Audio line state detection method and device based on lc resonant circuit

Abstract

The application provides an LC resonant circuit-based audio line state detection method and device, and relates to the technical field of audio line state detection.The method comprises the following steps: after disconnecting the power amplifier connection of the audio line to be detected, connecting a detection board to the first end of the audio line to be detected and connecting a passive device board to the second end of the audio line to be detected; generating a first alternating-current test signal at a first resonant frequency and a second alternating-current test signal at a second resonant frequency through the signal generation circuit of the detection board; inputting the amplified and filtered signals to the positive lead of the audio line to be detected through a filter amplifier circuit, and connecting the negative lead to the signal ground of the detection board through a sampling resistor; performing double-frequency voltage detection and outputting a state judgment.The application solves the technical problem that the prior art mostly relies on direct measurement of the current or voltage of the audio line to judge the state thereof, cannot accurately reflect the state of the audio line under different working frequencies, and results in low precision and accuracy of audio line state detection.

Description

Technical Field

[0001] This invention relates to the field of audio line status detection technology, and specifically to an audio line status detection method and apparatus based on an LC resonant circuit. Background Technology

[0002] In modern public address systems, audio cables are crucial components for audio signal transmission, widely used in large venues such as schools, shopping malls, and train stations. To ensure stable audio signal transmission, the status of audio cables needs to be monitored in real time. Most existing technologies rely on directly measuring the current or voltage of the audio cable to determine its status. These methods require continuous monitoring of the audio cable or manual testing by disconnecting the cable. They cannot accurately reflect the status of the audio cable at different operating frequencies, especially when there are complex frequency variations or resonance phenomena. Voltage or current fluctuations are not easily identified accurately. For example, fluctuations caused by electrical noise or signal interference can lead to false alarms or missed alarms. These shortcomings result in low accuracy and precision in audio cable status detection, affecting the reliability and stability of the audio system. Summary of the Invention

[0003] This application provides an audio line status detection method and apparatus based on an LC resonant circuit, aiming to solve the technical problem that most existing technologies rely on directly measuring the current or voltage of the audio line to determine its status, which cannot accurately reflect the status of the audio line at different operating frequencies, resulting in low precision and accuracy of audio line status detection.

[0004] The first aspect disclosed in this application provides an audio line status detection method based on an LC resonant circuit. The method includes: after disconnecting the power amplifier connection of the audio line to be tested, connecting a detection board to a first end of the audio line to be tested and connecting a passive device board to a second end of the audio line to be tested; generating a first AC test signal at a first resonant frequency and a second AC test signal at a second resonant frequency through a signal generation circuit of the detection board; amplifying and filtering the first AC test signal and the second AC test signal through a filtering and amplification circuit, and inputting them to the positive conductor of the audio line to be tested, wherein the negative conductor of the audio line to be tested is connected to the signal ground of the detection board through a sampling resistor; and performing dual-frequency voltage detection of the sampling resistor through a signal processing circuit to output a status judgment of the audio line to be tested.

[0005] The second aspect disclosed in this application provides an audio line status detection device based on an LC resonant circuit. The device includes: a detection board; a passive device board, the passive device board being composed of an inductor L and a capacitor C connected in series; wherein the detection board is connected to the first end of the audio line to be detected, the passive device board is connected to the second end of the audio line to be detected, and N speakers are connected in the middle of the audio line to be detected.

