APOGEE SQ-647 Quantum Light Pollution Sensor Owner’s Manual

OWNER’S MANUAL
QUANTUM LIGHT POLLUTION
SENSOR

Model SQ-647
Rev: 28-Oct-2020

CERTIFICATE OF COMPLIANCE

EU Declaration of Conformity
This declaration of conformity is issued under the sole responsibility of the manufacturer:
Apogee Instruments, Inc.
721 W 1800 N
Logan, Utah 84321
USA

for the following product(s):
Models: SQ-647
Type: Extended Range PFD Sensor
The object of the declaration described above is in conformity with the relevant Union harmonization legislation:

2014/30/EU Electromagnetic Compatibility (EMC) Directive
2011/65/EU Restriction of Hazardous Substances (RoHS 2) Directive
2015/863/EU Amending Annex II to Directive 2011/65/EU (RoHS 3)

Standards referenced during compliance assessment:

EN 61326-1:2013 Electrical equipment for measurement, control, and laboratory use – EMC requirements
EN 50581:2012 Technical documentation for the assessment of electrical and electronic products with respect to the restriction of hazardous substances
Please be advised that based on the information available to us from our raw material suppliers, the products manufactured by us do not contain, as intentional additives, any of the restricted materials including lead (see note below), mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB), polybrominated biphenyls (PBDE), bis(2-Ethylhexyl) phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), and diisobutyl phthalate (DIBP). However, please note that articles containing greater than 0.1% lead concentration are 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. Signed for and on behalf of Apogee Instruments, January 2021

Bruce Bugbee
President
Apogee Instruments, Inc.

INTRODUCTION

Radiation that drives photosynthesis is called photosynthetically active radiation (PAR) and is typically defined as total radiation across a range of 400 to 700 nm. PAR is almost universally quantified as photosynthetic photon flux density (PPFD) in units of micromoles per square meter per second (µmol m-²s-¹, equal to microEinsteins per square meter per second) summed from 400 to 700 nm (total number of photons from 400 to 700 nm). However, ultraviolet and far-red photons outside the defined PAR range of 400-700 nm can also contribute to photosynthesis and influence plant responses (e.g., flowering).
Sensors that measure PPFD are often called quantum sensors due to the quantized nature of radiation. A quantum refers to the minimum quantity of radiation, one photon, involved in physical interactions (e.g., absorption by photosynthetic pigments). In other words, one photon is a single quantum of radiation. Sensors that function like traditional quantum sensors, but measure a wider range of wavelengths can be thought of as an ‘extended range’ quantum sensor.

Typical applications of traditional quantum sensors include incoming PPFD measurement over plant canopies in outdoor environments or in greenhouses and growth chambers and reflected or under-canopy (transmitted) PPFD measurement in the same environments. The Extended Range PFD Sensor detailed in this manual uses a detector that is sensitive to radiation up to about 1100 nm, well beyond the range of wavelengths that influence photosynthesis and plant responses. This means this particular sensor should only be used for photon flux density measurements under LEDs.
Apogee Instruments SQ-600 series Quantum Light Pollution 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. SQ-600 series sensors are designed for continuous photon flux density measurements in indoor environments under LEDs. The SQ-640 Quantum Light Pollution models output a voltage that is directly proportional to photon flux density. The SQ-647 sensors output a digital signal using the SDI-12 communication protocol.

SENSOR MODELS

This manual covers the digital model SQ-647 SDI-12 Quantum Light Pollution Sensor (in bold below). Additional models are covered in their respective manuals.

The sensor model number and serial number are located on the bottom of the sensor. If the manufacturing date of a specific sensor is required, please contact Apogee Instruments with the serial number of the sensor.

