A low-frequency attenuation fourth-order high-pass filter phantom output circuit

Abstract

The present invention discloses a low-frequency attenuation fourth-order high-pass filter phantom output circuit, comprising a sound sensor, a fourth-order high-pass filter circuit, a first-stage audio amplifier circuit, a second-stage audio amplifier phantom output circuit, and a power filter circuit, wherein the input end of the fourth-order high-pass filter circuit is connected to the sound sensor, the output end is connected to the first-stage audio amplifier circuit, the output end of the first-stage audio amplifier circuit is connected to the second-stage audio amplifier phantom output circuit, and the power filter circuit is respectively connected to the sound sensor, the fourth-order high-pass filter circuit, the first-stage audio amplifier circuit, and the second-stage audio amplifier phantom output circuit. The present invention achieves the purpose of single-line bidirectional transmission noise reduction by amplifying the microphone signal into a fourth-order high-pass filter in the front stage and using two transistors to follow the phantom output in the back stage to connect to the navigation host, so that the power supply and signal are superimposed.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle-mounted microphones, in particular to a low-frequency attenuation fourth-order high-pass filtering phantom output circuit. Background Art

[0002] With the rapid development of intelligent connected vehicles and the increasing demand for personalized consumer experiences, the use of in-vehicle microphones in voice interaction systems is increasing. However, as automakers continue to upgrade and optimize their vehicles' intelligent systems, the electrical characteristics of currently used standard microphones are unable to fully meet the needs of these newer in-vehicle intelligent interaction systems. Because the electrical characteristics of standard in-vehicle microphones lack special processing for the low-frequency range of 50Hz to 200Hz, low-frequency noise signals in the 50Hz to 200Hz range are picked up by the microphones and introduced into the voice interaction system. The average human voice frequency ranges from 300Hz to 6kHz. This low-frequency noise affects the functionality of the vehicle's intelligent voice interaction system, resulting in low voice recognition rates, loud noise during hands-free calls, and inaccurate sound source localization. Summary of the Invention

[0003] The purpose of the present invention is to provide a low-frequency attenuation fourth-order high-pass filter phantom output circuit. The microphone signal is amplified in the front stage to a fourth-order high-pass filter, and two transistors are used in the back stage to follow the phantom output and connect it to the navigation host. The power supply and signal are superimposed to achieve the purpose of single-line two-way transmission noise reduction. The technical problems of existing vehicle-mounted microphones due to the generation of low-frequency noise, which affects the function of the car's intelligent voice interaction system, resulting in low voice recognition rate, high noise in car hands-free calls, and inaccurate sound source positioning, etc.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a low-frequency attenuation fourth-order high-pass filter phantom output circuit, comprising a sound sensor, a fourth-order high-pass filter circuit, a first-stage audio amplifier circuit, a second-stage audio amplifier phantom output circuit, and a power supply filter circuit. The fourth-order high-pass filter circuit has an input connected to the sound sensor, an output connected to the first-stage audio amplifier circuit, an output connected to the second-stage audio amplifier phantom output circuit, and the power supply filter circuit is respectively connected to the sound sensor, the fourth-order high-pass filter circuit, the first-stage audio amplifier circuit, and the second-stage audio amplifier phantom output circuit, and provides electrical energy to the sound sensor, the fourth-order high-pass filter circuit, the first-stage audio amplifier circuit, and the second-stage audio amplifier phantom output circuit.

[0005] Preferably, the audio signal that can be picked up by the sound sensor is between 50HZ and 10KHZ.

[0006] Preferably, the fourth-order high-pass filter circuit is composed of a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, an operational amplifier U1 and an operational amplifier U2, wherein the non-inverting input terminal of the operational amplifier U1 is respectively connected to the resistor R5 and the capacitor C4, the reverse input terminal of the operational amplifier U1 is connected to the output terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is respectively connected to the capacitor C5 and the resistor R4, one end of the capacitor C3 is connected to the sound sensor, and the other end is respectively connected to the capacitor C4 and the resistor R4, the non-inverting input terminal of the operational amplifier U2 is respectively connected to the resistor R6 and the capacitor C6, the reverse input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2, and the output terminal of the operational amplifier U2 is respectively connected to the resistor R3 and the first-level audio amplifier circuit.

[0007] Preferably, the first-stage audio amplifier circuit is composed of a capacitor C10, a capacitor C11, a capacitor C15, a capacitor C16, a resistor R9, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and a transistor Q1A, wherein the resistor R11 and the capacitor C10 are connected in series and then connected in parallel with the resistor R12, one end of the capacitor C11 is connected to the output end of the operational amplifier U2, and the other end is connected to the resistor R13, the resistor R14 and the capacitor C16 are connected in parallel, the emitter and collector of the transistor Q1A are respectively connected to the capacitor C15, one end of the resistor R9 is grounded, and the other end is connected to the collector of the transistor Q1A.

