Engineering vehicle onboard microphone filtering circuit and onboard communication equipment
By introducing a signal bias module and a filtering module into the onboard microphone circuit of engineering vehicles, the noise interference problem was solved, high-quality audio signal transmission and accurate communication were achieved, and the work efficiency of construction workers and drivers was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HUIZHOU HAOSHENG ELECTRONIC CO LTD
- Filing Date
- 2025-04-09
- Publication Date
- 2026-05-26
AI Technical Summary
The onboard microphones of engineering vehicles have difficulty effectively filtering out noise in noisy environments, resulting in poor reliability of voice recognition and communication.
The engineering vehicle-mounted microphone filtering circuit adopts a communication main control chip, audio amplification module, signal biasing module and filtering module. Through components such as signal amplification switching tube, coupling capacitor, bias resistor and filtering capacitor, it can achieve accurate signal bias and effective filtering and reduce noise interference.
It significantly improved the quality of audio signals, reduced communication interruptions and misjudgments caused by noise interference, and improved the accuracy of construction workers' instruction judgment and the operational coordination efficiency of engineering vehicle drivers.
Smart Images
Figure CN224289992U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the technical field of voice communication for engineering vehicles, and in particular to an on-board microphone filtering circuit and on-board communication equipment for engineering vehicles. Background Technology
[0002] In engineering vehicle applications (such as excavators, loaders, and concrete mixers), vehicle-mounted microphones serve as crucial sound acquisition and communication devices, essential for effective communication inside and outside the vehicle. However, engineering vehicles typically operate in extremely noisy environments, including engine roar, mechanical noise, and construction site noise. These noise sources are complex, diverse, and intense, posing significant challenges to the sound recognition and monitoring capabilities of vehicle-mounted microphones.
[0003] Traditional engineering vehicle microphone circuits lack effective noise reduction and filtering mechanisms, resulting in a large amount of environmental noise being recorded and transmitted along with the audio signal. This seriously affects the clarity and recognizability of the speech and easily causes signal distortion, thereby reducing the accuracy of voice recognition and the reliability of vehicle communication. Utility Model Content
[0004] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide an engineering vehicle on-board microphone filtering circuit and on-board communication equipment that improves the accuracy of sound recognition.
[0005] The purpose of this disclosure is achieved through the following technical solution:
[0006] A filtering circuit for an onboard microphone in an engineering vehicle includes a communication main control chip, an audio amplification module, a signal biasing module, and a filtering module. The audio amplification module includes a signal amplification switch transistor, a coupling capacitor, a first bias resistor, and a first voltage divider resistor. One end of the coupling capacitor is connected to the control terminal of the signal amplification switch transistor, and the other end of the coupling capacitor is used to connect to the positive input terminal of the microphone. The first terminal of the signal amplification switch transistor is connected to the input terminal of the filtering module, and the second terminal of the signal amplification switch transistor is grounded. The first terminal of the first bias resistor is connected to the first terminal of the signal amplification switch transistor, and the second terminal of the first bias resistor is connected to the control terminal of the signal amplification switch transistor. The first terminal of the first voltage divider resistor is used to connect to an external power supply terminal, and the second terminal of the first voltage divider resistor is connected to the first terminal of the signal amplification switch transistor.
[0007] The input terminal of the signal bias module is connected to the bias signal control terminal of the communication main control chip, and the output terminal of the signal bias module is connected to the control terminal of the signal amplification switch; the output terminal of the filtering module is connected to the microphone signal input terminal of the communication main control chip.
[0008] In one embodiment, the audio amplification module further includes a voltage suppression diode, one end of which is connected to the positive input terminal of the microphone, and the other end of which is grounded.
[0009] In one embodiment, the audio amplification module further includes a feedback resistor, the first end of which is connected to the second end of the signal amplification switching transistor, and the second end of which is grounded.
[0010] In one embodiment, the signal amplification switch is an NPN transistor.
[0011] In one embodiment, the signal biasing module includes a second biasing resistor and a first filtering capacitor. The first end of the second biasing resistor is connected to the bias signal control terminal of the communication main control chip and an external power supply, respectively. The second end of the second biasing resistor is connected to the control terminal of the signal amplification switch. One end of the first filtering capacitor is used to connect to the external power supply, and the second end of the first filtering capacitor is grounded.