SPECIFICATIONS

| SQ-647-SS
---|---
Input Voltage| 5.5 to 24 V DC
Current Draw| 1.4 mA (quiescent), 1.8 mA (active)
Calibration Uncertainty| ± 5 % (see Calibration Traceability below)
Measurement Range| 0 to 200 µmol m-2 s-1
Measurement Repeatability| Less than 0.5 %
Calibrated Output Range| 0 to 200 mV
Long-term Drift (Non-stability)| Less than 2 % per year
Non-linearity| Less than 1 % (up to 4000 µmol m-2 s-1)
Response Time| 0.6 s, time for detector signal to reach 95 % following a step change; fastest data transmission rate for SDI-12 circuitry is 1 s
Field of View| 180°
Spectral Range| 340 to 1040 nm ± 5 nm (wavelengths where the response is greater than 50 %; see Spectral Response below)
Directional (Cosine) Response| ± 2 % at 45° zenith angle, ± 5 % at 75° zenith angle (see Directional Response below)
Azimuth Error| Less than 0.5 %
Tilt Error| Less than 0.5 %
Temperature Response| -0.11 ± 0.04 % per C
Uncertainty in Daily Total| Less than 5 %
Housing| Anodized aluminum body with acrylic diffuser
IP Rating| IP68
Operating Environment| -40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions| 30.5 mm diameter, 37 mm height
Mass (with 5 m of cable)| 140 g
Cable| 5 m of two-conductor, shielded, twisted-pair wire; TPR jacket; pigtail lead wires; stainless steel (316), M8 connector

Calibration Traceability
Apogee Instruments SQ-600 series quantum light pollution sensors are calibrated through side-by-side comparison to the mean of four transfer standard quantum light pollution sensors under a reference lamp. The transfer standard quantum light pollution sensors are recalibrated with a quartz halogen lamp traceable to the National Institute of Standards and Technology (NIST).

Spectral Response

Mean spectral response measurements of six replicate Apogee SQ-600 series Extended Range PFD Sensors. Spectral response measurements were made at 10 nm increments across a wavelength range of 300 to 1100 nm in a monochromator with an attached electric light source. Measured spectral data from each PFD sensor were normalized by the measured spectral response of the monochromator/electric light combination, which was measured with a spectroradiometer

Cosine Response

Directional, or cosine, the response is defined as the measurement error at a specific angle of radiation incidence. Error for Apogee SQ-600 series Extended Range PFD Sensor is approximately ± 2 % and ± 5 % at solar zenith angles of 45° and 75°, respectively.

DEPLOYMENT AND INSTALLATION

Mount the sensor to a solid surface with the nylon mounting screw provided. To accurately measure photon flux density incident on a horizontal surface, the sensor must be level. An Apogee Instruments model AL-100 leveling plate is recommended for this purpose. To facilitate mounting on a cross arm, an Apogee Instruments model AL120 mounting bracket is recommended.

To minimize azimuth error, the sensor should be mounted with the cable pointing toward true north in the northern hemisphere or true south in the southern hemisphere. Azimuth error is typically less than 0.5 %, but it is easy to minimize by proper cable orientation.

In addition to orienting the cable to point toward the nearest pole, the sensor should also be mounted such that obstructions (e.g., weather station tripod/tower or other instrumentation) do not shade the sensor. Once mounted, the blue cap should be removed from the sensor. The blue cap can be used as a protective covering for the sensor when it is not in use.

CABLE CONNECTORS

Apogee started offering cable connectors on some bare-lead sensors in March 2018 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 environmental conditions.

Instructions
Pins and Wiring Colors: All Apogee connectors have six pins, but not all pins are used for every sensor. There may also be unused wire colors inside the cable. To simplify the datalogger connection, we remove the unused pigtail lead colors at the datalogger end of the cable.

If a replacement cable is required, please contact Apogee directly to ensure ordering the proper pigtail configuration.

Alignment: When reconnecting a sensor, arrows on the connector jacket and an aligning notch ensure proper orientation.
Disconnection for extended periods: When disconnecting the sensor for an extended period of time from a station, protect the remaining half of the connector still on the station from water and dirt with electrical tape or another method.
Tightening: Connectors are designed to be firmly finger-tightened only. There is an o-ring inside the connector that can be overly compressed if a wrench is used. Pay attention to thread alignment to avoid cross-threading. When fully tightened, 1-2 threads may still be visible.
WARNING: Do not tighten the connector by twisting the black cable or sensor head, only twist the metal connector (yellow arrows).

OPERATION AND MEASUREMENT

The SQ-647 quantum light pollution sensor has an SDI-12 output, where photosynthetically active radiation is returned in digital format. Measurement of SQ-647 quantum light pollution sensors requires a measurement device with SDI-12 functionality that includes the M or C command.

