The CSAT3A 3-D Sonic Anemometer is the 3-D sonic anemometer of choice for eddy-covariance measurements. It has an aerodynamic design, a 10 cm vertical measurement path, operates in a pulsed acoustic mode, and withstands exposure to harsh weather conditions. Three orthogonal wind components (ux, uy, uz) and the speed of sound (c) are measured and output at a maximum rate of 50 Hz. The CSAT3A head is operated by the EC100 electronics, which also control either an EC150 or EC155 gas analyzer.
Measurements can be triggered from two sources:
The SDM protocol supports a group trigger for synchronizing multiple CSAT3As.Read More
|Measurement Path Length||
|Path Angle from Horizontal||60°|
|Construction||Sealed sonic transducers and electronics|
|Anemometer Head Materials||Stainless-steel tubing|
|Electronics Box Materials||Welded aluminum|
|Operating Temperature Range||-30° to +50°C|
|Voltage Supply||10 to 16 Vdc|
|Digital SDM Output Signal||CSI 33.3 k baud serial interface for data logger/sensor communication. (Data type is 2-byte integer per output plus 2-byte diagnostic.)|
|Support Arm Diameter||1.59 cm (0.63 in.)|
|Transducer Diameter||0.64 cm (0.25 in.)|
|Transducer Mounting Arm Diameter||0.84 cm (0.33 in.)|
|Anemometer Head Dimensions||47.3 x 42.4 cm (18.6 x 16.7 in.)|
|Anemometer Head Weight||1.7 kg (3.7 lb)|
ux, uy, uz, c
(ux, uy, uz are wind components referenced to the anemometer axes; c is speed of sound.)
|Speed of Sound||Determined from three acoustic paths; corrected for crosswind effects.|
|Measurement Rate||Programmable from 1 to 60 Hz, instantaneous measurements. Two over-sampled modes are block averaged to either 20 Hz or 10 Hz.|
|Output Bandwidths||5, 10, 12.5, or 20 Hz|
|Output Rate||10, 20, 25, or 50 Hz|
|Rain||Innovative ultrasonic signal processing and user-installable wicks considerably improve the performance of the anemometer under all rain events.|
Digital USB and RS-485 Output Signal
|Baud Rate||230400 bps (maximum)|
|Data Type||Comma-delimited ASCII|
SDM, USB, & RS-485 Digital Outputs Reporting Range
|Full-Scale Wind||±65.535 m/s autoranging between four ranges (Least significant bit is 0.25 to 2 mm/s.)|
|Speed of Sound||300 to 366 m/s (-50° to +60°C) Least significant bit is 1 mm/s (0.002°C).|
Number of FAQs related to CSAT3A: 23
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No. The CSAT3 does not report time with the wind measurements. A time stamp will be assigned to the wind data by the data acquisition system—either a data logger or a PC.
No. The offset is a function of temperature and time. Once a year, spot-check the CSAT3 wind offset using the procedure outlined in the CSAT3 instruction manual. If the measured offset is outside the specification, return the CSAT3 to the factory for calibration. To request a returned material authorization (RMA) number, follow the steps listed on our Repair and Calibration page.
Campbell Scientific does not offer any mounting booms or hardware that enable easy and frequent positioning of the CSAT3 sensor head. This type of hardware must be provided by the user.
The CSAT3 measures three-dimensional wind in a right-handed Cartesian coordinate system. From these measurements, use trigonometry to compute the wind flow angle, horizontal angle, and wind speed.
The CSAT3, like other sonic anemometers, measures wind speed along the sonic path using ultrasonic signals. If the salt spray blocks the sonic path, the CSAT3 will not be able to make measurements. The same is true if a thick layer of salt is deposited on the transducer faces.
Ultrasonic anemometers are unable to make measurements if the sonic path is blocked. The path may become blocked by water that puddles on the lower transducer face or droplets that hang from the upper transducers.
The CSAT3 calibration applies a correction for transducer delay over temperature. Transducer delays cause an offset in the wind speed measurement, and to a lesser extent, an offset in the speed of sound measurement.
The CSAT3 speed of sound easement is corrected for the effects of wind blowing normal to the sonic path.
Approximately 59.5 Hz.
Yes. The CSAT3 measurement frequency can be changed by the user. It is set by the Execution Parameter. This parameter is described in detail in the CSAT3 instruction manual in the “Datalogger Instruction Parameters” section, as well as in the “CSAT3 RS-232 Commands” section of Appendix B.
The CSAT3 is calibrated over the temperature range of -30° to +50°C. The CSAT3 operating temperature range can be shifted by 10 degrees to cover the range of -40° to +40°C.
The instrument will continue to operate outside the calibrated temperature range; however, the proper calibration will not be applied to the measurements because it does not exist in the CSAT3 electronics.