The CSAT3 is a three-dimensional sonic anemometer that measures three orthogonal wind components and the speed of sound. In eddy covariance systems, it can measure the turbulent fluctuations of horizontal and vertical wind. These measurements are then used to calculate momentum flux and friction velocity. This sonic anemometer can also provide average horizontal wind speed and direction measurements. The CSAT3 comes with 25 ft cables.Read More
Whenever possible, use the CSAT3B (the CSAT3's replacement) instead.
The CSAT3 has a 10 cm vertical measurement path and operates in a pulsed acoustic mode. The three orthogonal wind components (ux, uy, uz) and the speed of sound (c) are measured and output at a maximum rate of 60 Hz. Analog outputs and two types of digital outputs are provided.
Measurements can be triggered from from the CSAT3’s internal clock, the PC-generated RS-232 command, or the datalogger’s SDM command. The SDM protocol supports a group trigger for synchronizing multiple CSAT3s.
The FW05 fine wire thermocouple (12.7 μm diameter) is available as an option for fast response temperature measurements.
|Measurement Path Length||
|Path Angle from Horizontal||60°|
|Construction||Sealed sonic transducers and electronics|
|Anemometer Head Materials||Stainless-steel tubing|
|Electronics Box Materials||Cast 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 datalogger/sensor communication. (Data type is 2-byte integer per output plus 2-byte diagnostic.)|
|Support Arms Diameter||1.59 cm (0.63 in.)|
|Transducer Diameter||0.64 cm (0.25 in.)|
|Transducer Mounting Fingers Diameter||0.84 cm (0.33 in.)|
|Cable Length||7.62 m (25 ft)|
|Anemometer Head Dimensions||47.3 x 42.4 cm (18.6 x 16.7 in.)|
|Anemometer Head Weight||1.7 kg (3.7 lb)|
|Electronics Box Dimensions||26 x 16 x 9 cm (10.24 x 6.3 x 3.54 in.)|
|Electronics Box Weight||3.8 kg (8.4 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.|
|Wind Direction Accuracy||±0.7° at 1 m/s (for horizontal wind)|
|Rain||Innovative ultrasonic signal processing and user-installable wicks considerably improve the performance of the anemometer under all rain events.|
Digital RS-232 Output Signal
|Baud Rate||9600, 19200 bps|
|Data Type||2-byte integer per output plus 2-byte diagnostic|
|Number of Outputs||4|
|Voltage Range||±5 V|
|Number of Bits||12|
SDM & RS-232 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).|
Analog Outputs Reporting Range
|ux||±30 m s-1, ±60 m s-1|
|uy||±30 m s-1, ±60 m s-1|
|uz||±8 m s-1|
|c||300 to 366 m s-1 (-50 to +60°C)|
Analog Outputs LSB
|ux||15 mm s-1, 30 mm s-1|
|uy||15 mm s-1, 30 mm s-1|
|uz||±8 m s-1|
|c||16 mm s-1 (0.026°C)|
|Datalogger Model||Datalogger Operating System (OS)
or PROMs Required
|CSAT3 OS Required|
|21X||1K 6145-3, 6146-5, 10006-1||2.1 or higher|
|21X||2K 6148-5, 6149-7, 6070-64||2.1 or higher|
|CR800, CR850||All OS||3.0 or higher|
4K is a Library Special
|2.1 or higher|
|CR10X||OS 1.4 or higher||2.1 or higher|
|CR1000||All OS||3.0 or higher|
|CR23X||All OS||2.1 or higher|
|CR3000||All OS||3.0 or higher|
|CR5000||All OS||3.0 or higher|
|CR9000||2.01 or higher||2.1 or higher|
|CR9000X||All OS||2.1 or higher|
Number of FAQs related to CSAT3: 26
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The CSAT3 has been optimized for most terrestrial applications. If the CSAT3 is to be used in a marine environment or in an environment where it is exposed to corrosive chemicals (for example, sulfur-containing compounds in viticulture), expect the sonic transducers to age more quickly and require replacement sooner than a unit deployed in an inland, chemical-free environment. If possible, mount the CSAT3 in a way that reduces exposure to saltwater spray/splash and/or corrosive chemicals.
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 datalogger or a PC.
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.
No. The CSAT3 is a sensor. Time stamps are assigned to the CSAT3 data by the data acquisition system—typically a Campbell Scientific datalogger or PC.
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.
Approximately 59.5 Hz.
Yes. The CSAT3 electronics contain unique calibration and sensor head geometry information. The sensor head and electronics are a matched set. (The serial number on the sensor head must match the electronics to make valid measurements.)
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.
The CSAT3 offset specification is ±8 cm/s. Therefore, it cannot be used in an application where the expected wind speed is in the range of ±5 cm/s.
The CSAT3 is compatible with three output signals: analog, RS-232, and Synchronous Device for Measurement (SDM). The CSAT3 can be interfaced to any data acquisition system that is compatible with analog measurements or RS-232 serial communications. SDM is used with Campbell Scientific dataloggers.