Rail transit microphone human voice signal acquisition device

Abstract

The utility model discloses a track traffic microphone human voice signal acquisition device which comprises an audio signal sampling circuit, an audio signal amplification circuit, an audio signal rectification circuit and an audio signal processing circuit. The audio signal sampling circuit is electrically connected with the microphone and accesses an audio signal output by the microphone; the audio signal amplification circuit is electrically connected with the output end of the audio signal sampling circuit, and pre-amplifies the audio signal to obtain an amplified audio signal; the audio signal rectification circuit is electrically connected with the output end of the audio signal amplification circuit, and rectifies the amplified audio signal to obtain a direct current audio signal; and the audio signal processing circuit is electrically connected with the output end of the audio signal rectifying circuit, is in communication connection with a receiving end, and is used for performing analog-to-digital conversion on the direct-current audio signal to obtain a converted audio signal and sending the converted audio signal to the receiving end. According to the utility model, acquisition and transmission of voice signals of the microphone are realized, voice is restored to the greatest extent, and the use experience of a broadcast and talkback system is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of rail transit, in particular to a rail transit microphone human voice signal acquisition device. Background Art

[0002] In the broadcasting and intercom systems of rail transit (such as trains), microphones are usually required to transmit human voice signals, which are actually audio signals. The complete communication process of the audio signal is that the audio signal is processed at the sending end (i.e., the microphone), sent to the bus, and then transmitted to the receiving end.

[0003] In the communication process of the above audio signal, on the one hand, due to the considerable distance between trains, the influence of physical quantities such as transmission medium and temperature will inevitably bring impedance to the transmission line. Therefore, the transmission process of the audio signal is inevitably accompanied by energy loss. For this reason, it is necessary to add an amplifier circuit to the audio signal at the transmitting end to increase the audio intensity to reduce the influence of transmission loss. However, the amplifier circuit not only enhances the audio signal, but also increases the noise, which will cause distortion. Therefore, after the audio signal is amplified and then transmitted over a long distance, it often only focuses on energy and ignores the content of the audio signal. On the other hand, the transmission process is accompanied by interference. Since the audio signal is an analog signal, and the analog signal is essentially a continuous signal whose signal strength changes with time, the changes in the external electric field, magnetic field, and temperature during the transmission process will inevitably cause changes in the signal strength at certain moments. These changes are reflected in the receiving end as distortion. Therefore, the current acquisition of rail transit human voice signals often suffers from distortion, which seriously affects the user experience of the broadcasting and intercom systems. Utility Model Content

[0004] In view of this, the utility model provides a rail transit microphone human voice signal acquisition device to solve the problem that distortion is prone to occur in the existing rail transit microphone human voice signal technology, thereby seriously deteriorating the user experience of the broadcasting and intercom systems.

[0005] The utility model provides a rail transit microphone human voice signal acquisition device, including an audio signal sampling circuit, an audio signal amplifying circuit, an audio signal rectifying circuit and an audio signal processing circuit;

[0006] The audio signal sampling circuit is electrically connected to the microphone and receives the audio signal output by the microphone; the audio signal amplifying circuit is electrically connected to the output end of the audio signal sampling circuit and pre-amplifies the audio signal to obtain an amplified audio signal; the audio signal rectifying circuit is electrically connected to the output end of the audio signal amplifying circuit and rectifies the amplified audio signal to obtain a DC audio signal; the audio signal processing circuit is electrically connected to the output end of the audio signal rectifying circuit and is communicatively connected to an external receiving end and performs analog-to-digital conversion on the DC audio signal to obtain the converted audio signal and send it to the receiving end.

[0007] Optionally, the audio signal sampling circuit includes a first resistor R28, a second resistor R29, a third resistor R34, a first capacitor C33, a second capacitor C39, a third capacitor C102 and a connector J4 with two pins;

[0008] Both pins of the connector J4 are electrically connected to the microphone, and pin 1 of the connector J4 is also electrically connected to the +3.3V power supply terminal through the second resistor R29 and the first resistor R28 in sequence; the first end of the first capacitor C33 and the first end of the third capacitor C102 are both connected to the common connection end between the second resistor R29 and the first resistor R28, and the second end of the first capacitor C33 and the second end of the third capacitor C102 are both grounded; pin 2 of the connector J4 is also grounded through the third resistor R34, the first end of the second capacitor C39 is connected to the common connection end between pin 1 of the connector J4 and the second resistor R29, and the second end of the second capacitor C39 is connected to the common connection end between pin 2 of the connector J4 and the third resistor R34.

[0009] Optionally, the audio signal amplifying circuit includes a first Schottky diode D3, a second Schottky diode D4, a fourth resistor R27, a fifth resistor R30, a sixth resistor R31, a seventh resistor R32, an eighth resistor R33, a ninth resistor R35, a fourth capacitor C34, a fifth capacitor C35, a sixth capacitor C36, a seventh capacitor C37, an eighth capacitor C38, a ninth capacitor C40, a tenth capacitor C41 and a first dual operational amplifier consisting of a first operational amplifier U6A and a second operational amplifier U6B;

[0010] The positive power supply pin VCC of the first operational amplifier U6A is electrically connected to the +5V power supply terminal, the cathode of the first Schottky diode D3, the first end of the fourth capacitor C34 and the first end of the fifth capacitor C35 are all connected to the common connection terminal between the positive power supply pin VCC of the first operational amplifier U6A and the +5V power supply terminal, and the anode of the first Schottky diode D3, the second end of the fourth capacitor C34 and the second end of the fifth capacitor C35 are all grounded;

[0011] The negative power supply pin VEE of the first operational amplifier U6A is electrically connected to the -5V power supply terminal, the positive electrode of the second Schottky diode D4, the first end of the ninth capacitor C40 and the first end of the tenth capacitor C41 are all connected to the common connection terminal between the negative power supply pin VEE of the first operational amplifier U6A and the -5V power supply terminal, and the negative electrode of the second Schottky diode D4, the second end of the ninth capacitor C40 and the second end of the tenth capacitor C41 are all grounded;

