An ultrasonic transducer based on FSK ultrasonic ranging

Abstract

This invention provides a passively adjustable ultrasonic transducer with its electrode divided into a driving end and a control end. The control end controls the operating frequency of the ultrasonic transducer by closing and opening a switch. When the switch of the control end is open, the operating frequency of the ultrasonic transducer is f1; when the switch of the control end is closed, the operating frequency of the ultrasonic transducer is f2. According to the piezoelectric hardening theory, the operating frequency f1 is greater than f2. When Δf = f1 - f2 is as large as possible, it can be ensured that the ultrasonic transducer can operate at two significantly different frequency points, which can meet the requirements of high-performance FSK operating mode.

Description

Technical Field

[0001] This invention relates to an ultrasonic ranging method, and more particularly to an ultrasonic transducer based on FSK ultrasonic ranging. Background Technology

[0002] Ultrasonic ranging offers high resolution, relatively low technical difficulty, and low-cost measurement equipment, meeting the requirements of general industrial measurements. Typically, ultrasonic ranging transducers operate in an easily implemented pulse-echo mode. However, the range and accuracy of ultrasonic measurements are affected by various factors, such as the transducer's performance, signal power, signal-to-noise ratio, ambient temperature and humidity, and timer accuracy. For these reasons, researchers have proposed FSK-based ultrasonic ranging technology. This technology uses FSK to transmit and receive ultrasonic waves of two different frequencies to determine the echo leading edge, thereby reducing measurement errors. Excitation signals with frequencies f1 and f2 are transmitted time-division multiplexed at the ultrasonic transmitter, and the moment the transmitted wave frequency changes from f1 to f2 is recorded. The waveforms of the FSK-modulated ultrasonic wave and its echo on the time axis are shown below. Figure 1 As shown. Figure 1 Time t0 is the frequency transition point of the emitted ultrasonic wave. Before time t0, the emitted ultrasonic wave has a period of T1 and a frequency of f1; after time t0, the emitted ultrasonic wave has a period of T2 and a frequency of f2. The timer starts counting from time t0. Time t1 is the moment when the ultrasonic wave emitted at time t0 reaches the ultrasonic receiver after traveling through the medium, i.e., the moment of the echo frequency transition. The difference between t1 and t0 is the transit time of the ultrasonic wave in the medium.

[0003] However, in FSK-based ultrasonic ranging methods, the greater the difference between the frequencies f1 and f2 of the two emitted ultrasonic waves, the easier it is to detect the frequency shift point during measurement. In reality, due to the bandwidth limitations of the ultrasonic transducer, f1 and f2 are very close, posing a challenge to detecting the frequency shift point. A high-speed counter must be used to accurately record the timing of the ultrasonic echo edge to detect the frequency shift point, which undoubtedly increases the cost of the ranging system. To address this problem, this invention proposes an ultrasonic transducer based on FSK ultrasonic ranging. Summary of the Invention

[0004] This invention proposes an ultrasonic transducer based on FSK ultrasonic ranging, which can ensure that the ultrasonic transducer can operate at two significantly different frequency points, thus meeting the requirements of high-performance FSK operation. To achieve the aforementioned effect, the technical solution of this invention is to provide a passively adjustable ultrasonic transducer with electrodes divided into a driving end and a control end. The control end controls the operating frequency of the ultrasonic transducer by opening and closing a switch. When the switch of the control end is open, the operating frequency of the ultrasonic transducer is f1; when the switch of the control end is closed, the operating frequency of the ultrasonic transducer is f2. According to the piezoelectric hardening theory, the operating frequency f1 is greater than f2. When Δf = f1 - f2 is as large as possible, FSK ultrasonic ranging will be easier and more accurate.

[0005] Furthermore, the structural design of the present invention is reasonably allocated. Under the premise that the proportion of the electrode at the driving end is not too low, the ratio of the driving end and the control end is reasonably allocated. The beneficial effect of doing so is that it will not seriously affect the power of the output ultrasonic signal and ensure that the difference between f1 and f2 is as large as possible.

[0006] Furthermore, while ensuring power output, the materials used in this invention can be further selected, with piezoelectric materials with high electromechanical coupling coefficients being preferred for fabricating the ultrasonic transducer. Attached Figure Description

[0007] Figure 1 This is an ultrasonic ranging method based on FSK.

[0008] Figure 2 This invention relates to an ultrasonic transducer based on FSK ultrasonic ranging. Detailed Implementation

[0009] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0010] like Figure 2The diagram shows a passively adjustable ultrasonic transducer with a variable operating frequency proposed in this invention. The transducer's electrodes are divided into a driving end and a control end. The control end controls the transducer's operating frequency by opening and closing a switch. When the control end switch is open, the transducer's operating frequency is f1; when the control end switch is closed, the transducer's operating frequency is f2. According to piezoelectric hardening theory, the operating frequency f1 is greater than f2. In FSK-based ultrasonic ranging methods, the greater the difference between the emitted ultrasonic frequencies f1 and f2, the easier it is to detect the frequency conversion point during measurement. To obtain the largest possible Δf = f1 - f2 for the ultrasonic transducer designed in this way, one approach is to rationally allocate the ratio of the driving end to the control end from a structural design perspective. However, the proportion of the driving end electrodes cannot be too low, otherwise it will seriously affect the power of the output ultrasonic signal. Another approach is to consider material selection, using piezoelectric materials with high electromechanical coupling coefficients to fabricate the ultrasonic transducer while ensuring power output.

[0011] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An ultrasonic transducer based on FSK ultrasonic ranging, characterized in that, Its electrodes are divided into a driving end and a control end. The control end controls the operating frequency of the ultrasonic transducer by closing and opening a switch. When the switch of the control end is open, the operating frequency of the ultrasonic transducer is f1; when the switch of the control end is closed, the operating frequency of the ultrasonic transducer is f2. According to the piezoelectric hardening theory, the operating frequency f1 is greater than f2. Furthermore, the ratio of the driving end to the control end is reasonably allocated under the premise that the proportion of the driving end electrode is not too low, so as to ensure that Δf = f1 – f2 is as large as possible. At the same time, the ultrasonic transducer is made of a piezoelectric material with a high electromechanical coupling coefficient.

2. An ultrasonic transducer based on FSK ultrasonic ranging according to claim 1, characterized in that, This ultrasonic transducer is a passively adjustable ultrasonic transducer with a working frequency.

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