7.2. UHDAS-VMDAS comparison

The figures below are from presentations about UHDAS and VmDAS. This is a sparsely-annotated collection, comparing various aspects of UHDAS to VmDAS. A brief written explanation can be downloaded here.

7.2.1. Acquisition

At present, there is one company that makes science-quality vessel-mounted ADCPs.

There are two acquisition systems for these systems:

  • VmDAS: provided by the manufacturer with purchase

  • UHDAS: developed at University of Hawaii

Data acquisition systems should provide three different functionalities:

  1. Required: satisfy basic requirements for logging data:

    • Control ADCP settings

    • Acquire ADCP data

    • Acquire ancillary data

      • position

      • attitude (heading)

    • timestamp all

  2. Desireable: Processing

  3. Desireable: Monitoring Core acquisition: Overview

UHDAS and VmDAS have different goals and software style:

uhdas-vmdas-acquisition-overview Core acquisition: Serial Setup

UHDAS is more configurable than VmDAS, making it easier to collect the right messages and collect data from enough feeds to provide some insurance against unexpected failures.

uhdas-vmdas-acquisition-serial-setup Core acquisition: Data Logging

Many of the decisions made in the data logging architecture were related to the operating system (linux vs/ windows) and and styles of running programs on those operating systems.


7.2.2. Processing Components:

If all has gone well up to this stage, there might not be much difference in the potential final data quality from UHDAS or VmDAS, but there are many ways in which UHDAS will yield a better final dataset. Most of that comes down to the single-ping editing done in CODAs processing.

uhdas-vmdas-processing-comparison Accessing Data Products

Differences betwen UHDAS and VMDAS are related to the scope and audience: UHDAS is meant to be a useful at-sea system for ocean-going scientists; VmDAS is meant to be turn-key for a variety of users.


7.2.3. Monitoring

Much of what keeps UHDAS ADCP data quality high at sea is the monitoring, which provides the opportunity for feedback to the operator at sea that there is a problem, usually in under 24 hours. VmDAS was never designed for that extra boutique level of interaction.