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Related Manuals for Apogee Instruments SQ-421
Summary of Contents for Apogee Instruments SQ-421
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Page 1: Owner's Manual
OWNER’S MANUAL QUANTUM SENSOR Model SQ-421 Rev: 28-Oct-2020 APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM Copyright © 2020 Apogee Instruments, Inc. -
Page 2: Table Of Contents
TABLE OF CONTENTS Owner’s Manual ....................................1 Certificate of Compliance ................................. 3 Introduction ..................................... 4 Sensor Models ..................................5 Specifications ................................... 6 Deployment and Installation ..............................9 Cable Connectors ................................... 10 Operation and Measurement ..............................11 Maintenance and Recalibration ............................. 21 Troubleshooting and Customer Support .......................... -
Page 3: Certificate Of Compliance
RoHS 3 compliant using exemption 6c. Further note that Apogee Instruments does not specifically run any analysis on our raw materials or end products for the presence of these substances, but rely on the information provided to us by our material suppliers. -
Page 4: Introduction
(transmitted) PPFD measurement in the same environments. Apogee Instruments SQ series quantum sensors consist of a cast acrylic diffuser (filter), photodiode, and signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor to a measurement device. -
Page 5: Sensor Models
SENSOR MODELS This manual covers the SDI-12 communication protocol, original quantum sensor model SQ-421. Additional models are covered in their respective manuals. Model Signal Calibration SQ-421 SDI-12 Sunlight and Electric light SQ-110 Self-powered Sunlight SQ-120 Self-powered Electric light SQ-311 Self-powered... -
Page 6: Specifications
SPECIFICATIONS SQ--421 Input Voltage 5.5 to 24 V DC Requirement Current Drain 1.4 mA (quiescent), 1.8 mA (active) Calibration Uncertainty ± 5 % (see Calibration Traceability below) Measurement Less than 1 % Repeatability Long-term Drift Less than 2 % per year (Non-stability) Non-linearity Less than 1 % (up to 4000 µmol m... - Page 7 Spectral Response Mean spectral response of six SQ-100 series quantum sensors (error bars represent two standard deviations above and below mean) compared to defined plant response to photons. Spectral response measurements were made at 10 nm increments across a wavelength range of 300 to 800 nm with a monochromator and an attached electric light source.
- Page 8 Cosine Response Directional (cosine) response is defined as the measurement error at a specific angle of radiation incidence. Error for Apogee SQ-100 series quantum sensors is approximately ± 2 % and ± 5 % at solar zenith angles of 45° and 75°, respectively.
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Page 9: Deployment And Installation
Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure PPFD incident on a horizontal surface, the sensor must be level. An Apogee Instruments model AL-100 Leveling Plate is recommended to level the sensor when used on a flat surface or being mounted to surfaces such as wood. To facilitate mounting on a mast or pipe, the Apogee Instruments model AL-120 Solar Mounting Bracket with Leveling Plate is recommended. -
Page 10: Cable Connectors
CABLE CONNECTORS Apogee sensors offer cable connectors to simplify the process of removing sensors from weather stations for calibration (the entire cable does not have to be removed from the station and shipped with the sensor). The ruggedized M8 connectors are rated IP68, made of corrosion-resistant marine-grade stainless-steel, and designed for extended use in harsh Cable connectors are attached directly to the head. -
Page 11: Operation And Measurement
OPERATION AND MEASUREMENT The SQ-421 quantum sensor has a SDI-12 output, where shortwave radiation is returned in digital format. Measurement of SQ-421 quantum sensors requires a measurement device with SDI-12 functionality that includes the M or C command. VERY IMPORTANT: Apogee changed the wiring colors of all our bare-lead sensors in March 2018 in conjunction with the release of inline cable connectors on some sensors. - Page 12 “!”. SDI-12 language supports a variety of commands. Supported commands for the Apogee Instruments SQ-421 quantum sensors are listed in the following table (“a” is the sensor address. The following ASCII Characters are valid addresses: “0-9” or “A-Z”).
- Page 13 Command Response Response to 0D0! aM! or aM0! a0011<cr><If> Returns µmol m using electric light calibration aM1! a0011<cr><If> Returns millivolt output aM2! a0011<cr><If> Returns µmol m using sunlight calibration aM3! a0011<cr><If> Returns immersed µmol m for underwater measurements with electric light calibration aM4! a0011<cr><If>...
