Frequency modulation signal transmission system and digital headset

Abstract

Embodiments of the present application provide a frequency modulation (FM) signal transmission system and a digital headset, which are applied to the technical field of terminals. The system comprises an electronic device and a digital headset; the electronic device comprises an FM chip and a first external interface; the digital headset comprises a digital headset chip, a second external interface, and one or more of the following: a left channel, a right channel or a microphone; a connecting line is arranged between the left channel, the right channel or the microphone and the second external interface; and when the digital headset is connected to the first external interface of the electronic device by means of the second external interface, the FM chip is connected to a target pin of the first external interface, and the target pin is further connected to at least one of the left channel, the right channel or the microphone, wherein there is no FM signal path between any one of the microphone, the left channel or the right channel and a grounding end of the digital headset chip. In this way, the probability of poor quality of an FM signal received by the electronic device can be reduced.

Description

FM signal transmission system and digital headphones

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 4, 2023, with application number 202311650991.3 and application name “FM signal transmission system and digital headphones”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of terminal technology, and in particular to a frequency modulation signal transmission system and a digital headset. Background Art

[0003] To make electronic devices thinner and lighter, some electronic devices are equipped with frequency modulation (FM) chips instead of FM antennas. In some implementations, the electronic device receives FM signals through a connected wired headset, processes the FM signals using the FM chip, and plays the processed FM signals through the electronic device's speakers or wired headset, thus achieving FM functionality. Frequency modulation (FM) is abbreviated as frequency modulation.

[0004] However, when an electronic device receives FM signals through a connected wired headset, there is a problem of poor FM signal quality.

[0005] Summary of the Invention

[0006] The embodiment of the present application provides an FM signal transmission system and a digital headset, which are applied to the field of terminal technology. The system includes an electronic device and a digital headset. There is a connecting line between the left channel of the digital headset, the right channel of the digital headset, or the microphone of the digital headset and the external interface of the digital headset. When the digital headset is connected to the electronic device through the external interface: the FM chip of the electronic device is connected to the target pin of the external interface, and the target pin is also connected to at least one of the left channel, the right channel or the microphone; wherein, there is no FM signal path between any one of the microphone, the left channel or the right channel and the ground terminal of the digital headset chip. In this way, the electronic device can receive FM signals through the radio frequency link composed of the FM chip, the target pin and the headphone cable, and the FM signal will not be transmitted to the ground terminal of the digital headset chip, reducing the probability of poor quality of the FM signal received by the electronic device.

[0007] In the first aspect, an embodiment of the present application proposes a frequency modulation (FM) signal transmission system, which includes an electronic device and a digital headset. The electronic device includes an FM chip and a first external interface, and the digital headset includes a digital headset chip, a second external interface, and one or more of the following: a left channel, a right channel, or a microphone. There is a connecting line between the left channel, the right channel, or the microphone and the second external interface. When the digital headset is connected to the first external interface of the electronic device through the second external interface: the FM chip is connected to the target pin of the first external interface, and the target pin is also connected to at least one of the left channel, the right channel, or the microphone. There is no path for the FM signal between any of the microphone, the left channel, or the right channel and the ground terminal of the digital headset chip.

[0008] In this way, with a connecting cable (or headphone cable) between at least one of the left channel, right channel, or microphone and the second external interface serving as an antenna, the electronic device can receive FM signals via a radio frequency link formed by the FM chip, the target pin of the first external interface, the target pin of the second external interface, and at least one of the left channel, right channel, or microphone. Because there is no FM signal path between the microphone, the left channel, or the right channel and the ground terminal of the digital headphone chip, the FM signal is not transmitted to the ground terminal of the digital headphone chip before reaching the electronic device, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0009] In one possible implementation, the target pin includes a function expansion SBU pin. The FM chip is connected to the SBU pin of the first external interface, and the SBU pin is further connected to at least one of the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone.

[0010] In this way, the connection line between the SBU pin of the second external interface and at least one of the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone can serve as an antenna. The FM chip of the electronic device can receive FM signals via a link formed by the FM chip, the SBU pin of the first external interface, the SBU pin of the second external interface, and at least one of the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone. There is no FM signal path between the positive electrode of the microphone, the positive electrode of the left channel, or the positive electrode of the right channel and the ground terminal of the digital headphone chip. The FM signal will not be transmitted to the ground terminal of the digital headphone chip before reaching the pin of the second external interface, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0011] In one possible implementation, the digital headset further includes at least one high-pass filter configured to pass FM signals and block low-frequency signals. The at least one high-pass filter included in the digital headset is configured to satisfy at least one of the following conditions: a first high-pass filter is provided in the path between the SBU pin and the positive electrode of the left channel; a second high-pass filter is provided in the path between the SBU pin and the positive electrode of the right channel; and a third high-pass filter is provided in the path between the SBU pin and the positive electrode of the microphone. The first high-pass filter, the second high-pass filter, or the third high-pass filter is any one of the at least one high-pass filter.

[0012] In this way, when the FM chip of the electronic device receives FM signals through a link formed by the FM chip, the SBU pin of the first external interface, the SBU pin of the second external interface, the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone, at least one high-pass filter included in the digital headset can block low-frequency signals to reduce interference of low-frequency signals on the FM signals received by the electronic device, further reducing the probability of poor quality of the FM signals received by the electronic device.

[0013] In one possible implementation, the digital headset further includes a first low-pass filter, a second low-pass filter, and a first resistor. The low-pass filter is configured to pass low-frequency signals and block FM signals. The first low-pass filter is connected between the digital headset chip and the positive electrode of the left channel. The second low-pass filter is connected between the digital headset chip and the positive electrode of the right channel. The first resistor is connected between the digital headset chip and the positive electrode of the microphone.

[0014] In this way, the first and second low-pass filters can reduce the probability of FM signals being transmitted to the digital headphone chip, further reducing the probability of poor FM signal quality received by the electronic device. The first resistor can present a high-impedance state to high-frequency signals, thereby reducing the probability of FM signals being transmitted to the digital headphone chip, further reducing the probability of poor FM signal quality received by the electronic device. The first resistor can be a 2.2 kΩ resistor.

[0015] In one possible implementation, the digital headset further includes a third low-pass filter and a fourth low-pass filter. The third low-pass filter is connected between the digital headset chip and the cathode of the left channel. The fourth low-pass filter is connected between the digital headset chip and the cathode of the right channel.

[0016] In this way, when the electronic device receives an FM signal, the interference of the FM signal on the low-frequency signal output by the digital headphone chip can be reduced.

[0017] In one possible implementation, the target pin includes a function expansion SBU pin. The FM chip is connected to the SBU pin of the first external interface, and the SBU pin is further connected to at least one of the negative electrode of the left channel, the negative electrode of the right channel, or the negative electrode of the microphone.

[0018] In this way, the connection line between the SBU pin of the second external interface and at least one of the negative pole of the left channel, the negative pole of the right channel, or the negative pole of the microphone can be used as an antenna, and the FM chip of the electronic device can receive FM signals through a link formed by the FM chip, the SBU pin of the first external interface, the SBU pin of the second external interface, the negative pole of the left channel, the negative pole of the right channel, or the negative pole of the microphone, and there is no FM signal path between the negative pole of the microphone, the negative pole of the left channel, or the negative pole of the right channel and the ground terminal of the digital headphone chip. The FM signal will not be transmitted to the ground terminal of the digital headphone chip before reaching the SBU pin of the second external interface, thereby reducing the probability of poor quality of the FM signal received by the electronic device.

[0019] In one possible implementation, the digital headset further includes a fifth low-pass filter, a sixth low-pass filter, and a second resistor. The fifth low-pass filter is connected between the digital headset chip and the positive electrode of the left channel. The sixth low-pass filter is connected between the digital headset chip and the positive electrode of the right channel. The second resistor is connected between the digital headset chip and the positive electrode of the microphone.

[0020] In this way, when the electronic device receives an FM signal, the interference of the FM signal on the low-frequency signal output by the digital headphone chip can be reduced, further reducing the probability of poor quality of the FM signal received by the electronic device.

[0021] In one possible implementation, the electronic device further includes a fourth high-pass filter and a seventh low-pass filter. The fourth high-pass filter is connected between the FM chip and the SBU pin. One end of the seventh low-pass filter is connected to the fourth high-pass filter and the SBU pin, respectively, and the other end of the seventh low-pass filter is grounded. The fourth high-pass filter is configured to pass FM signals and block low-frequency signals. The seventh low-pass filter is configured to pass low-frequency signals and block FM signals.

[0022] In this way, the electronic device can receive FM signals via a link formed by the FM chip, the fourth high-pass filter, the SBU pin of the first external interface, the SBU pin of the second external interface, and at least one of the negative terminal of the left channel, the negative terminal of the right channel, or the negative terminal of the microphone. The fourth high-pass filter can also reduce interference of low-frequency signals on the FM signal received by the electronic device, further reducing the probability of poor quality of the FM signal received by the electronic device. One end of the seventh low-pass filter is connected to the fourth high-pass filter and the SBU pin, respectively, and the other end of the seventh low-pass filter is grounded. This allows the FM signal received by the electronic device to be played through digital headphones.