[0006] One or more technical solutions provided in this application have at least the following beneficial effects:

[0007] By disconnecting the audio cable under test from the power amplifier, interference from the amplifier's output signal is prevented, ensuring the purity and accuracy of subsequent test signals. Connecting the test board and the passive device board allows for precise monitoring of the audio cable's condition using test signals, ensuring the signal transmission path is unaffected by external factors. Generating two AC test signals at different frequencies comprehensively tests the audio cable's operating status at various frequencies; the signal at the resonant frequency exhibits the strongest response, while signals far from the resonant frequency show a lower response. This dual-frequency test more accurately reflects the audio cable's health. Through a filtering and amplification circuit, the test signal is effectively amplified and noise is filtered out, ensuring sufficient signal strength for transmission to the audio cable while avoiding misjudgments caused by noise. Sampling... The resistor configuration allows for precise sampling of voltage changes after the audio line transmits signals, providing data for status determination. The signal processing circuit compares the sampled dual-frequency voltages and outputs the audio line's status. This dual-frequency detection method relies on the differences in signal response at different frequencies, making the determination of the audio line's status more accurate and reliable. The signal processing circuit can automatically distinguish the audio line's status based on the peak voltage changes, avoiding errors from manual detection and judgment, and improving the system's intelligence and automation. The LC resonant circuit's device structure uses a combination of a passive device board and a detection board, which is both simple and efficient. By utilizing the frequency characteristics of the resonant circuit to enhance the signal response, it can accurately and quickly determine whether the audio line is normal, short-circuited, or open-circuited, making it suitable for large and complex audio system environments.

[0008] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0009] Figure 1 A schematic diagram of the structure of an audio line state detection device based on an LC resonant circuit provided in an embodiment of this application.

[0010] Figure 2 This is a schematic flowchart of an audio line state detection method based on an LC resonant circuit provided in an embodiment of this application.

[0011] Figure 3 A schematic diagram of the impedance amplitude characteristics of one LC series circuit in the audio line state detection method based on LC resonant circuit provided in the embodiments of this application.

[0012] Explanation of reference numerals in the attached diagram: Detection board 10, passive device board 20, audio cable to be tested 30. Detailed Implementation

[0013] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0014] Example 1, as Figure 1 As shown in the figure, this application provides an audio line state detection device based on an LC resonant circuit, the device comprising:

[0015] Detection plate 10.

[0016] The detection board 10 is one of the core components of the entire audio cable status detection device. It is mainly responsible for switching the audio cable connection status, generating test signals, processing signals, sampling loop signals, amplifying signals, and finally judging the status.

[0017] The passive device board 20 is composed of an inductor L and a capacitor C connected in series.

[0018] The passive device board 20, consisting of an inductor L and a capacitor C connected in series, is part of the detection terminal. It is connected in parallel with the speaker on the audio cable and at the ends of the two audio cables. Its function is to form an LC resonant circuit with the audio cable 30 to be tested, and to detect the state of the audio cable through its resonant characteristics.

[0019] The detection board 10 is connected to the first end of the audio line 30 to be tested, the passive device board 20 is connected to the second end of the audio line 30 to be tested, and N speakers are connected in the middle of the audio line 30 to be tested.

[0020] The audio line under test 30 consists of a positive wire and a negative wire. These two wires are used to connect the source and load of the audio signal, such as multiple speakers. The state of the audio line under test 30, such as normal, short circuit, open circuit, etc., is reflected by the change of the signal between these two wires. Each speaker on the audio line under test 30 is connected in parallel between these two wires and is electrically isolated by a transformer.

[0021] The working principle is as follows: First, the detection board 10 disconnects the audio cable from the power amplifier and connects the detection cable to the detection board. Then, the detection board 10 generates an AC signal, which is filtered and amplified before being transmitted to the positive terminal of the audio cable 30 under test. This signal then passes through an LC resonant circuit (passive device board 20) to the negative terminal of the audio cable 30 under test. The negative terminal of the audio cable 30 under test is connected to a sampling resistor connected to signal ground. The voltage value across the sampling resistor reflects the state of the audio cable. Through signal processing circuitry, including amplification, filtering, peak detection, and comparison, the state of the audio cable is ultimately determined: if the voltage at the resonant frequency is much greater than the voltage at other frequencies, the audio cable is normal; if the voltages are close, it indicates a short circuit; if the voltage is zero, it indicates an open circuit.