- Page 14 where a is the sensor address (“0-9”, “A-Z”, “a-z”, “*”, “?”) and C is an upper-case ASCII character. For example (0 is the address): Command Sensor Response 0C0! 000101<cr><lf> 0D0! 0+2000.0<cr><lf> 0C1! 000101<cr><If> 0D0! 0+400.0<cr><If> 0C2! 000101<cr><lf> 0D0! 0+2000.0<cr><lf> 0C3! 000101<cr><If>...
- Page 15 Metadata Commands Identify Measurement Commands The Identify Measurement Commands can be used to view the command response without making a measurement. The command response indicates the time it takes to make the measurement and the number of data values that it returns. It works with the Verification Command (aV!), Measurement Commands (aM!, aM1! … aM9!, aMC!, aMC1! …...
- Page 16 Sunlight and Electric light Calibration Apogee SQ-421 quantum sensors are calibrated to measure PPFD for both sunlight and electric light. The difference between the calibrations is 12 %. The electric light calibration (calibration source is T5 cool white fluorescent lamps) will read approximately 12 % low in sunlight.
- Page 17 Spectral Error The combination of diffuser transmittance, interference filter transmittance, and photodetector sensitivity yields spectral response of a quantum sensor. A perfect photodetector/filter/diffuser combination would exactly match the defined plant photosynthetic response to photons (equal weighting to all photons between 400 and 700 nm, no weighting of photons outside this range), but this is challenging in practice.
- Page 18 Yield Photon Flux Density (YPFD) Measurements Photosynthesis in plants does not respond equally to all photons. Relative quantum yield (plant photosynthetic efficiency) is dependent on wavelength (green line in figure below) (McCree, 1972a; Inada, 1976). This is due to the combination of spectral absorptivity of plant leaves (absorptivity is higher for blue and red photons than green photons) and absorption by non-photosynthetic pigments.
- Page 19 Correlation between photosynthetic photon flux density (PPFD) and yield photon flux density (YPFD) for multiple different radiation sources. YPFD is approximately 90 % of PPFD. Measurements were made with a spectroradiometer (Apogee Instruments model PS-200) and weighting factors shown in the previous figure were used to calculate PPFD and YPFD.
- Page 20 Immersion Effect Correction Factor When a radiation sensor is submerged in water, more of the incident radiation is backscattered out of the diffuser than when the sensor is in air (Smith, 1969; Tyler and Smith, 1970). This phenomenon is caused by the difference in the refractive index for air (1.00) and water (1.33), and is called the immersion effect.
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Page 21: Maintenance And Recalibration
3. Salt deposit accumulation from evaporation of sea spray or sprinkler irrigation water. Apogee Instruments upward-looking sensors have a domed diffuser and housing for improved self-cleaning from rainfall, but active cleaning may be necessary. Dust or organic deposits are best removed using water, or window cleaner, and a soft cloth or cotton swab. - Page 22 Homepage of the Clear Sky Calculator. Two calculators are available: one for quantum sensors (PPFD) and one for pyranometers (total shortwave radiation). Clear Sky Calculator for quantum sensors. Site data are input in blue cells in middle of page and an estimate of PPFD is returned on right-hand side of page.
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Page 23: Troubleshooting And Customer Support
TROUBLESHOOTING AND CUSTOMER SUPPORT Independent Verification of Functionality If the sensor does not communicate with the datalogger, use an ammeter to check the current draw. It should be near 1.4 mA when the sensor is not communicating and spike to approximately 1.8 mA when the sensor is communicating. -
Page 24: Return And Warranty Policy
RETURN AND WARRANTY POLICY RETURN POLICY Apogee Instruments will accept returns within 30 days of purchase as long as the product is in new condition (to be determined by Apogee). Returns are subject to a 10 % restocking fee. WARRANTY POLICY... - Page 25 84321, USA 5. Upon receipt, Apogee Instruments will determine the cause of failure. If the product is found to be defective in terms of operation to the published specifications due to a failure of product materials or craftsmanship, Apogee Instruments will repair or replace the items free of charge.
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