[0023] In one possible implementation, the digital headset further includes a first switch, a third resistor, a fourth resistor, a first button, a second button, a headphone function control button (HOOK), a fifth resistor, and a sixth resistor. The control end of the first switch is connected to the digital headset chip, one end of the first switch is grounded, and the other end of the first switch is connected to the external device detection CC pin of the second external interface. One end of the third resistor is connected to the other end of the first switch, the other end of the third resistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the digital headset chip. The first button is connected between one end of the fifth resistor and the ground, and the other end of the fifth resistor is connected to the digital headset chip. The second button is connected between one end of the sixth resistor and the ground, and the other end of the sixth resistor is connected to the digital headset chip. HOOK is connected between the digital headset chip and the ground. The first and second buttons are used to adjust the volume of the digital headset. The first button (V+) and the second button (V-) can also be used to select a channel when the electronic device receives FM signals.

[0024] In this way, the electronic device can determine that the type of headphones connected to the electronic device is a digital headphone by detecting the third resistor, and the first button, the second button and the HOOK button on the electronic device can be operated by the user to adjust the volume or select the channel of the digital headphone.

[0025] In one possible implementation, the target pin includes an external device detection CC pin. The FM chip is connected to the CC pin of the first external interface, and the CC pin is also connected to at least one of the positive poles of the left channel, the right channel, or the microphone. An eighth low-pass filter is provided in the path between the CC pin and the digital headphone chip. The eighth low-pass filter is configured to pass low-frequency signals and block FM signals. The eighth low-pass filter is configured to prevent an FM signal from passing between the positive pole of the microphone, the positive pole of the left channel, or the positive pole of the right channel and the ground terminal of the digital headphone chip.

[0026] In this way, the connection line between the CC pin of the second external interface and at least one of the positive electrodes of the left channel, the right channel, or the microphone can serve as an antenna, and the FM chip of the electronic device can receive FM signals via a link formed by the FM chip, the CC pin of the first external interface, the CC pin of the second external interface, and at least one of the positive electrodes of the left channel, the right channel, or the microphone. The eighth low-pass filter is configured to prevent an FM signal path from passing between the positive electrodes of the microphone, the left channel, or the right channel and the ground terminal of the digital headphone chip. Therefore, the FM signal is not transmitted to the ground terminal of the digital headphone chip before reaching the CC pin of the second external interface. This reduces the probability of poor FM signal quality received by the electronic device and enables playback of FM signals through digital headphones.

[0027] In one possible implementation, the digital headset further includes at least one high-pass filter configured to pass FM signals and block low-frequency signals. The at least one high-pass filter included in the digital headset is configured to satisfy at least one of the following conditions: a fifth high-pass filter is provided in the path between the CC pin and the positive electrode of the left channel. A sixth high-pass filter is provided in the path between the CC pin and the positive electrode of the right channel. A seventh high-pass filter is provided in the path between the CC pin and the positive electrode of the microphone. The fifth high-pass filter, the sixth high-pass filter, or the seventh high-pass filter is any one of the at least one high-pass filter.

[0028] In this way, when the FM chip of the electronic device receives FM signals through a link formed by the FM chip, the CC pin of the first external interface, the CC pin of the second external interface, the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone, at least one high-pass filter included in the digital headset can block low-frequency signals to reduce interference of low-frequency signals on the FM signals received by the electronic device, further reducing the probability of poor quality of the FM signals received by the electronic device.

[0029] In one possible implementation, the digital headset further includes an eighth low-pass filter, a ninth low-pass filter, and a seventh resistor. The eighth low-pass filter is connected between the digital headset chip and the positive electrode of the left channel. The ninth low-pass filter is connected between the digital headset chip and the positive electrode of the right channel. The seventh resistor is connected between the digital headset chip and the positive electrode of the microphone.

[0030] In this way, the eighth low-pass filter, the ninth low-pass filter, and the seventh resistor can reduce the probability of FM signals being transmitted to the digital headset chip 407, thereby further reducing the probability of poor quality of FM signals received by the electronic device. The seventh resistor can be the same as the first resistor.

[0031] In one possible implementation, the digital headset further includes a tenth low-pass filter and an eleventh low-pass filter. The tenth low-pass filter is connected between the digital headset chip and the cathode of the left channel. The eleventh low-pass filter is connected between the digital headset chip and the cathode of the right channel.

[0032] In this way, when the electronic device receives an FM signal, the interference of the FM signal on the low-frequency signal output by the digital headphone chip can be reduced.

[0033] In one possible implementation, the digital headset further includes a first switch, a third resistor, a fourth resistor, a first button, a second button, a headset function control button (HOOK), a fifth resistor, and a sixth resistor. The control end of the first switch is connected to the digital headset chip, one end of the first switch is grounded, the other end of the first switch is connected to one end of the eighth low-pass filter, and the other end of the eighth low-pass filter is connected to the CC pin of the second external interface. One end of the third resistor is connected to the other end of the first switch, the other end of the third resistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the digital headset chip. The first button is connected between one end of the fifth resistor and the ground end, and the other end of the fifth resistor is connected to the digital headset chip. The second button is connected between one end of the sixth resistor and the ground end, and the other end of the sixth resistor is connected to the digital headset chip. HOOK is connected between the digital headset chip and the ground end. The first and second buttons are used to adjust the volume of the digital headset.

[0034] In this way, when the electronic device receives an FM signal, the eighth low-pass filter can reduce the probability of the FM signal being transmitted to the ground terminal through the conductive first switch M1 before reaching the CC pin, thereby reducing the probability of poor FM signal quality received by the electronic device. The electronic device can also determine that the type of headphones connected to the electronic device is a digital headphone by detecting the third resistor, and the first button, second button, and HOOK button on the electronic device can be operated by the user to adjust the volume or select a channel for the digital headphone.

[0035] In one possible implementation, the electronic device further includes an eighth high-pass filter, a CC chip, and a twelfth low-pass filter. The eighth high-pass filter is connected between the FM chip and the CC pin. The twelfth low-pass filter is connected between the CC chip and the CC pin. The eighth high-pass filter is configured to pass FM signals and block low-frequency signals. The twelfth low-pass filter is configured to pass low-frequency signals and block FM signals.

[0036] In this way, the eighth high-pass filter can further reduce the probability of poor quality of the FM signal received by the electronic device. When a digital headset is connected to the electronic device, if the CC chip 606 detects the third resistor, the CC chip 606 can determine that the headset connected to the electronic device is a digital headset.

[0037] In a second aspect, an embodiment of the present application provides a digital headset, comprising a digital headset chip, a second external interface, and one or more of the following: a left audio channel, a right audio channel, or a microphone. A connecting wire connects the left audio channel, the right audio channel, or the microphone to the second external interface. A target pin of the second external interface is connected to at least one of the left audio channel, the right audio channel, or the microphone. There is no path for FM signals between the microphone, the left audio channel, or the right audio channel and a ground terminal of the digital headset chip.

[0038] In this way, when the first external interface of the electronic device is connected through the second external interface and the FM chip of the electronic device is connected to the target pin in the first external interface, the electronic device can receive FM signals through the headphone cable of the digital headset. Because there is no FM signal path between the microphone, any of the left channel or the right channel and the ground terminal of the digital headset chip in the digital headset, the FM signal will not be transmitted to the ground terminal of the digital headset chip before reaching the electronic device, thereby reducing the probability of poor quality of the FM signal received by the electronic device. The FM signal received by the electronic device can be played through the digital headset or through the speaker of the electronic device. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG1 is a schematic diagram of a Type-C interface provided in an embodiment of the present application;

[0040] FIG2 is a diagram illustrating a scenario in which an electronic device provided by an embodiment of the present application is connected to a wired digital headset via a Type-C interface;

[0041] FIG3 is a circuit diagram of a possible implementation of a connection between an electronic device and a digital headset;

[0042] FIG4 is a circuit diagram of an FM signal transmission system provided in an embodiment of the present application;

[0043] FIG5 is another circuit diagram of an FM signal transmission system provided in an embodiment of the present application;

[0044] FIG6 is another circuit diagram of the FM signal transmission system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] To facilitate a clear description of the technical solutions of the embodiments of the present application, some of the terms and technologies involved in the embodiments of the present application are briefly introduced below:

[0046] 1. Digital headphones

[0047] Digital headphones can be understood as headphones with a built-in digital-to-analog converter (DAC) and amplifier. When connected to an electronic device, the DAC decodes the undecoded digital signal output by the electronic device for playback. The DAC can be integrated into the audio processing chip (codec) of the digital headphones.

[0048] For example, the digital headset can be connected to the external interface of the electronic device through the external interface on the digital headset to achieve the connection between the digital headset and the electronic device.

[0049] The external interface can be any one of a universal serial bus Type-C (USB Type-C) interface, a universal serial bus Type-A (USB Type-A) interface, or a universal serial bus Type-B (USB Type-B) interface.

[0050] The Universal Serial Bus Type-C interface can be referred to as the Type-C interface. For ease of understanding, the second clause of the terminology explanation uses the Type-C interface as an example to explain the external interface.

[0051] 2. Type-C interface

[0052] FIG1 shows a schematic diagram of a Type-C interface provided in an embodiment of the present application.

[0053] As shown in Figure 1, the Type-C interface consists of 24 pins, designated A1-A12 and B1-B12. Because pins A1-A12 and B1-B12 have similar functions, the following uses pins A1-A12 as an example to explain the function of each pin.

[0054] Pins A1 and A12: Ground pins, also known as GND pins.

[0055] Pins A2 and A3: data transmission pins, also known as TX1+ and TX1- pins, can be used for compatibility with USB3.0 and USB3.1.

[0056] Pins A4 and A9: Connected to the power supply module in the terminal device so that the terminal device can power the Type-C interface. That is, the terminal device provides VBUS for the Type-C interface. Also called VBUS pins.

