The gradiometer survey was carried out using Sensys MAGNETO� MXPDA ATV towed-cart magnetometer system (see Appendix 2). The Sensys cart utilises up to sixteen FGM650/3 fluxgate gradiometer sensors mounted upon a frame along with data logging equipment and batteries. Data was be collected using zig-zag traverses alongside a constant stream of GPS data collected through a Carlson BRx7 GPS, enabling the collected data to be spatially georeferenced without the need for a pre-determined grid system. The data and measured tracks were collected through the data acquisition unit MXPDA and visualised through a tablet PC in the ATV. Care was also be taken to attempt to avoid metal obstacles present within the survey area, such as metal objects within and adjacent to the survey area as gradiometer survey is affected by 'above-ground ferrous disturbance' and avoiding them improves the overall data quality and results obtained. The data was exported in ASCII file before being processed along with the GPS data in TerraSurveyor 64. Data processing, storage and documentation was carried out in accordance with the good practice specifications detailed in the guidelines issued by the Archaeology Data Service (Schmidt and Ernenwein, 2009). Interpretations of the data were created as shapefile layers in ArcGIS Pro. All geophysical survey work was carried out in accordance with recommended good practice specified in the EAC guideline documents published by Historic England (Schmidt et al. 2016) and the Chartered Institute for Archaeologists Standard and Guidance for archaeological geophysical survey (2014). The survey has succeeded in locating, recording and characterising surviving sub-surface remains within the Site, though more remains may be present that are not suitable for detection using magnetic gradiometry. The survey will help in determining the next stage of works as it has provided evidence that remains of possible archaeological, historical and uncertain origin are most likely present on site, and has provided a number of targets for further investigation; The survey has resulted in a comprehensive report and archive
Rob Legg (Wed,) studied this question.