[0012] The positive input pin IN+ of the first amplifier U6A is electrically connected to the pin No. 2 of the connector J4 through the fifth resistor R30 and the sixth capacitor C36 in sequence, and the positive input pin IN+ of the first amplifier U6A is also grounded through the fourth resistor R27; the inverting input pin IN- of the first amplifier U6A is electrically connected to the pin No. 1 of the connector J4 through the seventh resistor R32 and the eighth capacitor C38 in sequence, and the inverting input pin IN- of the first amplifier U6A is also electrically connected to the output pin of the first amplifier U6A through the ninth resistor R35; The output pin of the first operational amplifier U6A is electrically connected to the input end of the audio signal rectification circuit through the seventh capacitor C37; the positive input pin IN+ of the second operational amplifier U6B is electrically connected to the +5V power supply end through the sixth resistor R31, the first end of the eighth resistor R33 is connected to the common connection end between the positive input pin IN+ of the second operational amplifier U6B and the sixth resistor R31, and the second end of the eighth resistor R33 is electrically connected to the -5V power supply end; the inverting input pin IN- of the second operational amplifier U6B is electrically connected to the output pin of the second operational amplifier U6B.

[0013] Optionally, the audio signal amplifying circuit further includes a -5V power supply circuit;

[0014] The input end of the -5V power supply circuit is electrically connected to the +5V power supply end, and the output end of the -5V power supply circuit is electrically connected to the negative power supply pin VEE of the first operational amplifier U6A and the second end of the eighth resistor R33.

[0015] Optionally, the -5V power supply sub-circuit includes a power conversion chip U8, a tenth resistor R36, an eleventh resistor R37, a twelfth resistor R39, an eleventh capacitor C44, a twelfth capacitor C47 and a thirteenth capacitor C48;

[0016] The capacitor positive pin CAP+ of the power conversion chip U8 is electrically connected to the capacitor negative pin CAP- of the power conversion chip U8 through the eleventh capacitor C44; the input pin IN of the power conversion chip U8 is electrically connected to the +5V power supply end, the digital ground pin GND of the power conversion chip U8 is grounded, the first end of the twelfth capacitor C47 is connected to the common connection end between the input pin IN of the power conversion chip U8 and the +5V power supply end, and the second end of the twelfth capacitor C47 is grounded; the enable pin EN of the power conversion chip U8 is electrically connected to the +5V power supply end through the tenth resistor R36, and the feedback pin FB of the power conversion chip U8 is electrically connected to the +5V power supply end through the eleventh resistor R37; the output of the power conversion chip U8 Pin OUT is electrically connected to the negative power pin VEE of the first operational amplifier U6A and the second end of the eighth resistor R33; the first end of the twelfth resistor R39 is connected to the common connection end between the feedback pin FB of the power conversion chip U8 and the eleventh resistor R37, and the second end of the twelfth resistor R39 is connected to the common connection end between the output pin OUT of the power conversion chip U8 and the negative power pin VEE of the first operational amplifier U6A; the analog ground pin AGND of the power conversion chip U8 is grounded, the first end of the thirteenth capacitor C48 is connected to the common connection end between the output pin OUT of the power conversion chip U8 and the negative power pin VEE of the first operational amplifier U6A, and the second end of the thirteenth capacitor C48 is grounded.

[0017] Optionally, the audio signal rectification circuit includes a third Schottky diode D5, a fourth Schottky diode D7, a first diode D18, a second diode D19, a thirteenth resistor R38, a fourteenth resistor R40, a fifteenth resistor R41, a sixteenth resistor R42, a seventeenth resistor R43, a fourteenth capacitor C42, a fifteenth capacitor C43, a sixteenth capacitor C45, a seventeenth capacitor C46, ​​an eighteenth capacitor C49 and a second dual operational amplifier consisting of a third operational amplifier U7A and a fourth operational amplifier U7B;

[0018] The positive input pin IN+ of the fourth operational amplifier U7B is grounded, and the inverting input pin IN- of the fourth operational amplifier U7B is electrically connected to the output end of the audio signal amplifying circuit through the thirteenth resistor R38; the cathode of the first diode D18 and the first end of the fourteenth resistor R40 are both connected to the common connection end between the inverting input pin IN- of the fourth operational amplifier U7B and the thirteenth resistor R38, the anode of the first diode D18 is electrically connected to the output pin OUT of the fourth operational amplifier U7B, and the second end of the fourteenth resistor R40 is electrically connected to the output pin OUT of the fourth operational amplifier U7B through the second diode D19;

[0019] The positive power supply pin VCC of the third operational amplifier U7A is electrically connected to the +5V power supply terminal, the cathode of the third Schottky diode D5, the first end of the fourteenth capacitor C42 and the first end of the fifteenth capacitor C43 are all connected to the common connection terminal between the positive power supply pin VCC of the third operational amplifier U7A and the +5V power supply terminal, and the anode of the third Schottky diode D5, the second end of the fourteenth capacitor C42 and the second end of the fifteenth capacitor C43 are all grounded;

[0020] The negative power supply pin VEE of the third operational amplifier U7A is electrically connected to the -5V power supply terminal, the positive electrode of the fourth Schottky diode D7, the first end of the sixteenth capacitor C46 and the first end of the seventeenth capacitor C47 are all connected to the common connection terminal between the negative power supply pin VEE of the third operational amplifier U7A and the -5V power supply terminal, and the negative electrode of the fourth Schottky diode D7, the second end of the sixteenth capacitor C46 and the second end of the seventeenth capacitor C47 are all grounded;

[0021] The positive input pin IN+ of the third operational amplifier U7A is grounded, and the second end of the fourteenth resistor R40 is also electrically connected to the inverting input pin IN- of the third operational amplifier U7A through the fifteenth resistor R41; the first end of the sixteenth resistor R42 is connected to the common connection end between the fifteenth resistor R41 and the inverting input pin IN- of the third operational amplifier U7A, and the second end of the sixteenth resistor R42 is electrically connected to the output pin of the third operational amplifier U7A; the first end of the seventeenth resistor R43 is connected to the common connection end between the thirteenth resistor R38 and the output end of the audio signal amplifying circuit, and the second end of the seventeenth resistor R43 is connected to the common connection end between the second end of the sixteenth resistor R42 and the output pin of the third operational amplifier U7A through the eighteenth capacitor C49; the output pin of the third operational amplifier U7A is electrically connected to the input end of the audio signal processing circuit.