[0012] In one embodiment, the signal biasing module further includes a second voltage divider resistor, the first end of which is connected to an external power supply, and the second end of which is grounded.
[0013] In one embodiment, the filtering module includes a low-pass filter resistor and a low-pass filter capacitor. The first end of the low-pass filter resistor is connected to the first end of the signal amplification switch transistor, the second end of the low-pass filter resistor is connected to the microphone signal input terminal of the communication main control chip, the first end of the low-pass filter capacitor is connected to the second end of the low-pass filter resistor, and the second end of the low-pass filter capacitor is grounded.
[0014] In one embodiment, the filtering module includes a high-pass filter resistor and a high-pass filter capacitor. The first terminal of the high-pass filter capacitor is connected to the second terminal of the low-pass filter resistor. The second terminal of the high-pass filter capacitor is connected to the first terminal of the high-pass filter resistor and the microphone signal input terminal, respectively. The second terminal of the high-pass filter resistor is grounded.
[0015] In one embodiment, the audio amplification module further includes a third voltage divider resistor, the first end of which is connected to an external power supply terminal, and the second end of which is connected to the first end of the first voltage divider resistor.
[0016] This application also provides a vehicle-mounted communication device, including the vehicle-mounted microphone filtering circuit of any embodiment of the engineering vehicle.
[0017] Compared with the prior art, this disclosure has at least the following advantages:
[0018] The aforementioned vehicle-mounted microphone filtering circuit for engineering vehicles, based on traditional vehicle-mounted microphone circuits, adds a precise signal bias module and an effective filtering module, thereby significantly improving the audio signal quality transmitted from the microphone to the communication main control chip. Furthermore, the clear audio signal enables construction personnel to obtain accurate audio information through the vehicle-mounted camera system, reducing communication interruptions or misjudgments caused by signal interference or noise. This meets the audio acquisition needs of engineering vehicles in complex environments, thus assisting construction personnel in making accurate command judgments and improving the operational efficiency and communication accuracy of engineering vehicle drivers. Attached Figure Description
[0019] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0020] Figure 1 This is a circuit diagram of an embodiment of an engineering vehicle's on-board microphone filtering circuit. Detailed Implementation
[0021] To facilitate understanding of this disclosure, a more complete description will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the present disclosure. However, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.
[0022] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.
[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0024] To better understand the technical solutions and beneficial effects of this disclosure, the following detailed description is provided in conjunction with specific embodiments:
[0025] like Figure 1 As shown, an embodiment of the engineering vehicle on-board microphone filtering circuit 10 of this disclosure includes a communication main control chip U1, an audio amplification module 100, a signal biasing module 200, and a filtering module 300. The audio amplification module 100 includes a signal amplification switch Q1, a coupling capacitor C1, a first bias resistor R5, and a first voltage divider resistor R6. One end of the coupling capacitor C1 is connected to the control terminal of the signal amplification switch Q1, and the other end of the coupling capacitor C1 is used to connect to the positive input terminal MIC+ of the microphone. The first end of the signal amplification switch Q1 is connected to the input terminal of the filtering module 300, and the second end of the signal amplification switch Q1 is grounded. The first end of the first bias resistor R5 is connected to the first end of the signal amplification switch Q1, and the second end of the first bias resistor R5 is connected to the control terminal of the signal amplification switch Q1. The first end of the first voltage divider resistor R6 is used to connect to an external power supply terminal, and the second end of the first voltage divider resistor R6 is connected to the first end of the signal amplification switch Q1.
[0026] The input terminal of the signal bias module 200 is connected to the bias signal control terminal MIC-BIAS of the communication main control chip U1, and the output terminal of the signal bias module 200 is connected to the control terminal of the signal amplification switch Q1; the output terminal of the filter module 300 is connected to the microphone signal input terminal of the communication main control chip U1.
