UHDAS+CODAS DocumentationΒΆ


As of April 2013, this version of the documentation is no longer maintained; however, it is consistent with the last (now retired) version of CODAS processing that used Matlab. We no longer update or fix the Matlab processing code, but we will maintain the Matlab code that reads CODAS Matlab output. Although the notes refer to both Python and Matlab processing, none of the code here will be maintained. This (now retired) documentation and code will remain available for awhile longer.

Python processing code is actively maintained and developed, and CODAS Python processing is documented here.

An ADCP (Acoustic Doppler Current Profiler) is a device made by Teledyne RD Instruments that uses the Doppler frequency shift of an acoustic ping to infer water velocity. It is a registered trade name. ADCPs are attached to moorings, lowered on CTD rosette packages, and mounted on ship hulls. This web site deals with shipboard ADCPs.

If you are unfamilar with how and ADCP works, please visit the Teledyne R.D.Instruments website and download the ADCP (BroadBand) Practical Primer. They will ask you to create an account, but there is no cost. This outlines the underlying concepts behind how an ADCP works.

An overview of shipboard ADCP systems was written for the GO_SHIP Repeat Hydrography Manual. For convenience, an html version of the shipboard ADCP contribution is included here.

A CODAS (Common Ocean Data Access System) database is a way to store and access oceanographic data. CODAS was developed in the late 1980’s as a portable, self-describing format for oceanographic data, with emphasis on processed ADCP data.

CODAS processing” refers to the ADCP data processing software and procedures that were developed around the CODAS format. The processing steps have become increasingly automated, but human judgement is still required for the final product, and the software is highly flexible in allowing manual configuration and execution of individual steps.

UHDAS” (University of Hawaii Data Acquisition System) acquires data from RDI ADCPs and ancillary sensors (eg. gps, gyrocompass, gps and inertial attitude sensors...) and uses CODAS processing to incrementally build a dataset of averaged, edited ocean velocities for each ADCP and ping type specified. Processed data and plots are served on the shipboard network, and daily status summaries are emailed.


UHDAS is not a program, but a complex set of codes and system configurations. Setting up a new UHDAS installation requires Linux system administation skills, an understanding of UHDAS, and detailed knowledge of the particular suite of instruments and network environment on the ship. We are working to make the installation process easier and more automated, but at present it is not sufficiently documented to be done without specific training.

CODAS documentation has accumulated over the years as acquisition programs, instruments, and processing programs have changed. Some of the old (but highly detailed) documentation contains references that are obsolete, but still relevant to old data sets; and many of the problems described in the old documentation still occur.

UHDAS+CODAS Documentation is evolving, as we gradually include more of it under the unifying framework facilitated by Sphinx. The full documentation is available at various entry points: