Design and Development of an Electronic Interface for Acquiring Signals from a Piezoelectric Sensor for Ultrasound Imaging Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have implemented an electronic interface designed to enable the real-time visualization of ultrasound (US) signals without interfering with the operation of a commercial US imaging system. They implemented a printed circuit board (PCB) equipped with multi-channel input and output connectors, effectively acting as a parallel adapter between the US imaging system and an external oscilloscope. This setup allows signal acquisition for detailed analysis of noise characteristics, which could be helpful in future noise suppression strategies. The work is primarily focused on electronics and instrumentation. However, I have several concerns regarding the technical depth and rigor of the study:

1. The authors did not mention any technical details about the impedance matching of the interface. This is a critical omission, as impedance mismatches between the transducer, interface, and oscilloscope could introduce signal reflections, additional noise, or waveform distortions.
2. There is no indication that the PCB includes electromagnetic (EM) shielding. Without proper shielding, the interface itself could become a source or receptor of EM interference, thereby compromising the very signals it aims to preserve and analyze.
3. In high-frequency analog signal acquisition systems such as this, proper grounding is essential. The use of multiple ground vias is a well-known method for minimizing ground inductance and suppressing noise. The PCB design does not seem to follow these practices, raising concerns about its signal integrity.
4. Figure 4 is insufficiently annotated; it does not clearly indicate which terminals represent input and output connections. This lack of clarity makes it difficult to evaluate the physical layout and potential coupling effects.
5. The type of filtering used on the digital storage oscilloscope (DSO) is not specified. Many DSOs have built-in filters (e.g., full bandwidth vs. 20 MHz), and whether signal averaging was used is also absent from the text. These parameters significantly affect the appearance and interpretation of the captured waveforms.
6. The discussion section reads more like a conclusion without interpretation of the acquired signals or any quantitative metrics (e.g., SNR, NEP,  and so on) that would support the claims made.
7. While the interface may be practically useful, its design appears relatively simple and routine. Similar signal tapping configurations are often implemented informally in research labs when required. Thus, the novelty of this approach is limited.
8. The authors suggest that analog filtering could reduce the computational burden of digital processing inside US imaging systems. However, implementing external active filters would also introduce power, space, and integration overhead. If such analog pre-processing were indeed beneficial, commercial systems developed through decades of rigorous research and optimization would likely already incorporate it. Moreover, any integration of external filters or interfaces requires careful consideration of impedance matching, isolation, and overall compatibility to avoid degrading the US imaging system performance.
9. Finally, they did not perform any image reconstruction as claimed in their title.

Author Response

The authors have implemented an electronic interface designed to enable the real-time visualization of ultrasound (US) signals without interfering with the operation of a commercial US imaging system. They implemented a printed circuit board (PCB) equipped with multi-channel input and output connectors, effectively acting as a parallel adapter between the US imaging system and an external oscilloscope. This setup allows signal acquisition for detailed analysis of noise characteristics, which could be helpful in future noise suppression strategies. The work is primarily focused on electronics and instrumentation. However, I have several concerns regarding the technical depth and rigor of the study:

1. The authors did not mention any technical details about the impedance matching of the interface. This is a critical omission, as impedance mismatches between the transducer, interface, and oscilloscope could introduce signal reflections, additional noise, or waveform distortions.

In this proposal, the experimental setup does not require impedance matching. Figure 1 shows the proposed system, where it can be observed that a function generator is not used to test the performance of the piezoelectric sensor. Additionally, signal filtering tests have not yet been conducted. We are currently in the stage of acquiring the raw signal directly from the sensor, which is controlled by the medical equipment. For this reason, impedance matching is not necessary at this point.

Figure 1. Proposed system to acquire piezoelectric sensor signals in parallel and in real time.

 

The sampling and storage of the acoustic signals were performed using a UNI-T UPO1202CS oscilloscope, with the following specifications: 200 MHz bandwidth, which exceeds the acoustic signal frequency of 3.5 MHz by more than five times; 1 Gsps sampling rate, which is more than sufficient, as at least 10 samples per cycle are required for a 3.5 MHz signal (i.e., 35 Msps); a storage depth of 56 Mpts, providing ample capacity for capturing long-duration signals with high temporal resolution—particularly useful for subsequent analysis; and a 1 MΩ/16 pF input impedance on the channel, which ensures reliable measurements with minimal interference when acquiring signals from the interface terminal. The passive probe used was the UT-P05 high-impedance probe with a switchable attenuation factor of 1x/10x and a bandwidth ranging from 6 MHz to 200 MHz, offering accurate, distortion-free signal measurements. It is important to emphasize that the oscilloscope was configured to acquire the raw signal, without any averaging or filtering. For instance, in [1], an impedance adapter is employed because the sensor is actively driven by a signal generator. The authors highlight the usefulness of impedance matching in extending the operational bandwidth of the transducer and improving the stability of the emitted acoustic power.

[1] Y. Yao, B. Tan, Z. He, and X. Liu, "A Filter Structure Based Broadband Electrical Impedance Matching Method for Piezoelectric Transducer of Acoustic Well-Logging," IEEE Access, vol. 10, pp. 63567–63578, 2022, doi: 10.1109/ACCESS.2022.3181725.

2. There is no indication that the PCB includes electromagnetic (EM) shielding. Without proper shielding, the interface itself could become a source or receptor of EM interference, thereby compromising the very signals it aims to preserve and analyze.

The interface includes a housing made of anodized aluminum alloy, which is grounded as part of the electromagnetic shielding. This enclosure contains the interface, which is properly insulated, and uses aluminum screws with washers to maintain electrical conductivity. These screws are used to connect both the interface and the equipment to the chassis ground terminal. The enclosure has a thickness of 4 mm, which enhances low-frequency attenuation, and features a Type II anodized finish, improving its resistance to corrosion.

 

3. In high-frequency analog signal acquisition systems such as this, proper grounding is essential. The use of multiple ground vias is a well-known method for minimizing ground inductance and suppressing noise. The PCB design does not seem to follow these practices, raising concerns about its signal integrity.

To preserve signal integrity and minimize interference, the PCB traces of the interface were designed with the following considerations: a trace width of 0.4 mm; 45° angles to smooth the electronic signal flow from the piezoelectric sensor; a spacing of 0.6 mm between traces; and an average maximum trace length of 125 mm. Additionally, a ground frame was implemented around the perimeter of the interface to reduce electromagnetic interference, improve signal isolation, and protect the signals from external noise sources. This design is illustrated in Figure 2.

Figura 2. Top layer de la placa PCB de la interfaz.

 

4. Figure 4 is insufficiently annotated; it does not clearly indicate which terminals represent input and output connections. This lack of clarity makes it difficult to evaluate the physical layout and potential coupling effects.

We have updated Figure 4 to include clear annotations identifying the input terminals (connection to the piezoelectric sensor), the output terminals (oscilloscope acquisition terminal), and the terminal for connection to the medical ultrasound equipment. This modification is already reflected in the revised version of the manuscript.

5. The type of filtering used on the digital storage oscilloscope (DSO) is not specified. Many DSOs have built-in filters (e.g., full bandwidth vs. 20 MHz), and whether signal averaging was used is also absent from the text. These parameters significantly affect the appearance and interpretation of the captured waveforms.

The sampling and storage of the acoustic signals were performed using a UNI-T UPO1202CS oscilloscope, with the following specifications: a bandwidth of 200 MHz, which exceeds the acoustic signal frequency of 3.5 MHz by more than a factor of five; a sampling rate of 1 Gsps, which is more than sufficient considering that at least 10 samples per cycle are required for a 3.5 MHz signal (i.e., 35 Msps); and a storage depth of 56 Mpts, which offers ample capacity to capture long-duration signals with high temporal resolution—particularly valuable for subsequent analysis. The channel input impedance is 1 MΩ/16 pF, which ensures reliable measurements with minimal susceptibility to interference when acquiring signals at the interface terminal. The passive probe used was the high-impedance UT-P05, with a switchable attenuation factor of 1x/10x and a bandwidth ranging from 6 MHz to 200 MHz, providing accurate, distortion-free signal measurements. It is important to note that the oscilloscope was configured to acquire the raw signal, without any averaging or filtering.

6. The discussion section reads more like a conclusion without interpretation of the acquired signals or any quantitative metrics (e.g., SNR, NEP,  and so on) that would support the claims made.

A graph with the SNR data of the 80 signals acquired from the commercial equipment used has been added to the discussion section.

7. While the interface may be practically useful, its design appears relatively simple and routine. Similar signal tapping configurations are often implemented informally in research labs when required. Thus, the novelty of this approach is limited.

At this stage of the work, we focused on the design and validation of the electronic interface for the acquisition of ultrasonic signals, as an essential preliminary step toward image reconstruction. Although the reconstruction stage is not yet included, the acquired signals have been validated to be of sufficient quality for that purpose. To avoid ambiguity, we have revised the manuscript title to: "Design and Development of an Electronic Interface for Acquiring Signals from a Piezoelectric Sensor for Ultrasound Imaging Applications", which more accurately reflects the actual scope of the study.

8. The authors suggest that analog filtering could reduce the computational burden of digital processing inside US imaging systems. However, implementing external active filters would also introduce power, space, and integration overhead. If such analog pre-processing were indeed beneficial, commercial systems developed through decades of rigorous research and optimization would likely already incorporate it. Moreover, any integration of external filters or interfaces requires careful consideration of impedance matching, isolation, and overall compatibility to avoid degrading the US imaging system performance.

At this stage of the work, we focused on the design and validation of the electronic interface for the acquisition of ultrasonic signals, as an essential preliminary step for image reconstruction. Although the proposed filtering stage and the reconstruction stage are not yet included, the acquired signals have been validated to be of sufficient quality for that purpose.

9. Finally, they did not perform any image reconstruction as claimed in their title.

To avoid ambiguity, we have revised the manuscript title to: "Design and Development of an Electronic Interface for Acquiring Signals from a Piezoelectric Sensor for Ultrasound Imaging Applications," which more accurately reflects the actual scope of the study.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

（1）The highlights to contributions should be clearly stated in the introduction section.

（2）The principle of electronic interface is not clearly illustrated. The design details should be given. 

（3）The discussion only have one paragraph. It is too long. It should be divided into several paragraghs to illustrate.

（4）It should use table or data analysis to dicuss, while not only word.

（5）The experiments reuslt are too simple. More performance metric are used to evaluate your work function. The comparative results is suggested to provide to highlight your proposed work. 

Author Response

Reviewer 2

We would like to express our sincere gratitude for your thoughtful and constructive feedback. Your expertise has helped us refine our arguments and improve the presentation of our results. We have carefully considered each of your recommendations and implemented them in the revised manuscript. Thank you for your role in enhancing the rigor of our study.

 

(1）The highlights to contributions should be clearly stated in the introduction section.

The introduction section has been revised and expanded to explicitly highlight the main contributions of this work. The following key contributions are included:

With the objective of addressing speckle noise reduction and the associated challenges in enhancing the quality of diagnostic ultrasound imaging, this work proposes the use of a piezoelectric sensor coupled to medical equipment through a custom-designed electronic interface for the acquisition of acoustic signals. This strategy aims to provide innovative solutions in a more efficient and timely manner. The main contributions of this article are summarized as follows:

• The design and development of an electronic interface for acquiring ultrasonic signals generated by a piezoelectric transducer in a commercial ultrasound device, with a focus on improving medical image reconstruction.
• The implementation of a low-cost, modular, and replicable acquisition system that can be integrated into future portable medical imaging solutions.
• The functional validation through the acquisition of real signals and testing under controlled experimental conditions, providing preliminary evidence of its potential usefulness for future clinical and research applications.

As a novel aspect, this study analyzes the underlying causes of speckle noise in medical images and reviews previous research that proposes alternatives based on sensor design and image reconstruction algorithms. In such studies, the acquisition process is often time-consuming due to the use of a single sensor per test. In contrast, this work presents an accessible, functional, and efficient solution.

The article is organized as follows: Section II describes the design and technical specifications of the electronic interface, as well as the development of the biological tissue emulator and the experimental methods employed. Section III presents the obtained results, which are discussed in Section IV. Finally, Section V outlines the conclusions and projections for future work.

 

(2）The principle of electronic interface is not clearly illustrated. The design details should be given. 

To preserve signal integrity and minimize interference, the interface was designed without the inclusion of active electronic components. The layout of the PCB traces was carefully engineered with the following characteristics: a trace width of 0.4 mm; 45° angles to smooth the flow of the electrical signal originating from the piezoelectric sensor; a trace spacing of 0.6 mm; and an average maximum trace length of 125 mm. Additionally, a ground frame was incorporated around the perimeter of the interface to reduce electromagnetic interference (EMI), enhance signal isolation, and thereby protect the system from external noise sources.

