What is QOCA?
QOCA (Quasi-Observation Combination Analysis) is a software package that combines various loosely constrained geodetic site coordinate and velocity solutions (as quasi observations) to obtain crustal deformation information. QOCA is free for any non-commercial user. To respect the support of JPL and QOCA developer, please give the appropriate credit in your research work.

QOCA is used as the post-processing software package by many geodetic data analysis groups. Currently it can combine space-geodetic quasi-observations (GPS, VLBI, SLR, ... etc.) and terrestrial geodetic survey quasi-observations (EDM, triangulation, leveling, ... etc.). It has the potential to combine SAR data and gravity, seismicity, and ground motion data.

QOCA was designed and developed at Jet Propulsion Laboratory, California Institute of Technology. California Institute of Technology holds all the copyrights and Caltech licenses the users.

What is cool?
• QOCA accepts various formats from GIPSY, GAMIT, FONDA, GLOBK, BERNESE programs. It also accepts SINEX and Blue Book formats.
• QOCA solves for site positions, velocities, network parameters, and the coseismic and postseismic deformation parameters simultaneously. There is no need for other procedures. By-products, such as strain rates and gamma rates, are also obtained simultaneously.
• QOCA has the ability to detect outliers hidden in the quasi-observations.
• QOCA can directly deal with the noisy time series through robust analysis.

What is hot?
• QOCA runs fast.
• Space-saving.
• Flexible.
• User-friendly. Novices can run QOCA in basic mode within 4 hours.
• Online registration, online manual, online help board (Q/A) make the information exchange efficiently.

What is weak?
• Due to manpower shortage (see History), some parts of the software are incomplete.
• The author of the QOCA has no time to write a detailed manual.
• There is no funding to support full service for the QOCA users.

What is new?

08/15/2005: QOCA new version 1.30     The new QOCA version 1.30 has been put in JPL's ftp directory. The changes from the previous version are:   1. Activate strain calculation in separate mode.   2. In strain analysis, subnetwork mode outputs site names.   3. For grid and subnetwork modes, it no longer outputs robust fit solution.   4. Fix index bug when there are pmu rate observables.   5. Local unused site will not show up in the output files. Registered QOCA users can get the new version from JPL ftp site. 03/01/2003: "Help board" now is read only     The new QOCA web server does not allow write files to the web directory. So that the current 'Help board' becomes read only, you can see previous posters but can't poster your comment. Sorry for the inconvenience. We are still working on it.

Created by Danan Dong
Space Geodesy and Geodynamics Systems Group
email: Danan.Dong@jpl.nasa.gov
08/02/98