Microphone background noise testing system

Abstract

This application discloses a microphone background noise testing system, relating to the field of electroacoustic technology. The system includes a purified power supply, a voltage divider testing module, a shielding device, and a testing instrument. The purified power supply is connected to the input terminal of the voltage divider testing module and outputs a supply voltage lower than a preset noise value to the module. The voltage divider testing module includes a voltage divider switch, which connects to the microphone to be tested located within the shielding device. Under the control of the voltage divider switch, the module provides test voltages of different values ​​to the microphone. The shielding device includes a suspension device, which suspends the shielding device. The inner cavity of the shielding device is used to house the microphone. The testing instrument is connected to the microphone and tests the microphone's background noise value based on its output signal. This microphone background noise testing system completely eliminates electromagnetic interference and acoustic vibration interference, greatly improving the accuracy of the test results.

Description

Technical Field

[0001] This application relates to the field of electroacoustic technology, and in particular to a microphone background noise testing system. Background Technology

[0002] The standard for testing the background noise of a microphone is that, when there is no sound input from the microphone, including air disturbances, the output signal voltage of the microphone should be as low as possible. The standard requires it to be below 30 microvolts (μV), which is a very weak output signal.

[0003] Existing microphone noise floor testing typically uses expensive and bulky regulated power supplies to power the microphones. Even when the noise floor of this regulated power supply itself exceeds the requirement of below 30µV, the microphone's noise floor must be subtracted from the test results. This makes obtaining the microphone noise floor test results inconvenient and inconvenient. Furthermore, the measurement error of the regulated power supply's noise floor also leads to inaccurate microphone noise floor test results. Summary of the Invention

[0004] This application provides a microphone background noise testing system, which can solve the problems of high requirements for the testing environment and insufficient intuitiveness, convenience and accuracy in obtaining test results when testing microphone background noise.

[0005] One embodiment of this application provides a microphone background noise testing system, including:

[0006] Purified power supply, voltage divider test module, shielding device and tester;

[0007] The purified power supply is connected to the input terminal of the voltage divider test module and is used to output a power supply voltage lower than the preset noise value to the voltage divider test module;

[0008] The voltage divider test module includes a voltage divider switch, which is connected to the microphone to be tested located inside the shielding device. The voltage divider test module is used to provide different test voltages to the microphone under the control of the voltage divider switch.

[0009] The shielding device includes a suspension device, the shielding device is suspended in the air by the suspension device, and the inner cavity of the shielding device is used to house the microphone.

[0010] The tester is connected to the microphone and is used to test the microphone's background noise value based on the microphone's output signal.

[0011] As can be seen from the above embodiments of this application, the microphone background noise testing system includes a shielding device for placing the microphone whose background noise is to be tested. The shielding device can shield the noise of the surrounding space and is suspended by a suspension device to reduce vibration interference in the environment. This allows the microphone's background noise to be tested without an anechoic chamber environment. The microphone background noise testing system uses a purified power supply that can output a power supply voltage without internal noise, reducing the circuit noise generated during the microphone background noise test, improving the test accuracy of the tester in testing the microphone's background noise, and the tester directly outputs the tested background noise value, which is convenient and intuitive. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A schematic diagram of a microphone background noise testing system provided in an embodiment of this application;

[0014] Figure 2 A schematic diagram of a microphone background noise testing system provided in another embodiment of this application;

[0015] Figure 3 This is a schematic diagram of the circuit principle of the microphone background noise testing system in the embodiments of this application;

[0016] Figure 4 This is a schematic diagram of the shielding device in the microphone background noise testing system in the embodiments of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This application provides a microphone noise floor testing system for testing microphone noise floor. See also... Figure 1 The microphone background noise testing system includes:

[0019] Purified power supply 10, voltage divider test module 20, shielding device 30 and tester 40;

[0020] The purification power supply 10 is connected to the input terminal of the voltage divider test module 20, and is used to output a supply voltage lower than a preset noise value to the voltage divider test module 20. This preset noise value can specifically be >10µV. This preset noise value refers to the noise level in a normal environment where environmental electromagnetic interference is not deliberately eliminated, and devices such as the switching power supply, wireless gateway, and mobile phone are operating at a distance of 0.3 meters from the purification power supply. The purification power supply 10 can specifically be a 5V lithium battery, model BYD-05-20000, with an internal resistance of less than 0.1Ω.

[0021] The voltage divider test module 20 includes a voltage divider switch 21. The voltage divider test module 20 is connected to the microphone 50 under test located in the shielding device 30 through the voltage divider switch 21, and is used to provide different test voltages to the microphone 50 under test under the control of the voltage divider switch 21.

[0022] The shielding device 30 includes a suspension device 31, which suspends the shielding device 30 in the air. The inner cavity of the shielding device 30 is used to place the microphone 50 to be tested. The suspension device 31 specifically includes a suspension spring.

[0023] The tester 40 is connected to the microphone 50 to be tested and is used to test the background noise value of the microphone 50 to be tested based on the output signal of the microphone 50.

[0024] In this embodiment, the microphone background noise testing system includes a shielding device for placing the microphone whose background noise is to be tested. The shielding device can shield the noise of the surrounding space and is suspended by a suspension device to reduce vibration interference in the environment. This allows the microphone's background noise to be tested without an anechoic chamber environment. The microphone background noise testing system uses a purified power supply that can output no internal noise, reducing the circuit noise generated during the microphone background noise test, improving the test accuracy of the tester, and the tester directly outputs the tested background noise value, which is convenient and intuitive.

[0025] See Figure 2 , Figure 2 This is a schematic diagram of a microphone background noise testing system provided in another embodiment of this application. The voltage divider test module 20 includes: a constant current module 22 and a voltage divider module 23.

[0026] One end of the constant current module 22 is connected to the purification power supply 10, and the other end is connected to the voltage divider module 23;

[0027] The constant current module 22 is used to provide a constant current to the voltage divider module 23, which is used to generate different values ​​of the test voltage by switching the voltage divider switch 21.

[0028] Further, see Figure 3 , Figure 3 The circuit structure diagram of the microphone background noise testing system provided in the embodiments of this application is specifically a circuit diagram including a purified power supply, a voltage divider test module and a shielding device.

[0029] Voltage divider module 23 includes multiple diodes connected in series and an adjustable resistor R1;

[0030] In this embodiment, the number of diodes is related to the number of voltage dividers. Preferably, the test voltage required by the microphone can be 1.5V, 2V, 3V and 4.5V. Different test voltages can meet the working requirements of different models of microphones. By connecting multiple diodes in series, multiple different test voltages can be obtained by varying the voltage by 0.5V, thereby providing a stable test voltage for the microphone. Figure 3 Taking four diodes as an example, that is Figure 3 The diodes D2, D3, D4, and D5 are all silicon diodes. Silicon diodes have low thermal noise and do not generate active noise.

[0031] Each diode has a voltage divider terminal at its anode. Figure 3 The diagram shows four voltage divider terminals, A, B, C, and D. The voltage divider switch K generates different test voltages by connecting to each voltage divider terminal.

[0032] The adjustable resistor R1 is used to control the voltage division value of the diodes, preferably 0.5V for each diode.

[0033] Furthermore, the constant current module 22 includes a constant current diode D1, the positive terminal of which is connected to the positive terminal of the purification power supply 10, and the negative terminal of which can be connected to the positive terminal of D2.

[0034] Furthermore, the voltage divider module 23 also includes: a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4;

[0035] The first capacitor C1 is connected to the negative terminal of the constant current diode D1 and the purified power supply 10. Figure 3 The negative terminal of the lithium battery is used to stabilize the supply voltage output by the lithium battery through the constant current diode D1.