 Top layer de la placa PCB de la interfaz.

The sampling and storage of the acoustic signals were performed using a UNI-T UPO1202CS oscilloscope, which features the following specifications: a 200 MHz bandwidth—exceeding the acoustic signal frequency of 3.5 MHz by more than a factor of five; a 1 GSa/s sampling rate—given that at least 10 samples per cycle are required for a 3.5 MHz signal, a minimum of 35 MSa/s would be sufficient; and a 56 Mpts storage depth—which provides ample capacity for capturing long-duration signals with high temporal resolution, particularly valuable for subsequent signal analysis. The input channel impedance is 1 MΩ / 16 pF, ensuring safe and interference-resistant signal acquisition at the interface terminal. The measurement was performed using a high-impedance passive probe (UT-P05), featuring a switchable attenuation factor (×1/×10) and a bandwidth range from 6 MHz to 200 MHz, allowing for accurate, distortion-free signal measurement. Importantly, the oscilloscope was configured to acquire the raw signal, i.e., without averaging or filtering, ensuring the integrity and fidelity of the captured waveform.

(3）The discussion only have one paragraph. It is too long. It should be divided into several paragraghs to illustrate.

The discussion section has been revised and updated as follows:

The obtained results indicate that the acoustic signals acquired with the oscilloscope through the proposed interface demonstrate the feasibility of measuring, evaluating, and storing the acoustic waveform information from each of the 80 piezoelectric sensors. The relative amount of signal and noise present in a waveform is commonly quantified using the signal-to-noise ratio (SNR). Equation 1 was used, based on the root mean square (RMS) amplitude values of each of the 80 acquired signals. The results are presented in Figure 12, which illustrates the SNR behavior, showing a value of approximately –13 dB. This indicates the presence of noise at a level comparable to or exceeding that of the useful signal power [37]. Such findings suggest that the signals contain a significant level of noise, potentially originating from electronic interference due to power system switching, internal reflections, or limitations of the acquisition system itself. Therefore, to achieve higher-quality analysis or imaging, it would be advisable to apply pre-acquisition filtering and signal processing strategies aimed at increasing the signal-to-noise ratio.

Figure 12. Signal-to-noise ratio graph of the 80 sensors in dB.

A critical challenge in medical imaging lies in addressing artifacts caused by electromagnetic interference, which degrade ultrasound image quality and diagnostic accuracy. Conventional approaches rely on digital filters and reconstruction algorithms that demand substantial computational resources. However, the simultaneous processing of noise and acoustic signals can suppress diagnostically relevant information or amplify artifacts, potentially introducing false structures in the reconstructed images and compromising diagnostic reliability. Our electronic interface facilitates a deeper understanding of acoustic phenomena in medical systems by enabling the observation of signals in parallel without disrupting the operation of the device, thereby providing the opportunity to analyze and propose effective solutions.

(4）It should use table or data analysis to dicuss, while not only word.

 A figure with the SNR data of the 80 signals acquired from the commercial equipment used has been added to the discussion section.

(5）The experiments reuslt are too simple. More performance metric are used to evaluate your work function. The comparative results is suggested to provide to highlight your proposed work.

Performance metrics such as the signal-to-noise ratio (SNR) were introduced. No data were found in the literature regarding the parameters of commercial medical ultrasound equipment for direct comparison, as most published studies employ sensors developed in research laboratories and do not analyze commercial systems. The advantage of implementing our interface lies in the ability to utilize a commercial sensor, which opens the possibility of proposing improvements in image reconstruction in future work.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This study focuses on ultrasound for medical diagnosis as the research object. Considering the generality of this detection method, any progress in it is useful and beneficial. The authors designed an electronic interface device that facilitates real-time interference analysis and is used for efficient and time-saving filtering analysis, while also being able to save data from sensors and data acquisition systems during the diagnostic process. Also, they provided the location and working connection process of the proposed electronic interface device, which was tested and monitored using an oscilloscope. These results have some novelty and may have reference value for peers or users.

However, there are many issues that need to be modified:

Electromagnetic interference and speckle noise are indeed the main problems in ultrasound imaging, but the reconstruction mentioned by the author did not see any images or reconstructed targets, Nevertheless, the mentioned anti-noise ability lacks relevant information, especially for data without quantified signal-to-noise ratio, and the results obtained are not completely convincing, Why was money chosen as the research object in the experiment? And it cannot be a part of human tissue.