[0008] Preferably, the secondary audio amplification phantom output circuit is composed of a capacitor C12, a capacitor C13, a capacitor C14, an inductor FB1, an inductor FB2, a bidirectional transient suppression diode D1 and a transistor Q1B, wherein the capacitor C12, the capacitor C13, the capacitor C14, the bidirectional transient suppression diode D1 and the transistor Q1B are connected in parallel, the base of the transistor Q1B is connected to the primary audio amplifier circuit, and the inductor FB1 and the inductor FB2 are respectively connected to the output port CN1.

[0009] Preferably, the power supply filter circuit is composed of a resistor R1, a capacitor C1, a capacitor C2 and a Zener diode Z1, wherein the capacitor C1, the capacitor C2 and the Zener diode Z1 are connected in parallel and then connected in series with the resistor R1.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. The present invention provides a low-frequency attenuation fourth-order high-pass filter phantom output circuit. The circuit comprises a sound sensor, a fourth-order high-pass filter circuit, a first-stage audio amplifier circuit, a second-stage audio amplification phantom output circuit, and a power filter circuit. The sound sensor picks up a microphone signal, the fourth-order high-pass filter circuit pre-amplifies the picked-up microphone signal into a fourth-order high-pass filter, the first-stage audio amplifier circuit amplifies the microphone signal, and the second-stage audio amplification phantom output circuit performs a phantom output. The processed microphone signal is connected to an in-vehicle navigation host, and the power supply and signal are superimposed, achieving the purpose of single-line bidirectional transmission noise reduction. This solves the technical problems of existing in-vehicle microphones, such as the generation of low-frequency noise that affects the function of the car's intelligent voice interaction system, resulting in low voice recognition rate, loud noise in in-vehicle hands-free calls, and inaccurate sound source positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a principle block diagram of the present invention;

[0013] Figure 2 Schematic diagram of the circuit of the present invention.

[0014] The reference numerals and names in the figures are as follows:

[0015] 1. Sound sensor; 2. Fourth-order high-pass filter circuit; 3. First-stage audio amplifier circuit; 4. Second-stage audio amplifier phantom output circuit; 5. Power supply filter circuit. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] See also Figure 1 The present invention provides an embodiment of a low-frequency attenuation fourth-order high-pass filter phantom output circuit, comprising a sound sensor 1, a fourth-order high-pass filter circuit 2, a first-stage audio amplifier circuit 3, a second-stage audio amplifier phantom output circuit 4, and a power supply filter circuit 5. The fourth-order high-pass filter circuit 2 has an input end connected to the sound sensor 1, an output end connected to the first-stage audio amplifier circuit 3, an output end of the first-stage audio amplifier circuit 3 connected to the second-stage audio amplifier phantom output circuit 4, and the power supply filter circuit 5 is respectively connected to the sound sensor 1, the fourth-order high-pass filter circuit 2, the first-stage audio amplifier circuit 3, and the second-stage audio amplifier phantom output circuit 4, and provides power to the sound sensor 1, the fourth-order high-pass filter circuit 2, the first-stage audio amplifier circuit 3, and the second-stage audio amplifier phantom output circuit 4.

[0018] Specifically, the sound sensor 1 can pick up audio signals between 50HZ and 10KHZ. When the audio signal picked up by the sound sensor 1 is between 50Hz and 200Hz, the audio signal will be sequentially processed through the fourth-order high-pass filter circuit 2, the first-level audio amplifier circuit 3 and the second-level audio amplification phantom output circuit 4 for noise reduction to meet the user's usage needs.

[0019] See also Figure 2 The above-mentioned fourth-order high-pass filter circuit 2 is composed of a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, an operational amplifier U1 and an operational amplifier U2, wherein the non-inverting input terminal of the operational amplifier U1 is connected to the resistor R5 and the capacitor C4 respectively, the inverting input terminal of the operational amplifier U1 is connected to the output terminal of the operational amplifier U1, the output terminal of the operational amplifier U1 is connected to the capacitor C5 and the resistor R4 respectively, one end of the capacitor C3 is connected to the sound sensor 1, and the other end is connected to the capacitor C4 and the resistor R4 respectively, the non-inverting input terminal of the operational amplifier U2 is connected to the resistor R6 and the capacitor C6 respectively, the inverting input terminal of the operational amplifier U2 is connected to the output terminal of the operational amplifier U2, and the output terminal of the operational amplifier U2 is connected to the resistor R3 and the first-level audio amplifier circuit 3 respectively.

[0020] Please refer again Figure 2 The first-stage audio amplifier circuit 3 is composed of a capacitor C10, a capacitor C11, a capacitor C15, a capacitor C16, a resistor R9, a resistor R11, a resistor R12, a resistor R13, a resistor R14, and a transistor Q1A. The resistor R11 and the capacitor C10 are connected in series and then connected in parallel with the resistor R12. One end of the capacitor C11 is connected to the output end of the operational amplifier U2, and the other end is connected to the resistor R13. The resistor R14 and the capacitor C16 are connected in parallel. The emitter and collector of the transistor Q1A are respectively connected to the capacitor C15. One end of the resistor R9 is grounded, and the other end is connected to the collector of the transistor Q1A.

