INSTRUCTION MANUAL Q-7.1 Net Radiometer Revision: 5/96 C o p y r i g h t ( c ) 1 9 9 1 - 1 9 9 6 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The Q-7.1 NET RADIOMETER is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
Q-7.1 NET RADIOMETER The Q-7.1 is a high-output thermopile sensor which measures the algebraic sum of incoming and outgoing all-wave radiation (i.e. short-wave and long-wave components). Incoming radiation consists of direct (beam) and diffuse solar radiation plus long-wave irradiance from the sky. Outgoing radiation consists of reflected solar radiation plus the terrestrial long-wave component. 1.
Q-7.1 NET RADIOMETER 2.2 WIRING If a differential measurement is made, connect the red (+) lead to the high side (e.g. 1H) of any datalogger differential channel and the black (-) lead to the low side (e.g. 1L). Also, connect a jumper wire between the low channel and analog ground to prevent common mode errors. Connect the clear (shield) lead to ground (G on the CR10(X), ground on the 21X and CR7).
Q-7.1 NET RADIOMETER FIGURE 2. Correction Functions as a Function of Wind Speed The inverse of this data gives the required correction factors to give the correct reading as a function of wind speed (u). Figure 2 shows the manufacturer’s data plus correction curves fitted by Campbell Scientific, using functions which can be easily encoded in a datalogger.
Q-7.1 NET RADIOMETER 3.2 PROGRAMMING EXAMPLE WITH FIXED WIND SPEED CORRECTION The following CR10(X) program measures the output of a Q-7.1. A static wind correction is applied to each measurement. Example 1. CR10(X) Program with the Static Wind Speed Correction ;Measure the Q7.1.
Q-7.1 NET RADIOMETER 07: 08: Do (P86) 1: 1* 09: ;Negative calibration and wind ;speed corrections ; 10: Beginning of Subroutine (P85) 1: 2* Subroutine 2* Else (P94) ;Apply the negative calibration and ;wind speed correction. ; 09: Do (P86) 1: 2* Call Subroutine 2* 10: 11: End (P95) *Table 3 Subroutines 12: ;Positive calibration and wind ;speed correction. ; 01: Beginning of Subroutine (P85) 1: 1* Subroutine 1 02: Z=X*F (P37) 1: 1* 2: .
Q-7.1 NET RADIOMETER Inspect the silica gel monthly to ensure it is still blue and white. If the color changes to pink and white, replace it with dry silica gel (this may have to be done more frequently in wet weather). Wet (pink and white) silica gel can be dried by removing it from the desiccant tube and baking at 130°C until it returns to a blue and white color. Remove the desiccant tube end cap to remove and replace the silica gel.
Q-7.1 NET RADIOMETER 4.4 WINDSHIELD REPLACEMENT Polyethylene deteriorates with exposure to solar radiation. Inspect the windshields frequently and replace as required (probably every 3-6 months). Always check for: CAUTION: Do not attempt to dismantle the instrument body. If internal attention is needed, contact Campbell Scientific, Inc. for repair. If the windshields become dented, remove the dents as follows: 1. Condensation inside the windshields, possibly indicating a leak. 1.
Q-7.1 NET RADIOMETER recommends recalibration every six months, depending on the climate where the sensors are used. Each instrument is calibrated by the manufacturer in a temperature-controlled calibration chamber by comparison to a transfer standard. The chamber uses a combination of tungsten-halide source and black body chambers. The transfer standard is calibrated by comparison to a precision pyranometer using a partial shading technique developed by Radiation Energy Balance Systems.
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