[0022] Furthermore, the detection plate 10 includes:

[0023] The audio interface has a positive pin connected to the positive wire of the first end of the audio cable 30 to be tested; an audio interface has a negative pin connected to the negative wire of the first end of the audio cable 30 to be tested; a signal generation circuit; a filter amplifier circuit, the input of which is connected to the signal generation circuit, and the output of which is connected to the positive pin of the audio interface; a sampling resistor, which is connected in series between the negative pin of the audio interface and the signal ground of the detection board 10, and the resistance of which is 20Ω; and a signal processing circuit, the input of which is connected to the sampling resistor, and the output of which is connected to the MCU of the detection board 10.

[0024] The positive pin of the audio interface is connected to the positive wire at the first end of the audio line 30 to be tested. It is the interface for input signals and is responsible for transmitting signals to the audio line 30 to be tested. The AC signal generated by the detection board 10 is transmitted to the audio line 30 to be tested through this positive pin.

[0025] The negative pin of the audio interface is connected to the negative wire at the first end of the audio line 30 to be tested. The negative pin and the positive pin together form the signal loop of the audio line 30 to be tested, and together with the positive pin, they form a complete loop of the audio line 30 to be tested. The voltage signal of the negative pin is collected by the sampling resistor and used to analyze the state of the audio line 30 to be tested.

[0026] The signal generation circuit is responsible for generating an AC signal for testing. The frequency of this AC signal is designed to be a dynamic frequency range. The signal generation circuit generates an AC signal according to the designed frequency, and after filtering and amplification, it outputs it to the positive pin of the audio interface to drive the transmission signal of the audio line 30 under test.

[0027] The task of the filter amplifier circuit is to amplify the AC signal generated above and filter out unwanted noise or interference signals. Its input terminal receives the AC signal output from the signal generation circuit, and its output terminal, after amplification and filtering, outputs the signal to the positive pin of the audio interface for use by the audio cable 30 under test. After processing by the filter and amplifier, the signal is ensured to be clear and have sufficient amplitude to effectively propagate on the audio cable 30 under test and to obtain reliable sampling results in subsequent testing.

[0028] A sampling resistor is connected in series between the negative pin of the audio interface and signal ground (GND) to sample the current and voltage of the audio line under test 30. The resistance value is set to 20Ω, a design that meets the testing accuracy requirements. The audio line under test 30 is connected to signal ground through the sampling resistor. During testing, the audio line under test, the speaker, the passive device board, and the sampling resistor together form a loop. The speaker and the passive device board are connected in parallel, and connected in series with the audio line under test, the passive device board, and the sampling resistor. The voltage signal across the sampling resistor is also a sine wave. The peak value of the sine wave reflects the state of the audio line under test 30. For example, when the audio line under test 30 is normal, the peak value of the sine wave across the sampling resistor will be larger at the resonant frequency of the passive device board than at other frequencies. When the audio line under test 30 is short-circuited, the passive device board is short-circuited, and the peak voltage of the sampling resistor is the same regardless of the frequency. When the audio line under test 30 is open-circuited, the entire loop is broken, and the voltage across the sampling resistor is almost zero regardless of the frequency.

[0029] The sampling resistor is set between the negative pin and the signal ground. On the one hand, the sampling resistor senses the voltage change of the negative terminal of the audio line 30 to be tested. The change in the peak value of the voltage reflects the state of the audio line 30 to be tested. On the other hand, one end of the sampling resistor is connected to the negative pin of the audio interface and the other end is connected to the signal ground. In this way, the voltage change can be transmitted to the microcontroller through the signal processing circuit, so as to make a state judgment.

[0030] The task of the signal processing circuit is to process the signal obtained from the sampling resistor and finally output the state judgment of the audio line 30 to be detected. Signal processing includes amplification, filtering, peak detection and comparison.

[0031] Furthermore, the signal processing circuit includes:

[0032] An amplifier amplifies the voltage across the sampling resistor using an operational amplifier; a peak detection circuit, with its input connected to the output of the amplifier, detects the peak value of the amplified sine wave; a comparator, with its input connected to the output of the peak detection circuit, compares the peak value with a specific voltage; and a microcontroller, with its input connected to the output of the comparator and its output connected to a status indicator.

