User Manual

SPECIFICATIONS
Calibration Traceability
Apogee SQ 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
quartz halogen lamp traceable to the National Institute of Standards and Technology (NIST).
SQ--421
Input Voltage
Requirement
5.5 to 24 V DC
Current Drain
0.6 mA (quiescent), 1.3 mA (active)
Calibration Uncertainty
± 5 % (see Calibration Traceability below)
Measurement
Repeatability
Less than 1 %
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
410 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 (see Temperature Response below)
Operating Environment
-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions
44.0 mm height, 23.5 mm diameter
Mass
117 g (with 5 m cable)
Cable
5 m of two conductor, shielded, twisted-pair wire; TPR jacket (high water resistance, high UV
stability, flexibility in cold conditions); pigtail lead wires; stainless steel (316), M8 connector
located 25 cm from sensor head