[0027] In this embodiment, the microphone acquires ambient sound signals and converts them into electrical signals, which are then transmitted to the audio amplification module 100 via its positive input terminal MIC+. At this time, the communication main control chip U1 outputs a bias voltage through the bias signal control terminal MIC-BIAS. This voltage is transmitted to the control terminal of the signal amplification switch Q1 via the signal bias module 200, ensuring that the signal amplification switch Q1 operates at a suitable operating point and correctly amplifies the microphone input signal. Since the coupling capacitor C1 can isolate the DC bias voltage while allowing AC sound signals to pass through, the AC signal generated by the microphone can be transmitted to the control terminal of the signal amplification switch Q1 via the coupling capacitor C1, enabling the signal amplification switch Q1 to amplify the input signal after receiving it. The amplified signal is output from the first terminal of the signal amplification switch Q1 and transmitted to the input terminal of the filtering module 300. Then, the signal, after being filtered by the filtering module 300 to remove high-frequency noise and interference, is transmitted to the microphone signal input terminal BT-MICIN of the communication main control chip U1. Finally, the communication main control chip U1 further processes the received audio signal and uses it as the audio input for the vehicle-mounted camera system. This allows construction personnel to obtain clear audio information through the vehicle-mounted camera and make accurate command judgments, thereby improving the communication accuracy and reliability of the construction vehicle driver. Furthermore, the preferred model of the main control chip U1 is the TLV320AIC3106, which has built-in programmable MIC-BIAS and PGA, and can be directly adapted to the signal bias module 200 and the audio amplification module 100.
[0028] The aforementioned vehicle-mounted microphone filtering circuit 10, based on a traditional vehicle-mounted microphone circuit, adds a precise signal bias module 200 and an effective filtering module 300, thereby significantly improving the audio signal quality transmitted from the microphone to the communication main control chip U1. Furthermore, the clear audio signal enables construction personnel to obtain accurate audio information through the vehicle-mounted camera system, reducing communication interruptions or misjudgments caused by signal interference or noise. This meets the audio acquisition needs of construction vehicles in complex environments, thereby assisting construction personnel in making accurate command judgments and improving the operational efficiency and communication accuracy of construction vehicle drivers.
[0029] like Figure 1As shown, in one embodiment, the audio amplification module 100 further includes a voltage suppression diode D1. One end of the voltage suppression diode D1 is connected to the positive input terminal MIC+ of the microphone, and the other end of the voltage suppression diode D1 is grounded. In this embodiment, when the microphone normally acquires the ambient sound signal and converts it into an electrical signal, the electrical signal is transmitted to the audio amplification module 100 through the positive input terminal MIC+. At this time, since the signal voltage is within the normal range, the voltage suppression diode D1 is in a reverse bias state and exhibits high impedance characteristics, approximately an open circuit state, having almost no impact on the normal AC audio signal. The signal can be smoothly transmitted through the coupling capacitor C1 to the control terminal of the signal amplification switch Q1, and then amplified normally by the signal amplification switch Q1. In the complex electromagnetic environment of an engineering vehicle, abnormally high voltages may be generated at the positive input terminal MIC+ of the microphone due to static electricity, lightning strikes, power surges, etc. When the abnormally high voltage exceeds the reverse breakdown voltage of the voltage suppression diode D1, the voltage suppression diode D1 will break down and conduct. At this time, the voltage suppression diode D1 changes from a high impedance state to a low impedance state, providing a low impedance discharge path for the abnormally high voltage. Abnormally high voltage is directly grounded through voltage suppression diode D1, thereby preventing excessive voltage from being transmitted to signal amplification switch Q1, and thus effectively preventing abnormally high voltage from damaging signal amplification switch Q1 and communication main control chip U1.
[0030] like Figure 1 As shown, in one embodiment, the audio amplification module 100 further includes a feedback resistor R4. The first end of the feedback resistor R4 is connected to the second end of the signal amplification switch Q1, and the second end of the feedback resistor R4 is grounded. In this embodiment, when the sound signal acquired by the microphone is transmitted to the control terminal of the signal amplification switch Q1 through the coupling capacitor C1, the signal amplification switch Q1 amplifies the signal. The amplified signal is output from the first terminal of the signal amplification switch Q1, and at the same time, the voltage drop generated by the current at the second terminal of the signal amplification switch Q1 across the feedback resistor R4 forms negative feedback to stabilize the operating point of Q1. When the voltage of the amplified signal increases, the voltage fed back to the emitter of the signal amplification switch Q1 through the feedback resistor R4 also increases. This causes the voltage difference between the control terminal and the second terminal of the signal amplification switch Q1 to decrease, thereby reducing the gain effect of the signal amplification switch Q1 and making the output signal voltage tend to stabilize. Conversely, when the output signal voltage decreases, the negative feedback will enhance the amplification effect of the signal amplification switch Q1 to maintain the stability of the output signal. The negative feedback mechanism also helps stabilize the operating point of the signal amplification switch Q1, thereby automatically adjusting the amplification factor and operating point of the signal amplification switch Q1 to keep it in the optimal state, thus improving the stability of the audio amplification module 100.
