GNSS and its Uses at Berkeley

The second and third days of Dig Berkeley saw our technician Nick Hannon starting to teach our students how to use our new GNSS machine, with the intention of producing a topographical survey to the north of Trench 8 in the Paddock field. GNSS stands for Global Navigation Satellite System, and it uses a collection of navigational systems to produce accurate 3-D positioning.

Technician Nick Hannon with the GNSS machine.

GNSS was first developed in the 20th century to help military navigation, and is still used for navigation today by aircraft, ships, airplanes and even spacecraft! GNSS receivers use a variety of satellite systems, including the American GPS, the European Galileo and the Russian GLONASS, which allows for a high accuracy 15mm of the pole base, the end point of which is inserted into the ground to mark the position point that needs recording. The light and portable size of the GNSS equipment makes it ideal for archaeological fieldwork and this is the first time we are using this at Dig Berkeley.

Nick and students laying out the tape for the GNSS machine.

The Paddock Field has a deeper depth of made-up soil at the south end where kitchen gardens were installed in the 18th century and were in use up until the Victorian period. This means that most of the archaeological features in this area have been obscured by the adding of up to 1m of topsoil.

It is hoped that by using the GNSS on the shallower soils of the northern end we may get an indication of what archaeology lies beneath. This recording of all the lumps, bumps or troughs will help us to make a decision as to whether we choose to open another trench in this area or not.

Nick and students taking measurements on the GNSS machine.

Nick and the students are using the GNSS equipment to create transects of points across the
northern side of the Paddock. The machine takes a point every 50cm and this data will eventually produce a virtual 3D image of the surveyed area. In addition to helping us decide where to dig next, this survey will help us to restore the Paddock surface to the level it was before we started.

The screen of the GNSS machine, showing an aerial view of the Paddock.

Nick says: "This is a way of collecting data really accurately and quickly, and it is good for the students to experience the on-site application of cutting edge technology." Nick will also be directing the students in undertaking a GPR (Ground Penetrating Radar) survey, as well as re-doing the magnetometry and resistivity surveys done in previous years. The GNSS survey should be finished soon, as will the GPR, magnetometry and resistivity surveys, and the resulting images will be shared once they have been processed.

- Emily Glass and Abbie O'Connell.