Application Cases

Experiment Name: Acoustic Performance Testing of Transducer Arrays

Research Direction: Underwater Acoustic Measurement

Objective:
Based on the testing of electrical and acoustic characteristic parameters of underwater acoustic transducers, an automated detection method utilizing the reciprocity principle was developed. The study focused on using multi-frequency point detection to simultaneously measure directivity, building upon the foundational theory of single-frequency point directivity detection.

Equipment:
ATA-4012B High-Voltage Power Amplifier, Signal Generator, Test Specimen, Oscilloscope

Procedure:
Connections were established between the computer, signal source, cathode-ray oscilloscope, and rotary system, with control managed by the computer. The signal source provided the input, i.e., the drive signal. However, as its output signal is typically too small to directly drive the transducer, a power amplifier was used to amplify the signal to a level sufficient for transducer operation. The hydrophone receives signals emitted by the transmitting transducer after propagation in water, as well as reflected noise signals generated by collisions with other objects in the water. These signals usually require processing to remove noise that could affect measurement results. Due to their generally small amplitude, they are further amplified for subsequent processing. A filtering amplifier was employed to address these requirements. To measure directivity, a rotary system was used to rotate the transmitting transducer, enabling scanning across different angles. For automated reciprocity-based measurements, a switch module was utilized to automatically toggle the transducer states to ensure reciprocity during pairwise testing.

Figure: Schematic Diagram of the Experimental Setup

The instruments used in this testing system mainly include a signal generator, cathode-ray oscilloscope, power amplifier, filtering amplifier, and a rotary system for controlling the turntable. This rotary system is primarily used to measure the directivity of transducers by adjusting the emission angle of the underwater acoustic transducer in water, commonly employed in underwater acoustic measurements.

Results:

Step 1:
Connect RO and L1 to drive the transmitting transducer to emit acoustic signals. Connect R1 and L5 to display the hydrophone's received signal on Channel 1 of the oscilloscope. This allows obtaining the voltage (U) and current (I) converted from voltage values for the FJ transducer pair on Channels 1 and 3 of the oscilloscope.

Figure: Step 1 - FJ Transducer Pair

Step 2:
Disconnect R1 and L5, and connect R2 and L3 to display the reciprocal transducer's received signal on Channel 2 of the oscilloscope. This allows obtaining the voltage (U) and current (I) converted from voltage values for the FH transducer pair on Channels 2 and 3 of the oscilloscope.

Figure: Step 2 - FH Transducer Pair

Step 3:
Disconnect R2 and L3, disconnect RO and L1, connect RO and L3, and connect R1 and L5 to drive the reciprocal transducer to emit acoustic signals. This allows obtaining the voltage (U) and current (I) converted from voltage values for the HJ transducer pair on Channels 1 and 3 of the oscilloscope. The hydrophone sensitivity level is then calculated using Formula (2-18).

Figure: Step 3 - HJ Transducer Pair

The software testing process for automated sensitivity measurement using the reciprocity method is similar to other parameter measurement processes. First, the required parameters are set, and the measurement range is manually selected. The measurement begins from the starting frequency and proceeds in cycles. Each measurement cycle follows the steps: sending signals, setting the range, reading voltage/current values, calculating sensitivity, plotting results, and changing the frequency. This process repeats until the termination frequency is reached, completing all measurements.

Figure: Final Experimental Results

Figure: Specifications of the ATA-4012C High-Voltage Power Amplifier