Wiring

Sensor Calibration
All Apogee SDI-12 quantum light pollution sensor models (SQ-600 series) have sensor-specific calibration coefficients determined during the custom calibration process. Coefficients are programmed into the microcontrollers at the factory.

SDI-12 Interface
The following is a brief explanation of the serial digital interface SDI-12 protocol instructions used in Apogee SQ427 quantum light pollution 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 (version 1.4, August 10, 2016).

Overview
During normal communication, the data recorder sends a packet of data to the sensor that consists of an address and a command. Then, the sensor sends a response. In the following descriptions, SDI-12 commands and responses are enclosed in quotes. The SDI-12 address and the command/response terminators are defined as follows:

Sensors come from the factory with the address of “0” for use in single sensor systems. Addresses “1 to 9” and “A to Z”, or “a to z”, can be used for additional sensors connected to the same SDI-12 bus.

“!” is the last character of a command instruction. In order to be compliant with SDI-12 protocol, all commands must be terminated with a “!”. SDI-12 language supports a variety of commands. Supported commands for the Apogee Instruments SQ-627 Extended Range PFD sensors are listed in the following table (“a” is the sensor address. The following ASCII Characters are valid addresses: “0-9” or “A-Z”).

Supported Commands for Apogee Instruments SQ-647 Quantum Light Pollution Sensors

the line
Send Identification Command| aI!| Responds with sensor information
Measurement Command| aM!| Tells the sensor to take a measurement
Measurement Command w/ Check Character| aMC!| Tells the sensor to take a measurement and return it with a check character
Change Address Command| aAb!| Changes the sensor address from a to b
Concurrent Measurement Command| aC!| Used to take a measurement when more than one sensor is used on the same data line
Concurrent Measurement Command w/ Check Character| aCC!| Used to take a measurement when more than one sensor is used on the same data line. Data is returned with a check character.
Address Query Command| ?!| Used when the address is unknown to have the sensor identify its address, all sensors on data line respond
Get Data Command| aD0!| Retrieves the data from a sensor
Verification Command| **** aV!| Returns sensor coefficients as multiplier, offset, solar multiplier, and immersion effect correction factor
Running Average Command| aXAVG!| Returns or sets the running average for sensor measurements.

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. M commands are shown in the following examples:

if pointed up, 180 degrees if pointed down.) Available in sensors with serial number 3033 or greater.
aMC! or aMC0!| a0011| Returns µmol m-2 s-1 w/CRC
aMC1!| a0011| Returns millivolt output w/ CRC
aMC2!| a0011| Returns µmol m-2 s-1 w/ CRC
aMC3!| a0011| Returns immersed µmol m-2 s-1 for underwater measurements w/ CRC
aMC4!| a0011| Returns angle offset from vertical in degrees w/CRC. (0 degrees if pointed up, 180 degrees if pointed down.) Available in sensors with serial numbers 3033 or greater.

where a is the sensor address (“0-9”, “A-Z”, “a-z”) and M is an upper-case ASCII character.
The data values are separated by the sign “+”, as in the following example (0 is the address):

where 2000.0 is µmol m-2 s-1.

Concurrent Measurement Command: aC!
A concurrent measurement is one that 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. Communicating with other sensors will NOT abort a concurrent measurement. Data values generated in response to this command are stored in the sensor’s buffer for subsequent collection using “D” commands. The data will be retained in the sensor until another “M”, “C”, or “V” command is executed:

measurements
aC4!| a00101| Returns angle offset from vertical in degrees. (0 degrees if pointed up, 180 degrees if pointed down.) Available in sensors with serial number 3033 or greater.
aCC! or aCC0!| a00101| Returns µmol m-2 s-1 w/CRC
aCC1!| a00101| Returns millivolt output w/ CRC
aCC2!| a00101| Returns µmol m-2 s-1 w/ CRC
aCC3!| a00101| Returns immersed µmol m-2 s-1 for underwater measurements w/ CRC
aCC4!| a00101| Returns angle offset from vertical in degrees w/CRC. (0 degrees if pointed up, 180 degrees if pointed down.) Available in sensors with serial numbers 3033 or greater.

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):

where 2000.0 is µmol m-2 s-1 and 400.0 is mV.