In the fourth section of the Discussion, the author mentioned the significance of ultrasound compared to MRI, CT, etc. These are common knowledge and do not need to be written about. In fact, there is not much novelty in this section.

Author Response

Electromagnetic interference and speckle noise are indeed the main problems in ultrasound imaging, but the reconstruction mentioned by the author did not see any images or reconstructed targets, Nevertheless, the mentioned anti-noise ability lacks relevant information, especially for data without quantified signal-to-noise ratio, and the results obtained are not completely convincing.

In this phase of the study, we focus on the design and validation of the electronic interface for ultrasonic signal acquisition, which serves as an essential prerequisite for image reconstruction. Although the reconstruction stage is not yet included, we have verified that the acquired signals exhibit sufficient quality for this purpose. To avoid ambiguity, we have refined the manuscript title to:

"Design and Development of an Electronic Interface for Acquiring Signals from a Piezoelectric Sensor for Ultrasound Imaging Applications"

This revision more accurately reflects the actual scope of the study.

Why was money chosen as the research object in the experiment? And it cannot be a part of human tissue.

The article describes the development of an electronic interface to optimize raw signal acquisition from a piezoelectric sensor. Its purpose is to ensure that captured ultrasonic signals exhibit high quality while being free from electromagnetic interference (EMI) and noise, thereby enabling subsequent image reconstruction stages. Table 1 compares the characteristics of coins and human tissue. Coins were selected as controlled test objects due to their homogeneous metallic composition (copper, nickel, or zinc alloys), which generates predictable and repeatable acoustic responses. Human tissues were not used because this study focuses on validating the electronic acquisition stage rather than in vivo biomedical applications. Moreover, human tissues would introduce uncontrolled variables (heterogeneity, degradation, ethical requirements) that would deviate from the technical objective. Coins provide uniform density and elasticity, eliminating the inherent variability of fresh biological samples. The experiment described in the manuscript emulates echogenic targets: coins were embedded in a biological tissue-mimicking phantom (agar with acoustic properties equivalent to soft tissues). This approach allowed us to study the sensor's response to high-impedance metallic interfaces within a tissue-like medium. Furthermore, it enabled quantitative evaluation of the interface's ability to distinguish meaningful signals from artifacts in controlled environments. Coin usage addressed ethical and logistical limitations:

 

• Human tissues require ethics committees, specialized preservation, and biosafety protocols—resources beyond this study's scope.

 

• Coins maintain stable properties during repeated testing; unlike biological samples whose acoustic impedance degrades over time.

 

The coin selection followed rigorous technical criteria aligned with the study's objective: validating an electronic interface for ultrasonic signal acquisition. This approach enabled precise experimental control when evaluating EMI, noise, and sensor linearity. These results establish a foundation for future tests with anatomical phantoms or ex vivo tissues once the electronic stage is optimized.

We appreciate the reviewer's opportunity to clarify this point. The proposed adjustments will enhance the methodological transparency without diverting from the original focus: hardware design for signal acquisition, not clinical image reconstruction.

Table 1: Technical Comparison between Coins and Human Tissues in Piezoelectric Sensor Tests.

Parameter	Coins (Cu/Ni)	Human Tissues	Relevance to the Study
Homogeneity	High (crystal structure)	Low (cellular heterogeneity)	Control of variables
Temporal stability	>1000 test cycles	Hours (degradation)	Reproducibility
Signal strength	High voltage signals (≥90V)	Weak signals (mV–V)	Calibration sensitivity threshold
Ethical requirements	None	Biosafety committees	Focus on electronics
Cost	Low	High	Economic feasibility

 

In the fourth section of the Discussion, the author mentioned the significance of ultrasound compared to MRI, CT, etc. These are common knowledge and do not need to be written about. In fact, there is not much novelty in this section.

