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

SQ-420 Smart Quantum Sensor

The SQ-420 sensor can be connected to a desktop, laptop, or tablet computer via USB 2.0 type A plug, to be used with the Apogee software. The included Apogee software gives the user control of data logging and calibration settings, as well as providing a real time output display and graph of PPFD measurements, and also allowing the data set to be saved as a csv file.
The SQ-420 is a stand-alone PAR sensor/datalogger with 10,000 measurement internal data storage that can be uploaded to a computer. If continuously connected, the software graphs real-time PPFD.

The SQ-420 is used to measure incoming and reflected PPFD around plants and other organisms in outdoor environments, greenhouses, growth chambers, and underwater.

Internal Data Storage
The sensor has internal data storage with the ability to hold up to 10,000 measurements. This allows the sensor to collect data while connected to a stand-alone 5 Volt DC power supply such as an independent USB battery pack or USB wall adapter.

No External Datalogger Required. apogee_sq_420_2__02006.1444667650.1280.1280
Independent Calibration
The SQ-420 is calibrated independently for sunlight and electric light to improve measurement accuracy. The light source calibration can be selected in the settings menu of the Apogee software.
Resolution: 0.1 µmol m-2 s-1
Calibration Factor: Custom for each sensor and stored in the firmware
Calibration Uncertainty: ±5% (see Calibration Traceability below)
Measurement Repeatability: Less than 1%
Non-stability (Long-term Drift): Less than 2% per year.
Non-linearity: Less than 1% (up to 3000 µmol m-2 s-1)
Response Time: Software updates every second.
Field of View: 180°
Spectral Range: 410 nm to 655 nm (wavelengths where response is greater than 50% of maximum; see Spectral Response below)
Directional (Cosine) Response: ±5% at 75° zenith angle (see Cosine Response below)
Temperature Response: 0.06 ± 0.06% per °C
Operating Environment: -40 to 70°C, 0 to 100% relative humidity; Can be submerged in water up to depths of 30m
Dimensions: 2.4cm diameter and 2.8cm height
Mass: Sensor head weighs 90g
USB Cable: 4.6m (15 ft)
Current Draw (when Logging): 0.35mA
Warranty: 4 years

The versatile SQ-420 can be used two ways – it can be connected directly to a computer for real-time measurements and data logging using the provided software, or it can be connected to a standard USB power source and act as a stand-alone datalogger capable of storing 10,000 periodic measurements internally that can be downloaded to a computer later for analysis.

Apogee Instruments Quantum Sensors consist of a cast acrylic diffuser (filter), photodiode, and signal processing circuitry mounted in an anodised aluminium housing, and a cable to connect the sensor to a measurement device. The sensor is potted solid with no internal air space. It is designed for continuous PPFD measurement in indoor, outdoor, and underwater environments. The SQ-420 sensor output increases linearly with PPFD under sunlight (natural setting) or electric lights (electric setting). The signal from the sensor is directly proportional to radiation incident on a flat surface where the radiation comes from all angles of a hemisphere.