Application Cases

Experiment Name: Application of Power Amplifier in Soil Moisture Content Monitoring Based on Stress Wave Time Reversal Method

Experiment Objective: To address the issue of monitoring soil moisture content over large areas, this study investigates a soil moisture content monitoring technology based on stress wave time-reversed focusing signals.

Experimental Equipment: Piezoelectric sensors, arbitrary waveform generator, power amplifier, charge amplifier, data acquisition card, computer

Figure: Data Acquisition System Configuration Diagram

Experimental Content:
This paper proposes a monitoring method based on piezoelectric active sensing, utilizing time reversal technology to enhance the signal-to-noise ratio. The relationship between the time-reversed focusing signal and soil moisture content is established.

Experimental Procedure:
The data acquisition system consisted of an arbitrary waveform generator, a power amplifier (ATA-2041), a charge amplifier, a data acquisition card, a computer, and transmitting/receiving piezoelectric sensors, as shown in the figure. The arbitrary waveform generator (AFG-1022) generated the signal, which was amplified by the ATA-2041 high-voltage amplifier to an output voltage of 400 V. The received signal was amplified by the HK-9210 charge amplifier and then acquired by the NI-6366 multifunction data acquisition card for storage on the computer.

Figure: Soil Test Specimen and Sensor Layout Diagram

Figure: Data Acquisition System

Experimental Results:

Figure: Ten Acquired Focusing Signals at 24% Moisture Content

Figure: Relationship between Focusing Signal Amplitude and Moisture Content

1. The amplitude of the focusing signal decreases as the moisture content increases. The soil moisture content can be determined by analyzing the focusing signal amplitude. This method can serve as an effective means for regional monitoring of soil moisture content.

2. The focusing signal obtained through the time reversal method can effectively improve the signal-to-noise ratio. Therefore, the piezoelectric active sensing time reversal method has promising application prospects in regional soil moisture content monitoring.

   

Figure: Specifications of the ATA-2041 High-Voltage Amplifier