[0033] The amplifier's function is to amplify the voltage signal obtained from the sampling resistor, enabling subsequent circuits to process and interpret these signals more accurately. The positive input terminal is connected to the line terminal of the sampling resistor, i.e., the negative terminal of the audio line 30 to be tested, the sampling point. The negative input terminal is connected to signal ground (GND) to form a differential input, ensuring signal amplification accuracy and stability. Through these two input terminals, the amplifier can receive and amplify the voltage signal obtained from the sampling resistor. Because the voltage across the sampling resistor is relatively small, amplification makes the signal more apparent and easier for further analysis.

[0034] The peak detection circuit's task is to extract the peak voltage of the amplified signal. The peak voltage represents the signal's maximum amplitude. By comparing the peak voltage at different frequencies, the state of the audio line 30 under test can be determined, such as normal, short-circuited, or open-circuited. This circuit receives the output signal from the amplifier, processes it, extracts the maximum voltage value in the signal, and avoids being affected by signal fluctuations. The peak voltage is the maximum voltage at a specific point in time, used for comparison with a preset voltage value.

[0035] The comparator's function is to compare the voltage value extracted by the peak detection circuit with a preset standard voltage value and output a logic signal. The state of the audio line 30 under test is determined by comparing the logic signals at different frequencies. The comparator's input is connected to the output of the peak detection circuit to receive the peak voltage signal, which is then compared with a preset reference voltage value. If the peak voltage is greater than the reference value, the comparator outputs a specific signal to the microcontroller.

[0036] The microcontroller is responsible for the final state determination and control output. It determines the state of the audio line 30 under test by comparing the comparator signals at different frequencies and controls the status indicator to display the final result. The microcontroller's input is connected to the comparator's output, receiving the status signal from the comparator. Based on the received comparison result, the microcontroller makes a judgment and executes corresponding operations, such as transmitting the status to the status indicator. Based on the microcontroller's output, the status indicator, such as an LED or display screen, displays the detection result of the audio line 30 under test. For example, if the audio line 30 is normal, it displays green; if a short circuit occurs, it displays red; if an open circuit occurs, it displays other indicators.

[0037] After the judgment is completed, switch the audio cable back to the amplifier connection to restore normal audio playback function.

[0038] Furthermore, the passive device board 20 includes:

[0039] A positive electrical connection terminal is connected to the positive wire at the second end of the audio line 30 to be tested; a negative electrical connection terminal is connected to the negative wire at the second end of the audio line 30 to be tested, forming an LC resonant circuit.

[0040] The positive electrical connection terminal connects the passive device board 20 to the positive wire at the second end of the audio cable 30 under test. It serves as the entry point for the signal into the passive device 20, connecting to the positive portion of the second end of the audio cable 30. The second end of the audio cable 30 is the connection point of the passive device board, with its positive wire connected to the board via the positive connection terminal. The function of this positive electrical connection terminal is to ensure that the signal from the audio cable 30 under test can be smoothly transmitted to the inductor L in the LC resonant circuit. In the LC circuit, the signal is transmitted to the inductor through this terminal and further enters the circuit.

[0041] The negative electrical connection terminal connects the passive device board 20 to the negative wire at the second end of the audio cable 30 under test. It serves as the signal outlet for the passive device 20 and connects to the negative portion of the audio cable 30. The negative wire at the second end of the audio cable 30 is connected to the passive device board 20 via the negative connection terminal. Through this connection, the negative portion of the audio cable 30 is connected to the capacitor C in the LC resonant circuit. The function of the negative electrical connection terminal is to help form an LC resonant circuit. The characteristic of an LC resonant circuit is that the circuit impedance is lowest at a specific frequency, and this characteristic can be used to determine the state of the audio cable 30 under test.

