Section 2
Functional Description
13
FT742-SM (RS422 & RS485) Sensors
– User Manual
2.11 Acoustic Temperature
The Acoustic Temperature feature takes a measurement of the ambient temperature via measurable acoustic
properties of the airflow. Sections 7.4.2 to 7.4.4 describe related software commands.
Averaged data should be used. The averaging system can be performed for 0 to 50 seconds (in increments of 10
seconds), or between 1 to 10 minutes (in increments of 1 minute).
See Section 2.1 for details regarding operating specifications. Operation with high temperature gradients
(between sensor body and ambient airflow), extreme humidity levels and low wind conditions (below 5m/s) may
result in reduced accuracy.
Software version V7.5.1 introduced the DFC mode (combined data format) that includes AT Temperature data
within the CU data output and WV Query commands. See Sections 7.4.7, 7.4.8 and 7.4.29 for further information.
Caution: The acoustic temperature feature requires calibration at FT Technologies. If the sensor has had
a software upgrade to 7.5 (or above) then the data will be uncalibrated and may not comply with the official
specification. Testing is recommended to confirm suitability for the application.