[0022] Optionally, the audio signal processing circuit includes a microcontroller U9B and a DC signal input subcircuit;

[0023] The input end of the DC signal input subcircuit is electrically connected to the output end of the audio signal rectification circuit, the output end of the DC signal input subcircuit is electrically connected to the input end of the microcontroller U9B, and the microcontroller U9B is also communicatively connected to the external receiving end.

[0024] Optionally, the DC signal input subcircuit includes an eighteenth resistor R56 and a nineteenth resistor R57;

[0025] The first end of the eighteenth resistor R56 is electrically connected to the output end of the audio signal rectification circuit, and the second end of the eighteenth resistor R56 is electrically connected to the analog-to-digital conversion pin of the microcontroller U9B; the first end of the nineteenth resistor R57 is connected to the common connection end between the second end of the eighteenth resistor R56 and the analog-to-digital conversion pin of the microcontroller U9B, and the second end of the nineteenth resistor R57 is grounded.

[0026] Optionally, the microcontroller 9B is specifically a single chip microcomputer of the LPC1788FBD144 model.

[0027] Beneficial effects of the utility model: the chip circuits preset on the wafer are interconnected with the metal layer through the pads and silicon through vias, and then combined with the plastic sealing layer, which not only realizes the chip packaging, but also ensures the functionality of the IGBT power module;

[0028] The rail transit microphone human voice signal acquisition device of the utility model first directly acquires the audio signal output by the microphone through the audio signal sampling circuit, and can acquire the audio signal with maximum distortion-free degree at the sending end (i.e., the microphone); then, the audio signal amplification circuit is used to pre-amplify the acquired audio signal, and the human voice signal can be amplified with maximum distortion-free degree at the sending end, and it can ensure that after the subsequent audio restoration, the human voice signal has sufficient clarity when played at the receiving end; then, the audio signal rectification circuit is used to rectify the amplified audio signal, so that it is convenient to use the audio signal processing circuit to process the rectified DC audio signal Analog-to-digital conversion is performed to obtain a digitized converted audio signal which is then sent to the receiving end. Since the vocal signal output by the microphone is an analog signal, and the digitized converted audio signal obtained by the utility model is a series of continuously changing voltage pulses or light pulses, it only focuses on the transmission of binary numbers 0 and 1, and the possibility of the signal level jumping from 0 to 1 or from 1 to 0 is low. Therefore, it has stronger anti-interference ability, less noise at the sending end, and less loss during transmission, thereby realizing the collection and transmission of the weak vocal signal from the microphone, maximally restoring the vocal sound, and effectively ensuring the user experience of the rail transit broadcasting and intercom system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0030] Figure 1 A structural diagram of a rail transit microphone human voice signal acquisition device in an embodiment of the utility model is shown;

[0031] Figure 2 The design diagram of the audio signal sampling circuit in the embodiment of the utility model is shown;

[0032] Figure 3 and Figure 4 The design diagram of the audio signal amplifying circuit in the embodiment of the utility model is shown;

[0033] Figure 5 The design diagram of the -5V power supply circuit in the audio signal amplification circuit in the embodiment of the utility model is shown;

[0034] Figure 6 The design diagram of the audio signal rectification circuit in the embodiment of the utility model is shown;

[0035] Figure 7 The design diagram of the audio signal processing circuit in the embodiment of the utility model is shown. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0037] Example

[0038] A rail transit microphone human voice signal acquisition device, such as Figure 1 As shown, it includes an audio signal sampling circuit, an audio signal amplifying circuit, an audio signal rectifying circuit and an audio signal processing circuit;

[0039] The audio signal sampling circuit is electrically connected to the microphone and receives the audio signal output by the microphone; the audio signal amplifying circuit is electrically connected to the output end of the audio signal sampling circuit and pre-amplifies the audio signal to obtain an amplified audio signal; the audio signal rectifying circuit is electrically connected to the output end of the audio signal amplifying circuit and rectifies the amplified audio signal to obtain a DC audio signal; the audio signal processing circuit is electrically connected to the output end of the audio signal rectifying circuit and is communicatively connected to an external receiving end and performs analog-to-digital conversion on the DC audio signal to obtain the converted audio signal and send it to the receiving end.

[0040] The rail transit microphone human voice signal acquisition device of this embodiment first directly acquires the audio signal output by the microphone through the audio signal sampling circuit, and can acquire the audio signal with maximum distortion-free degree at the transmitting end (i.e., the microphone); then, the acquired audio signal is pre-amplified by the audio signal amplification circuit, and the human voice signal can be amplified with maximum distortion-free degree at the transmitting end, which can ensure that after the subsequent audio restoration, it has sufficient clarity when played at the receiving end; then, the amplified audio signal is rectified by the audio signal rectification circuit, which is convenient for the subsequent use of the audio signal processing circuit to rectify the rectified DC audio signal Analog-to-digital conversion is performed to obtain a digitized converted audio signal which is then sent to the receiving end. Since the vocal signal output by the microphone is an analog signal, and the digitized converted audio signal obtained by the utility model is a series of continuously changing voltage pulses or light pulses, it only focuses on the transmission of binary numbers 0 and 1, and the possibility of the signal level jumping from 0 to 1 or from 1 to 0 is low. Therefore, it has stronger anti-interference ability, less noise at the sending end, and less loss during transmission, thereby realizing the collection and transmission of the weak vocal signal from the microphone, maximally restoring the vocal sound, and effectively ensuring the user experience of the rail transit broadcasting and intercom system.