 

The discussion section has been thoroughly revised and updated. Our results demonstrate that the proposed interface, when used with an oscilloscope, enables measurement, evaluation, and storage of acoustic wave data from each of the 80 piezoelectric sensors. The relative signal-to-noise ratio in the waveforms was quantified using the signal-to-noise ratio (SNR) metric. As shown in Equation 1, we calculated this parameter using the root mean squared (RMS) amplitude values obtained from all 80 signals. Figure 12 presents the SNR results, revealing a characteristic value of -13 dB. This SNR level indicates that the noise power is comparable to or exceeds the useful signal power [37], suggesting significant noise contamination in the acquired signals. Potential noise sources include, electronic interference from power switching systems, internal signal reflections, inherent limitations of the acquisition system. These findings imply that implementing pre-acquisition signal filtering and advanced processing techniques would be necessary to improve SNR for higher quality analysis and imaging applications.

Figure 12. Signal-to-noise ratio graph of the 80 sensors in dB.

A critical challenge in medical imaging involves addressing artifacts caused by electromagnetic interference, which degrade ultrasonic image quality and diagnostic accuracy. Conventional approaches employ digital filters and reconstruction algorithms that demand substantial computational resources. However, simultaneous processing of noise and acoustic signals may suppress diagnostically relevant information or amplify artifacts, potentially introducing false structures in reconstructed images and compromising diagnostic reliability. Our electronic interface provides a novel solution by enabling real-time observation of acoustic phenomena in medical systems through parallel signal monitoring without interrupting device operation. This capability facilitates comprehensive analysis and targeted solution development for interference-related artifacts.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Great improvement.

Author Response

We would like to express our sincere gratitude for your thoughtful and constructive feedback. Your expertise has helped us refine our arguments and improve the presentation of our results. Thank you for your role in enhancing the rigor of our study.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have completed the paper revisions according to the reviewers' comments. 

Author Response

Thank you very much for your thorough review and insightful suggestions. Your feedback has been invaluable in clarifying several aspects of our research and addressing areas that required further elaboration. We are grateful for your guidance.

Reviewer 3 Report

Comments and Suggestions for Authors

These authors have made significant revisions compared to the original version. The logical relationship and readability of the study have now increased significantly, making it easier for readers or relevant researchers to grasp the core idea of the article. The added images and results demonstrate that the study has reached a certain level. Although not everything in the article satisfied me, considering the timeliness of the research results, I agree with its publication. However, I still suggest making a small modification by adding explanations and units of coordinate value variables in Figures 9 and 10.

Author Response

Thank you for your detailed and insightful comments. We appreciate the time and effort you dedicated to reviewing our manuscript. Your suggestions have been instrumental in helping us clarify key aspects of our study, and we believe they have strengthened the overall quality of our work. We have addressed each of your points in the revised version and highlighted the changes for clarity. Thank you once again for your valuable input.

These authors have made significant revisions compared to the original version. The logical relationship and readability of the study have now increased significantly, making it easier for readers or relevant researchers to grasp the core idea of the article. The added images and results demonstrate that the study has reached a certain level. Although not everything in the article satisfied me, considering the timeliness of the research results, I agree with its publication. However, I still suggest making a small modification by adding explanations and units of coordinate value variables in Figures 9 and 10.

The following description and enlarged image of the oscilloscope are added:

Likewise, Figure 9 shows the acquired signals corresponding to the piezoelectric transducers numbered 71 to 80, in which the emission and reception of the ultrasound signal echo can be observed. These signals (figure 8, 9 and 10) were obtained using a conventional probe without attenuation adjustment. In figure 11 presents a zoomed-in view at the focal distance of the image obtained by the oscilloscope for the acoustic signal. The central frequency of 3.046 MHz, indicated on the screen. This corresponds to the fundamental frequency of the acoustic signal detected by the sensor. Voltage scale: The signal is shown on a scale of 20.0 V per vertical division (CH1). Time scale: The horizontal scale is 400 nanoseconds (ns) per division, with a sampling rate of 500 MS/s (millions of samples per second). Waveform: Presents a main pulse with a very pronounced positive peak, followed by a larger negative peak and produces a series of damped oscillations. This is characteristic of an acoustic echo signal, where the initial pulse represents the arrival of the main wave and the subsequent oscillations can correspond to reverberations or internal echoes. To clearly observe the amplitude of the echoes. Figure 12 presents a zoomed-in view at the focal distance of the image obtained by the oscilloscope for the acoustic signal echo and a GND reference signal from the system.

Figure 11. Magnification at the focal length of one image of 8, 9 and 10 acoustic signals.

Author Response File: Author Response.pdf