[0031] like Figure 1As shown, in one embodiment, the signal amplification switch Q1 is an NPN transistor. In this embodiment, the first terminal of the signal amplification switch Q1 is the collector of the NPN transistor, the second terminal is the emitter of the NPN transistor, and the control terminal is the base of the NPN transistor. When the audio signal acquired by the microphone is transmitted to the base of the signal amplification switch Q1 through the coupling capacitor C1, the change in the base current will cause a larger change in the collector current, thereby amplifying the signal. Specifically, when the base current increases, the collector current will also increase accordingly, and the increase ratio is much greater than the increase ratio of the base current, thereby amplifying the weak input audio signal. In addition, the communication main control chip U1 outputs a bias voltage through the bias signal control terminal MIC-BIAS. This voltage is transmitted to the base of the signal amplification switch Q1 through the signal bias module 200, so that the signal amplification switch Q1 operates at a suitable operating point.
[0032] like Figure 1As shown, in one embodiment, the signal biasing module 200 includes a second biasing resistor R11 and a first filtering capacitor C6. The first end of the second biasing resistor R11 is connected to the bias signal control terminal MIC-BIAS of the communication main control chip U1 and an external power supply, respectively. The second end of the second biasing resistor R11 is connected to the control terminal of the signal amplification switch Q1. One end of the first filtering capacitor C6 is connected to the external power supply, and the second end of the first filtering capacitor C6 is grounded. In this embodiment, the bias voltage output by the bias signal control terminal MIC-BIAS of the communication main control chip U1 is transmitted to the base of the signal amplification switch Q1 through the second biasing resistor R11. The second biasing resistor R11 works in conjunction with the first biasing resistor R5 and the first voltage divider resistor R6 to jointly determine the bias current at the base of the signal amplification switch Q1. According to Ohm's law, the magnitude of the bias current depends on the voltage division relationship between the bias voltage and the resistors such as the second biasing resistor R11. Since the second bias resistor R11 acts as a voltage divider, it prevents excessively high voltage from being applied directly to the base of the signal amplification switch Q1, avoiding damage or abnormal operation of Q1 due to excessive voltage. Simultaneously, when the external power supply voltage or the voltage output from the bias signal control terminal MIC-BIAS fluctuates, the second bias resistor R11 buffers and adjusts the voltage to a certain extent, ensuring a relatively stable bias voltage applied to the base of the signal amplification switch Q1. By appropriately selecting the value of the second bias resistor R11, the static operating point of the signal amplification switch Q1 can be precisely set, allowing Q1 to operate at an appropriate position in the amplification region. This ensures linear amplification of the audio signal input from the microphone, reducing distortion and improving the amplification quality of the audio signal. The first filter capacitor C6 is connected in parallel between the second bias resistor R11 and the external power supply, enabling it to filter out high-frequency noise and interference from the power supply. When there is high-frequency noise in the external power supply, the noise will be transmitted to the base of the signal amplification switch Q1 through the second bias resistor R11. However, C6 will provide a low-impedance path to bypass the high-frequency noise to ground, thereby protecting the base of the signal amplification switch Q1 from noise interference. This will help improve the anti-interference capability of the entire circuit and enable the engineering vehicle on-board microphone filter circuit 10 to maintain a stable working state in a complex and ever-changing electromagnetic environment.
