Communication equipment based on external antenna

Abstract

The present invention relates generally to the technical field of communications. More specifically, the present invention relates to a communication device based on an external antenna, comprising: an earphone interface comprising a left channel interface, a right channel interface, an MIC interface, and an ANT interface, the ANT interface being used for wireless communication; the audio circuit is used for performing analog-to-digital conversion on the signal; the MCU is in wireless communication with the ANT interface through a wireless communication module, and the wireless communication module is used for receiving the radio frequency signal and converting the radio frequency signal into a second digital signal; the antenna tuning matching circuit comprises an antenna coordinator and a single-pole four-throw switch SP4T; and the antenna coordinator selects one tuning circuit according to the frequency of the radio frequency signal, so that the tuning circuit is conducted with the wireless communication module, and the modulation circuit performs frequency selection on the radio frequency signal input into the wireless communication module. According to the invention, the quality of the signal received by the communication equipment is high.

Description

Technical Field

[0001] The present invention generally relates to the field of communication technology. More specifically, the present invention relates to a communication device based on an external antenna. Background Art

[0002] Antennas are key components for receiving electromagnetic wave signals. Their principle is based on the coupling effect between electromagnetic waves and antennas. In receiving signals in different frequency bands, the length and shape of the antenna directly affect its efficiency and receiving ability. The size of the antenna is usually proportional to the wavelength of the signal. The longer the wavelength, the longer the antenna length required.

[0003] In the design of existing headphones, the headphone cable is not only used as an audio transmission cable, but also integrated with an external antenna for receiving wireless signals, so that users can directly use the headphone cable to receive signals when using wireless communication devices, eliminating the trouble of carrying an additional antenna. In order to improve the reception effect, some solutions add additional antenna enhancement devices to the headphone cable, such as built-in circuits or amplifiers, so that even if the antenna is short, the reception capability can still be enhanced.

[0004] However, for low-frequency communication devices, the relatively large bandwidth, for example, the working frequency band of UHF walkie-talkies is 400-470MHz, and the working frequency band of 433Mlora communication devices is 410-490MHz. The antenna cannot take into account the entire frequency band. At this time, the design frequency of the antenna is usually targeted at the center frequency of the working frequency band of the communication device. At this time, the antenna in the headset receives signals that are within the working frequency band of the communication device, but the frequency is far from the center frequency band of the antenna (for example, the upper and lower limits of the working frequency band of the communication device). The quality of the signal received by the communication device is poor, and the gain and efficiency of the antenna will be significantly reduced. Summary of the invention

[0005] In order to solve the technical problem that when the antenna in the above-mentioned earphone receives a signal with a frequency that is within the working frequency band of the communication device but has a large difference from the center frequency band of the antenna, the gain and efficiency of the antenna will be significantly reduced, the present invention proposes a communication device based on an external antenna.

[0006] A communication device based on an external antenna includes: an earphone interface, which includes a left channel interface, a right channel interface, a MIC interface and an ANT interface, wherein the ANT interface is used to connect to an external antenna 4 for wireless communication, or the ANT interface is also used for grounding, when an MCU wirelessly communicates with the ANT interface through a wireless communication module, the ANT is wirelessly connected to the wireless communication module; when the MCU receives a second digital signal or outputs a first digital signal, the ANT interface is grounded; an audio circuit, which receives a first audio signal output by the MIC interface and converts the first audio signal into a first digital signal, and the audio circuit receives a second digital signal output by the MCU, and after converting the second digital signal into a second audio signal, sends the second digital signal to the left channel interface. The port and the right channel interface output a second audio signal; an MCU, which communicates wirelessly with the ANT interface through a wireless communication module, and the wireless communication module is used to receive a radio frequency signal and convert the radio frequency signal into the second digital signal; an antenna tuning and matching circuit, which includes an antenna coordinator, a single-pole four-throw switch SP4T, and three modulation circuits, any of which includes a varactor diode, and the three modulation circuits include: a first tuning circuit, a second tuning circuit, and a third tuning circuit; the antenna coordinator selects a tuning circuit according to the frequency of the radio frequency signal to conduct between the tuning circuit and the wireless communication module, and enables the modulation circuit to perform frequency selection on the radio frequency signal input to the wireless communication module, wherein the frequency domains for frequency selection of each tuning circuit are different.