[0057] Pin A5: External device detection pin, also known as CC1 pin, is used to detect the type of external device. External device types can include downstream facing port (DFP) and upstream facing port (UFP).

[0058] Pins A6 and A7: Data transmission pins, also known as D+ and D-, are used to transmit audio, video, or files. Electronic devices can also use the D+ and D- pins to output voltage signals to the charger based on the fast-charging protocol. The charger's built-in USB decoding chip can use this voltage signal to determine the required output voltage for fast charging. In normal charging mode (not using fast charging), the VBUS pin typically transmits a charging voltage no greater than 5V. In fast-charging mode, the transmitted charging voltage can reach up to 20V.

[0059] In the embodiment of the present application, the D+ pin may also be referred to as a first data transmission pin, and the D- pin may also be referred to as a second data transmission pin.

[0060] Pins A6 and A7 can be used for compatibility with USB2.0.

[0061] Pin A8: Function expansion pin, also known as SBU1 pin.

[0062] Pins A10 and A11: data receiving pins, also known as RX2+ and RX2- pins, can be used for compatibility with USB3.0 and USB3.1.

[0063] The functions of B1-B12 correspond to A1-A12 and are not repeated here. B1-B12 can be called: GND, TX2+, TX2-, VBUS, CC2, D+, D-, SBU2, VBUS, RX1+, RX1-, GND respectively.

[0064] Pins A1-A12 correspond to the A-layer gold fingers, and pins B1-B12 correspond to the B-layer gold fingers. As shown in Figure 1, the A-layer gold fingers and the B-layer gold fingers are asymmetric at CC1, SBU2, CC2, and SBU1, but the signals are symmetric elsewhere.

[0065] 3. High-pass filter

[0066] A high-pass filter can be used to pass high-frequency signals and block low-frequency signals.

[0067] The high-frequency signal may include an FM signal. The low-frequency signal may include a low-frequency signal transmitted by a CC pin of an external interface and used to determine the type of external device connected to the electronic device, or a signal transmitted by a data transmission pin of an external interface. The low-frequency signal transmitted by a CC pin of an external interface and used to determine the type of external device connected to the electronic device may also be referred to as a CC signal.

[0068] The high-pass filter can be in the form of an LC circuit consisting of an inductor and a capacitor, or in the form of an RC circuit consisting of a capacitor and a resistor.

[0069] 4. Low-pass filter

[0070] A low-pass filter is used to pass low-frequency signals while blocking high-frequency signals. It can also be an LC circuit consisting of an inductor and a capacitor. It can also be an RC circuit consisting of a capacitor and a resistor.

[0071] 5. Bandpass filter

[0072] A bandpass filter can be understood as a circuit that allows signals within a specific frequency range to pass through, while suppressing signals outside of that frequency range. A bandpass filter can be in the form of an RLC circuit consisting of resistors, inductors, and capacitors.

[0073] In some implementations, the low-pass filter may be replaced with a band-pass filter to pass low-frequency signals and block high-frequency signals.

[0074] It is understandable that in other implementations, the high-pass filter may be replaced by a band-pass filter to pass high-frequency signals and block low-frequency signals.

[0075] 6. In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0076] In the embodiments of the present application, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0077] In the embodiment of the present application, "at..." can be the instant when a certain situation occurs, or it can be a period of time after the situation occurs, and the embodiment of the present application does not specifically limit this. In addition, the display interface provided in the embodiment of the present application is only an example, and the display interface can also include more or less content.

[0078] Some electronic devices have Type-C interfaces, and some wired digital headphones also have Type-C interfaces. Electronic devices and wired digital headphones can be connected via the Type-C interface. Figure 2 shows a scenario diagram of an electronic device provided by an embodiment of the present application being connected to a wired digital headphone via the Type-C interface.

[0079] As shown in Figure 2, this scenario may include an electronic device 100 and a wired digital headset 102. The electronic device 100 is provided with a Type-C port 101, and the digital headset 102 is provided with a Type-C port 103, a microphone 104, a left audio channel 105, and a right audio channel 106. In this scenario, the electronic device can be connected to the Type-C port 103 of the digital headset 102 via the Type-C port 101 to receive FM signals through the digital headset 102 to implement FM functionality.

[0080] Among them, the Type-C interface 103 on the digital headset 102 can be called a Type-C male connector, and the Type-C interface 101 on the electronic device 100 can be called a Type-C female connector.

[0081] FIG3 shows a circuit diagram of connecting an electronic device to a digital headset in a possible implementation.

[0082] As shown in FIG3 , the digital headset is connected to the Type-C interface 302 of the electronic device via the Type-C interface of the digital headset, thereby achieving connection between the digital headset and the electronic device.

[0083] The CC pin of the Type-C port 302 is connected between the frequency modulation (FM) demodulator chip 301 of the electronic device and the positive terminal of the left audio channel 305 of the digital headset. The FM filter 304 is connected between the CC pin of the Type-C port 302 and the positive terminal of the left audio channel 305. The electronic device can receive FM signals through the path formed by the FM demodulator chip 301, the CC pin of the Type-C port 302, the CC pin of the Type-C port of the digital headset, the FM filter 304, and the left audio channel 305. The connection line between the left audio channel 305 and the CC pin of the Type-C port of the digital headset can serve as an antenna.

[0084] The CC pin of the Type-C interface 302 is also connected to one end of a switch M1. The other end of the switch M1 is grounded. The control end of the switch M1 is connected to the GPIO signal terminal of the digital headphone chip 307. One end of the switch M1 is also connected to one end of a 5.1 kilo-ohm (KΩ) resistor. The other end of the 5.1 KΩ resistor is connected to one end of a 100 KΩ resistor. The other end of the 100 KΩ resistor is connected to the digital headphone chip 307.

[0085] The VBUS pin of the Type-C interface 302 is connected to the power supply (or VDD) terminal of the digital headset chip 307. The power supply circuit 303 of the digital headset is connected between the VBUS pin of the Type-C interface 302 and the VDD terminal of the digital headset chip 307.

[0086] The digital headphone chip 307 is connected to the data transmission pins (D+ and D-) of the Type-C interface 302. The digital headphone chip 307 is also connected to the positive electrode of the left channel 305 and the right channel 306 of the digital headphone. The negative electrodes of the left channel 305 and the right channel 306 are both grounded.

[0087] The 5.1KΩ resistor can be used to enable the electronic device to identify the connected earphone as a digital earphone when the digital earphone is connected to the electronic device.

[0088] The FM demodulation chip 301 can demodulate the received FM signal to obtain a demodulated signal. The electronic device converts and processes the demodulated signal to obtain a low-frequency signal. The electronic device transmits the low-frequency signal to the digital headset via the data transmission pin of the Type-C interface 302. The digital headset can play the low-frequency signal transmitted by the electronic device.

[0089] However, as shown in Figure 3, when the electronic device is connected to the digital headset via the Type-C interface 302, the electronic device supplies power to the digital headset via the VBUS pin of the Type-C interface 302, and the GPIO signal terminal of the digital headset chip 307 outputs a high-level signal, causing the switch M1 to be in the on state. When the electronic device receives an FM signal via the CC pin of the Type-C interface 302 and the headphone cable of the left channel 305, because the switch M1 is in the on state, some of the FM signal will be transmitted to the ground terminal of the switch M1 through the link formed by the left channel 305, the FM filter 304, and the switch M1 before reaching the CC pin of the Type-C interface 302. This may result in poor FM signal quality when the electronic device receives the FM signal, or may result in poor FM signal quality received by the electronic device.

[0090] In view of this, an embodiment of the present application provides a frequency modulation (FM) signal transmission system, which includes an electronic device and a digital headset, wherein a connecting line is provided between the left channel of the digital headset, the right channel of the digital headset, or the microphone of the digital headset and the external interface of the digital headset. When the digital headset is connected to the electronic device through the external interface: the FM chip of the electronic device is connected to the target pin of the external interface, and the target pin is also connected to at least one of the left channel, the right channel, or the microphone; wherein, there is no FM signal path between any one of the microphone, the left channel, or the right channel and the ground terminal of the digital headset chip. In this way, the electronic device can receive FM signals through the radio frequency link formed by the FM chip, the target pin, and the headphone cable, and the FM signal will not be transmitted to the ground terminal of the digital headset chip, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0091] The electronic devices of the embodiments of the present application may include handheld devices, vehicle-mounted devices, etc. For example, some electronic devices include: mobile phones, tablet computers, PDAs, laptop computers, mobile internet devices (MIDs), wearable devices, virtual reality (VR) devices, augmented reality (AR) devices, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, cellular phones, cordless phones, session initiation protocol (SIP) phones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to wireless modems, in-vehicle devices (such as car computers), wearable devices, terminal devices in 5G networks or future evolved public land mobile communication networks (PLMNs), and the like. The terminal equipment in the network (PLMN), etc., is not limited to this in the embodiments of the present application.

[0092] For example, the FM signal transmission system provided in the embodiment of the present application is described by taking the external interface of the electronic device as the first external interface and the external interface of the digital headset as the second external interface as an example.

[0093] In the FM signal transmission system provided in an embodiment of the present application, the electronic device includes an FM chip and a first external interface, and the digital headset includes a digital headset chip, a second external interface, and one or more of the following: a left audio channel, a right audio channel, or a microphone. A connecting cable is provided between the left audio channel, the right audio channel, or the microphone and the second external interface. The connecting cable may also be referred to as a headphone cable.

