band group delay, wide-band group delay, phase and amplitude of coherence function.

  5. VLBI analysis system archives the output of correlator post-processing software into the databases, computes theoreticals values of delay and delay/rate, finds adjustments to the parameters of the model by LSQ fit, calculates statistics of the solution, generates tables and plots of the final results and and make a lot of other things.

Mark-5 VLBI Analysis Software Calc/Solve has been developing since middle of 70-s. It is maintained in Goddard Space Flight Center NASA and is widely used around the world. Calc/Solve was developed for analyzing experiments processed in Mark-3/Mark-4/Mark-5 correlators but it has convenient interface to the experiment processed in K4 and S2 correlators. Mark-5 VLBI Analysis Software Calc/Solve runs under Linux and HP-UX operating systems on processors with i386, PA-RISC architectures. It consists of 109 programs, 3680 modules of 1.02 million lines of source code written mainly in Fortran-95.

Description of some algorithms.

  1. Multigroup LSQ method and its generalization.
    Abstract | Full text
  2. Group delay ambiguity resolution algorithm. Full text
  3. Outlier elimination algorithm. Full text
  4. Observations reweighting algorithm UPWEI by Leonid Petrov. Full text
  5. Observations reweighting algorithm MYWAY by John Gipson Full text
  6. Constraints, covariances and chi-square in Solve by John Gipson. Full text

Memos related to Calc/Solve.

  1. Implementation of fast algorithms in SOLVE.
  2. Fast extension of SOLVE. User guide.
  3. About problems with speed in SOLVE.
  4. How f-SOLVE is working.
  5. Comparison of results produced by f-SOLVE and s-SOLVE.
  6. Speed of SOLVE.
  7. Once more about speed of SOLVE.
  8. Calc/Solve interface.
  9. Undocumented features of Calc.

Recent release notes of Calc/Solve.

Release notes of 2014.02.21

Previous release notes

Known problems of Calc/Solve.

Posted bug fixes after the latest release of Calc/Solve.

How to get Calc/Solve.

Download Distributive kit   (117.4 Mb)   updated on 06-MAR-2014 14:20:00

For first installation you need file.

Refer to the general installation instruction and specific instructions for HP-UX or Linux operating systems.

Calc/Solve runs only under Linux, and HP-UX operating systems on processors i386, x86_64 and PA-RISC architectures.

User documentation related to Calc/Solve.

List of a priori files.

Calc/Solve requires a priori files. You can find below links to the versions of these files maintained by VLBI team of the Goddard Space Flight Center.

Lists of sessions with problems.

  1. List of 245 databases with wrong order of observations. Calc/Solve is unable to process them and issues an error message like IUER=8320 LOOP "Wrong order of observations detected in the session $88AUG31X <14> : 686-th observation occurred BEFORE the previous one at 6.000002 sec. Database file should be cured!!!" Such databases should be cured. Corrected versions of the databases are available on-line in Goddard Space Flight Center and off-line in Geodetic Institute of the University of Bonn.
  2. List of 9 databases with mixed baselines. It means that the database contains both baselines AB and BA. Advanced programs of Calc/Solve such as GAMB, PAMB, ELIM are unable to process such sessions.
  3. List of the databases with huge clock offsets. Imposing a priori clock model is strongly recommended in data analysis of these sessions.
  4. List of the databases with huge clock rates. Imposing a priori clock model is strongly recommended in data analysis of these sessions.
  5. List of signs of applied cable calibrations for (almnost) all databases and stations.
  6. List of clock breaks from the gsf2007c solution.

Mailing list

Mailing list  is for discussing issues related to the Mark-5 VLBI analysis software package which are of interest for all users and for posting messages about changes. Only subscribers can post messages to the list. The messages posted to the list are available for viewing to all from the mail archive.

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Web curator: Karen Baver (karen.d.baver "at"
Last update: 2014.02.21_16:11:02