[0021] Please refer again Figure 2 The secondary audio amplification phantom output circuit 4 is composed of a capacitor C12, a capacitor C13, a capacitor C14, an inductor FB1, an inductor FB2, a bidirectional transient suppression diode D1, and a transistor Q1B. The capacitor C12, the capacitor C13, the capacitor C14, the bidirectional transient suppression diode D1, and the transistor Q1B are connected in parallel. The base of the transistor Q1B is connected to the primary audio amplifier circuit 3. The inductor FB1 and the inductor FB2 are respectively connected to the output port CN1.

[0022] Please refer again Figure 2The power filter circuit 5 is composed of a resistor R1, a capacitor C1, a capacitor C2 and a Zener diode Z1, wherein the capacitor C1, the capacitor C2 and the Zener diode Z1 are connected in parallel and then connected in series with the resistor R1.

[0023] In summary, the low-frequency attenuation fourth-order high-pass filter phantom output circuit in this embodiment amplifies the microphone signal in the front stage into a fourth-order high-pass filter, and uses two transistors to follow the phantom output in the back stage to connect to the navigation host, so that the power supply and signal are superimposed, thereby achieving the purpose of single-line two-way transmission noise reduction. It solves the technical problems of existing vehicle-mounted microphones due to the generation of low-frequency noise, which affects the function of the car's intelligent voice interaction system, resulting in low voice recognition rate, loud noise in car hands-free calls, and inaccurate sound source positioning.

[0024] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A low-frequency attenuation fourth-order high-pass filter phantom output circuit, characterized in that: The invention comprises a sound sensor (1), a fourth-order high-pass filter circuit (2), a first-level audio amplifier circuit (3), a second-level audio amplification phantom output circuit (4) and a power filter circuit (5). The input end of the fourth-order high-pass filter circuit (2) is connected to the sound sensor (1), and the output end is connected to the first-level audio amplifier circuit (3). The output end of the first-level audio amplifier circuit (3) is connected to the second-level audio amplification phantom output circuit (4). The power filter circuit (5) is respectively connected to the sound sensor (1), the fourth-order high-pass filter circuit (2), the first-level audio amplifier circuit (3) and the second-level audio amplification phantom output circuit (4), and provides electric energy to the sound sensor (1), the fourth-order high-pass filter circuit (2), the first-level audio amplifier circuit (3) and the second-level audio amplification phantom output circuit (4). The sound sensor (1) can pick up an audio signal at 50 Hz. The fourth-order high-pass filter circuit (2) is composed of a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6, an operational amplifier U1, and an operational amplifier U2, wherein the same-direction input end of the operational amplifier U1 is connected to the resistor R5 and the capacitor C4 respectively, the reverse input end of the operational amplifier U1 is connected to the output end of the operational amplifier U1, the output end of the operational amplifier U1 is connected to the capacitor C5 and the resistor R4 respectively, one end of the capacitor C3 is connected to the sound sensor (1), and the other end is connected to the capacitor C4 and the resistor R4 respectively, the same-direction input end of the operational amplifier U2 is connected to the resistor R6 and the capacitor C6 respectively, the reverse input end of the operational amplifier U2 is connected to the output end of the operational amplifier U2, and the output end of the operational amplifier U2 is connected to the resistor R3 and the first-level audio amplifier circuit (3).

2. The low-frequency attenuation fourth-order high-pass filter phantom output circuit according to claim 1, characterized in that: The first-stage audio amplifier circuit (3) is composed of a capacitor C10, a capacitor C11, a capacitor C15, a capacitor C16, a resistor R9, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and a transistor Q1A, wherein the resistor R11 and the capacitor C10 are connected in series and then connected in parallel with the resistor R12, one end of the capacitor C11 is connected to the output end of the operational amplifier U2, and the other end is connected to the resistor R13, the resistor R14 and the capacitor C16 are connected in parallel, the emitter and the collector of the transistor Q1A are respectively connected to the capacitor C15, one end of the resistor R9 is grounded, and the other end is connected to the collector of the transistor Q1A.

3. The low-frequency attenuation fourth-order high-pass filter phantom output circuit according to claim 1, characterized in that: The secondary audio amplifier phantom output circuit (4) is composed of a capacitor C12, a capacitor C13, a capacitor C14, an inductor FB1, an inductor FB2, a bidirectional transient suppression diode D1 and a transistor Q1B, wherein the capacitor C12, the capacitor C13, the capacitor C14, the bidirectional transient suppression diode D1 and the transistor Q1B are connected in parallel, the base of the transistor Q1B is connected to the primary audio amplifier circuit (3), and the inductor FB1 and the inductor FB2 are respectively connected to the output port CN1.

4. The low-frequency attenuation fourth-order high-pass filter phantom output circuit according to claim 1, characterized in that: The power supply filter circuit (5) is composed of a resistor R1, a capacitor C1, a capacitor C2 and a voltage-stabilizing diode Z1, wherein the capacitor C1, the capacitor C2 and the voltage-stabilizing diode Z1 are connected in parallel and then connected in series with the resistor R1.

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