[0033] like Figure 1As shown, in one embodiment, the signal biasing module 200 further includes a second voltage divider resistor R10. The first end of the second voltage divider resistor R10 is connected to an external power supply, and the second end of the second voltage divider resistor R10 is grounded. In this embodiment, the second voltage divider resistor R10 is connected in series between the external power supply and the ground terminal to form a voltage divider branch. When the external power supply provides voltage, the second bias resistor R11 transmits the bias voltage output from the bias signal control terminal MIC-BIAS of the communication main control chip U1 to the base of the signal amplification switch Q1. The second voltage divider resistor R10 and the second bias resistor R11, through voltage division, change the resistance ratio between the resistors, causing a change in the voltage across the second bias resistor R11, thereby affecting the bias current of the base of Q1. Furthermore, in the actual working environment of the engineering vehicle, the voltage of the external power supply may fluctuate to some extent. When the external power supply voltage increases, the voltage drop across the second bias resistor R11 is relatively small due to the voltage division effect of the second voltage divider resistor R10, thus ensuring the stability of the base bias voltage of the signal amplification switch Q1. Conversely, when the external power supply voltage decreases, the second voltage divider resistor R10 also acts as a buffer, preventing a significant drop in the base bias voltage of the signal amplification switch Q1. This helps the signal amplification switch Q1 always operate at a suitable operating point, thereby improving the stability of its amplification performance.
[0034] like Figure 1As shown, in one embodiment, the filtering module 300 includes a low-pass filter resistor R12 and a low-pass filter capacitor C7. The first terminal of the low-pass filter resistor R12 is connected to the first terminal of the signal amplification switch Q1, and the second terminal of the low-pass filter resistor R12 is connected to the microphone signal input terminal of the communication main control chip U1. The first terminal of the low-pass filter capacitor C7 is connected to the second terminal of the low-pass filter resistor R12, and the second terminal of the low-pass filter capacitor C7 is grounded. In this embodiment, after the signal amplification switch Q1 amplifies the audio signal input from the microphone, the amplified signal is output from the first terminal of the signal amplification switch Q1 and transmitted to the first terminal of the low-pass filter resistor R12. At this time, the low-pass filter resistor R12 and the low-pass filter capacitor C7 together form a low-pass filter circuit. This circuit allows low-frequency signals to pass smoothly while attenuating high-frequency interference signals. Specifically, according to the RC filtering principle, when the signal frequency is low, the capacitive reactance of the low-pass filter capacitor C7 is relatively large, equivalent to a large resistor. Together with the low-pass filter resistor R12, it divides the signal voltage. However, due to the low signal frequency, the charging and discharging time constant of the capacitor is relatively large, allowing the signal to be transmitted smoothly through the low-pass filter resistor R12 to the subsequent circuits. When the signal frequency is high, the capacitive reactance of the low-pass filter capacitor C7 is relatively small, equivalent to a short circuit. At this time, most of the high-frequency signal will bypass to ground through the low-pass filter capacitor C7, thereby reducing the impact of the high-frequency signal on the subsequent circuits. This allows the low-frequency audio signal to be transmitted smoothly through the low-pass filter resistor R12 to the microphone signal input terminal BT-MICIN of the communication main control chip U1, while high-frequency noise and interference are attenuated, thus achieving signal filtering.
[0035] like Figure 1 As shown, in one embodiment, the filtering module 300 includes a high-pass filter resistor R13 and a high-pass filter capacitor C8. The first terminal of the high-pass filter capacitor C8 is connected to the second terminal of the low-pass filter resistor R12. The second terminal of the high-pass filter capacitor C8 is connected to the first terminal of the high-pass filter resistor R13 and the microphone signal input terminal BT-MICIN. The second terminal of the high-pass filter resistor R13 is grounded. In this embodiment, the high-pass filter resistor R13 and the high-pass filter capacitor C8 together constitute a high-pass filter circuit. When the signal after low-pass filtering is output from the second terminal of the low-pass filter resistor R12, it will be transmitted to the first terminal of the high-pass filter capacitor C8. The working principle of the high-pass filter circuit is based on the capacitive reactance characteristic of the capacitor. The capacitive reactance formula is: Xc = 1 / (2πfc), where f is the signal frequency and C is the capacitance value. When the signal frequency is low, the capacitive reactance Xc of the high-pass filter capacitor C8 is low. CThe voltage drop across the high-pass filter capacitor C8 is relatively large. At this point, most of the low-frequency signal voltage drops across the high-pass filter resistor R13, making it difficult for the low-frequency signal to reach the microphone signal input of the communication main control chip U1 through the high-pass filter resistor R13, thus effectively attenuating it. When the signal frequency is high, the capacitive reactance X of the high-pass filter capacitor C8 increases. C The signal is relatively small. At this time, the high-pass filter capacitor C8 is approximately short-circuited, and the high-frequency signal can pass through the high-pass filter capacitor C8 relatively smoothly, and then through the high-pass filter resistor R13 to the microphone signal input terminal of the communication main control chip U1.