[0041] It should be understood that the present invention only improves the hardware circuit structure of the microphone human voice signal acquisition device for rail transit to achieve the maximum distortion-free acquisition and transmission of human voice signals and to restore human voice to the maximum extent, without involving computer level improvements. The computer programs involved are all conventional computer programs in the field.

[0042] The rail transit in this embodiment includes but is not limited to subways, trains, etc. This embodiment takes the subway as an example.

[0043] Preferably, if Figure 2 As shown, the audio signal sampling circuit includes a first resistor R28, a second resistor R29, a third resistor R34, a first capacitor C33, a second capacitor C39, a third capacitor C102 and a connector J4 with two pins;

[0044] Both pins of the connector J4 are electrically connected to the microphone, and pin 1 of the connector J4 is also electrically connected to the +3.3V power supply terminal through the second resistor R29 and the first resistor R28 in sequence; the first end of the first capacitor C33 and the first end of the third capacitor C102 are both connected to the common connection end between the second resistor R29 and the first resistor R28, and the second end of the first capacitor C33 and the second end of the third capacitor C102 are both grounded; pin 2 of the connector J4 is also grounded through the third resistor R34, the first end of the second capacitor C39 is connected to the common connection end between pin 1 of the connector J4 and the second resistor R29, and the second end of the second capacitor C39 is connected to the common connection end between pin 2 of the connector J4 and the third resistor R34.

[0045] In the audio signal sampling circuit of the above structure, connector J4 is used to connect to the electret microphone, which is equivalent to a variable resistor after being connected to the pull-up circuit (i.e., a circuit composed of resistors R28, R29 and capacitors C102, C103). The size of the audio signal at the microphone will cause the change of the variable resistor, which in turn causes the change of the output voltage. The collection of the output voltage can realize the collection of the audio signal; and in the pull-up circuit, capacitors C102 and C103 form a parallel structure, which can make the output signal smoother and isolate high-frequency noise, so as to collect the audio signal with maximum distortion.

[0046] In the above audio signal sampling circuit, the specific specifications of each resistor and capacitor are as follows: Figure 2 As shown, the details are not listed here.

[0047] Preferably, if Figure 3 and Figure 4 As shown, the audio signal amplifying circuit includes a first Schottky diode D3, a second Schottky diode D4, a fourth resistor R27, a fifth resistor R30, a sixth resistor R31, a seventh resistor R32, an eighth resistor R33, a ninth resistor R35, a fourth capacitor C34, a fifth capacitor C35, a sixth capacitor C36, a seventh capacitor C37, an eighth capacitor C38, a ninth capacitor C40, a tenth capacitor C41 and a first dual operational amplifier consisting of a first operational amplifier U6A and a second operational amplifier U6B;

[0048] The positive power supply pin VCC of the first operational amplifier U6A is electrically connected to the +5V power supply terminal, the cathode of the first Schottky diode D3, the first end of the fourth capacitor C34 and the first end of the fifth capacitor C35 are all connected to the common connection terminal between the positive power supply pin VCC of the first operational amplifier U6A and the +5V power supply terminal, and the anode of the first Schottky diode D3, the second end of the fourth capacitor C34 and the second end of the fifth capacitor C35 are all grounded;

[0049] The negative power supply pin VEE of the first operational amplifier U6A is electrically connected to the -5V power supply terminal, the positive electrode of the second Schottky diode D4, the first end of the ninth capacitor C40 and the first end of the tenth capacitor C41 are all connected to the common connection terminal between the negative power supply pin VEE of the first operational amplifier U6A and the -5V power supply terminal, and the negative electrode of the second Schottky diode D4, the second end of the ninth capacitor C40 and the second end of the tenth capacitor C41 are all grounded;

[0050] The positive input pin IN+ of the first amplifier U6A is electrically connected to the pin No. 2 of the connector J4 through the fifth resistor R30 and the sixth capacitor C36 in sequence, and the positive input pin IN+ of the first amplifier U6A is also grounded through the fourth resistor R27; the inverting input pin IN- of the first amplifier U6A is electrically connected to the pin No. 1 of the connector J4 through the seventh resistor R32 and the eighth capacitor C38 in sequence, and the inverting input pin IN- of the first amplifier U6A is also electrically connected to the output pin of the first amplifier U6A through the ninth resistor R35; The output pin of the first operational amplifier U6A is electrically connected to the input end of the audio signal rectification circuit through the seventh capacitor C37; the positive input pin IN+ of the second operational amplifier U6B is electrically connected to the +5V power supply end through the sixth resistor R31, the first end of the eighth resistor R33 is connected to the common connection end between the positive input pin IN+ of the second operational amplifier U6B and the sixth resistor R31, and the second end of the eighth resistor R33 is electrically connected to the -5V power supply end; the inverting input pin IN- of the second operational amplifier U6B is electrically connected to the output pin of the second operational amplifier U6B.

[0051] In the above audio signal amplification circuit, the audio signal (i.e. Figure 3 The signals connected to the MIC0_N port and the MIC0_P port in the amplifier circuit are respectively connected to the capacitors C36 and C38 to isolate the DC voltage and connect the pure microphone AC signal to the amplifier circuit in the form of differential signals. Amplification in the form of differential signals can isolate the influence of the system ground on the microphone signal and can achieve maximum distortion-free amplification of the signal.

