RETIRED ›
This product is no longer available and has been replaced by: CSAT3B. Some accessories, replacement parts, or services may still be available.
CSAT3 3D Sonic Anemometer
Services Available
Repair Yes
Calibration Yes
Free Support Yes

Overview

The CSAT3 is a three-dimensional (3D) 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 7.6 M cables.

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Benefits and Features

  • Provides precision turbulence measurements with minimal flow distortion
  • FW05 fine wire thermocouple (12.7 μm diameter) is available as an option for fast response temperature measurements
  • Withstands exposure to harsh weather conditions
  • Measurements can be used to calculate momentum flux and friction velocity
  • Compatible with most Campbell Scientific data loggers

Images

Technical Description

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.

Specifications

Measurement Path Length
  • 10.0 cm (3.94 in.) vertical
  • 5.8 cm (2.28 in.) horizontal
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
Current
  • 200 mA (60 Hz measurement rate)
  • 100 mA (20 Hz measurement rate)
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 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)

Measurements
Outputs 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.
Measurement Resolution
  • Resolution values are for instantaneous measurements made on a constant signal; noise is not affected by sample rate.
  • 1 mm/s rms (ux, uy)
  • 0.5 mm/s rms (uz)
  • 15 mm/s (0.025°C) rms (c)
  • 0.06° rms (wind direction)
Offset Error
  • Offset error and gain error values assume the -30° to +50°C range, wind speeds of < 30 m/s, and wind angles between ±170°.
  • < ±8.0 cm/s (ux, uy)
  • < ±4.0 cm/s (uz)
Gain Error
  • Offset error and gain error values assume the -30° to +50°C range, wind speeds of < 30 m/s, and wind angles between ±170°.
  • < ±2% of reading (wind vector within ±5° of horizontal)
  • < ±3% of reading (wind vector within ±10° of horizontal)
  • < ±6% of reading (wind vector within ±20° of horizontal)
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

Analog
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)

Compatibility

Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Dataloggers

Product Compatible Note
21X (retired)
CR10 (retired)
CR1000 (retired)
CR10X (retired)
CR200X (retired)
CR211X (retired)
CR216X (retired)
CR23X (retired)
CR300
CR3000 (retired)
CR500 (retired)
CR5000 (retired)
CR510 (retired)
CR6
CR800 (retired)
CR850 (retired)
CR850 (retired)
CR9000 (retired)
CR9000X (retired)

Additional Compatibility Information

Data Logger Considerations

Required Operating Systems or PROMs
Data Logger Model Data Logger 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
CR10 2K 5954-396;
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

Downloads

CSAT3 (567 KB) 24-03-1998

PC support software for monitoring and configuring the CSAT3.

Related FAQs

Number of FAQs related to CSAT3: 11

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  1. What is the natural frequency of the CSAT3?

    Approximately 59.5 Hz.

  2. If the polymer coating at the ends of the CSAT3 transducers starts coming off, is that a problem?

    Yes. If the matching layer is damaged or missing, return the CSAT3 to the factory for repair. Follow the steps listed on our Repair and Calibration page to request a returned material authorization (RMA) number. 

  3. Can the CSAT3 measurement frequency be changed? If so, what frequencies are supported by the CSAT3?

    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.

  4. Is the offset relatively constant for a single CSAT3?

    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. 

  5. Are there any datalogger programming changes that must be made to a program when using a long Synchronous Device for Measurement (SDM) cable with a CSAT3?

    With long cable lengths, monitor the SDM data collected from the CSAT3. If the CSAT3 diagnostic word is 61441 or NAN, there are SDM communications errors. If the SDM bit period is increased, SDM communications should be restored. Use the SDMSpeed() instruction to change the SDM bit period. Use the following values for the listed dataloggers:

    • CR3000: 50
    • CR800, CR850, or CR1000: 100
    • CR5000: 90
  6. Can the bubble level on the CSAT3 be replaced?

    Yes. The bubble level can be replaced in the field using pn 2842, Replacement Bubble Level G&B #2-12000.

  7. What should be done if the CSAT3 cannot be found in the Short Cut list of sensors?

    The sensors used in the eddy-covariance application are not compatible with SCWin. An open-path eddy-covariance program is available for purchase as pn 18442, CRBasic Basic Eddy Covariance Program. This is the program without energy balance sensors. Also available is pn 18443, CRBasic Extended Eddy Covariance Program, with energy balance sensors. To order a custom configured program, contact an application engineer in the Micrometeorology Flux group for assistance.

  8. Is the CSAT3 only compatible with Campbell Scientific dataloggers?

    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.

  9. How often do CSAT3 anemometers need to be recalibrated?

    When the CSAT3 is in need of calibration, it will set one of four diagnostic flags. Once a year, spot-check the CSAT3 wind offset using the procedure outlined in the CSAT3 instruction manual. In general, it is good practice to calibrate instruments on a regular basis, for example, every three to five years.

  10. How sensitive are the CSAT3 velocity measurements to sea spray in periods of high 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.

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