Royal Netherlands Institute for Sea Research

WATLAS - technical specifications

Local receiving mast as part of the WATLAS system. Photo: Allert Bijleveld


Wadden Sea Advanced Tracking and Localisation of Animals in real life Systems (WATLAS) tracks birds using Time-Of-Arrival (TOA) principles, unique tag-IDs for radio transmitters, ground stations with tower-mounted antennas, and central data-processing and storage servers. Radio transmissions sent from each bird attached tag are received by several ground stations. The system uses time-of-arrival estimates to estimate the location of the animal and stores the location in a database.

ATLAS is developed by Sivan Toledo from Tel-Aviv University and Ran Nathan from the Hebrew University of Jerusalem in Israel. In collaboration with the developers, ATLAS is deployed in the Dutch Wadden Sea since 2017.

TOA principle

The principle of TOA tracking explained for the position of a test transmitter (star) on intertidal mudflats northeast of the Islet of Griend, Dutch Wadden Sea. The hyperbolic curves indicate possible positions of the transmitter calculated from the measured difference in signal arrival times at three pairs of automated receiver stations. The transmitter is located at the intersection of these curves. Earlier and later locations are presented as a track of blue dots. The accuracy of the system is confirmed by the light-green line, that represents a simultaneously acquired GPS track while the transmitter was moved by boat.

The principle of TOA tracking explained for the position of a transmitter (star).

The first test of the TOA principle took place in 2009.  In the following years NIOZ and the Cornell University (Ithaca, New York, USA) have joined forces to implement the Time Of Arrival (toa) tracking system that was devised at Cornell (MacCurdy et al. 2009, 2011).  It was then deployed in three different ones field situations. In 2011 we followed Red Knots in the western Wadden Sea, in 2012 we tried to describe the movements of the Golden Plover in Friesland, and in 2013 we again followed Red Knot movements. This time in a similar ecosystem in West Africa, Banc d'Arguin, Mauritania.

From 2012, Sivan Toledo developed time-of-arrival tracking further and the first ATLAS system has been operational in the Hula valley, Israel since the spring of 2014.


For technical specifications or other information, please contact Allert Bijleveld by email (preferred). You will get a response as soon as possible. In very urgent matters, you can contact him directly. 

T +31 (0) 222 578