CSAT3B 3-D Sonic Anemometer with Integrated Electronics
Precision Measurements
Designed for flux and other turbulence research projects
weather applications supported water applications supported energy applications supported gas flux & turbulence applications supported infrastructure applications supported soil applications supported


Campbell Scientific’s CSAT3B 3-D Sonic Anemometer is an update and replacement to the original CSAT3, and remains 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 sonic temperature (Ts) are measured and output at a maximum rate of 100 Hz.

The most conspicuous innovation of the new design is the elimination of the electronics box. Instead, the electronics are packaged inside the mounting block of the CSAT3B head. This design feature makes installation easier and offers greater flexibility in instrument placement.

Measurements can be triggered from three sources:

  • Data logger SDM command
  • Data logger CPI command
  • CSAT3B internal clock

The SDM and CPI protocols both support mechanisms for synchronizing multiple CSAT3Bs.

Benefits and Features

  • New conformal coating helps protect sonic transducers in corrosive environments
  • Integrated electronics that provide easy mounting of a single piece of hardware
  • Integrated inclinometer
  • High-precision measurements ideal for turbulence and eddy-covariance studies
  • An improved design with a thin, aerodynamic support strut close to the ends of the sensor arms, creating greater rigidity and improved accuracy of sonic temperature
  • Data logger sampling supported for any frequency between 1 and 100 Hz
  • New CPI communications for more robust, higher bandwidth measurements
  • Multiple communication options including SDM, CPI, USB, and RS-485
  • Internal temperature and humidity measurements with easily replaced desiccant
  • Version 5 algorithm for calculating data outputs; combines the signal sensitivity of version 3 with the rain performance of version 4
  • Includes options to filter high frequencies for applications requiring analysis of non-aliased spectra



Sensor 3-dimensional sonic anemometer
Measurement Description Highest-quality wind speed and direction
Operating Temperature Range -40 to +50°C (equivalent to 305 to 368 m s-1 in speed of sound)
Outputs ux, uy, uz, Ts (ux, uy, uz are wind components referenced to the anemometer axes; Ts is sonic temperature in degrees Celsius.)
Signal Type/Output SDM, CPI, USB, RS-485
Speed of Sound Determined from three acoustic paths. (Corrected for crosswind effects.)
Wind Direction Range 2.5 to 357.5° in CSAT3B coordinate system (0 to 360° customized)
Range ± 65 m s–1 (full-scale wind)
Filter Bandwidths 5, 10, or 25 Hz
Measurement Path Length 10.0 cm (3.9 in.) vertical; 5.8 cm (2.3 in.) horizontal
Transducer Angle from Horizontal 60 degrees
Transducer Diameter 0.64 cm (0.25 in.)
Transducer Mounting Arm Diameter 0.84 cm (0.33 in.)
Support Arm Diameter 1.59 cm (0.63 in.)
Anemometer Head Weight 1.45 kg (3.2 lb)
Anemometer Dimensions 60.64 x 12.2 x 43.0 cm (23.87 x 4.8 x 16.9 in.)

Wind Accuracy

-NOTE- Accuracy specifications assume the following:
  • -40° to +50°C operating range
  • Wind speeds < 30 m s-1
  • Wind angles between ±170°
Maximum Offset Error < ±8.0 cm s-1 (ux, uy), < ±4.0 cm s-1 (uz)
Maximum Gain Error
  • < ±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)

Measurement Resolution

ux, uy 1 mm s-1 rms
uz 0.5 mm s-1 rms
Ts 0.002°C RMS (at 25°C)
Wind Direction < 0.058° (ux = uy ≤ 1 m s-1)

Measurement Rates

Data Logger Triggered 1 to 100 Hz
Unprompted Output (to PC) 10, 20, 50, or 100 Hz
Internal Self-Trigger Rate 100 Hz