[0094] When the digital headset is connected to the first external interface of the electronic device through the second external interface:

[0095] The FM chip is connected to a target pin of the first external interface, and the target pin of the first external interface is further connected to at least one of a left audio channel, a right audio channel, or a microphone. There is no FM signal path between the microphone, the left audio channel, or the right audio channel and a ground terminal of the digital headphone chip.

[0096] Exemplarily, the first external interface may be any one of a USB Type-A interface, a USB Type-B interface, or a Type-C interface. The target pin of the first external interface may be any pin of the first external interface. It should be understood that the second external interface has the same interface type as the first external interface. The interface type includes any one of a USB Type-A interface, a USB Type-B interface, or a Type-C interface.

[0097] In this way, with a connecting cable (or headphone cable) between at least one of the left channel, right channel, or microphone and the second external interface serving as an antenna, the electronic device can receive FM signals via a radio frequency link formed by the FM chip, the target pin of the first external interface, the target pin of the second external interface, and at least one of the left channel, right channel, or microphone. Because there is no FM signal path between the microphone, the left channel, or the right channel and the ground terminal of the digital headphone chip, the FM signal is not transmitted to the ground terminal of the digital headphone chip before reaching the electronic device, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0098] The following uses the example of the first external interface and the second external interface being both Type-C interfaces as an example, and describes the FM signal transmission system provided by the embodiment of the present application in conjunction with Figures 4 to 6. Figures 4 and 5 illustrate the example of the target pin being the function expansion (SBU) pin in the Type-C interface. Figure 6 illustrates the example of the target pin being the external device detection (CC) pin in the Type-C interface.

[0099] Taking the target pin as the SBU pin in the Type-C interface as an example, FIG4 shows a circuit diagram of the FM signal transmission system provided in an embodiment of the present application.

[0100] As shown in Figure 4 , the FM signal transmission system provided in an embodiment of the present application may include an electronic device and a digital headset. The electronic device includes an FM chip 401 and a Type-C interface 402. The digital headset includes a digital headset chip 407, a second external interface, and one or more of the following: a left channel 405, a right channel 406, or a microphone 408. The second external interface is not shown in Figure 4 .

[0101] There is a connection line between the left audio channel 405, the right audio channel 406 or the microphone 408 and the second external connection interface.

[0102] The power supply circuit (power) 403 of the digital headset is connected between the VBUS pin of the Type-C interface 402 and the power supply (VDD) terminal of the digital headset chip 407. When the digital headset is connected to the Type-C interface 402 of the electronic device through the second external interface, the electronic device can power the digital headset chip 407 through the VBUS pin of the Type-C interface 402 and the power supply circuit 403.

[0103] When the digital headset is connected to the Type-C interface 402 of the electronic device via the second external interface, the FM chip 401 can be connected to the SBU pin of the Type-C interface 402, the SBU pin of the Type-C interface 402 is connected to the SBU pin of the second external interface, and the SBU pin of the second external interface can be connected to at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408. Thus, the FM chip 401 can be connected to the SBU pin of the Type-C interface 402, and the SBU pin can also be connected to at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408.

[0104] For example, the SBU pins of the Type-C interface 402 may include the SBU1 pin of the Type-C interface 402 and / or the SBU2 pin of the Type-C interface 402. The SBU pins of the second external interface may include the SBU1 pin of the second external interface and / or the SBU2 pin of the second external interface.

[0105] In the FM signal transmission system, the FM chip 401 is connected to the SBU1 pin and the SBU2 pin of the Type-C interface 402. The SBU1 pin of the second external interface is connected to at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408, and / or the SBU2 pin of the second external interface is connected to at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408.

[0106] Optionally, in the FM signal transmission system, the FM chip 401 is connected to the SBU1 pin of the Type-C interface 402, and / or the FM chip 401 is connected to the SBU2 pin of the Type-C interface 402. The SBU1 pin of the second external interface is connected to at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408, and the SBU2 pin of the second external interface is connected to at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408.

[0107] There is no FM signal path between the positive electrode of the microphone 408 , the positive electrode of the left channel 405 , or the positive electrode of the right channel 406 and the ground terminal of the digital headphone chip 407 .

[0108] In this way, the connection line between the SBU pin of the second external interface and at least one of the positive terminals of the left audio channel 405, the positive terminals of the right audio channel 406, or the positive terminals of the microphone 408 can serve as an antenna. The FM chip 401 of the electronic device can receive FM signals via a link formed by the FM chip 401, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, and at least one of the positive terminals of the left audio channel 405, the positive terminals of the right audio channel 406, or the positive terminals of the microphone 408. Because there is no FM signal path between the positive terminals of the microphone 408, the positive terminals of the left audio channel 405, or the positive terminals of the right audio channel 406 and the ground terminal of the digital headphone chip 407, the FM signal will not be transmitted to the ground terminal of the digital headphone chip 407 before reaching the SBU pin of the second external interface, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0109] Optionally, as shown in FIG4 , in the FM signal transmission system provided in the embodiment of the present application, the digital headset may further include at least one high-pass filter, which is used to pass FM signals and block low-frequency signals.

[0110] The digital headset includes at least one high-pass filter that is deployed in a manner that satisfies at least one of the following:

[0111] A first high-pass filter 404 is provided in the path between the SBU pin of the Type-C interface 402 and the positive electrode of the left audio channel 405;

[0112] A second high-pass filter 409 is provided in the path between the SBU pin of the Type-C interface 402 and the positive electrode of the right channel 406;

[0113] A third high-pass filter 410 is provided in the path between the SBU pin of the Type-C interface 402 and the positive terminal of the microphone 408 .

[0114] The first high-pass filter 404 , the second high-pass filter 409 or the third high-pass filter 410 is any one of the at least one high-pass filter included in the digital headset.

[0115] It should be understood that, as shown in FIG4 , the electronic device and the digital headset are connected, so the deployment method of at least one high-pass filter included in the digital headset in the embodiment of the present application satisfies at least one of the following:

[0116] A first high-pass filter 404 is provided in the path between the SBU pin of the second external interface and the positive electrode of the left channel 405;

[0117] A second high-pass filter 409 is provided in the path between the SBU pin of the second external interface and the positive electrode of the right channel 406;

[0118] A third high-pass filter 410 is provided in the path between the SBU pin of the second external interface and the positive electrode of the microphone 408 .

[0119] In this way, when the FM chip 401 of the electronic device receives the FM signal through the link formed by the FM chip 401, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408, at least one high-pass filter included in the digital headset can block the low-frequency signal to reduce the interference of the low-frequency signal on the FM signal received by the electronic device, further reducing the probability of poor quality of the FM signal received by the electronic device.

[0120] Optionally, the first high-pass filter 404, the second high-pass filter 409 and the third high-pass filter 410 can all be 100p capacitors. In this way, the number of components of the digital headset can be reduced while reducing the probability of poor quality of the FM signal received by the electronic device.

[0121] Optionally, as shown in FIG4 , in the FM signal transmission system provided in the embodiment of the present application, the digital headset may further include a first low-pass filter, a second low-pass filter, and a first resistor R1 .

[0122] The first low-pass filter may be connected between the digital headphone chip 407 and the positive terminal of the left channel 405 .

[0123] The second low-pass filter may be connected between the digital headphone chip 407 and the positive terminal of the right channel 406 .

[0124] The first resistor R1 may be connected between the digital earphone chip 407 and the positive electrode of the microphone 408 .

[0125] For example, the low-pass filter can also be a magnetic bead. Magnetic beads present a high impedance to high-frequency signals and a low impedance to low-frequency signals. Therefore, magnetic beads can be used to pass low-frequency signals while blocking high-frequency signals. The first low-pass filter can be the first magnetic bead B1 shown in Figure 4. The second low-pass filter can be the second magnetic bead B2 shown in Figure 4.

[0126] As shown in Figure 4, one end of the first magnetic bead B1 is connected to the digital headphone chip 407, and the other end of the first magnetic bead B1 is connected to the first high-pass filter 404 and the positive electrode of the left channel 405. This can reduce the probability of FM signals being transmitted to the digital headphone chip 407, further reducing the probability of poor FM signal quality received by the electronic device.

[0127] One end of the second magnetic bead B2 is connected to the digital headphone chip 407, and the other end of the second magnetic bead B2 is connected to the second high-pass filter 409 and the positive electrode of the right channel 406. This can also reduce the probability of FM signals being transmitted to the digital headphone chip 407, thereby further reducing the probability of poor FM signal quality received by the electronic device.

[0128] One end of the first resistor R1 is connected to the digital headphone chip 407, and the other end of the first resistor R1 is connected to the positive electrode of the third high-pass filter 410 and the microphone 408, respectively. The first resistor R1 can be a 2.2 kΩ resistor. The first resistor R1 can present a high impedance to high-frequency signals, thereby reducing the probability of FM signals being transmitted to the digital headphone chip 407, further reducing the probability of poor FM signal quality received by the electronic device. The first resistor R1 can also be used to transmit a DC bias voltage to the microphone 408.

[0129] Optionally, as shown in FIG4 , in the FM signal transmission system provided in an embodiment of the present application, the digital headset may further include a third low-pass filter and a fourth low-pass filter. The third low-pass filter may be the third magnetic bead B3 shown in FIG4 . The fourth low-pass filter may be the fourth magnetic bead B4 shown in FIG4 .

[0130] The third low-pass filter is connected between the digital headphone chip 407 and the negative terminal of the left channel 405 .

[0131] The fourth low-pass filter is connected between the digital headphone chip 407 and the negative electrode of the right channel 406 .

