Sensors

Settings — Sensors

The Sensors settings section configures the behaviour of each connected sensor. Navigate to Settings → Sensors to open it.

It is divided into four tabs: Gamma, Spectral, GPS, and PTH.

Gamma

The Gamma tab configures the hardware settings of the gamma spectrometer.

Setting	Description
Gain	(Only visible for systems that use silicon photomultiplier) The gain applied to the analog signal coming out of the detector. The default value is unique to each detector and set by Medusa before shipping.
High voltage	(Only visible for systems that use photmultiplier tubes (PMT)) The high voltage applied to the PMT. The default value is unique to each detector and set by Medusa before shipping.
Interval	How often the spectrometer measures a spectrum. Options: 5 Hz, 2 Hz, 1 Hz, 0.5 Hz, 0.1 Hz.
Use custom interval	When enabled, a custom measurement interval can be entered in milliseconds (200–300,000 ms).
Channels	The number of channels in the measured spectrum. Options: 256, 512, 1024, 2048. Default is 512.

Warning: The gamma spectrometer is carefully calibrated before leaving the Medusa office. Only change these settings if you have a specific reason to do so. Incorrect gain settings can result in poor or incomplete spectra.

Note: Short measurement intervals fill storage much faster. For most surveys, 1 Hz is sufficient.

Click Save to apply changes.

Spectral

The Spectral tab configures how spectrometer data is processed and which calibration files are used.

Managing MCF Files

Click Manage MCF files to open a dialog for uploading or deleting MCF files stored on the detector. The maximum file size for uploading is 1 MB. Deleting an MCF file cannot be undone.

MCF Stabilization and Calibration Files

Setting	Description
MCF Stabilization file	The MCF file used for energy stabilization. Click the [ICON: info] button to view its contents.
MCF Calibration file	The MCF file used for spectral analysis and calculating radionuclide concentrations. Click the [ICON: info] button to view its contents.

MCF files are detector-specific and cannot be used on a different sensor. See Viewing the Spectrum — The Calibration File for a description of the MCF contents viewer.

Active Nuclides

Selects which nuclides are included in the spectral analysis. The available nuclides depend on the active MCF Calibration file. Active nuclides determine which concentrations are shown on the Spectrum page, included in sample measurements, and written to the Concentrations CSV on download.

Fit Mode

Mode	Description
Full Spectrum Analysis (FSA)	Fits standard spectra to the measured data. Default mode.
NNLS Full Spectrum Analysis	Same as FSA, but only includes standard spectra that result in a positive concentration. Useful when negative concentrations are undesirable — see Troubleshooting.
Windows Analysis	Uses fixed energy windows to determine concentrations.

Spectra to Sum

The number of spectra accumulated before one analysis result is calculated. Increasing this value reduces uncertainty in individual data points but coarsens the spatial resolution of the measurement — each data point then represents a longer time interval.

Note: The number of spectra to sum is independent of the gamma-ray measurement interval. If the measurement interval is changed, review the spectra-to-sum setting to maintain the desired output frequency of analyzed records.

Display Units

The unit used to display radionuclide concentrations in the interface.

Unit	Notes
Bq/kg	SI unit for activity concentration
ppm	Parts per million. Conversions: 1% ⁴⁰K = 313 Bq/kg; 1 ppm ²³⁸U = 12.4 Bq/kg; 1 ppm ²³²Th = 4.1 Bq/kg
ppm of oxides	As above, expressed as oxide equivalents

Note: Display units only affect what is shown in the interface. Data stored on the detector is always in Bq/kg.

Click Save to apply changes.

GPS

The GPS tab configures the GPS sensor.

Setting	Description
Enable GPS	Enables or disables the GPS sensor.
GPS Interval	How often the GPS records a position. Options: 2 Hz, 1 Hz, 0.50 Hz, 0.25 Hz, 0.10 Hz.

Click Save to apply changes.

PTH

The PTH tab configures the pressure, temperature, and humidity sensor.

Setting	Description
Enable PTH	Enables or disables the PTH sensor.
PTH Interval	How often the PTH sensor records a measurement. Options: 2 Hz, 1 Hz, 0.50 Hz, 0.25 Hz, 0.10 Hz.

Click Save to apply changes.