[0052] In the above audio signal amplifying circuit, the amplification factor of the in-phase input terminal of the first dual operational amplifier composed of the first operational amplifier U6A and the second operational amplifier U6B is slightly less than 30 / 11, and the voltage amplification factor of the inverting input terminal is slightly less than 2. The sum of the two can amplify the collected audio signal by nearly 5 times.

[0053] In the audio signal sampling circuit of this embodiment, the first dual operational amplifier uses the operational amplifier of the OPA1662AID model, the first Schottky diode and the second Schottky diode both use the Schottky diode of the MMSZ5246BT1G model, and the specific specifications of each resistor and capacitor are detailed in Figure 3 and Figure 4 As shown, the details are not listed here.

[0054] Preferably, the audio signal amplifying circuit further comprises a -5V power supply circuit;

[0055] The input end of the -5V power supply circuit is electrically connected to the +5V power supply end, and the output end of the -5V power supply circuit is electrically connected to the negative power supply pin VEE of the first operational amplifier U6A and the second end of the eighth resistor R33.

[0056] Through the -5V power supply circuit, a -5V DC voltage can be provided to the audio signal sampling circuit without providing an additional -5V power supply, thereby reducing power consumption and hardware costs.

[0057] Specifically, Figure 5 As shown, the -5V power supply sub-circuit includes a power conversion chip U8, a tenth resistor R36, an eleventh resistor R37, a twelfth resistor R39, an eleventh capacitor C44, a twelfth capacitor C47 and a thirteenth capacitor C48;

[0058] The capacitor positive pin CAP+ of the power conversion chip U8 is electrically connected to the capacitor negative pin CAP- of the power conversion chip U8 through the eleventh capacitor C44; the input pin IN of the power conversion chip U8 is electrically connected to the +5V power supply end, the digital ground pin GND of the power conversion chip U8 is grounded, the first end of the twelfth capacitor C47 is connected to the common connection end between the input pin IN of the power conversion chip U8 and the +5V power supply end, and the second end of the twelfth capacitor C47 is grounded; the enable pin EN of the power conversion chip U8 is electrically connected to the +5V power supply end through the tenth resistor R36, and the feedback pin FB of the power conversion chip U8 is electrically connected to the +5V power supply end through the eleventh resistor R37; the output of the power conversion chip U8 Pin OUT is electrically connected to the negative power pin VEE of the first operational amplifier U6A and the second end of the eighth resistor R33; the first end of the twelfth resistor R39 is connected to the common connection end between the feedback pin FB of the power conversion chip U8 and the eleventh resistor R37, and the second end of the twelfth resistor R39 is connected to the common connection end between the output pin OUT of the power conversion chip U8 and the negative power pin VEE of the first operational amplifier U6A; the analog ground pin AGND of the power conversion chip U8 is grounded, the first end of the thirteenth capacitor C48 is connected to the common connection end between the output pin OUT of the power conversion chip U8 and the negative power pin VEE of the first operational amplifier U6A, and the second end of the thirteenth capacitor C48 is grounded.

[0059] The above-mentioned -5V power supply circuit uses the power conversion chip U8 to convert +5V DC into -5V DC, thereby providing a -5V negative DC power supply for the first dual operational amplifier. Therefore, there is no need to provide a DC bias voltage. This design can reduce the power consumption caused by the bias voltage.

[0060] In the -5V power supply circuit of this embodiment, the power conversion chip U8 uses the MAX889TESA model power conversion chip, and the specific specifications of other resistors and capacitors are detailed in Figure 5 As shown, the details are not listed here.

[0061] Preferably, if Figure 6 As shown, the audio signal rectification circuit includes a third Schottky diode D5, a fourth Schottky diode D7, a first diode D18, a second diode D19, a thirteenth resistor R38, a fourteenth resistor R40, a fifteenth resistor R41, a sixteenth resistor R42, a seventeenth resistor R43, a fourteenth capacitor C42, a fifteenth capacitor C43, a sixteenth capacitor C45, a seventeenth capacitor C46, ​​an eighteenth capacitor C49 and a second dual operational amplifier composed of a third operational amplifier U7A and a fourth operational amplifier U7B;

[0062] The positive input pin IN+ of the fourth operational amplifier U7B is grounded, and the inverting input pin IN- of the fourth operational amplifier U7B is electrically connected to the output end of the audio signal amplifying circuit through the thirteenth resistor R38; the cathode of the first diode D18 and the first end of the fourteenth resistor R40 are both connected to the common connection end between the inverting input pin IN- of the fourth operational amplifier U7B and the thirteenth resistor R38, the anode of the first diode D18 is electrically connected to the output pin OUT of the fourth operational amplifier U7B, and the second end of the fourteenth resistor R40 is electrically connected to the output pin OUT of the fourth operational amplifier U7B through the second diode D19;

[0063] The positive power supply pin VCC of the third operational amplifier U7A is electrically connected to the +5V power supply terminal, the cathode of the third Schottky diode D5, the first end of the fourteenth capacitor C42 and the first end of the fifteenth capacitor C43 are all connected to the common connection terminal between the positive power supply pin VCC of the third operational amplifier U7A and the +5V power supply terminal, and the anode of the third Schottky diode D5, the second end of the fourteenth capacitor C42 and the second end of the fifteenth capacitor C43 are all grounded;

[0064] The negative power supply pin VEE of the third operational amplifier U7A is electrically connected to the -5V power supply terminal, the positive electrode of the fourth Schottky diode D7, the first end of the sixteenth capacitor C46 and the first end of the seventeenth capacitor C47 are all connected to the common connection terminal between the negative power supply pin VEE of the third operational amplifier U7A and the -5V power supply terminal, and the negative electrode of the fourth Schottky diode D7, the second end of the sixteenth capacitor C46 and the second end of the seventeenth capacitor C47 are all grounded;