[0036] The second capacitor C2 and the third capacitor C3 are both connected in parallel with the first capacitor C1 to filter out radio frequency and other electromagnetic interference signals.

[0037] The fourth capacitor C4 is connected to the positive terminal of the output. The background noise of the microphone in the shielding device is transmitted to the test instrument through the output of C4.

[0038] The capacitors C1-C4 mentioned above are tantalum capacitors with extremely low leakage current. Since the voltage across the capacitor cannot change abruptly, capacitor C1 has a sufficiently large capacitance to provide voltage regulation without power consumption. Capacitors C2 and C3 serve as high-frequency filters. If there are strong interference signals in the environment that enter the circuit through wires, capacitors C2 and C3 can filter out these interference signals.

[0039] The circuit principle described above is as follows: The 5V DC voltage provided by the lithium battery is constant current through the constant current diode D1, and then through the voltage divider circuit composed of diodes D2-D5 and adjustable resistor R1. The current generates voltage values ​​U1, U2, U3 and U4 on the voltage divider terminals A, B, C and D. From U1 to U4, the voltage increases by 0.5V in sequence. The voltage divider switch K is connected to the voltage divider terminals A, B, C and D respectively to obtain different voltage values. Different operating voltages can be further provided to the microphone under test through R2, so that the microphone is in working state, and thus the background noise of the microphone can be tested.

[0040] Further, see Figure 4 , Figure 4 This is a schematic diagram of the structure of the double-layer shielding device 30 in the microphone background noise test system of this application embodiment. The outer shell of the shielding device 30 is made of metal and is grounded through a wire. Grounding can effectively shield external electromagnetic interference signals.

[0041] Specifically, the shielding device 30 includes an outer shielding cavity 32 and an inner shielding cavity 33;

[0042] The inner shielding cavity 33 is disposed in the outer shielding cavity 32.

[0043] The outer shell of the outer shielding cavity 32 is made of metal, and the outer shell of the inner shielding cavity 33 is also made of metal.

[0044] The outer shell of the outer shielding cavity 32 is grounded, shielding external electromagnetic interference signals so that electromagnetic interference signals will not enter the microphone under test and generate noise, thus improving the test accuracy.

[0045] A first sound-absorbing layer 34 is provided between the outer shielding cavity 32 and the inner shielding cavity 33, and a second sound-absorbing layer 35 is provided on the inner side of the inner shielding cavity 33. The microphone 50 to be tested is placed in the inner shielding cavity 33.

[0046] The first sound-absorbing layer 34 and the second sound-absorbing layer 35 are both made of sound-absorbing cotton, which can absorb noise, prevent the inner and outer shielding cavities from moving and colliding, and further reduce the noise inside the cavity.

[0047] The shielding device 30 also includes a lead wire channel 36;

[0048] The outer shielding cavity 32, the inner shielding cavity 33, the first sound-absorbing layer 34, and the second sound-absorbing layer 35 are all provided with lead wire channel through holes. Figure 4 (Not marked in the text) This lead channel through hole is used to accommodate and set the lead channel 36.

[0049] The microphone background noise testing system also includes: connecting lead 37;

[0050] Connecting lead 37 is disposed in lead channel 36. One end of connecting lead 37 includes connector 371, which is used to connect to microphone 50. The other end 372 of connecting lead 37 is connected to purification power supply 10 through relevant circuits or components. Figure 4 (not indicated in the text) and tester 50 ( Figure 4 (Not marked in the text) Connection, specifically, through Figure 3 R2 and D1 are connected to the lithium battery, and capacitor C4 is connected to the tester.

[0051] The outer shielding cavity 32 has a removable outer shielding cavity cover 321, and the inner shielding cavity 33 has a removable inner shielding cavity cover 331. By opening the outer shielding cavity cover 321 and the inner shielding cavity cover 331, the microphone 50 can be inserted or removed.