[0132] In this way, when the electronic device receives an FM signal, the interference of the FM signal on the low-frequency signal output by the digital headphone chip can be reduced.

[0133] It is understood that the cathode of the left channel 405 can be connected to the ground terminal of the digital headphone chip 407 via a third low-pass filter. The cathode of the right channel 406 can be connected to the ground terminal of the digital headphone chip 407 via a fourth low-pass filter. In this way, the FM signal received by the electronic device can be played through the digital headphone.

[0134] For example, when the FM chip 401 of the electronic device receives an FM signal via a link consisting of the FM chip 401, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408, the FM chip 401 can decode and convert the received FM signal to obtain a low-frequency signal to be played. The electronic device can transmit the low-frequency signal to be played to the digital headphone chip 407 via the data transmission pin of the Type-C interface 402 and the data transmission pin of the second external interface.

[0135] It can be understood that the digital headphone chip 407 can convert the signal transmitted according to the USB interface protocol into a signal transmitted according to the integrated circuit built-in audio bus (inter-IC sound, I2S) interface protocol (i.e. USB TO I2S), and can also convert the signal transmitted according to the I2S interface protocol into an analog signal (i.e. I2S TO analog).

[0136] Upon receiving a low-frequency signal to be played, the digital headphone chip 407 can convert the low-frequency signal to generate a processed sound signal. The processed sound signal is an analog signal. The processed sound signal is a low-frequency signal. The digital headphone chip 407 transmits the processed sound signal to the left channel 405 via the positive terminal of the left channel 405. The digital headphone chip 407 also transmits the processed sound signal to the right channel 406 via the positive terminal of the right channel 406.

[0137] The processed sound signal is also returned to the ground via the negative electrode of the left channel 405 and the ground terminal of the digital headphone chip 407 , so as to be played through the left channel 405 .

[0138] The processed sound signal is also returned to the ground via the negative electrode of the right channel 406 and the ground terminal of the digital headphone chip 407 , so as to be played through the right channel 406 .

[0139] Optionally, the FM signal received by the electronic device may also be played through a speaker of the electronic device.

[0140] Optionally, as shown in Figure 4, in the FM signal transmission system provided in an embodiment of the present application, the digital headset may further include a first switch M1, a third resistor R3, a fourth resistor R4, a first button V+, a second button V-, a headset function control button HOOK, a fifth resistor R5 and a sixth resistor R6.

[0141] A control end of the first switch M1 is connected to the digital headset chip 407 , one end of the first switch M1 is grounded, and the other end of the first switch M1 is connected to the CC pin of the second external interface.

[0142] One end of the third resistor R3 is connected to the other end of the first switch M1 , the other end of the third resistor R3 is connected to one end of the fourth resistor R4 , and the other end of the fourth resistor R4 is connected to the digital earphone chip 407 .

[0143] The first button V+ is connected between one end of the fifth resistor R5 and the ground end, and the other end of the fifth resistor R5 is connected to the digital earphone chip 407 .

[0144] The second button V− is connected between one end of the sixth resistor R6 and the ground end, and the other end of the sixth resistor R6 is connected to the digital earphone chip 407 .

[0145] HOOK is connected between the digital earphone chip 407 and the ground terminal.

[0146] The first button V+ and the second button V- can be used to adjust the volume of the digital headset. The first button V+ and the second button V- can also be used to select a song to play. The first button V+ and the second button V- can also be used to select a channel when the electronic device receives FM signals.

[0147] Exemplarily, the third resistor R3 can be a 5.1KΩ resistor. As shown in Figure 4, when the digital headset is connected to the Type-C interface 402 of the electronic device through the second external interface, the electronic device can detect the 5.1KΩ resistor through the CC pin of the Type-C interface 402. The electronic device can power the digital headset chip 407 through the VBUS pin of the Type-C interface 402, the VBUS pin of the second external interface and the power supply circuit 403. The GPIO end of the digital headset chip 407 can output a high level, so that the first switch M1 is turned on, thereby grounding the CC pin of the Type-C interface 402. The electronic device can detect a 0Ω resistor through the CC pin of the Type-C interface 402. Thus, the electronic device can determine that the type of the connected headset is a digital headset.

[0148] Optionally, when headphones are connected to the electronic device, if the electronic device detects a third resistor (e.g., a 5.1 kΩ resistor), the electronic device can determine that the connected headphones are digital headphones. It should be understood that 5.1 kΩ is an example of a resistance value of the third resistor, and is not intended to limit the resistance value of the third resistor.

[0149] The fourth resistor R4 can stabilize the voltage of the digital headset when the digital headset is powered on. The fourth resistor R4 can be a 100KΩ resistor.

[0150] In the FM signal transmission system shown in FIG4 , the target pin may include an SBU pin. The FM chip 401 of the electronic device may receive the FM signal through a link consisting of the FM chip 401, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408. The FM signal will not be transmitted to the ground terminal of the digital headphone chip 407 before reaching the SBU pin of the second external interface, thereby reducing the probability of poor quality of the FM signal received by the electronic device. The FM signal received by the electronic device can be played through the left channel 405 and the right channel 406, or through the speaker of the electronic device. The electronic device can determine that the type of headphones connected to the electronic device is a digital headphone by detecting the third resistor. The first button V+, the second button V-, and HOOK on the electronic device can be operated by the user to adjust the volume of the digital headphones or select a channel.

[0151] Still taking the target pin as the SBU pin in the Type-C interface as an example, FIG5 shows another circuit diagram of the FM signal transmission system provided in an embodiment of the present application.

[0152] As shown in FIG5 , in the FM signal transmission system provided in an embodiment of the present application, the deployment method and technical effects of the power supply circuit 403 of the digital headset can refer to the deployment method and technical effects of the power supply circuit 403 in FIG4 , which will not be repeated here.

[0153] When the digital headset is connected to the Type-C interface 402 of the electronic device via the second external interface of the digital headset: the FM chip 401 can be connected to the SBU pin of the Type-C interface 402, the SBU pin of the Type-C interface 402 is connected to the SBU pin of the second external interface, and the SBU pin of the second external interface can be connected to at least one of the negative electrode of the left channel 405, the negative electrode of the right channel 406, or the negative electrode of the microphone 408. In this way, the FM chip 401 is connected to the SBU pin of the Type-C interface 402, and the SBU pin of the Type-C interface 402 is also connected to at least one of the negative electrode of the left channel 405, the negative electrode of the right channel 406, or the negative electrode of the microphone 408. The second external interface is not shown in Figure 5.

[0154] There is no FM signal path between the negative electrode of the microphone 408 , the negative electrode of the left channel 405 , or the negative electrode of the right channel 406 and the ground terminal of the digital headphone chip 407 .

[0155] It is understood that the SBU pin of the Type-C interface 402 may include the SBU1 pin of the Type-C interface 402 and / or the SBU2 pin of the Type-C interface 402. The SBU pin of the second external interface may include the SBU1 pin of the second external interface and / or the SBU2 pin of the second external interface. The connection method between the FM chip 401 and at least one of the negative electrode of the left channel 405, the negative electrode of the right channel 406, or the negative electrode of the microphone 408 and the SBU1 pin and the SBU2 pin is similar to the connection method between the FM chip 401 and at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408 and the SBU1 pin and the SBU2 pin in the embodiment of FIG. 4 , and will not be repeated here.

[0156] In this way, the connection line between the SBU pin of the second external interface and at least one of the negative electrode of the left audio channel 405, the negative electrode of the right audio channel 406, or the negative electrode of the microphone 408 can serve as an antenna, and the FM chip 401 of the electronic device can receive FM signals via a link formed by the FM chip 401, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the negative electrode of the left audio channel 405, the negative electrode of the right audio channel 406, or the negative electrode of the microphone 408. Because there is no FM signal path between the negative electrode of the microphone 408, the negative electrode of the left audio channel 405, or the negative electrode of the right audio channel 406 and the ground terminal of the digital headphone chip 407, the FM signal will not be transmitted to the ground terminal of the digital headphone chip 407 before reaching the SBU pin of the second external interface, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0157] Optionally, as shown in FIG5 , in the FM signal transmission system provided in the embodiment of the present application, the digital headset may further include a fifth low-pass filter, a sixth low-pass filter and a second resistor R2 .

[0158] The fifth low-pass filter is connected between the digital earphone chip 407 and the positive electrode of the left channel 405. The fifth low-pass filter can be the fifth magnetic bead B5 shown in FIG5 .

[0159] The sixth low-pass filter is connected between the digital earphone chip 407 and the positive electrode of the right channel 406. The sixth low-pass filter can be the sixth magnetic bead B6 shown in FIG5.

[0160] The second resistor R2 is connected between the digital earphone chip 407 and the positive electrode of the microphone 408. The second resistor R2 may be the same as the first resistor R1 in FIG4 .

[0161] In this way, when the electronic device receives an FM signal, the interference of the FM signal on the low-frequency signal output by the digital headphone chip can be reduced, further reducing the probability of poor quality of the FM signal received by the electronic device.

[0162] Optionally, as shown in FIG5 , in the FM signal transmission system provided in an embodiment of the present application, the electronic device further includes a fourth high-pass filter 501 and a seventh low-pass filter 502 .

[0163] The fourth high-pass filter 501 is connected between the FM chip 401 and the SBU pin of the Type-C interface 402 .

[0164] In this way, the electronic device can receive FM signals through a link consisting of the FM chip 401, the fourth high-pass filter 501, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the negative pole of the left channel 405, the negative pole of the right channel 406, or at least one of the negative poles of the microphone 408. The fourth high-pass filter 501 can also reduce the interference of low-frequency signals on the FM signals received by the electronic device, further reducing the probability of poor quality of the FM signals received by the electronic device.

