em38 translates *.n38 binary files generated by the Geonics EM38-MKII ground conductivity meter, commonly used in soil research and precision agriculture. EM38 devices are supported by an official translation app called DAT38MK2, but this lacks a command-line interface and is not easy to use in a reproducible workflow. This package can output a decoded *.M38-formatted text file as described in the EM38-MKII's manual, or an
sf point spatial object.
Install from github with
This package is in early development phase. Improving its reliability requires access to a wide variety of test datasets, so if you have an *.n38 file that fails to decode correctly, please consider sending it to me. I have been able to test decoding on around 50 sample files from two different EM38-MKII devices, but could always use more. The device and its logger have a large number of possible setting combinations, and I have not seen all of them. Additionally, a third-party GPS needs to be attached to the device and its data-logger, and GPS output data are notoriously variable by brand and model.
em38 is accompanied by a demo dataset:
library(em38) # all-in-one wrapper function: em38_sf <- n38_to_points(path = system.file("extdata", "em38_demo.n38", package = "em38"), hdop_filter = 3, out_mode = 'Vertical') # Plot spatialised output (calibrated conductivity for coil separation 0.5m) plot(em38_sf['cond_05'], pch = 20)
Its surprisingly difficult to walk in a straight line across a paddock :no_mouth:
If you want to look at the intermediate data more closely,
# import binary file as raw() type matrix n38_mat <- n38_import(system.file("extdata", "em38_demo.n38", package = "em38")) # break matrix into sections according to file spec n38_chunks <- n38_chunk(n38_mat) # decode matrix chunks into useable data n38_decoded <- n38_decode(n38_chunks) # output an m38 file (comparable to official decode) m38_example <- n38_to_m38(n38_decoded) # write to file as e.g. write(m38_example, paste0('m38_from_R_', Sys.Date(), '.m38')) # spatialise the decoded data em38_sf <- em38_spatial(n38_decoded, hdop_filter = 3, out_mode = 'Vertical')
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