[0042] Example 2 is based on the same inventive concept as the audio line state detection device based on the LC resonant circuit in the previous examples, such as... Figure 2 As shown in the figure, this application provides an audio line state detection method based on an LC resonant circuit, the method comprising:

[0043] After disconnecting the amplifier connection of the audio cable under test, connect the test board to the first end of the audio cable under test and connect the passive device board to the second end of the audio cable under test.

[0044] In the actual testing process, the audio cable under test is first disconnected from the power amplifier to ensure that the test signal is not interfered with by the power amplifier output. This ensures that only the response of the test signal is involved in the testing process. Multiple speakers are connected in parallel on the audio cable. After each speaker is connected to an audio transformer, the equivalent resistance seen through the audio transformer is in the kiloohm range, increasing with frequency. The total impedance is denoted as Z1. A passive terminal LC series circuit is used, with impedance Z2 = R0 + j(ωL-1 / (ωC)), where R0 is the resistance of the inductor coil, ω is the angular frequency (lowest at the resonant frequency), and the sampling resistor R is used. Z1 and Z2 are connected in parallel and then in series with the sampling resistor. The total impedance of the speakers and passive terminal in parallel is... Voltage across the sampling resistor .

[0045] Connect the detection board to the first end of the audio cable. The detection board is the core of the entire system, responsible for generating test signals, amplifying signals, and processing test data. Connect the passive device board to the second end of the audio cable. The passive device board consists of an LC circuit, forming a resonant circuit for the test signal, used to determine the state of the audio cable.

[0046] The signal generation circuit of the detection board generates a first AC test signal at the first resonant frequency and a second AC test signal at the second resonant frequency.

[0047] Two different AC test signals are generated by the detection board. These signals are used to detect the response of the audio cable at different frequencies. The signal generation circuit generates a first AC test signal based on a first resonant frequency, which is a specific frequency of the LC resonant circuit. At this frequency, the impedance of the LC circuit is at its minimum, and the circuit's response to the signal is strongest. The signal generation circuit also generates a second AC test signal based on a second resonant frequency, which is far from the first resonant frequency. This second frequency is used to compare the signal's response at both the resonant and non-resonant frequencies. Figure 3 The figure shows the impedance amplitude characteristics of an exemplary LC series circuit.

[0048] After the filtering and amplification circuit amplifies and filters the first AC test signal and the second AC test signal, it is input to the positive wire of the audio line to be tested. The negative wire of the audio line to be tested is connected to the signal ground of the detection board through a sampling resistor.

[0049] The first and second AC test signals output from the signal generation circuit enter the filtering and amplification circuit. During filtering, unnecessary noise and interference signals are removed to ensure signal purity. During amplification, the signal amplitude is increased to ensure sufficient signal strength for detection. The amplified and filtered test signal is then input to the positive terminal of the audio cable under test through the output terminal of the detection board. Simultaneously, the negative terminal of the audio cable under test is connected to the signal ground of the detection board through a 20Ω sampling resistor. This sampling resistor is used to sample the voltage change through the audio cable, reflecting the state of the audio cable.

[0050] The dual-frequency voltage of the sampling resistor is detected by the signal processing circuit, and the state judgment of the audio line to be detected is output.

[0051] The signal processing circuit detects the voltage passing through the sampling resistor. This circuit detects dual-frequency voltage, that is, it obtains voltage values ​​at two different frequencies through the sampling resistor: the voltage at the first frequency, which is the first frequency of the test signal, and the voltage should have a large peak value, indicating that the audio line is working normally; the voltage at the second frequency, which is the second frequency of the test signal, and the voltage should be lower or close to zero, reflecting that the circuit impedance increases when the signal frequency is far from the resonant frequency.