[0036] Specifically, when low-pass and high-pass filter circuits are used together, they form a band-pass filter circuit. The band-pass filter circuit only allows signals within a specific frequency range to pass through, while attenuating signals outside that range. The low-pass filter circuit is responsible for filtering out high-frequency noise and interference, while the high-pass filter circuit is responsible for filtering out low-frequency noise and interference. Together, they ensure that only audio signals within the middle frequency range can pass smoothly through the filter module 300 and be transmitted to the microphone signal input terminal BT-MICIN of the communication main control chip U1. Furthermore, since there may be low-frequency mechanical vibration noise and high-frequency electromagnetic radiation noise around the construction vehicle, the aforementioned band-pass filter circuit can filter out these noises, making the audio signal received by the communication main control chip U1 purer. The clear audio signal allows construction personnel to obtain accurate audio information through the vehicle-mounted camera system, reducing communication interruptions or misjudgments caused by signal interference or noise. This meets the audio acquisition needs of construction vehicles in complex environments, thereby assisting construction personnel in making accurate command judgments and improving the operational efficiency and communication accuracy of construction vehicle drivers.
[0037] like Figure 1As shown, in one embodiment, the audio amplification module further includes a third voltage divider resistor R7. The first end of the third voltage divider resistor R7 is connected to the external power supply terminal, and the second end of the third voltage divider resistor R7 is connected to the first end of the first voltage divider resistor R6. In this embodiment, the third voltage divider resistor R7, the external power supply terminal, and the first voltage divider resistor R6 together form a voltage divider branch. When the external power supply provides voltage, the voltage is distributed according to the resistance ratio of the third voltage divider resistor R7 and the first voltage divider resistor R6. Since the other end of the first voltage divider resistor R6 is connected to the collector of the signal amplification switch Q1, its function is to provide a suitable voltage to the collector of the signal amplification switch Q1. At this time, the third voltage divider resistor R7 affects the voltage value of the collector of the signal amplification switch Q1 through its voltage division effect. When the external power supply voltage changes, the voltage change is relatively gradual due to the voltage division of the third voltage divider resistor R7. This avoids sudden changes in the collector voltage of the signal amplification switch Q1, which helps the signal amplification switch Q1 to work at a suitable operating point. This also prevents the signal amplification switch Q1 from becoming unstable due to large fluctuations in the collector voltage, thus ensuring that the signal amplification switch Q1 can amplify the microphone input signal normally.
[0038] This application also provides a vehicle-mounted communication device, including a vehicle-mounted microphone filtering circuit 10 of any embodiment. In this embodiment, the microphone acquires the ambient sound signal and converts it into an electrical signal, which is then transmitted to the audio amplification module 100 through its positive input terminal MIC+. At this time, the communication main control chip U1 outputs a bias voltage through the bias signal control terminal MIC-BIAS. This voltage is transmitted to the control terminal of the signal amplification switch Q1 through the signal bias module 200, so that the signal amplification switch Q1 operates at a suitable operating point and can correctly amplify the signal input by the microphone. Since the coupling capacitor C1 can be used to isolate the DC bias voltage and allow the AC sound signal to pass through, the AC signal generated by the microphone can be transmitted to the control terminal of the signal amplification switch Q1 through the coupling capacitor C1, so that the signal amplification switch Q1 amplifies the input signal after receiving the signal input by the microphone. The amplified signal is output from the first terminal of the signal amplification switch Q1 and transmitted to the input terminal of the filtering module 300. Then, the signal after the high-frequency noise and interference are filtered out by the filtering module 300 is transmitted to the microphone signal input terminal BT-MICIN of the communication main control chip U1. Finally, the communication main control chip U1 further processes the received audio signal and uses it as the audio input for the vehicle-mounted camera system, enabling construction personnel to obtain clear audio information through the vehicle-mounted camera and make accurate command judgments, thereby improving the communication accuracy and reliability of the engineering vehicle driver.
