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Help & Support for TEManalyze

Selecting the right TEM system for a specific task can be challenging. Model resolution and depth of investigation (DOI) depend not only on system configuration, but also on background noise levels and the subsurface resistivity structure. TEManalyze brings all these parameters together, helping users make informed decisions before going to the field.

With TEManalyze, users can identify the most suitable TEM system and configuration, determine optimal stacking time, and evaluate achievable resolution and DOI using only basic knowledge of expected layer resistivities and thicknesses.

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TEManalyze guide

Your guide to configuring and using TEManalyze efficiently before field measurements.

Quick start guide

Follow these steps to perform an analysis in TEManalyze:

  1. Define the geological model
    Enter the resistivity and thickness of each expected subsurface layer.

  2. Select a TEM system
    Choose from supported TEMcompany systems (sTEM, tTEM, TEM2Go).

  3. Choose inversion type
    Select whether the inversion should emphasize a Smooth (L2-norm) or Blocky (L1-norm) model.

  4. Set noise level and stacking time
    Adjust expected noise conditions and measurement duration.

  5. Click Analyze
    After a few seconds, TEManalyze displays the input model, inversion results, and calculated DOI.

Key terminology

TEManalyze uses a nonlinear optimization algorithm, commonly referred to in geophysics as an inversion algorithm. The inversion considers:

  • The geological model (layer resistivity and thickness)

  • TEM system parameters (coil size, power, separation, waveform, filtering)

  • Model smoothness (regularization)

  • Noise level and stacking time

Some parameters may be uncertain prior to fieldwork. By adjusting layer properties or noise levels, users can quickly explore achievable resolution and how sensitive results are to changing conditions.

To keep the analysis focused, TEManalyze supports systems within the TEMcompany product family and allows variation of noise level and stacking time.

Modelling details

The effective noise level depends on both the TEM system and the stacking time. It is used to estimate data uncertainty, determine which data points are included in the inversion, and calculate DOI.

Initial noise levels (at 1 ms) are defined as:

  • Low (⅓ × Normal): 3.3–9 V/m²

  • Normal: 1.0–8 V/m²

  • High (3 × Normal): 3.0–8 V/m²

Noise decreases proportionally to t-0.5.

, characteristic of random noise in logarithmic gating schemes.

The stack size is calculated from the stacking time and repetition period and is shown in the System/Modeling Information panel.

Normal Stack Times by System

  • sTEM (20×20, 40×40, 80×80): 5 min

  • sTEM Profiler: 30 s

  • tTEM (221, 331, 333, 443): 5 s

  • TEM2Go: 10 s

Users may select:

  • Short stacking (¼ × Normal): higher effective noise

  • Long stacking (4 × Normal): lower effective noise

Data error bars

Data uncertainties are calculated using the effective noise level, signal-to-noise ratio, and an additional uniform uncertainty of 3%. Data points with uncertainty greater than 30% are automatically excluded from the inversion.

Inversion

Users can choose between:

  • Smooth model (L2-norm) — suitable for gradual resistivity variations

  • Blocky model (L1-norm) — suitable for sharp layer boundaries

The inversion considers:

  • Non-excluded data and uncertainties

  • System setup (geometry, waveform, filters)

  • A 1D multilayer model (up to 30 layers) with vertical constraints

Inversion Output

  • Resistivity model

  • Depth of Investigation (DOI)

  • Data misfit

A misfit < 1 indicates a fit within data uncertainties. If the forward response cannot be fitted adequately, a warning is shown when misfit exceeds 1.5.

Depth of Investigation (DOI)

The displayed DOI is calculated based on:

  • Selected TEM system

  • Noise level and data uncertainties

  • Smooth or blocky inversion result

This provides a realistic estimate of how deeply and reliably the system can image the subsurface.

Inversion & Modeling Code

TEManalyze uses the Lupus TEM inversion code for forward modeling, inversion, and DOI calculations. The DOI methodology follows:

Christiansen, A. V. & Auken, E. (2012). A global measure for depth of investigation.
Geophysics, 77(4).

Advanced settings

Default program settings are stored in:

TEManalyze_settings.json
typically located at: C:\Program Files\TEMcompany\TEManalyze\

This file includes settings such as:

  • Fwr_NoiseLevel_SingleTransient – initial noise level

  • InstrumentType_StackTime – normal stack time per instrument

Advanced users may modify these settings to customize analysis behavior.

Your questions answered

A customer asking a question about an sTEM geophysical scanner.

What is TEManalyze used for?

TEManalyze is designed to help users choose the optimal TEM system, configuration, and stacking time before performing field measurements. By modeling expected geological conditions, it predicts achievable resolution and depth of investigation (DOI).

Do I need detailed geological knowledge to use TEManalyze?

No. Users only need a basic estimate of expected layer resistivities and layer thicknesses. TEManalyze handles the forward modeling, noise simulation, and inversion internally.

How does TEManalyze calculate DOI?

The software computes DOI using the inversion results, noise level, data uncertainties, and system properties. It relies on the established DOI methodology implemented in the Lupus TEM inversion code.

What is the difference between Smooth and Blocky inversion?

A Smooth (L2-norm) inversion is ideal for gradual subsurface transitions, while a Blocky (L1-norm) inversion highlights sharper boundaries. TEManalyze allows users to choose the model type that best matches their expectations.

If you still have questions or need further guidance, our support team is here to help.
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