RM Frobisher (1986) Ltd

Downloads, Product Information and Further Reading

Product Information Leaflets

RRM Pro Cart System (340kB)
RM Frobisher’s Non-Magnetic Cart with Four Sensys FGM650 sensors
RM Frobisher (1986) Ltd Insert (150kB)
RM Frobisher (1986) Ltd. Company information and current products
DFG-1 Magnetic Gradiometer Leaflet (600kB)
DFG-1 Magnetic Gradiometer Sensor Unit (dual fluxgate gradiometer)
TAR-3 Resistance Meter Leaflet (50kB)
TAR-3 Resistance Meter System
TAR-3 Resistance Meter Accessories (184kB)
Expand your TAR Resistance Meter system with a Pseudosection Kit or Wenner Array cross bar
Using the DFG-1 Magnetic Gradiometer (520kB)
A brief summary of using the DFG-1 Magnetic Gradiometer in Yorkshire.



Result Conversion Software
RM Frobisher have a collection of web based software that can be accessed over the internet to convert your results from measured resistance (Ra in Ohms (Ω)) to resistivity (Rσ in Ohm.m (Ω.m)). These are internet based and run on RM Frobisher’s server – you can access them over the internet and do not have to install them. Please contact us for details on how to access them.

You can now convert TAR-3 data files into ‘Insite’ data files using our online conversion programme.

You can also convert TAR-3 'BIN' or 'SWP' binary data files to TAR3DATA.TXT ASCII text files using our online conversion software.

We have an online tool to rotate the grid data in your TAR3DATA.TXT so you can convert grids started at different corners (and traversed in different directions) to a standard, consistent orientation and direction.

Our online tools can also convert your TAR3DATA.TXT grids into 'XYZ' format.

We also have 'cloud based' software to accompany our DFG-1 Magnetic Gradiometer system.

Snuffler Geophysics Software
You can download Free Geophysics Software here (opens a new window or tab)
Geotomo Software’s RES2DINV
The RES2DINVx32/x64 program uses the smoothness-constrained Gauss-Newton least-squares method inversion technique to produce a 2D model of the subsurface from the apparent resistivity data. It can be downloaded from Geotomo Software’s Website

TerraSurveyor from DW Consulting
Specifically designed to meet the needs of Archaeological and Near Surface Geophysicists, TerraSurveyor is a complete package for downloading, assembling, enhancing, publishing and saving the geophysical data from a range of instruments. You can find our more On their website


Product Manuals

DFG-1 Magnetic Gradiometer Manual (1MB)
A PDF copy of the manual for the current software version
TAR-3 Resistance Meter Manual (1.5MB)
A PDF copy of the manual for the current software version
TAR-3 Resistance Meter – RS232 GNSS Data Logging Manual
The TAR-3 Meter can be upgraded with an additional PCB with an isolated RS323 port for NMEA 0138 data logging or serial data from other GNSS equipment.

Application Notes (html files)

RM Frobisher (1986) Ltd TAR-3 Array Bar (Wenner and 1.5m Twin Probe)
Information on how to attach and setup the TAR-3 Array Bar
Application Note: Analysing TAR-3 Resistance Meter Results.html
How to Import TAR-3 data files into Snuffler and grid numbering conventions
Application Note: SD Cards, Files and File System
How to format the SD card and what files are stored on the SD card.
Application Note: TAR-3 Results File
A guide to the TAR-3 Resistance Meter Results File – what it contains and how it is formatted.
Application Note: Batteries and Charging
A guide to the DFG-1 Magnetic Gradiometer and TAR-3 Resistance Meter’s batteries and how to charge them
Using the TAR-3 Resistance Meter with the Wenner Array Bar
Using the TAR-3 System with the extension bar and Wenner array bar


Our Products in Use

The TAR-3 Resistance Meter in use (See page 9)
The Friends of Croome have used their TAR-3 in the grounds of Croome Park. They completed 68 grids, their results are in their Spring 2019 (Issue 30) news letter (PDF download). You can find out more about the Friends of Croome Here
Medieval Village of Rowley – Resistance Survey
Bradford on Avon Museum surveyed 49 grids at the medieval village of Rowley (five weeks in August and September, 2020).


Reading List

Seeing Beneath the Soil: Prospecting Methods in Archaeology
Clark, O.A., Clark, A., 9781134611201, 2003, Taylor & Francis.
Revealing the Buried Past: Geophysics for Archaeologists
Gaffney, C.F., Gater, J., 9780752425566, Revealing history, 2003, Tempus.
Earth Resistance for Archaeologists (Geophysical Methods for Archaeology)
Schmidt, A., 0759112045, Geophysical methods for archaeology, 2013, AltaMira Press.
Magnetometry for Archaeologists (Geophysical Methods for Archaeology)
Aspinall, A., Gaffney, C., and Schmidt, A., 0759113483, AltaMira Press (January 16, 2009).
A Field Guide to Geophysics in Archaeology
Oswin, J., 9783540766919 Springer‐Praxis, Chichester, UK 2009.
EAC GUIDELINES 2 978-963-9911-73-4, Europae Archaeologia Consilium (EAC), 2015. All RM Frobisher (1986) Ltd’s products meet the requirements of these guidelines
Wenner, F
A copy of Frank Wenner’s original article : A method of Measuring Earth Resistivity, in the Bulletin of the Bureau of Standards, 1916
GPS for Land Surveyors
Van Sickle, J., 9781466583108, Geophysical methods for archaeology, 14 July 2015, CRC Press; 4 edition.

Press Information

TAR-3 High Resolution Images (png)
High resolutuion images of the TAR-3 System are Here, 26MB zipped file

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