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 require 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:

where a is the current (old) sensor address (“0-9”, “A-Z”), A is an upper-case ASCII character denoting the instruction for changing the address, b is the new sensor address to be programmed (“0-9”, “A-Z”), and ! is the standard character to execute the command. If the address change is successful, the datalogger will respond with the new address and a .

Send Identification Command: aI!

The send identification command responds with sensor vendor, model, and version data. Any measurement data in the sensor’s buffer is not disturbed:

identifying values are returned

where a is the sensor address (“0-9”, “A-Z”, “a-z”, “*”, “?”), 521 is the sensor model number, vvv is a three-character field specifying the sensor version number, and xx…xx is the serial number.

Running Average Command

The running average command can be used to set or query the number of measurements that are averaged together before returning a value from an M! or MC! command. For example, if a user sends the command “0XAVG10!” to the sensor with address 0, that sensor will average 10 measurements before sending the averaged value to the logger. To turn off the average, the user should send the command “aXAVG1” to the sensor. To query the sensor to see how many measurements are being averaged, send the command “aXAVG!” and the sensor will return the number of measurements being averaged (see table below). The default for sensors is to have averaging turned off.

measurements used in the average calculation. Note: n may be multiple digits.
Set running Average| aXAVGn!| a| a = sensor address, n = number of measurements to be used in the average calculation. Note: n may be any value from 1 to 100.

Low Light Measurements
Accurate low light measurements are required in flowering and light pollution studies. Research indicates flowering can be triggered in some plants at photosynthetic and/or far-red photon flux densities less than 0.1 l_tmol rn-2 s-1. The threshold photon flux density at which flowering is triggered is variable among species. Two of the most light-sensitive species are Poinsettias and Cannabis. For reference, the photon flux density of moonlight when the moon is full and near the minimum zenith angle is 0.005!Arno! ril-2 S-¹.
The model SQ-620 Extended Range Quantum Sensor can measure a photon flux density range of 0-4000 vol m-2 s-1. The model SQ-640 Quantum Light Pollution Sensor is designed for low light measurements and can only measure a photon flux density range of 0-200!Arno! m-2 s-1(the sensor will output values beyond, 200 pmol m-2 s , but these are beyond the linear range of the sensor), and is referred to as the low light version. The sensitivity of the SQ-640 is twenty times higher than the sensitivity of the SQ-620 (1 mV per µr101 rr1-2 s-1 versus 0.05 mV per l_tmol rr1-2 S-1) to provide greater measurement resolution under low light conditions. For example, if the photon flux density were 0.1 µM01 rr1-2s-1, the SQ-640 would output 0.1 mV, whereas the SQ-620 would output 0.005 mV.

MAINTENANCE AND RECALIBRATION

Blocking of the optical path between the target and detector can cause low readings. Occasionally, accumulated materials on the diffuser of the upward- looking sensor can block the optical path in three common ways:

1. Moisture or debris on the diffuser.
2. Dust during periods of low rainfall.
3. Salt deposit accumulation from the 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. Salt deposits should be dissolved with vinegar and removed with a cloth or cotton swab. Salt deposits cannot be removed with solvents such as alcohol or acetone. Use only gentle pressure when cleaning the diffuser with a cotton swab or soft cloth to avoid scratching the outer surface. The solvent should be allowed to do the cleaning, not mechanical force. Never use abrasive material or cleaner on the diffuser.
It is recommended that two-band radiometers be recalibrated every two years. See the Apogee webpage for details regarding the return of sensors for recalibration (http://www.apogeeinstruments.com/tech-supportrecalibration- repairs/).

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. Any current drain greater than approximately 6 mA indicates a problem with the power supply to the sensors, wiring of the sensor, or sensor electronics.

Compatible Measurement Devices (Dataloggers/Controllers/Meters)
Any datalogger or meter with SDI-12 functionality that includes the M or C command.
An example datalogger program for Campbell Scientific dataloggers can be found on the Apogee webpage at https://www.apogeeinstruments.com/content/Quantum- Digital.CR1.

Modifying Cable Length
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 the Apogee webpage for details on how to extend sensor cable length (http://www.apogeeinstruments.com/how-to-make-aweatherproof-cable-splice/).