[0165] One end of the seventh low-pass filter 502 is connected to the fourth high-pass filter 501 and the SBU pin of the Type-C interface 402 respectively, and the other end of the seventh low-pass filter 502 is grounded, so that the FM signal received by the electronic device can be played through the digital headset.

[0166] For example, the electronic device can receive FM signals via a link consisting of the FM chip 401, the fourth high-pass filter 501, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the negative electrode of the left channel 405, the negative electrode of the right channel 406, or the negative electrode of the microphone 408. The FM chip 401 can decode and convert the received FM signal to obtain a low-frequency signal to be played. The electronic device can transmit the low-frequency signal to be played to the digital headphone chip 407 via the data transmission pin of the Type-C interface 402 and the data transmission pin of the second external interface. The digital headphone chip 407 can process the low-frequency signal to be played to obtain a processed sound signal.

[0167] The digital headphone chip 407 transmits the processed sound signal to the left channel 405 through the positive terminal of the left channel 405. The digital headphone chip 407 also transmits the processed sound signal to the right channel 406 through the positive terminal of the right channel 406. The processed sound signal can be played through the left channel 405 and the right channel 406.

[0168] For example, if the negative pole of the left channel 405 is connected to the SBU pin of the second external interface, the processed sound signal is transmitted to the ground end through the positive pole of the left channel 405, the negative pole of the left channel 405, the SBU pin of the second external interface, the SBU pin of the Type-C interface 402 and the seventh low-pass filter 502 to achieve return ground, so as to achieve playback through the left channel 405.

[0169] If the cathode of the left channel 405 is not connected to the SBU pin of the second external interface, the cathode of the left channel 405 is connected to the ground terminal of the digital headphone chip 407. The specific implementation principle of the FM signal received by the electronic device and played through the left channel 405 can be found in the specific implementation principle of the FM signal received by the electronic device and played through the left channel 405 in the embodiment of FIG. 4 , which will not be repeated here.

[0170] In this way, the FM signal received by the electronic device can be played through the left channel 405. It can be understood that the specific implementation principle of the FM signal received by the electronic device being played through the right channel 406 is similar to the specific implementation principle of the FM signal received by the electronic device being played through the left channel 405 in the embodiment of the present application, and will not be repeated here.

[0171] Optionally, the seventh low-pass filter 502 may be replaced by a band-pass filter that passes the sound signal processed by the digital earphone chip 407 and blocks the FM signal.

[0172] Optionally, as shown in Figure 5, in the FM signal transmission system provided in an embodiment of the present application, the digital headset may further include a first switch M1, a third resistor R3, a fourth resistor R4, a first button V+, a second button V-, a headset function control button HOOK, a fifth resistor R5 and a sixth resistor R6.

[0173] The deployment mode and technical effects of the first switch M1, the third resistor R3, the fourth resistor R4, the first button V+, the second button V-, the headphone function control button HOOK, the fifth resistor R5 and the sixth resistor R6 are similar to the deployment mode and technical effects of the first switch M1, the third resistor R3, the fourth resistor R4, the first button V+, the second button V-, the headphone function control button HOOK, the fifth resistor R5 and the sixth resistor R6 in the embodiment of FIG4 , and are not repeated here.

[0174] In the FM signal transmission system shown in FIG5 , the target pin may include an SBU pin. The FM chip 401 of the electronic device may receive the FM signal through a link consisting of the FM chip 401, the fourth high-pass filter 501, the SBU pin of the Type-C interface 402, the SBU pin of the second external interface, the negative electrode of the left channel 405, the negative electrode of the right channel 406, or the negative electrode of the microphone 408. The FM signal will not be transmitted to the ground terminal of the digital headphone chip 407 before reaching the SBU pin of the second external interface, thereby reducing the probability of poor quality of the FM signal received by the electronic device. The FM signal received by the electronic device can be played through the left channel 405 and the right channel 406, or through the speaker of the electronic device. The electronic device can determine that the type of headphones connected to the electronic device is a digital headphone by detecting the third resistor. The first button V+, the second button V-, and HOOK on the electronic device can be operated by the user to adjust the volume of the digital headphone or select a channel.

[0175] Taking the target pin as the CC pin in the Type-C interface as an example, FIG6 shows another circuit diagram of the FM signal transmission system provided in an embodiment of the present application.

[0176] As shown in FIG6 , in the FM signal transmission system provided in an embodiment of the present application, the deployment method and technical effects of the power supply circuit 403 of the digital headset can refer to the deployment method and technical effects of the power supply circuit 403 in FIG4 , which will not be repeated here.

[0177] When a digital headset is connected to the Type-C interface 402 of an electronic device via the second external interface, the FM chip 401 can be connected to the CC pin of the Type-C interface 402, which in turn is connected to the CC pin of the second external interface. The CC pin of the second external interface can be connected to at least one of the positive electrode of the left audio channel 405, the positive electrode of the right audio channel 406, or the positive electrode of the microphone 408. An eighth low-pass filter 604 is provided between the CC pin of the second external interface and the digital headset chip 407. Since the CC pin of the second external interface is connected to the CC pin of the Type-C interface 402, it should be understood that the eighth low-pass filter 604 is provided between the CC pin of the Type-C interface 402 and the digital headset chip 407. The provision of the eighth low-pass filter 604 prevents any FM signal from passing between the positive electrode of the microphone 408, the positive electrode of the left audio channel 405, or the positive electrode of the right audio channel 406, and the ground terminal of the digital headset chip 407.

[0178] This connects FM chip 401 to the CC pin of Type-C interface 402. The CC pin of Type-C interface 402 is also connected to at least one of the positive terminals of left channel 405, right channel 406, or microphone 408. An eighth low-pass filter 604 is located between the CC pin of Type-C interface 402 and digital headphone chip 407. The second external interface is not shown in FIG6 .

[0179] It is understood that the CC pin of the Type-C interface 402 may include the CC1 pin of the Type-C interface 402 and / or the CC2 pin of the Type-C interface 402. The CC pin of the second external interface may include the CC1 pin of the second external interface and / or the CC2 pin of the second external interface. The implementation principle of the connection between the FM chip 401 and at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408 and the CC1 pin and the CC2 pin is similar to the implementation principle of the connection between the FM chip 401 and at least one of the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408 and the SBU1 pin and the SBU2 pin in the embodiment of FIG. 4 , and will not be repeated here.

[0180] In this way, the connection line between the CC pin of the second external interface and at least one of the positive electrode of the left audio channel 405, the positive electrode of the right audio channel 406, or the positive electrode of the microphone 408 can serve as an antenna, and the FM chip 401 of the electronic device can receive FM signals via a link formed by the FM chip 401, the CC pin of the Type-C interface 402, the CC pin of the second external interface, the positive electrode of the left audio channel 405, the positive electrode of the right audio channel 406, or the positive electrode of the microphone 408. The configuration of the eighth low-pass filter 604 eliminates a path for FM signals between the positive electrode of the microphone 408, the positive electrode of the left audio channel 405, or the positive electrode of the right audio channel 406, and the ground terminal of the digital headphone chip 407. Therefore, the FM signal will not be transmitted to the ground terminal of the digital headphone chip 407 before reaching the CC pin of the second external interface, thereby reducing the probability of poor FM signal quality received by the electronic device.

[0181] Optionally, as shown in FIG6 , in the FM signal transmission system provided in an embodiment of the present application, the digital headset further includes at least one high-pass filter, which is configured to pass FM signals and block low-frequency signals;

[0182] The digital headset includes at least one high-pass filter that is deployed in a manner that satisfies at least one of the following:

[0183] A fifth high-pass filter 601 is provided in the path between the CC pin of the Type-C interface 402 and the positive terminal of the left audio channel 405;

[0184] A sixth high-pass filter 602 is provided in the path between the CC pin of the Type-C interface 402 and the positive terminal of the right audio channel 406;

[0185] A seventh high-pass filter 603 is provided in the path between the CC pin of the Type-C interface 402 and the positive electrode of the microphone 408 .

[0186] The fifth high-pass filter 601 , the sixth high-pass filter 602 or the seventh high-pass filter 603 is any one of the at least one high-pass filter included in the digital headset.

[0187] It should be understood that, as shown in FIG6 , the electronic device is connected to the digital headset, so the deployment method of at least one high-pass filter included in the digital headset in the embodiment of the present application satisfies at least one of the following:

[0188] A fifth high-pass filter 601 is provided in the path between the CC pin of the second external interface and the positive electrode of the left channel 405;

[0189] A sixth high-pass filter 602 is provided in the path between the CC pin of the second external interface and the positive electrode of the right channel 406;

[0190] A seventh high-pass filter 603 is provided in the path between the CC pin of the second external interface and the positive electrode of the microphone 408 .

[0191] In this way, when the FM chip 401 of the electronic device receives the FM signal through a link formed by the FM chip 401, the CC pin of the Type-C interface 402, the CC pin of the second external interface, the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408, at least one high-pass filter included in the digital headset can block low-frequency signals to reduce interference of low-frequency signals on the FM signal received by the electronic device, further reducing the probability of poor quality of the FM signal received by the electronic device.

[0192] Optionally, the fifth high-pass filter 601, the sixth high-pass filter 602 and the seventh high-pass filter 603 can all be 100p capacitors. In this way, the number of components of the digital headset can be reduced while reducing the probability of poor quality of the FM signal received by the electronic device.

