CMD – Single or Multi-depth  Electromagnetic Conductivity Measurements for: Engineering, Geotechnical, Shallow Groundwater, Agriculture and Environmental)

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Overview

Technical specifications

Downloads

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Key strength: These Conductivity measurement mappers have the ability to measure either Single-depth or Multiple-depth variations. This unique possibility of acquiring multi-depth measurements in one survey explains the popularity of these instruments, versatility and superiority above all competition products  in this class.

• Multi-depth profiling and mapping (0.15 – 60 m)
• Standard or custom-made probes (1 or 3 or 6 receivers)
• Fast sampling (up to 10 Hz), high temperature stability
• One control unit for all probes (B/W or colour display)
• Simple operation, optional smartphone app
• Manual and continuous measuring modes with GPS
• Two Bluetooth channels (for probe and external GPS)
• Real-time clock, map preview of area coverage
• Data download via USB or flash disk
• Rechargeable Li-Ion battery lasts for 2-3 working days
• Lightweight and rugged design

Applications:

Geological and geotechnical survey, agriculture, archaeology, groundwater protection, environmental monitoring, raw material prospecting, metal object and network detection.

Large family of CMD electromagnetic conductivity meters is designed for survey depth ranges from 0.15 to 60 m. Used contactless method allows fast measurement of conductivity and inphase under all field conditions (including very dry and icy ground). Probes are equipped with 1, 3 or 6 receivers with excellent temperature stability. This way makes high resolution depth graded mapping as well as imaging of sections possible and useful for wide range of walking and moving applications.

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CMD-MiniExplorer: three-depth probe with depth ranges 0.5 / 0.25 m, 1.0 / 0.5 m, 1.8 / 0.9 m for archaeology, agriculture and civil engineering, allowing immediate judgement of vertical conductivity gradient.

CMD-Explorer: three-depth probe with depth ranges 2.2 / 1.1 m, 4.2 / 2.1 m, 6.7 / 3.3 m for extra wide range of applications with evaluation of vertical and horizontal conductivity changes.

CMD-MiniExplorer 6L: six-depth probe with depth ranges 0.3 / 0.15 m, 0.5 / 0.25 m, 0.8 / 0.4 m, 1.1 / 0.5 m, 1.6 / 0.8 m, 2.3 / 1.1 m for high resolution mapping and section imaging.

CMD-explorer 6L: six-depth probe with depth ranges 0.9 / 0.45 m, 1.6 / 0.8 m, 2.4 / 1.2 m, 3.7 / 1.85 m, 5.0 / 2.5 m, 6.3 / 3.15 m for high resolution mapping and section imaging.

CMD-Tiny: single-depth probe with 0.7 / 0.35 m depth range for assessment of very shallow objects in the frame of civil engineering, agriculture and archaeology.

CMD-1: economy single-depth probe with 1.5 / 0.75 m depth range for archeology, agriculture and buried metal object detection.

CMD-2: single-depth probe with 3.0 / 1.5 m depth range frequently used for assessment of corrosivity risk at pipeline construction and for geologic judgement of construction sites.

CMD-4: single-depth probe with 6.0 / 3.0 m depth range with wide sphere of applications (geological survey, mapping of pollution plumes, raw material prospecting). s

CMD-4/6: single-depth probe with variable depth range 6.0 / 3.0 m or 9.0 /4.5 m for similar purposes like CMD-4 with significantly enhanced survey depth.

CMD-DUO: single-depth, two-men operated probe with variable depth range 15 / 7.5 m or 30 / 15 m or 60 / 30 m for measurement of deeper situated structures (weathered zones, bedrock, cavities).

CMD control unit

Selection guide for Electromagnetics

We offer two series of frequency domain instruments for conductivity and inphase measurement:

• CMD-Explorer with triple or sextuple simultaneously working electromagnetic system.
• CMD with single electromagnetic system.

	C M D – E x p l o r e r			C M D
	Explorer	MiniExplorer	Mini Explorer 6L	CMD-4/6	CMD-4	CMD-2	CMD-1	CMD-Tiny
Multidepth measurement	✔	✔	✔	−	−	−	−	−
In-situ EM inversion	✔	✔	−	−	−	−	−	−
Selectable arm length	−	−	−	✔	−	−	−	−
Manual and continuous measurement	✔	✔	✔	✔	✔	✔	✔	✔
GPS connectivity	✔	✔	✔	✔	✔	✔	✔	✔
Map preview	✔	✔	✔	✔	✔	✔	✔	✔
Selectable calibration for 0 m / 1 m	✔	−	−	✔	✔	✔	−	−
Export for EM inversion	✔	✔	✔	−	−	−	−	−
Export for mapping	✔	✔	✔	✔	✔	✔	✔	✔
Graphic display	✔	✔	✔	✔	✔	✔	✔	✔
Bluetooth connection as standard feature	−	✔	✔	−	−	−	✔	✔
Rechargeable / alkaline cells	✔	✔	✔	✔	✔	✔	✔	✔
For details see Technical specifications.

Electromagnetics – Frequently Asked Questions

• –  What is CMD Instrument?

• It is an electromagnetic conductivity meter (EM instrument working at a low induction number) providing calibrated values of apparent conductivity as well as inphase quantity measured with the specified depth range. (Not to be confused with electromagnetic ppt meters working in a wide range of induction numbers without specified depth range.)

• • Is CMD multifrequency instrument?

  No, it is a multidepth, frequency domain instrument. The selection of working frequency is connected with linearity of the calibration curve according to the distance of magnetic dipoles. To understand it see

Short guide for electromagnetics

• on these web sites.
  • What is the orientation of magnetic dipoles?
  CMD contains one or more coplanar sensors. This system provides mutual consistency of their individual depth ranges based on the same shape of antenna diagrams. Thus an easier possibility of EM inversion is achieved.

• • Compatibility of control units with probes
  CMD control unit can operate all single depth and multidepth CMD probes allowing firmware upgrade via internet.

• • EM inversion tools
  The choice of commercially available software for EM inversion is currently extremely poor. There is only a limited family of 1D EM inversion SW (as IX1D by Interpex) and no available 2D and 3D tool for EM inversion. Given the circumstances we have found a useful replacement for EM 2D and 3D inversions made by 2D and 3D inversion SW for DC methods. In addition, CMD is equipped with 1D in-situ EM inversion which converts individual multidepth measurements into 2 layered model (upper layer and bottom layer conductivities and depth of their border).

• • Depth ranges and method of calibration
  Each CMD probe has two depth ranges – high depth range with vertical orientation of magnetic dipoles and low depth range with horizontal orientation of magnetic dipoles. A separate calibration for each orientation of the probe is provided.

• • Are the CMDs water resistant?
  CMD probes are not submersible and are not designed to be exposed to heavy rains, unless covered with special protection.

• • How often should I recalibrate my CMD probe?
  – These are recommended recalibration periods for CMDs:
  – CMD-DUO, CMD-4/6, CMD 4, CMD 2: 10 years
  – CMD Explorer, CMD Mini Explorer, CMD 1: 5 years
  – CMD Tiny, CMD Mini Explorer 6L, special multidepth instruments: 3 years
  –  For occasional check or a case of probe damage, we recommend to establish your own check measurement point.