Measurement Delay

Data Logger Triggered (no filter) 1 trigger period (1 scan interval)
Unprompted Output (no filter) 10 ms
Filtered Output (data-logger-prompted or unprompted to PC)
  • 795 ms (with 5 Hz bandwidth filter)
  • 395 ms (with 10 Hz bandwidth filter)
  • 155 ms (with 25 Hz bandwidth filter)

Internal Monitor Measurements

Update Rate 2 Hz
Inclinometer Accuracy ±1°
Relative Humidity Accuracy
  • ±3% (over 10 to 90% range)
  • ±7% (over 0 to 10% range)
  • ±7% (over 90 to 100 % range)
Board Temperature Accuracy ±2°C


-NOTE- Used for data-logger-based data acquisition.
Bit Period 10 µs to 1 ms
Cable Length
  • 7.6 m (25 ft) max (@ 10 µs bit period)
  • 76 m (250 ft) max (@ 1 ms bit period)
Address Range 1 to 14
Bus Clocks per Sample ~200


-NOTE- Used for data-logger-based data acquisition.
Baud Rate 50 kbps to 1 Mbps
Cable Length
  • 15 m (50 ft) max (@ 1 Mbps)
  • 122 m (400 ft) max (@ 250 kbps)
  • 853 m (2800 ft) max (@ 50 kbps)
Address Range 1 to 120
Bus Clocks per Sample ~300


-NOTE- Used for configuration or PC-based data acquisition.
Baud Rate 9.6 kbps to 115.2 kbps
Cable Length
  • 305 m (1000 ft) max (@ 115.2 kbps)
  • 610 m (2000 ft) max (@ 9.6 kbps)
Bus Clocks per Sample ~500 (ASCII formatted)


-NOTE- Used for configuration or PC-based data acquisition.
Connection Speed USB 2.0 full speed 12 Mbps
Cable Length 5 m (16.4 ft) maximum

Power Requirements

Voltage Supply 9.5 to 32 Vdc
Current at 10 Hz Measurement Rate
  • 110 mA (@ 12 Vdc)
  • 65 mA (@ 24 Vdc)
Current at 100 Hz Measurement Rate
  • 145 mA (@ 12 Vdc)
  • 80 mA (@ 24 Vdc)


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


Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR211X (retired)
CR216X (retired)
CR3000 (retired)
CR9000X (retired)


CSAT3B Example Programs v.1 (4 kB) 20-10-2020

Three example programs. 

Simple SDM Program: SDM communications are used to collect data from a single CSAT3B.

Simple CPI Program: CPI communications are used to collect data from a single CSAT3B.

Advanced CPI Program: A single CSAT3B is properly configured and CPI communications are used to collect the data.

CSAT3B OS v.3.02 (548 KB) 14-10-2019

Current CSAT3B Operating System.

View Revision History

CPI Calculator v.1.0 (2.49 MB) 06-07-2016

The CPI Calculator is a downloadable Microsoft Excel spreadsheet used to estimate the usage and capacity of a CPI network.  The calculator provides an overview on CPI devices including the CDM-A108, CDM-A116, CDM-VW300, CDM-VW305, and the CSAT3B.  The calculator can also estimate the measurement speed of the CDM-A108 and CDM-A116 based on the number of channels and measurement parameters.


The CPI Calculator is an estimation tool and will help you better understand and design CPI networks by considering the following:

  1. What is the capability of each CDM or CPI device
  2. What is the CPI network capacity
  3. How much of the CPI capacity are the CDMs or CPI devices using


Related FAQs

Number of FAQs related to CSAT3B: 1

  1. The CSAT3A, CSAT3AH, CSAT3B, and CSAT3BH have been optimized for most terrestrial applications. If the sonic anemometer 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. Campbell Scientific offers a conformal coating option with our sonics to help alleviate corrosion; if your application poses a corrosive risk, consider adding this coating to your transducers. If possible, mount the sonic anemometer in a way that reduces exposure to saltwater spray/splash and/or corrosive chemicals. For applications that experience frozen precipitation, the heated versions of the CSAT3A and CSAT3B may be better suited.