[0065] The positive input pin IN+ of the third operational amplifier U7A is grounded, and the second end of the fourteenth resistor R40 is also electrically connected to the inverting input pin IN- of the third operational amplifier U7A through the fifteenth resistor R41; the first end of the sixteenth resistor R42 is connected to the common connection end between the fifteenth resistor R41 and the inverting input pin IN- of the third operational amplifier U7A, and the second end of the sixteenth resistor R42 is electrically connected to the output pin of the third operational amplifier U7A; the first end of the seventeenth resistor R43 is connected to the common connection end between the thirteenth resistor R38 and the output end of the audio signal amplifying circuit, and the second end of the seventeenth resistor R43 is connected to the common connection end between the second end of the sixteenth resistor R42 and the output pin of the third operational amplifier U7A through the eighteenth capacitor C49; the output pin of the third operational amplifier U7A is electrically connected to the input end of the audio signal processing circuit.

[0066] The above audio signal rectifier circuit forms a precision rectifier circuit, wherein Figure 6 The fourth op amp U7B, resistors R38, R40 and diodes D18, D19 in the left half form a half-wave precision rectifier circuit. Due to the unidirectional conductivity of the diode and the reverse amplification of the op amp, the voltage U at the input of the fourth op amp U7B is MIC_AP >0, at this time, D18 is turned off and D19 is turned on, so the voltage U at the output of the fourth op amp U7B O1 <0. When R40 and R38 are both 50kΩ, Therefore, in U MIC_AP When <0, D19 is cut off and D18 is turned on. Since there is no current on the feedback resistor R40, U O1 =0. In this circuit, the conduction voltage of diodes D18 and D19 is 0.7V, and the open-loop differential mode gain of the op amp is 501200. In order to make the diodes conduct, the net input voltage u P -u N =0.7 / 501200V=1.39μV, so it can be seen that even if the input voltage U MIC_AP The change of is very small, and the conduction state of D18 and D19 can also be changed, so the purpose of precise rectification can be achieved.

[0067] In addition, since the audio signal processing circuit (specifically the microcontroller in the audio signal processing circuit) cannot recognize negative signals, the inverting integral amplifier circuit of the right half is added after the half-wave rectifier circuit of the left half (that is, the circuit structure composed of the third op amp U7A, resistor R42, capacitor C49 and Schottky diodes D5 and D7 of the right half is an inverting integral amplifier circuit). O1 For example, the input resistor R41 is 50 kΩ, the feedback resistor R42 is 100 kΩ, and the gain is -R42 / R41=-2. MIC_AP For example, the input resistor R43 is 100kΩ, the feedback resistor R42 is 100kΩ, and the amplification factor is -R42 / R43=-1, which constitutes full-wave rectification. That is, for U MIC_AP The part greater than 0 in the signal is superimposed with the original signal after being inverted twice and amplified by one time, and the signal remains unchanged, that is, the output voltage U O2 (0+)=(-2)·[-U MIC_AP (0+)]-U MIC_AP (0+)=U MIC_AP (0+); for U MIC_AP The part less than 0 in the half-wave rectifier is 0, and the inverting integrator circuit inverts it. The two are superimposed to form -U MIC_AP (0-), which is UO2 (0-)=0-U MIC_AP (0-)=-U MIC_AP (0-). Combining the above two situations, the amplified audio signal (the signal is an AC signal) is rectified into a DC signal with a signal amplitude greater than 0. In addition, due to the addition of the 2.2uf capacitor C49, the circuit constitutes an integrating circuit, which makes the gain of the high-frequency noise signal smaller, and the frequency of the human voice signal is mostly 200~1000Hz, which is a low-frequency signal. Therefore, the circuit can enhance the low-frequency response of the audio, and the output human voice signal (that is, the DC audio signal) is clearer. In summary, the output voltage U of the third op amp U7A is O2 To amplify the DC waveform of the audio signal.

[0068] In this embodiment, the second dual operational amplifier uses an operational amplifier of the OPA1662AID model, the third Schottky diode and the fourth Schottky diode both use Schottky diodes of the MMSZ5246BT1G model, the first diode and the second diode both use diodes of the 1N4148WS model, and the specific specifications of the resistors and capacitors are detailed in Figure 6 As shown, the details are not listed here.

[0069] Preferably, the audio signal processing circuit includes a microcontroller U9B and a DC signal input subcircuit;

[0070] The input end of the DC signal input subcircuit is electrically connected to the output end of the audio signal rectification circuit, and the output end of the DC signal input subcircuit is electrically connected to the input end of the microcontroller U9B. The microcontroller U9B is also communicatively connected to the external receiving end.

[0071] Through the DC signal input sub-circuit, the DC voltage signal output by the audio signal rectification circuit is conveniently connected to the microcontroller U9B, so that the microcontroller can perform analog-to-digital conversion, sampling quantization and encoding to form a binary audio signal (i.e., convert the audio signal). The binary audio signal is then sent to the receiving end through communication between the microcontroller U9B and the external receiving end, and transmitted as a digital signal, which effectively improves the anti-interference ability of the human voice signal and reduces the loss, maximizes the restoration of the human voice, and effectively ensures the user experience of the rail transit broadcasting and intercom system.

[0072] Specifically, Figure 7 As shown, the DC signal input subcircuit includes an eighteenth resistor R56 and a nineteenth resistor R57;

[0073] The first end of the eighteenth resistor R56 is electrically connected to the output end of the audio signal rectification circuit, and the second end of the eighteenth resistor R56 is electrically connected to the analog-to-digital conversion pin of the microcontroller U9B; the first end of the nineteenth resistor R57 is connected to the common connection end between the second end of the eighteenth resistor R56 and the analog-to-digital conversion pin of the microcontroller U9B, and the second end of the nineteenth resistor R57 is grounded.