[0193] Optionally, as shown in FIG6 , in the FM signal transmission system provided in the embodiment of the present application, the digital headset may further include an eighth low-pass filter, a ninth low-pass filter and a seventh resistor R7 .

[0194] The eighth low-pass filter is connected between the digital headphone chip 407 and the positive electrode of the left channel 405. For example, the eighth low-pass filter can be the eighth magnetic bead B8 shown in Figure 6. One end of the eighth magnetic bead B8 is connected to the digital headphone chip 407, and the other end of the eighth magnetic bead B8 is connected to the fifth high-pass filter 601 and the positive electrode of the left channel 405, respectively.

[0195] In this way, the probability of the FM signal being transmitted to the digital headset chip 407 can be reduced, thereby further reducing the probability of the FM signal being received by the electronic device having poor quality.

[0196] The ninth low-pass filter is connected between the digital headphone chip 407 and the positive electrode of the right channel 406. For example, the ninth low-pass filter can be the ninth magnetic bead B9 shown in Figure 6. One end of the ninth magnetic bead B9 is connected to the digital headphone chip 407, and the other end of the ninth magnetic bead B9 is connected to the sixth high-pass filter 602 and the positive electrode of the right channel 406.

[0197] In this way, the probability of the FM signal being transmitted to the digital headset chip 407 can be reduced, thereby further reducing the probability of the FM signal being received by the electronic device having poor quality.

[0198] The seventh resistor R7 is connected between the digital headphone chip 407 and the positive electrode of the microphone 408. For example, one end of the seventh resistor R7 is connected to the digital headphone chip 407. The other end of the seventh resistor R7 is connected to the seventh high-pass filter 603 and the positive electrode of the microphone 408, respectively. The seventh resistor R7 can be the same as or different from the first resistor R1 in Figure 4. The technical effects achieved by the seventh resistor R7 can be referenced to the technical effects achieved by the first resistor R1 in Figure 4 and will not be further described here.

[0199] Optionally, as shown in FIG6 , in the FM signal transmission system provided in an embodiment of the present application, the digital headset may further include a tenth low-pass filter and an eleventh low-pass filter. The tenth low-pass filter may be the tenth magnetic bead B10 shown in FIG6 . The eleventh low-pass filter may be the eleventh magnetic bead B11 shown in FIG6 .

[0200] The tenth low-pass filter is connected between the digital headphone chip 407 and the negative electrode of the left channel 405 .

[0201] The eleventh low-pass filter is connected between the digital headphone chip 407 and the negative electrode of the right channel 406 .

[0202] In this way, when the electronic device receives an FM signal, the interference of the FM signal on the low-frequency signal output by the digital headphone chip can be reduced.

[0203] It is understood that, as shown in FIG6 , the negative electrode of the left channel 405 can be connected to the ground terminal of the digital headphone chip 407 via a third low-pass filter. The negative electrode of the right channel 406 can be connected to the ground terminal of the digital headphone chip 407 via a fourth low-pass filter. In the FM signal transmission system provided in the embodiment of the present application, the FM signal received by the electronic device can be played through the left channel 405 and can also be played through the right channel 406. The specific implementation principle can be found in the specific implementation principle of the FM signal received by the electronic device being played through the left channel 405 and through the right channel 406 in the embodiment of FIG4 , which will not be repeated here.

[0204] Optionally, as shown in Figure 6, in the FM signal transmission system provided in an embodiment of the present application, the digital headset also includes a first switch M1, a third resistor R3, a fourth resistor R4, a first button V+, a second button V-, a headset function control button HOOK, a fifth resistor R5 and a sixth resistor R6.

[0205] The arrangement of the first switch M1, the third resistor R3, the fourth resistor R4, the first button V+, the second button V-, the headphone function control button HOOK, the fifth resistor R5, and the sixth resistor R6 in FIG6 differs from the arrangement of the first switch M1, the third resistor R3, the fourth resistor R4, the first button V+, the second button V-, the headphone function control button HOOK, the fifth resistor R5, and the sixth resistor R6 in FIG4 in that:

[0206] The control end of the first switch M1 is connected to the digital headset chip 407, one end of the first switch M1 is grounded, the other end of the first switch M1 is connected to one end of the eighth low-pass filter 604, and the other end of the eighth low-pass filter 604 is connected to the CC pin of the second external interface. In this way, when the electronic device receives an FM signal, the probability of the FM signal being transmitted to the ground end through the conductive first switch M1 before reaching the CC pin can be reduced, thereby reducing the probability of poor quality of the FM signal received by the electronic device.

[0207] For the deployment mode and technical effects of the third resistor R3, the fourth resistor R4, the first button V+, the second button V-, the headphone function control button HOOK, the fifth resistor R5 and the sixth resistor R6 in Figure 6, please refer to the deployment mode and technical effects of the third resistor R3, the fourth resistor R4, the first button V+, the second button V-, the headphone function control button HOOK, the fifth resistor R5 and the sixth resistor R6 in Figure 4, and will not be repeated here.

[0208] Optionally, as shown in FIG6 , in the FM signal transmission system provided in the embodiment of the present application, the electronic device may further include an eighth high-pass filter 605 , a CC chip 606 and a twelfth low-pass filter 607 .

[0209] The eighth high-pass filter 605 is connected between the FM chip 401 and the CC pin of the Type-C interface 402. The eighth high-pass filter 605 can be used to pass FM signals and block low-frequency signals.

[0210] In this way, the FM chip 401 of the electronic device can receive FM signals through a link consisting of the FM chip 401, the eighth high-pass filter 605, the CC pin of the Type-C interface 402, the CC pin of the second external interface, the positive pole of the left channel 405, the positive pole of the right channel 406, or at least one of the positive poles of the microphone 408, and the eighth high-pass filter 605 can further reduce the interference of low-frequency signals on the FM signals received by the electronic device, so as to further reduce the probability of poor quality of the FM signals received by the electronic device.

[0211] One end of the twelfth low-pass filter 607 is connected to the CC chip 606, and the other end of the twelfth low-pass filter 607 is connected to the eighth high-pass filter 605 and the CC pin of the Type-C interface 402, respectively. The twelfth low-pass filter 607 can be used to pass low-frequency signals and block FM signals. Thus, when a digital headset is connected to an electronic device, if the CC chip 606 detects the third resistor, the CC chip 606 can determine that the headset connected to the electronic device is a digital headset.

[0212] For example, when a digital headset is connected to the Type-C interface 402 of an electronic device via the second external interface, the CC chip 606 can obtain a first signal containing third resistance information via a link formed by the twelfth low-pass filter 607, the CC pin of the Type-C interface 402, and the CC pin of the second external interface. The third resistance information may be, for example, the value of the third resistor. The CC chip 606 can demodulate the first signal to obtain the third resistance information. The CC chip 606 can control the electronic device to power the digital headset chip 407 via the VBUS pin of the Type-C interface 402, the VBUS pin of the second external interface, and the power supply circuit 403. The GPIO terminal of the digital headset chip 407 outputs a high level, turning on the first switch M1, thereby grounding the CC pin of the Type-C interface 402. The CC chip 606 then obtains a second signal containing 0Ω resistance information via a link formed by the twelfth low-pass filter 607, the CC pin of the Type-C interface 402, and the CC pin of the second external interface. The CC chip 606 can demodulate the first signal to obtain the 0Ω resistance information. Therefore, the CC chip 606 can determine that the type of the connected headset is a digital headset. Wherein, the first signal and the second signal are both CC signals.

[0213] Optionally, the twelfth low-pass filter 607 may be replaced by a band-pass filter that passes CC signals and blocks FM signals.

[0214] In the FM signal transmission system shown in Figure 6, the FM chip 401 of the electronic device can receive FM signals through a link consisting of the FM chip 401, the eighth high-pass filter 605, the CC pin of the Type-C interface 402, the CC pin of the second external interface, the positive electrode of the left channel 405, the positive electrode of the right channel 406, or the positive electrode of the microphone 408. Under the blocking of the eighth low-pass filter 604, the FM signal will not be transmitted to the ground terminal through the conductive first switch M1 before reaching the CC pin of the second external interface, thereby reducing the probability of poor quality of the FM signal received by the electronic device. The eighth high-pass filter 605 can also reduce the interference of the CC signal transmitted by the CC pin of the Type-C interface 402 on the FM signal, further reducing the probability of poor quality of the FM signal received by the electronic device. The FM signal received by the electronic device can be played through the left channel 405 and the right channel 406, or can be played through the speaker of the electronic device. When the digital headset is connected to the Type-C interface 402 of the electronic device through the second external interface, the CC chip 606 can obtain the first signal, or the first signal and the second signal, through a link formed by the twelfth low-pass filter 607, the CC pin of the Type-C interface 402 and the CC pin of the second external interface, thereby determining the type of headset connected to the electronic device.

[0215] The present application also provides a digital headset. The digital headset includes a digital headset chip, a second external interface, and one or more of the following: a left audio channel, a right audio channel, or a microphone. A cable connects the left audio channel, the right audio channel, or the microphone to the second external interface.

[0216] The target pin of the second external interface is connected to at least one of the left channel, the right channel or the microphone, wherein there is no FM signal path between the microphone, the left channel or the right channel and the ground terminal of the digital headphone chip.

[0217] For example, the digital headphone chip may be the digital headphone chip 407 in the above embodiment. The left channel may be the left channel 405 in the above embodiment. The right channel may be the right channel 406 in the above embodiment. The microphone may be the microphone 408 in the above embodiment.

