Campbell Scientific CSAT3B CSAT3B Three-Dimensional Sonic Anemometer - Page 53

CSAT3B Three-Dimensional Sonic Anemometer TABLE 7-3. CSAT3B Cable Wire Assignments CSAT3B Cable Type CSAT3BCBL1 CSAT3BCBL2 CSAT3BCBL3 Signal Description Power 9.5-32 Vdc Ground SDM GND SDM C1 SDM C2 SDM C3 Shield Power 9.5-32 Vdc Ground RxA RxB TxA TxB RGND Pigtail Color Red Black Brown White Yellow Blue Clear Red Black Brown Brown stripe Blue Blue stripe Green Connector Pin # 1 2 3 4 5 6 Shell 1 2 4 2 6 1 5 If a fine-wire thermocouple such as a model FW05 with FWC-L is being used, the wiring designations in TABLE 7-4 should be followed to connect the thermocouple to a differential voltage channel on a datalogger. TABLE 7-4. FW05/FWC-L Fine-Wire Thermocouple Description Signal high Signal low Color Purple Red 8. Operation 8.1 Theory of Operation The CSAT3B uses three pairs of non-orthogonally oriented transducers that transmit and receive ultrasonic signals. The time of flight of a sonic signal between a pair of transducers is directly related to the wind vector component that is parallel to the sonic axis. The CSAT3B is able to calculate the wind vector components along each sonic axis using the time difference between an outgoing and return sonic signal, along with the distance between sonic transducers. Trigonometric relationships are used to calculate the wind speed in an orthogonal x-y-z coordinate system. 43