[0007] Preferably, the MCU is also connected to the cathode of the varactor diode of each tuning circuit, the MCU determines the frequency of the RF signal according to the second digital signal, and transmits a control voltage signal to the cathode of the varactor diode of the modulation circuit connected to the wireless communication module according to the frequency of the RF signal.

[0008] Preferably, the single-pole four-throw switch SP4T is a HMC241ALP3E chip.

[0009] Preferably, the first tuning circuit also includes a first inductor L1, a first capacitor C1 and a first varactor diode VD1, one end of the first inductor L1 is grounded, the other end of the first inductor L1 is connected to pin 4 of the HMC241ALP3E chip, the anode of the first varactor diode VD1 is grounded, and the cathode of the first varactor diode VD1 is connected to pin 4 of the HMC241ALP3E chip through the first capacitor C1.

[0010] Preferably, the second tuning circuit also includes a second inductor L2, a second capacitor C2 and a second varactor diode VD2, one end of the second inductor L2 is grounded, the other end of the second inductor L2 is connected to pin 9 of the HMC241ALP3E chip, the anode of the second varactor diode VD2 is grounded, and the cathode of the second varactor diode VD2 is connected to pin 9 of the HMC241ALP3E chip through the second capacitor C2.

[0011] Preferably, the first tuning circuit also includes a third inductor L3, a third capacitor C3, and a third varactor diode VD3. One end of the third inductor L3 is grounded, and the other end of the third inductor L3 is connected to pin 12 of the HMC241ALP3E chip. The anode of the third varactor diode VD3 is grounded, and the cathode of the third varactor diode VD2 is connected to pin 12 of the HMC241ALP3E chip through the third capacitor C3.

[0012] Preferably, the models of the first varactor diode, the second varactor diode and the third varactor diode are all 1SV305.

[0013] Preferably, the external antenna 4 is arranged on the headphone cable of the wired headset, and the headphone cable includes a left channel audio cable 2, a right channel audio cable 1, a MIC audio cable 3 and an external antenna 4, one end of the left channel audio cable 2 is configured with the left channel interface, and the other end of the left channel audio cable 2 is connected to the left channel speaker, one end of the right channel audio cable 1 is configured with the right channel interface, and the other end of the right channel audio cable 1 is connected to the right channel speaker, one end of the MIC audio cable 3 is configured with the MIC interface, and the other end of the MIC audio cable 3 is connected to the MIC, and one end of the external antenna 4 is connected to the ANT interface.

[0014] Preferably, the headphone cable further includes a plastic jacket, which wraps the left channel audio cable 2 , the right channel audio cable 1 , the MIC audio cable 3 and the external antenna 4 .

[0015] Preferably, the wireless communication module is a LoRa_433M wireless module.

[0016] The beneficial effects of the present invention are: The MCU of the present invention selects one of the three tuning circuits according to the frequency of the radio frequency signal to be received and connects to the wireless communication module for receiving the radio frequency signal, wherein the three tuning circuits correspond to different frequency bands. The MCU also transmits a voltage signal to the varactor diode in the tuning circuit connected to the wireless communication module to reduce the gap between the resonant frequency of the tuning circuit connected to the wireless communication module and the frequency of the radio frequency signal. Based on this, by introducing multiple tuning circuits and adjusting the resonant frequency of the tuning circuit, the wireless communication device can obtain higher receiving efficiency and gain within a wider working frequency band, and also makes the quality of the signal received by the communication device higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 is a block diagram schematically showing a structure of a communication device based on an external antenna according to an embodiment of the present invention; Figure 2 is a cross-sectional view schematically showing an earphone cable according to an embodiment of the present invention; Figure 3 Is a circuit diagram schematically showing an antenna tuning and matching circuit according to an embodiment of the present invention; Figure 4 Schematically shows a characteristic curve diagram of reverse voltage and capacitance value of a 1SV305 type varactor diode according to an embodiment of the present invention; Figure 5 FIG. 4 is a diagram schematically showing the structure of a wired headset according to an embodiment of the present invention.