[0052] The signal processing circuit compares the peak voltages at two frequencies: if the voltage at the first frequency is much greater than the voltage at the second frequency, it means that the audio line is working normally at the resonant frequency and the circuit is in normal condition; if the voltages at the two frequencies are close to equal and close to the amplitude of the input signal, it means that the audio line is short-circuited. At this time, the impedance when the current passes through the circuit is close to zero, resulting in almost no voltage attenuation; if the voltages at both frequencies are close to zero, it means that the audio line is open-circuited, the signal cannot pass through the audio line, resulting in almost zero voltage on the sampling resistor.

[0053] The signal processing circuit ultimately outputs these comparison results through a microcontroller, indicating the status of the audio cable, such as normal, short circuit, or open circuit. The output of the microcontroller is connected to a status indicator device, such as an LED or a display screen, so that the user can see the status of the audio cable in real time.

[0054] Furthermore, the dual-frequency voltage detection of the sampling resistor is performed through a signal processing circuit, and the state judgment of the audio line to be detected is output, including:

[0055] The voltage of the sampling resistor is amplified by an amplifier to obtain a first amplified signal and a second amplified signal; the peak detection circuit receives and extracts the peak voltage of the first amplified signal and the second amplified signal to obtain the peak voltage of the first resistor and the peak voltage of the second resistor; the comparator receives and transmits the peak voltage of the first resistor and the peak voltage of the second resistor to the microcontroller to determine the state of the audio line to be detected.

[0056] The voltage across the sampling resistor reflects the state of the audio line. The signal strength is typically low, so an amplifier is needed to increase its amplitude. The amplifier amplifies the voltage signal generated by the sampling resistor, resulting in two amplified signals at different frequencies: the first amplified signal, based on the voltage signal at the audio line's resonant frequency, has increased amplitude after amplification; the second amplified signal, based on the voltage signal at a frequency far from the resonant frequency, also has increased amplitude after amplification. The amplified signals will have sufficient strength for subsequent voltage value extraction and analysis using a peak detection circuit.

[0057] The peak detection circuit receives the first and second amplified signals output from the amplifier and detects the maximum voltage value of the signals, i.e., the peak voltage. For each amplified signal, the peak detection circuit extracts the value of the maximum voltage in the signal. These two voltage values ​​are key data for analyzing the audio cable's condition: the first resistance peak voltage represents the peak voltage at the resonant frequency, indicating the audio cable's performance at that frequency; the second resistance peak voltage represents the peak voltage far from the resonant frequency, reflecting the audio cable's performance at non-resonant frequencies. These two peak voltage values ​​provide a basis for judging the audio cable's condition; changes in the signal at resonant and non-resonant frequencies reflect the health of the audio cable.

[0058] The comparator receives and compares the peak voltages of the first and second resistors extracted from the peak detection circuit. If the peak voltage of the first resistor is significantly greater than that of the second resistor, it indicates that the audio line has strong voltage transmission at the resonant frequency, indicating that the audio line is in normal working condition. If the two voltages are close and both are close to the amplitude of the input signal, it indicates that the audio line has a short circuit, because the impedance is close to zero in the case of a short circuit, resulting in almost no signal attenuation. If both the peak voltages of the first and second resistors are zero, it indicates that the audio line has an open circuit, because current cannot flow when the circuit is open, resulting in voltage transmission failure.

[0059] The comparator transmits the comparison result to the microcontroller. The microcontroller makes a judgment based on the received comparison result and displays the corresponding result according to the status of the audio line, such as normal status, short circuit status, or open circuit status.

[0060] Furthermore, if the peak voltage of the first resistor is much greater than the peak voltage of the second resistor, then the microcontroller outputs the status of the audio line to be tested as normal.

[0061] The peak voltage of the first resistor comes from the signal response at the resonant frequency, and the peak voltage of the second resistor comes from the signal response at a frequency far from the resonant frequency. If the peak voltage of the signal at the resonant frequency is significantly higher than the peak voltage at a frequency far from the resonant frequency, it means that the audio cable can transmit the signal normally at the resonant frequency, and the circuit impedance is low, so the signal can pass through smoothly. Therefore, the audio cable is in normal condition, and in this case, the microcontroller outputs the normal state of the audio cable.