[0074] Specifically, the microcontroller 9B is a single chip microcomputer of the LPC1788FBD144 model.

[0075] Through the above-mentioned DC signal input sub-circuit and microcontroller, the rectified audio signal can be accurately and efficiently converted into analog-to-digital, sampled, quantized and encoded, so as to restore the human voice to the maximum extent and effectively ensure the user experience of the rail transit broadcasting and intercom system.

[0076] The specific specifications of the eighteenth resistor R56 and the nineteenth resistor R57 in this embodiment are detailed in Figure 7 As shown, no more listing is given here.

[0077] Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A rail transit microphone human voice signal acquisition device, characterized in that: It includes an audio signal sampling circuit, an audio signal amplifying circuit, an audio signal rectifying circuit and an audio signal processing circuit; The audio signal sampling circuit is electrically connected to the microphone and receives the audio signal output by the microphone; the audio signal amplifying circuit is electrically connected to the output end of the audio signal sampling circuit and pre-amplifies the audio signal to obtain an amplified audio signal; the audio signal rectifying circuit is electrically connected to the output end of the audio signal amplifying circuit and rectifies the amplified audio signal to obtain a DC audio signal; the audio signal processing circuit is electrically connected to the output end of the audio signal rectifying circuit and is communicatively connected to an external receiving end and performs analog-to-digital conversion on the DC audio signal to obtain the converted audio signal and send it to the receiving end.

2. The rail transit microphone human voice signal acquisition device according to claim 1, characterized in that: The audio signal sampling circuit includes a first resistor R28, a second resistor R29, a third resistor R34, a first capacitor C33, a second capacitor C39, a third capacitor C102 and a connector J4 with two pins; Both pins of the connector J4 are electrically connected to the microphone, and pin 1 of the connector J4 is also electrically connected to the +3.3V power supply terminal through the second resistor R29 and the first resistor R28 in sequence; the first end of the first capacitor C33 and the first end of the third capacitor C102 are both connected to the common connection end between the second resistor R29 and the first resistor R28, and the second end of the first capacitor C33 and the second end of the third capacitor C102 are both grounded; pin 2 of the connector J4 is also grounded through the third resistor R34, the first end of the second capacitor C39 is connected to the common connection end between pin 1 of the connector J4 and the second resistor R29, and the second end of the second capacitor C39 is connected to the common connection end between pin 2 of the connector J4 and the third resistor R34.

3. The rail transit microphone human voice signal acquisition device according to claim 2, characterized in that: The audio signal amplifying circuit includes a first Schottky diode D3, a second Schottky diode D4, a fourth resistor R27, a fifth resistor R30, a sixth resistor R31, a seventh resistor R32, an eighth resistor R33, a ninth resistor R35, a fourth capacitor C34, a fifth capacitor C35, a sixth capacitor C36, a seventh capacitor C37, an eighth capacitor C38, a ninth capacitor C40, a tenth capacitor C41 and a first dual operational amplifier consisting of a first operational amplifier U6A and a second operational amplifier U6B; The positive power supply pin VCC of the first operational amplifier U6A is electrically connected to the +5V power supply terminal, the cathode of the first Schottky diode D3, the first end of the fourth capacitor C34 and the first end of the fifth capacitor C35 are all connected to the common connection terminal between the positive power supply pin VCC of the first operational amplifier U6A and the +5V power supply terminal, and the anode of the first Schottky diode D3, the second end of the fourth capacitor C34 and the second end of the fifth capacitor C35 are all grounded; The negative power supply pin VEE of the first operational amplifier U6A is electrically connected to the -5V power supply terminal, the positive electrode of the second Schottky diode D4, the first end of the ninth capacitor C40 and the first end of the tenth capacitor C41 are all connected to the common connection terminal between the negative power supply pin VEE of the first operational amplifier U6A and the -5V power supply terminal, and the negative electrode of the second Schottky diode D4, the second end of the ninth capacitor C40 and the second end of the tenth capacitor C41 are all grounded; The positive input pin IN+ of the first amplifier U6A is electrically connected to the pin No. 2 of the connector J4 through the fifth resistor R30 and the sixth capacitor C36 in sequence, and the positive input pin IN+ of the first amplifier U6A is also grounded through the fourth resistor R27; the inverting input pin IN- of the first amplifier U6A is electrically connected to the pin No. 1 of the connector J4 through the seventh resistor R32 and the eighth capacitor C38 in sequence, and the inverting input pin IN- of the first amplifier U6A is also electrically connected to the output pin of the first amplifier U6A through the ninth resistor R35; The output pin of the first operational amplifier U6A is electrically connected to the input end of the audio signal rectification circuit through the seventh capacitor C37; the positive input pin IN+ of the second operational amplifier U6B is electrically connected to the +5V power supply end through the sixth resistor R31, the first end of the eighth resistor R33 is connected to the common connection end between the positive input pin IN+ of the second operational amplifier U6B and the sixth resistor R31, and the second end of the eighth resistor R33 is electrically connected to the -5V power supply end; the inverting input pin IN- of the second operational amplifier U6B is electrically connected to the output pin of the second operational amplifier U6B.

4. The rail transit microphone human voice signal acquisition device according to claim 3, characterized in that: The audio signal amplifying circuit also includes a -5V power supply circuit; The input end of the -5V power supply circuit is electrically connected to the +5V power supply end, and the output end of the -5V power supply circuit is electrically connected to the negative power supply pin VEE of the first operational amplifier U6A and the second end of the eighth resistor R33.

