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Summary of Contents for Apogee SQ-421X
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Page 1: Owner's Manual
OWNER’S MANUAL QUANTUM SENSOR Model SQ-421X Rev: 30-Aug-2022 APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA TEL: (435) 792-4700 | FAX: (435) 787-8268 | WEB: APOGEEINSTRUMENTS.COM Copyright © 2022 Apogee Instruments, Inc. -
Page 2: Table Of Contents
TABLE OF CONTENTS Owner’s Manual ....................................1 Certificates of Compliance ............................... 3 Introduction ..................................... 5 Sensor Models ..................................6 Specifications ................................... 7 Deployment and Installation ..............................10 Cable Connectors ................................... 11 Operation and Measurement ..............................11 Maintenance and Recalibration ............................. 19 Troubleshooting and Customer Support .......................... -
Page 3: Certificates 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 we rely on the information provided to us by our material suppliers. - Page 4 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 we rely on the information provided to us by our material suppliers.
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Page 5: Introduction
(transmitted) PPFD measurement in the same environments. Apogee Instruments SQ-421X-SS quantum sensors consist of a cast acrylic diffuser (filter), interference filter, photodiode, and signal processing circuitry mounted in an anodized aluminum housing, and a cable to connect the sensor to a measurement device. -
Page 6: Sensor Models
SENSOR MODELS This manual covers the SDI-12 communication protocol, quantum sensor model SQ-421X. Additional models are covered in their respective manuals. Model Signal SQ-421X SDI-12 SQ-100X Self-powered SQ-202X 0-2.5 V SQ-204X 4-20 mA SQ-205X 0-5 V SQ-420X SQ-422X ModBus A sensor’s model number and serial number are located on the bottom of the sensor. -
Page 7: Specifications
(316), M8 connector Calibration Traceability Apogee SQX series quantum sensors are calibrated through side-by-side comparison to the mean of transfer standard quantum sensors under a reference lamp. The reference quantum sensors are recalibrated with a 200 W... - Page 8 Spectral Response Mean spectral response of four SQ-100x series quantum sensors compared to PPFD weighting function. Spectral response measurements were made at 10 nm increments across a wavelength range of 350 to 800 nm in a monochromator with an attached electric light source. Measured spectral data from each quantum sensor were normalized by the measured spectral response of the...
- Page 9 Cosine Response Directional (cosine) response is defined as the measurement error at a specific angle of radiation incidence. Error for Apogee SQ- 100x series quantum sensors is approximately ± 2 % and ± 5 % at solar zenith angles of 45° and 75°, respectively.
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Page 10: 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 11: 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, Cable connectors are attached directly to the head. -
Page 12: Operation And Measurement
OPERATION AND MEASUREMENT The SQ-421X quantum sensor has a SDI-12 output, where shortwave radiation is returned in digital format. Measurement of SQ-421X quantum sensors requires a measurement device with SDI-12 functionality that includes the M or C command. Wiring for SQ-421X... - Page 13 SDI-12 Interface The following is a brief explanation of the serial digital interface SDI-12 protocol instructions used in Apogee SQ- 421X quantum sensors. For questions on the implementation of this protocol, please refer to the official version of the SDI-12 protocol: http://www.sdi-12.org/specification.php...
- Page 14 Make Measurement Command: M! The make measurement command signals a measurement sequence to be performed. Data values generated in response to this command are stored in the sensor's buffer for subsequent collection using “D” commands. Data will be retained in sensor storage until another “M”, “C”, or “V” command is executed.
- Page 15 Concurrent Measurement Command: aC! A concurrent measurement is one which occurs while other SDI-12 sensors on the bus are also making measurements. This command is similar to the “aM!” command, however, the nn field has an extra digit and the sensor does not issue a service request when it has completed the measurement.
- Page 16 Change Sensor Address: aAb! The change sensor address command allows the sensor address to be changed. If multiple SDI-12 devices are on the same bus, each device will require a unique SDI-12 address. For example, two SDI-12 sensors with the factory address of 0 requires changing the address on one of the sensors to a non-zero value in order for both sensors to communicate properly on the same channel: Command...
- Page 17 The weighting function for PPFD is shown in the graph below, along with the spectral response of Apogee SQ-100X series quantum sensors. The closer the spectral response matches the defined PPFD spectral weighting functions, the smaller spectral errors will be.
- Page 18 Spectral Errors for PPFD Measurements with Apogee SQ-100X Series Quantum Sensors Radiation Source (Error Calculated Relative to Sun, Clear Sky) PPFD Error [%] Sun (Clear Sky) Sun (Cloudy Sky) Reflected from Grass Canopy Reflected from Deciduous Canopy Reflected from Conifer Canopy...
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Page 19: Maintenance And Recalibration
Never use abrasive material or cleaner on the diffuser. Although Apogee sensors are very stable, nominal calibration drift is normal for all research-grade sensors. To ensure maximum accuracy, recalibration every two years is recommended. Longer time periods between recalibration may be warranted depending on tolerances. - Page 20 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 21: Troubleshooting And Customer Support
SDI-12 protocol limits cable length to 60 meters. For multiple sensors connected to the same data line, the maximum is 600 meters of total cable (e.g., ten sensors with 60 meters of cable per sensor). See Apogee webpage for details on how to extend sensor cable length (http://www.apogeeinstruments.com/how-to-make-a-... -
Page 22: 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 23 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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