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Enabling better global research outcomes in soil, plant & environmental monitoring.

LSM Light Sensor Meter for Pyranometers

The Light Sensor Meter (LSM4) is a stand-alone data logging instrument for the measurement of global solar radiation and/or photosynthetically active radiation (PAR).

The LSM4 can support up to 5 sensors in total, including pyranometers, PAR and linear PAR sensors.


  • Climate and ecosystem modelling
  • Crop growth environment
  • Intercepted radiation within and beneath canopy
  • Photosynthetic activity within canopy and light use efficiency


  • Stand-alone, wireless data logging, low power requirement
  • Up to 5 sensor capacity
  • Solar radiation and/or PAR measurements
  • Automatic calculations of intercepted radiation by canopy
  • Flexible sensor calibration, look-up tables, and user scripts
  • IP-65 weather proof rated


The LSM4 is a stand-alone instrument and does not have extensive cabling and power requirements. All data is stored within the unit on a removable MicroSD card. Communication with the LSM4 is made either with a USB or wireless connection. Wireless is capable of a range of up to 250m.

The LSM4 has a Windows configuration software. The software is GUI based and extremely user-friendly. Custom calibration equations or data can be entered and edited via the software. Real-time measurements, diagnostics and sensor configuration can easily be made.

The LSM4 has 2 wire, non-polarised bus for power input. There is no chance of incorrect wiring of positive and negative voltage because the LSM4 is non-polarised.

The LSM4 has an internal lithium-polymer battery that is kept charged by an external power supply (solar panel or mains). The instrument has an internal voltage regulation for maximum power reliability.  The LSM4 is IP65 rated and has been demonstrated to operate in extreme environmental conditions.

Units are being used in diverse environments from hot Australian deserts, tropical Amazon rainforests, temperate German forests, Indian agricultural fields and North American Arctic cold.


Analogue Channels

5 differential





Minimum Logging Interval

1 second

Delayed Start

Suspend Logging, Customised Intervals

Sampling Frequency




USB, Wireless Radio Frequency 2.4 GHz

Data Storage

MicroSD Card, SD, SDHC & SDXC Compatible
(FAT32 Format)

Software Compatibility

Windows 8, 8.1, 10 and Mac OS X.

Data File Format

Comma Separated Values (CSV) format for compatibility with all software programs

Memory Capacity

Up to 16GB, 4GB microSD card included.


Temperature Range

-40°C to +80°C

R/H Range

0 -100%


User upgradeable firmware using USB bootstrap loader function


Internal Battery Specifications
960mAh Lithium Polymer, 4.20 Volts fully charged
External Power Requirements
Bus Power 8-30 Volts DC, non-polarised, current draw is 190mA maximum at 17 volts per logger
USB Power 5 Volts DC
Internal Charge Rate
Bus Power 60mA – 200mA Variable internal charge rate, maximum charge rate of 200mA active when the external voltage rises above 16 Volts DC
USB Power 100mA fixed charge rate
Internal Power Management
Fully Charged Battery 4.20 Volts
Low Power Mode 3.60 Volts – Instrument ceases to take measurements
Discharged Battery 2.90 Volts – Instrument automatically switches off at and below this voltage when no external power connected.
Battery Life varies
Example A: With a recommended solar panel and/or recommended power source connected, operation can be continuous.
Example B: Power consumption is dependent on number and type of sensors connected, frequency of measurement and measurement duration
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