[0039] Compared with the prior art, this disclosure has at least the following advantages:
[0040] The aforementioned vehicle-mounted microphone filtering circuit 10, based on a traditional vehicle-mounted microphone circuit, adds a precise signal bias module 200 and an effective filtering module 300, thereby significantly improving the audio signal quality transmitted from the microphone to the communication main control chip U1. Furthermore, the clear audio signal enables construction personnel to obtain accurate audio information through the vehicle-mounted camera system, reducing communication interruptions or misjudgments caused by signal interference or noise. This meets the audio acquisition needs of construction vehicles in complex environments, thereby assisting construction personnel in making accurate command judgments and improving the operational efficiency and communication accuracy of construction vehicle drivers.
[0041] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the disclosed patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.
Claims
1. A filtering circuit for an onboard microphone in an engineering vehicle, characterized in that, This includes a communication main control chip, an audio amplification module, a signal biasing module, and a filtering module. The audio amplification module includes a signal amplification switch transistor, a coupling capacitor, a first bias resistor, and a first voltage divider resistor. One end of the coupling capacitor is connected to the control terminal of the signal amplification switch transistor, and the other end of the coupling capacitor is used to connect to the positive input terminal of the microphone. The first terminal of the signal amplification switch transistor is connected to the input terminal of the filtering module, and the second terminal of the signal amplification switch transistor is grounded. The first terminal of the first bias resistor is connected to the first terminal of the signal amplification switch transistor, and the second terminal of the first bias resistor is connected to the control terminal of the signal amplification switch transistor. The first terminal of the first voltage divider resistor is used to connect to an external power supply terminal, and the second terminal of the first voltage divider resistor is connected to the first terminal of the signal amplification switch transistor. The input terminal of the signal bias module is connected to the bias signal control terminal of the communication main control chip, and the output terminal of the signal bias module is connected to the control terminal of the signal amplification switch; the output terminal of the filtering module is connected to the microphone signal input terminal of the communication main control chip.
2. The engineering vehicle on-board microphone filtering circuit according to claim 1, characterized in that, The audio amplification module also includes a voltage suppression diode, one end of which is connected to the positive input terminal of the microphone, and the other end of which is grounded.
3. The engineering vehicle on-board microphone filtering circuit according to claim 1, characterized in that, The audio amplification module also includes a feedback resistor, the first end of which is connected to the second end of the signal amplification switching transistor, and the second end of the feedback resistor is grounded.
4. The engineering vehicle on-board microphone filtering circuit according to claim 1, characterized in that, The signal amplification switching transistor is an NPN transistor.
5. The engineering vehicle on-board microphone filtering circuit according to claim 1, characterized in that, The signal biasing module includes a second biasing resistor and a first filtering capacitor. The first end of the second biasing resistor is connected to the biasing signal control terminal of the communication main control chip and the external power supply, respectively. The second end of the second biasing resistor is connected to the control terminal of the signal amplification switching transistor. One end of the first filtering capacitor is used to connect to the external power supply, and the second end of the first filtering capacitor is grounded.
6. The engineering vehicle on-board microphone filtering circuit according to claim 5, characterized in that, The signal biasing module further includes a second voltage divider resistor, the first end of which is used to connect to an external power supply, and the second end of which is grounded.
7. The engineering vehicle on-board microphone filtering circuit according to claim 1, characterized in that, The filtering module includes a low-pass filter resistor and a low-pass filter capacitor. The first end of the low-pass filter resistor is connected to the first end of the signal amplification switch transistor. The second end of the low-pass filter resistor is connected to the microphone signal input terminal of the communication main control chip. The first end of the low-pass filter capacitor is connected to the second end of the low-pass filter resistor, and the second end of the low-pass filter capacitor is grounded.
8. The engineering vehicle on-board microphone filtering circuit according to claim 7, characterized in that, The filtering module includes a high-pass filter resistor and a high-pass filter capacitor. The first end of the high-pass filter capacitor is connected to the second end of the low-pass filter resistor. The second end of the high-pass filter capacitor is connected to the first end of the high-pass filter resistor and the microphone signal input terminal, respectively. The second end of the high-pass filter resistor is grounded.
9. The vehicle-mounted microphone filtering circuit according to claim 1, characterized in that, The audio amplification module also includes a third voltage divider resistor, the first end of which is used to connect to an external power supply terminal, and the second end of which is connected to the first end of the first voltage divider resistor.
10. A vehicle-mounted communication device, characterized in that, Includes the vehicle-mounted microphone filtering circuit as described in any one of claims 1 to 9.