The EM38-4 provides measurement of both the quad-phase (conductivity) and in-phase (magnetic susceptibility) components within four distinct depth ranges, all simultaneously, without any requirement for soil-to-instrument contact. With a maximum effective depth of exploration of 1.5 m, applications in agriculture, archaeology and general soil sciences are common.

The EM38-4 includes four receiver coils, separated by 1 m, 0.88 m, 0.75 m and 0.5 m from the transmitter, providing data from effective depth ranges of 1.5 m, 1.3 m, 1.1 m and 0.75 m respectively when positioned in the vertical dipole orientation, and 0.75 m, 0.66 m, 0.57 m and 0.37 m respectively when in the horizontal dipole orientation.

Data from multiple depth ranges supports a more complete characterization of the soil profile through inverse modelling of data. Software included with the instrument provides two-layer modelling of the profile both in real-time and during data processing.

An external, lightweight rechargeable battery pack supports daily survey operations; a power input connector facilitates the use of alternate external power sources.

An optional, collapsible calibration stand facilitates a semi-automated calibration procedure; using the stand, the instrument can be calibrated within a few seconds without requirement for iterative adjustments.



Technical Specifications

Power source
12 V external battery

Operating temperature
-40°C to + 50°C

Instrument: 133 x 17 x 8 cm
Shipping: 140 x 25 x 15 cm

Instrument: 9 kg
Shipping: 20 kg

Manufacturer : GEONICS LTD (Canada).


Measured quantities
1: Apparent conductivity in millisiemens per metre (mS/m)
2: In-phase ratio of the secondary to primary magnetic field in parts per thousand (ppt)

Intercoil spacing :
0.5, 0.75, 0.88 and 1 m

Operating frequency:
14.5 KHz

Measuring range :
Conductivity: 0 to 1000 mS/m
In-phase: ± 28 ppt for 1 m, ± 22 ppt for 0.88 m, ± 16 for 0.75 m ; ± 7 for 0.5 m

Measurement resolution :

± 0.1 % of full scale

Measurement accuracy :
± 5 % at 30 mS/m

Noise levels
Conductivity: 0.5 mS/m at 1 m separation
In-phase: 0.02 ppt at 1 m separation

Data output : RS-232 serial port, Bluetooth, USB