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Last modified 14 months ago Last modified on 29.09.2016 10:44:55

Welcome to WARAN

WARAN is the acronym for Wireless ARray ANalysis. It describes the concept of a combined hard- and software development at the Institute of Earth and Environmental Sciences (former Institute of Geosciences) of the University of Potsdam for facilitating fast temporary deployments (hit and run operation) of small aperture passive seismological arrays in urban (or other potentially difficult) environments, allowing for real-time data acquisition, transmission and automatic in-field analysis of waveform data.

WARAN consists of a set of digital acquisition units attached to embedded devices supporting wireless data communication. Principally, the equipment might be of interest to a number of data acquisition problems, but here we trim the equipment for seismological multichannel recording. We call these acquisition units WAU (for Wireless Array Unit or Wireless Acquisition Unit, whichever expression you prefer).

Wireless data transmission is convenient and appreciated - however, setting up wireless communication during field work in rough conditions and under time pressure by re-programming routing tables etc. is rather annoying and error prone. Thus, the key issue with our WAUs is their true mesh capability making use of the olsr protocol implemented in the olsrd http://www.olsr.org (Note: since a couple of years we also make use of the batmand and the kernel-based batman-adv implementations).

This tiny technical detail of this multichannel (seismological) wireless acquisition system truly pays off during equipment installation and operation. Since having finished the development of this system, field work has become really easy - we just go, deploy and record (in real-time). Just as easy as that. And what is more: having the data available in real-time, we can immediately start data processing as well. From simple data quality control procedures to elaborated array signal processing - all computationally feasible processing steps can be started right away while recording. The striking advantage of this concept is the fact that any data related problems that show only after specific data analysis steps is not hidden until one is back in the laboratory. The loss of time (and money) can be reduced to a minimum.

To our knowledge WARAN has been the first seismological array based on WLAN mesh communication if it comes to more than quality control and status checking of recording instruments (i.e. real-time waveform analysis). The specific purpose of WARAN is the usage for in-field dispersion curve estimation from ambient seismic vibrations in urban environments. The real-time capability of the systems allows for designing repeatedly the experimental layout of the sensor geometry in the field based on the observed wavefield characteristics. Given this capability, experiments can be conducted fast and with low risk of failure, as the outcome is controlled while measuring. Any adjustments needed for improving estimation of phase velocities and direction of wavefield propagation can be immediately coped with.

Using modifiable-off-the-shelf (MOTS, only found in German wikipedia?) products (see also COTS, term for commercial off the shelf) and opensource software components, the WARAN system is kept as simple and robust and OPEN as possible.

The array is operating since spring 2006. The hardware has been funded within the BMBF Geotechnologien program (project "HADU - Hamburg a dynamic undergground"). Since this time, a lot of improvements both in hard- and software have been undertaken and this wiki is a try to summarize certain technical details (mostly hard- and software issues) and to put together a small FAQ and discussion platform as other people have started to use WLAN based mesh-technology for recording instrumentation in seismology.

Today (as of April 2010) we have proven the WARAN concept to be fruitful for the sake of dispersion curve estimation at 200+ real-time array measurements at more than 40 sites within Germany and Europe (i.e. EU-Project NERIES, JRA4). During the course of the years, there has been considerable help and contributions by a number of close colleagues, in particular M. Wathelet, A. Savviadis, C. Cornou, D. Kühn, and B. Endrun. Thanks to all of them! Furthermore other colleagues have been inspired by this project and have developed their own systems following our concept, which proves the importance of free and open developments, idea sharing and collaboration in science.

Some update here (09/2016): the project is still alive and has been taken further in terms of robustness and usability. Please Have a look here

Starting Points

For a complete list of local wiki pages, see TitleIndex.