ASL follows a 2-part calibration process for the AZFP: Calibrate

1) Calibrate
A calibrated source is aligned precisely with the transducer under test at one meter range. The calibrated source transmits into the AZFP transducer, allowing the receiver to be characterized. A calibrated hydrophone is then aligned precisely with the transducer under test, again at one meter range. The AZFP transmits into the hydrophone, allowing the transmitter to be characterized. At this point, the AZFP is calibrated. However, it’s important to check that we got it right.

2) Verify
The AZFP is placed in a large freshwater tank, and a tungsten-carbide (WC) sphere is moved through each of the AZFP’s beams. The theoretical target strength of the sphere is calculated for each AZFP channel. In order to pass this test, the AZFP must measure the target strength of the sphere to within a precision of +/- 1 dB of the theoretical target strength.