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
What is Covered
All products manufactured by Apogee Instruments are warranted to be free from defects in materials and craftsmanship for a period of four (4) years from the date of shipment from our factory. To be considered for warranty coverage an item must be evaluated by Apogee.
Products not manufactured by Apogee (spectroradiometers, chlorophyll content meters, EE08-SS probes) are covered for a period of one (1) year.

What is Not Covered
The customer is responsible for all costs associated with the removal, reinstallation, and shipping of suspected warranty items to our factory. The warranty does not cover equipment that has been damaged due to the following conditions:

1. Improper installation or abuse.
2. Operation of the instrument outside of its specified operating range.
3. Natural occurrences such as lightning, fire, etc.
4. Unauthorized modification.
5. Improper or unauthorized repair.

Please note that nominal accuracy drift is normal over time. Routine recalibration of sensors/meters is considered part of proper maintenance and is not covered under warranty.

Who is Covered
This warranty covers the original purchaser of the product or other party who may own it during the warranty period.
What Apogee Will Do
At no charge Apogee will:

1. Either repair or replace (at our discretion) the item under warranty.
2. Ship the item back to the customer by the carrier of our choice.

Different or expedited shipping methods will be at the customer’s expense.

How To Return An Item

1. Please do not send any products back to Apogee Instruments until you have received a Return Merchandise Authorization (RMA) number from our technical support department by submitting an online RMA form at www.apogeeinstruments.com/tech-support-recalibration-repairs/. We will use your RMA number for tracking of the
   service item. Call 435-245-8012 or email techsupport@apogeeinstruments.com with questions.

2. For warranty evaluations, send all RMA sensors and meters back in the following condition: Clean the sensor’s exterior and cord. Do not modify the sensors or wires, including splicing, cutting wire leads, etc. If a connector has been attached to the cable end, please include the mating connector – otherwise, the sensor connector will be removed in order to complete the repair/recalibration.
   Note: When sending back sensors for routine calibration that have Apogee’s standard stainless-steel connectors, you only need to send the sensor with the 30 cm section of cable and one-half of the connector. We have mating connectors at our factory that can be used for calibrating the sensor.

3. Please write the RMA number on the outside of the shipping container.

4. Return the item with freight pre-paid and fully insured to our factory address shown below. We are not responsible for any costs associated with the transportation of products across international borders.
   Apogee Instruments, Inc.
   721 West 1800 North Logan, UT
   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. If it is determined that your product is not covered under warranty, you will be informed and given an estimated repair/replacement cost.

PRODUCTS BEYOND THE WARRANTY PERIOD
For issues with sensors beyond the warranty period, please contact Apogee at techsupport@apogeeinstruments.com to discuss repair or replacement options.

OTHER TERMS
The available remedy of defects under this warranty is for the repair or replacement of the original product, and Apogee Instruments is not responsible for any direct, indirect, incidental, or consequential damages, including but not limited to loss of income, loss of revenue, loss of profit, loss of data, loss of wages, loss of time, loss of sales, accruement of debts or expenses, injury to personal property, or injury to any person or any other type of damage or loss.
This limited warranty and any disputes arising out of or in connection with this limited warranty (“Disputes”) shall be governed by the laws of the State of Utah, USA, excluding conflicts of law principles and excluding the Convention for the International Sale of Goods. The courts located in the State of Utah, USA, shall have exclusive jurisdiction over any Disputes.
This limited warranty gives you specific legal rights, and you may also have other rights, which vary from state to state and jurisdiction to jurisdiction, and which shall not be affected by this limited warranty. This warranty extends only to you and cannot be transferred or assigned. If any provision of this limited warranty is unlawful, void or unenforceable, that provision shall be deemed severable and shall not affect any remaining provisions. In case of any inconsistency between the English and other versions of this limited warranty, the English version shall prevail.

This warranty cannot be changed, assumed, or amended by any other person or agreement

APOGEE INSTRUMENTS, INC. | 721 WEST 1800 NORTH, LOGAN, UTAH 84321, USA
TEL: 435-792-4700 | FAX: 435-787-8268 | WEB: APOGEEINSTRUMENTS.COM
Copyright © 2021 Apogee Instruments, Inc.

References

• How to Make a Weatherproof Cable Splice
• Recalibration and Repair | Apogee Instruments
• SDI-12 Specification
• apogeeinstruments.com/content/Quantum-Digital.CR1

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