[0052] In this embodiment, the microphone background noise testing system includes a shielding device for placing the microphone whose background noise is to be tested. The shielding device can shield the noise and electromagnetic interference of the surrounding space and is suspended by a suspension device to reduce vibration interference in the environment. This allows the microphone's background noise to be tested without an anechoic chamber environment. The microphone background noise testing system uses a lithium battery as a purified power source to reduce circuit noise generated during microphone background noise testing, improve the testing accuracy of the tester for microphone background noise, and the tester directly outputs the tested background noise value, which is convenient and intuitive.

[0053] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0054] The above is a description of the microphone background noise testing system provided by the present invention. For those skilled in the art, based on the ideas of the embodiments of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A microphone background noise testing system, characterized in that, The system includes: Purified power supply, voltage divider test module, shielding device and tester; The purified power supply is connected to the input terminal of the voltage divider test module and is used to output a power supply voltage lower than the preset noise value to the voltage divider test module; The voltage divider test module includes a voltage divider switch, which is connected to the microphone to be tested located inside the shielding device. The voltage divider test module is used to provide different test voltages to the microphone under the control of the voltage divider switch. The shielding device includes a suspension device, which suspends the shielding device in the air. The inner cavity of the shielding device is used to house the microphone. The purification power supply and the voltage divider test module are both located outside the shielding device. The suspension device includes a suspension spring, which is used to suspend the entire shielding device in the air to reduce environmental vibration interference. The tester is connected to the microphone and is used to test the microphone's noise floor value based on the microphone's output signal.

2. The system according to claim 1, characterized in that, The voltage divider test module includes: a constant current module and a voltage divider module; One end of the constant current module is connected to the purification power supply, and the other end is connected to the voltage divider module; The constant current module is used to provide a constant current to the voltage divider module; The voltage divider module is used to generate different values ​​of the test voltage by switching the voltage divider switch.

3. The system according to claim 2, characterized in that, The voltage divider module includes: multiple diodes connected in series and an adjustable resistor; Each of the diodes has a voltage divider terminal at its anode, and the voltage divider switch generates a test voltage of a different value by connecting to each of the voltage divider terminals respectively.

4. The system according to claim 3, characterized in that, The constant current module includes a constant current diode; The positive terminal of the constant current diode is connected to the purification power supply.

5. The system according to claim 4, characterized in that, The voltage divider module further includes: a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; The first capacitor is connected to the negative terminal of the constant current diode and the purification power supply, and is used to stabilize the power supply voltage output by the purification power supply through the constant current diode; Both the second capacitor and the third capacitor are connected in parallel with the first capacitor to filter out interference signals; The fourth capacitor is connected to the positive terminal of the output.

6. The system according to claim 1, characterized in that, The purification power supply includes a lithium battery with an internal resistance less than a preset value.

7. The system according to claim 1, characterized in that, The outer casing of the shielding device is made of metal, and the outer casing is grounded through a wire.

8. The system according to claim 7, characterized in that, The shielding device includes: an outer shielding cavity and an inner shielding cavity; The inner shielding cavity is disposed within the outer shielding cavity; A first noise-absorbing layer is provided between the outer shielding cavity and the inner shielding cavity, and a second noise-absorbing layer is provided on the inner side of the inner shielding cavity. The microphone is placed in the inner shielding cavity.

9. The system according to claim 8, characterized in that, The shielding device also includes lead channels and connecting leads; The outer shielding cavity, the inner shielding cavity, the first sound-absorbing layer and the second sound-absorbing layer are all provided with lead wire channel through holes, which are used to accommodate the lead wire channels; The connecting lead is disposed in the lead channel, and one end of the connecting lead includes a connector for connecting to the microphone.

10. The system according to claim 9, characterized in that, The outer shielding cavity has a removable outer shielding cavity cover, and the inner shielding cavity has a removable inner shielding cavity cover.

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