[0062] Furthermore, if the peak voltage of the first resistor is equal to the peak voltage of the second resistor and is close to the peak value of the detected AC voltage, then the microcontroller outputs that the audio line to be detected is in a short-circuit state.

[0063] In a short-circuit state, the current path of the audio cable has almost no impedance, resulting in almost no signal attenuation. Since the impedance of the audio cable is close to zero, the signal response at the resonant frequency and far from the resonant frequency is almost the same, that is, the voltage is close and close to the input voltage value of the signal source, that is, the peak value of the AC voltage. This is a typical short-circuit phenomenon. The microcontroller outputs the short-circuit state of the audio cable based on this judgment result.

[0064] Furthermore, if both the peak voltage of the first resistor and the peak voltage of the second resistor are set to 0, then the microcontroller outputs that the audio line to be detected is in an open circuit state.

[0065] In the open circuit state, the audio line cannot transmit signals. Therefore, neither the test signal at the resonant frequency nor the test signal far from the resonant frequency can transmit current through the line, resulting in the voltage on the sampling resistor being almost zero. This means that the peak voltage of the first resistor and the peak voltage of the second resistor are both zero. The microcontroller outputs this result as the audio line being open circuit.

[0066] Furthermore, the second resonant frequency is much greater than the first resonant frequency, or the second resonant frequency is much less than the first resonant frequency. In the scenario where the second resonant frequency is much greater than the first resonant frequency, the second resonant frequency is an LC resonant frequency fluctuating at 38 kHz, the frequency value of the first resonant frequency fluctuates at 23 kHz, and both the first and second resonant frequencies are greater than 20 kHz.

[0067] The second resonant frequency is far from the first resonant frequency so that the state of the audio line can be accurately determined by comparing the signal response at the two different frequencies. Specifically, the second resonant frequency is greater than or equal to 1.5 times the first resonant frequency or less than or equal to 0.5 times the first resonant frequency. The design of the frequency difference makes the response at the two frequencies more distinguishable, which is conducive to the accurate detection of the state of the audio line.

[0068] In practical applications, the selection of the first and second resonant frequencies involves clear technical considerations. The second resonant frequency is set near the resonant frequency of the LC circuit. At this point, the LC circuit exhibits extremely low impedance, maximizing the circuit current and resulting in a high peak voltage captured by the sampling resistor. The first resonant frequency, serving as a reference point, avoids the resonant center. 38kHz is approximately 1.65 times that of 23kHz, satisfying a ratio design greater than 1.5 times. At this frequency, the LC circuit exhibits high impedance, and the peak voltage across the sampling resistor is extremely low. Through this extreme contrast of high and low frequencies, the microcontroller can eliminate interference caused by factors such as wire length and distributed capacitance, thereby accurately determining the circuit status.

[0069] Meanwhile, both the first and second resonant frequencies are greater than 20kHz. This design ensures that during the testing process, even if the audio cable is still connected to the speaker, the test signal is in the ultrasonic frequency band and will not drive the speaker to emit audible interference. This enables online silent testing, improves the user experience, and avoids acoustic impact on sensitive audio equipment.

[0070] After the judgment is completed, switch the audio cable back to the amplifier connection to restore normal audio playback function.

[0071] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An audio line state detection method based on an LC resonant circuit, characterized in that, The method includes: After disconnecting the amplifier connection of the audio cable under test, connect the test board to the first end of the audio cable under test and connect the passive device board to the second end of the audio cable under test. The signal generation circuit of the detection board generates a first AC test signal at the first resonant frequency and a second AC test signal at the second resonant frequency. After the filtering and amplification circuit amplifies and filters the first AC test signal and the second AC test signal, it is input to the positive wire of the audio line to be tested, wherein the negative wire of the audio line to be tested is connected to the signal ground of the detection board through a sampling resistor; The dual-frequency voltage of the sampling resistor is detected by the signal processing circuit, and the state judgment of the audio line to be detected is output.

