DOI: 10.5281/zenodo.18230064
title: Data sets of electromagnetic responses to the passage of four objects measured using an EM38-MK2 (three bottles filled with magnetite powder and an aluminum plate).
title: Jeux de données des réponses électromagnétiques au passage de quatre objets mesurés à l'aide d'un EM38-MK2 (trois bidons remplis de poudre de magnétite et une plaque d'aluminium).

description: This dataset consists of four files sharing identical column structures. Each file corresponds to measurements acquired from a different object:





B05L (Ø 0.084 × 0.14 m): data acquired by passing a 0.5 L bottle filled with magnetite powder.




B1L (Ø 0.102 × 0.18 m): data acquired by passing a 1 L bottle filled with magnetite powder.




B2L (0.205 × 0.109 × 0.096 m): data acquired by passing a 2 L bottle filled with magnetite powder.




Aluminum: data acquired by passing an aluminum plate (0.489 × 0.441 × 0.004 m) above the instrument.



All files contain the same variables and are directly comparable.

Method of acquisition : 

The objective of this experiment was to measure the electromagnetic response of various objects placed in a resistive environment. Each object was moved within a vertical plane aligned with the longitudinal axis of the instrument.

To minimize environmental effects, the objects were suspended in air above a calcareous substrate characterized by low electrical conductivity and low magnetic susceptibility. This configuration provides controlled conditions that are particularly relevant for near-surface archaeological applications.

A scaffold made of cellular concrete blocks supported a wooden beam, along which the objects were moved using a sledge. Each concrete block measured 0.31 × 0.25 × 0.05 m, resulting in a regular profile spacing of 0.05 m. Object positions were recorded using a Trimble S8 total station at a sampling frequency of up to 20 Hz. A 360° prism was mounted directly above the center of each object. The minimum distance between the object and the instrument was constrained by the combined thickness of the wooden beam and the sledge.

The Python code (Graph_generator_code.py) was used to generate the graphs shown in the article currently under review. 

Column explanation : 

The dataset includes the following columns:





index: measurement index.




x, y, z: original object coordinates prior to transformation into the instrument reference frame.




CH1.0, IH1.0, CH0.5, IH0.5: raw electromagnetic measurements, where





CH corresponds to the quadrature (conductivity-related) component,




IH corresponds to the in-phase component,




1.0 and 0.5 indicate coil spacings of 1.0 m and 0.5 m, respectively.






profil: profile number, with 1 corresponding to the profile farthest from the instrument.




IH1.0_regre, IH0.5_regre, CH1.0_regre, CH0.5_regre: background-corrected data obtained by subtracting an environmental signal.The background signal was estimated using a linear regression fitted to measurements at both ends of each profile, where the object response was no longer detectable. The low regression slope (< 0.03) indicates a stable background. This correction compensates for instrumental drift, particularly in the in-phase components, and normalizes the data. A corrected value of zero thus represents the expected signal in the absence of an object-induced response.




x_rotated, y_rotated, z_rotated: coordinates expressed in the instrument reference frame, where (0, 0, 0) corresponds to the top center of the instrument.




sens: direction of object displacement along the profile. Each profile was measured twice to assess repeatability:





–1: left-to-right movement




1: right-to-left movement