[0218] The second external interface may be a USB interface, and the target pin may be any pin of the second external interface.

[0219] Exemplarily, the second external interface may be a Type-C interface. The target pin may be any pin of the Type-C interface. For example, the target pin may be an SBU pin or a CC pin of the Type-C interface.

[0220] If the target pin is the SBU pin of the Type-C interface, the digital headset may include any circuit shown in the embodiments of FIG. 4-FIG . 5 .

[0221] If the target pin is the CC pin of the Type-C interface, the digital headset may include any circuit shown in the embodiment of FIG6 .

[0222] The digital headset provided in an embodiment of the present application, when connected to the first external interface of the electronic device through the second external interface, and the FM chip of the electronic device is connected to the target pin in the first external interface, can enable the electronic device to receive FM signals through the headphone cable of the digital headset. Since there is no FM signal path between the microphone, any of the left channel or the right channel and the ground terminal of the digital headset chip in the digital headset, the FM signal will not be transmitted to the ground terminal of the digital headset chip before reaching the electronic device, thereby reducing the probability of poor quality of the FM signal received by the electronic device. The FM signal received by the electronic device can be played through the digital headset or through the speaker of the electronic device.

[0223] The above specific implementation methods further illustrate the purpose, technical solutions and beneficial effects of this application in detail. It should be understood that the above are only specific implementation methods of this application and are not intended to limit the scope of protection of this application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solutions of this application should be included in the scope of protection of this application.

Claims

1. A frequency modulation (FM) signal transmission system, characterized in that: The system includes an electronic device and a digital headset; The electronic device includes an FM chip and a first external interface, and the digital headset includes a digital headset chip, a second external interface, and one or more of the following: a left channel, a right channel, or a microphone; a connecting line is provided between the left channel, the right channel, or the microphone and the second external interface; When the digital headset is connected to the first external interface of the electronic device through the second external interface: The FM chip is connected to a target pin of the first external interface, and the target pin is also connected to at least one of the left channel, the right channel, or the microphone; wherein there is no FM signal path between the microphone, any one of the left channel, or the right channel and the ground terminal of the digital headphone chip.

2. The FM signal transmission system according to claim 1, wherein: The target pin includes a function expansion SBU pin; The FM chip is connected to the SBU pin of the first external interface, and the SBU pin is also connected to at least one of the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone.

3. The FM signal transmission system according to claim 2, wherein: The digital headset further comprises at least one high-pass filter, wherein the high-pass filter is used to pass FM signals and block low-frequency signals; The digital headset includes at least one high-pass filter that is disposed in a manner that satisfies at least one of the following: A first high-pass filter is provided in the path between the SBU pin and the positive electrode of the left channel; A second high-pass filter is provided in the path between the SBU pin and the positive electrode of the right channel; A third high-pass filter is provided in the path between the SBU pin and the positive electrode of the microphone; The first high-pass filter, the second high-pass filter or the third high-pass filter is any one of the at least one high-pass filter.

4. The FM signal transmission system according to claim 3, wherein: The digital headset further includes a first low-pass filter, a second low-pass filter and a first resistor, wherein the low-pass filter is used to pass low-frequency signals and block FM signals; The first low-pass filter is connected between the digital headphone chip and the positive electrode of the left channel; The second low-pass filter is connected between the digital headphone chip and the positive electrode of the right channel; The first resistor is connected between the digital earphone chip and the positive electrode of the microphone.

5. The FM signal transmission system according to claim 4, characterized in that: The digital headset further includes a third low-pass filter and a fourth low-pass filter; The third low-pass filter is connected between the digital headphone chip and the negative electrode of the left channel; The fourth low-pass filter is connected between the digital headphone chip and the negative electrode of the right channel.

6. The FM signal transmission system according to claim 1, wherein: The target pin includes a function expansion SBU pin; The FM chip is connected to the SBU pin of the first external interface, and the SBU pin is further connected to at least one of the negative electrode of the left channel, the negative electrode of the right channel, or the negative electrode of the microphone.

7. The FM signal transmission system according to claim 6, wherein: The digital headset further includes a fifth low-pass filter, a sixth low-pass filter and a second resistor; The fifth low-pass filter is connected between the digital headphone chip and the positive electrode of the left channel; The sixth low-pass filter is connected between the digital headphone chip and the positive electrode of the right channel; The second resistor is connected between the digital earphone chip and the positive electrode of the microphone.

8. The FM signal transmission system according to claim 6 or 7, characterized in that: The electronic device further includes a fourth high-pass filter and a seventh low-pass filter; The fourth high-pass filter is connected between the FM chip and the SBU pin; one end of the seventh low-pass filter is connected to the fourth high-pass filter and the SBU pin respectively, and the other end of the seventh low-pass filter is grounded; The fourth high-pass filter is used to pass FM signals and block low-frequency signals; the seventh low-pass filter is used to pass low-frequency signals and block FM signals.

9. The FM signal transmission system according to any one of claims 1 to 8, characterized in that: The digital headset further includes a first switch, a third resistor, a fourth resistor, a first button, a second button, a headset function control button HOOK, a fifth resistor and a sixth resistor; The control end of the first switch is connected to the digital headset chip, one end of the first switch is grounded, and the other end of the first switch is connected to the external device detection CC pin of the second external interface; One end of the third resistor is connected to the other end of the first switch, the other end of the third resistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the digital headphone chip; The first button is connected between one end of the fifth resistor and the ground end, and the other end of the fifth resistor is connected to the digital earphone chip; The second button is connected between one end of the sixth resistor and the ground end, and the other end of the sixth resistor is connected to the digital earphone chip; The HOOK is connected between the digital earphone chip and the ground terminal; The first button and the second button are used for adjusting the volume of the digital headset.

10. The FM signal transmission system according to claim 1, wherein: The target pin includes an external device detection CC pin; The FM chip is connected to the CC pin of the first external interface, and the CC pin is further connected to at least one of the positive electrode of the left channel, the positive electrode of the right channel, or the positive electrode of the microphone; There is an eighth low-pass filter in the path between the CC pin and the digital headphone chip, and the eighth low-pass filter is used to pass low-frequency signals and block FM signals; the setting of the eighth low-pass filter ensures that there is no path for FM signals between the positive pole of the microphone, the positive pole of the left channel, or the positive pole of the right channel and the ground terminal of the digital headphone chip.

11. The FM signal transmission system according to claim 10, wherein: The digital headset further comprises at least one high-pass filter, wherein the high-pass filter is used to pass FM signals and block low-frequency signals; The digital headset includes at least one high-pass filter that is disposed in a manner that satisfies at least one of the following: A fifth high-pass filter is provided in the path between the CC pin and the positive electrode of the left channel; A sixth high-pass filter is provided in the path between the CC pin and the positive electrode of the right channel; A seventh high-pass filter is provided in the path between the CC pin and the positive electrode of the microphone; The fifth high-pass filter, the sixth high-pass filter or the seventh high-pass filter is any one of the at least one high-pass filter.

12. The FM signal transmission system according to claim 10 or 11, characterized in that: The digital headset further includes an eighth low-pass filter, a ninth low-pass filter and a seventh resistor; The eighth low-pass filter is connected between the digital headphone chip and the positive electrode of the left channel; The ninth low-pass filter is connected between the digital headphone chip and the positive electrode of the right channel; The seventh resistor is connected between the digital earphone chip and the positive electrode of the microphone.

13. The FM signal transmission system according to claim 12, wherein: The digital headset further includes a tenth low-pass filter and an eleventh low-pass filter; The tenth low-pass filter is connected between the digital headphone chip and the negative electrode of the left channel; The eleventh low-pass filter is connected between the digital headphone chip and the negative electrode of the right channel.

14. The FM signal transmission system according to any one of claims 10 to 13, characterized in that: The digital headset further includes a first switch, a third resistor, a fourth resistor, a first button, a second button, a headset function control button HOOK, a fifth resistor and a sixth resistor; A control end of the first switch is connected to the digital headset chip, one end of the first switch is grounded, the other end of the first switch is connected to one end of the eighth low-pass filter, and the other end of the eighth low-pass filter is connected to the CC pin of the second external interface; One end of the third resistor is connected to the other end of the first switch, the other end of the third resistor is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to the digital headphone chip; The first button is connected between one end of the fifth resistor and the ground end, and the other end of the fifth resistor is connected to the digital earphone chip; The second button is connected between one end of the sixth resistor and the ground end, and the other end of the sixth resistor is connected to the digital earphone chip; The HOOK is connected between the digital earphone chip and the ground terminal; The first button and the second button are used for adjusting the volume of the digital headset.

15. The FM signal transmission system according to any one of claims 10 to 14, characterized in that: The electronic device further includes an eighth high-pass filter, a CC chip and a twelfth low-pass filter; The eighth high-pass filter is connected between the FM chip and the CC pin; the twelfth low-pass filter is connected between the CC chip and the CC pin; The eighth high-pass filter is used to pass FM signals and block low-frequency signals; the twelfth low-pass filter is used to pass low-frequency signals and block FM signals.

16. A digital headset, characterized in that: The digital headset includes a digital headset chip, a second external interface, and one or more of the following: a left channel, a right channel, or a microphone; a connecting line is provided between the left channel, the right channel, or the microphone and the second external interface; The target pin of the second external interface is connected to at least one of the left channel, the right channel or the microphone; wherein there is no FM signal path between any one of the microphone, the left channel or the right channel and the ground terminal of the digital headphone chip.

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