2. The audio line state detection method based on LC resonant circuit as described in claim 1, characterized in that, The dual-frequency voltage detection of the sampling resistor is performed through a signal processing circuit, and the state judgment of the audio line to be detected is output, including: The voltage of the sampling resistor is amplified by an amplifier to obtain a first amplified signal and a second amplified signal; The peak detection circuit receives and extracts the peak voltages of the first amplified signal and the second amplified signal to obtain the peak voltage of the first resistor and the peak voltage of the second resistor. The comparator receives and transmits the peak voltage of the first resistor and the peak voltage of the second resistor to the microcontroller to determine the state of the audio line to be detected.

3. The audio line state detection method based on LC resonant circuit as described in claim 2, characterized in that, If the peak voltage of the first resistor is much greater than the peak voltage of the second resistor, then the microcontroller outputs that the status of the audio line to be tested is normal.

4. The audio line state detection method based on LC resonant circuit as described in claim 3, characterized in that, If the peak voltage of the first resistor is equal to the peak voltage of the second resistor and is close to the peak value of the detected AC voltage, then the microcontroller outputs that the audio line to be detected is in a short-circuit state.

5. The audio line state detection method based on LC resonant circuit as described in claim 4, characterized in that, If the peak voltage of the first resistor and the peak voltage of the second resistor are both set to 0, the microcontroller outputs that the audio line to be detected is in an open circuit state.

6. The audio line state detection method based on LC resonant circuit as described in claim 1, characterized in that, The second resonant frequency is much greater than the first resonant frequency, or the second resonant frequency is much less than the first resonant frequency. In the scenario where the second resonant frequency is much greater than the first resonant frequency, the second resonant frequency is an LC resonant frequency fluctuating at 38 kHz, the frequency value of the first resonant frequency fluctuates at 23 kHz, and both the first and second resonant frequencies are greater than 20 kHz.

7. An audio line status detection device based on an LC resonant circuit, characterized in that, The device includes: Detection plate; A passive device board, wherein the passive device board is composed of an inductor L and a capacitor C connected in series; The detection board is connected to the first end of the audio cable to be tested, the passive device board is connected to the second end of the audio cable to be tested, and N speakers are connected in the middle of the audio cable to be tested.

8. The audio line status detection device based on an LC resonant circuit as described in claim 7, characterized in that, The detection plate includes: The positive pin of the audio interface is connected to the positive wire at the first end of the audio cable to be tested; The negative pin of the audio interface is connected to the negative wire at the first end of the audio cable to be tested; Signal generation circuit; A filtering and amplifying circuit, wherein the input terminal of the filtering and amplifying circuit is connected to the signal generating circuit, and the output terminal of the filtering and amplifying circuit is connected to the positive pin of the audio interface; A sampling resistor is connected in series between the negative pin of the audio interface and the signal ground of the detection board, and the resistance of the sampling resistor is 20Ω. The signal processing circuit has an input terminal connected to a sampling resistor and an output terminal connected to the MCU of the detection board.

9. The audio line status detection device based on an LC resonant circuit as described in claim 8, characterized in that, The signal processing circuit includes: An amplifier that amplifies the voltage across the sampling resistor using an operational amplifier; The peak detection circuit, with its input terminal connected to the output terminal of the amplifier, detects the peak value of the amplified sine wave. A comparator, the input of which is connected to the output of the peak detection circuit, compares the peak value with a specific voltage; A microcontroller, wherein the input terminal of the microcontroller is connected to the output terminal of the comparator, and the output terminal is connected to a status indicator device.

10. The audio line status detection device based on an LC resonant circuit as described in claim 7, characterized in that, The passive device board includes: A positive electrical connection terminal, wherein the positive electrical connection terminal is connected to the positive wire at the second end of the audio line to be tested; A negative electrical connection terminal is provided, which is connected to the negative wire at the second end of the audio line to be tested, forming an LC resonant circuit.

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