5. The rail transit microphone human voice signal acquisition device according to claim 4, characterized in that: The -5V power supply sub-circuit includes a power conversion chip U8, a tenth resistor R36, an eleventh resistor R37, a twelfth resistor R39, an eleventh capacitor C44, a twelfth capacitor C47 and a thirteenth capacitor C48; The capacitor positive pin CAP+ of the power conversion chip U8 is electrically connected to the capacitor negative pin CAP- of the power conversion chip U8 through the eleventh capacitor C44; the input pin IN of the power conversion chip U8 is electrically connected to the +5V power supply end, the digital ground pin GND of the power conversion chip U8 is grounded, the first end of the twelfth capacitor C47 is connected to the common connection end between the input pin IN of the power conversion chip U8 and the +5V power supply end, and the second end of the twelfth capacitor C47 is grounded; the enable pin EN of the power conversion chip U8 is electrically connected to the +5V power supply end through the tenth resistor R36, and the feedback pin FB of the power conversion chip U8 is electrically connected to the +5V power supply end through the eleventh resistor R37; the output of the power conversion chip U8 Pin OUT is electrically connected to the negative power pin VEE of the first operational amplifier U6A and the second end of the eighth resistor R33; the first end of the twelfth resistor R39 is connected to the common connection end between the feedback pin FB of the power conversion chip U8 and the eleventh resistor R37, and the second end of the twelfth resistor R39 is connected to the common connection end between the output pin OUT of the power conversion chip U8 and the negative power pin VEE of the first operational amplifier U6A; the analog ground pin AGND of the power conversion chip U8 is grounded, the first end of the thirteenth capacitor C48 is connected to the common connection end between the output pin OUT of the power conversion chip U8 and the negative power pin VEE of the first operational amplifier U6A, and the second end of the thirteenth capacitor C48 is grounded.

6. The rail transit microphone human voice signal acquisition device according to claim 1, characterized in that: The audio signal rectification circuit includes a third Schottky diode D5, a fourth Schottky diode D7, a first diode D18, a second diode D19, a thirteenth resistor R38, a fourteenth resistor R40, a fifteenth resistor R41, a sixteenth resistor R42, a seventeenth resistor R43, a fourteenth capacitor C42, a fifteenth capacitor C43, a sixteenth capacitor C45, a seventeenth capacitor C46, ​​an eighteenth capacitor C49 and a second dual operational amplifier composed of a third operational amplifier U7A and a fourth operational amplifier U7B; The positive input pin IN+ of the fourth operational amplifier U7B is grounded, and the inverting input pin IN- of the fourth operational amplifier U7B is electrically connected to the output end of the audio signal amplifying circuit through the thirteenth resistor R38; the cathode of the first diode D18 and the first end of the fourteenth resistor R40 are both connected to the common connection end between the inverting input pin IN- of the fourth operational amplifier U7B and the thirteenth resistor R38, the anode of the first diode D18 is electrically connected to the output pin OUT of the fourth operational amplifier U7B, and the second end of the fourteenth resistor R40 is electrically connected to the output pin OUT of the fourth operational amplifier U7B through the second diode D19; The positive power supply pin VCC of the third operational amplifier U7A is electrically connected to the +5V power supply terminal, the cathode of the third Schottky diode D5, the first end of the fourteenth capacitor C42 and the first end of the fifteenth capacitor C43 are all connected to the common connection terminal between the positive power supply pin VCC of the third operational amplifier U7A and the +5V power supply terminal, and the anode of the third Schottky diode D5, the second end of the fourteenth capacitor C42 and the second end of the fifteenth capacitor C43 are all grounded; The negative power supply pin VEE of the third operational amplifier U7A is electrically connected to the -5V power supply terminal, the positive electrode of the fourth Schottky diode D7, the first end of the sixteenth capacitor C46 and the first end of the seventeenth capacitor C47 are all connected to the common connection terminal between the negative power supply pin VEE of the third operational amplifier U7A and the -5V power supply terminal, and the negative electrode of the fourth Schottky diode D7, the second end of the sixteenth capacitor C46 and the second end of the seventeenth capacitor C47 are all grounded; The positive input pin IN+ of the third operational amplifier U7A is grounded, and the second end of the fourteenth resistor R40 is also electrically connected to the inverting input pin IN- of the third operational amplifier U7A through the fifteenth resistor R41; the first end of the sixteenth resistor R42 is connected to the common connection end between the fifteenth resistor R41 and the inverting input pin IN- of the third operational amplifier U7A, and the second end of the sixteenth resistor R42 is electrically connected to the output pin of the third operational amplifier U7A; the first end of the seventeenth resistor R43 is connected to the common connection end between the thirteenth resistor R38 and the output end of the audio signal amplifying circuit, and the second end of the seventeenth resistor R43 is connected to the common connection end between the second end of the sixteenth resistor R42 and the output pin of the third operational amplifier U7A through the eighteenth capacitor C49; the output pin of the third operational amplifier U7A is electrically connected to the input end of the audio signal processing circuit.

7. The rail transit microphone human voice signal acquisition device according to claim 1, characterized in that: The audio signal processing circuit includes a microcontroller U9B and a DC signal input subcircuit; The input end of the DC signal input subcircuit is electrically connected to the output end of the audio signal rectification circuit, and the output end of the DC signal input subcircuit is electrically connected to the input end of the microcontroller U9B. The microcontroller U9B is also communicatively connected to the external receiving end.

8. The rail transit microphone human voice signal acquisition device according to claim 7, characterized in that: The DC signal input subcircuit includes an eighteenth resistor R56 and a nineteenth resistor R57; The first end of the eighteenth resistor R56 is electrically connected to the output end of the audio signal rectification circuit, and the second end of the eighteenth resistor R56 is electrically connected to the analog-to-digital conversion pin of the microcontroller U9B; the first end of the nineteenth resistor R57 is connected to the common connection end between the second end of the eighteenth resistor R56 and the analog-to-digital conversion pin of the microcontroller U9B, and the second end of the nineteenth resistor R57 is grounded.

9. The rail transit microphone human voice signal acquisition device according to claim 7, characterized in that: The microcontroller 9B is specifically a single chip microcomputer of the LPC1788FBD144 model.

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