[0018] 1. Right channel audio cable; 2. Right channel audio cable; 3. MIC audio cable; 4. External antenna; 5. Headphone jack; 6. Headphone cable. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0021] Figure 1It is a block diagram schematically showing a structure of a communication device based on an external antenna according to an embodiment of the present invention.

[0022] like Figure 1 As shown, a low-frequency band adjustable external antenna 4 based on a wired headset includes: a headset interface, an audio circuit, an MCU and an antenna tuning and matching circuit.

[0023] Among them, the headphone interface includes a left channel interface, a right channel interface, a MIC interface and an ANT interface, wherein the ANT interface is used to connect to an external antenna 4 for wireless communication, or the ANT interface is also used for grounding. When the MCU wirelessly communicates with the ANT interface through a wireless communication module, the ANT is wirelessly connected to the wireless communication module; when the MCU receives a second digital signal or outputs a first digital signal, the ANT interface is grounded; an audio circuit, which receives a first audio signal output by the MIC interface and converts the first audio signal into a first digital signal, and the audio circuit receives a second digital signal output by the MCU, and after converting the second digital signal into a second audio signal, sends the second digital signal to the left channel interface and the right channel interface. The MCU performs wireless communication with the ANT interface through a wireless communication module, and the wireless communication module is used to receive a radio frequency signal and convert the radio frequency signal into the second digital signal; an antenna tuning and matching circuit, which includes an antenna coordinator, a single-pole four-throw switch SP4T, and three modulation circuits, any of which includes a varactor diode, and the three modulation circuits include: a first tuning circuit, a second tuning circuit, and a third tuning circuit; the antenna coordinator selects a tuning circuit according to the frequency of the radio frequency signal to conduct between the tuning circuit and the wireless communication module, and enables the modulation circuit to perform frequency selection on the radio frequency signal input to the wireless communication module, wherein the frequency domains for frequency selection of each tuning circuit are different.

[0024] It should be noted that the ANT interface selects to be connected to an external antenna or the internal circuit of the headset through an electronic switch. Therefore, when the communication device needs to use an external antenna to receive wireless signals, the switch connects the ANT interface to the antenna; when the device needs to use headphones for audio output, the switch connects the ANT interface to the internal circuit of the headphones. At this time, the internal circuit of the headphones is grounded through the ANT interface.

[0025] Furthermore, the MCU is also connected to the cathode of the varactor diode of each tuning circuit, and the MCU determines the frequency of the RF signal according to the second digital signal, and transmits a control voltage signal to the cathode of the varactor diode of the modulation circuit connected to the wireless communication module according to the frequency of the RF signal.

[0026] Furthermore, the external antenna 4 is arranged on the headphone cable of the wired headset, and the headphone cable includes a left channel audio cable 2, a right channel audio cable 1, a MIC audio cable 3 and an external antenna 4, one end of the left channel audio cable 2 is configured with the left channel interface, and the other end of the left channel audio cable 2 is connected to the left channel speaker, one end of the right channel audio cable 1 is configured with the right channel interface, and the other end of the right channel audio cable 1 is connected to the right channel speaker, one end of the MIC audio cable 3 is configured with the MIC interface, and the other end of the MIC audio cable 3 is connected to the MIC, and one end of the external antenna 4 is connected to the ANT interface.

[0027] The earphone cable further includes a plastic jacket, which encloses the left channel audio cable 2, the right channel audio cable 1, the MIC audio cable 3 and the external antenna 4. Figure 2 As shown, in a cross section of the headphone cable, it can be seen that the plastic jacket separates the left channel audio cable 2, the right channel audio cable 1, the MIC audio cable 3 and the external antenna 4 respectively.

[0028] Figure 3 is a circuit diagram schematically showing an antenna tuning and matching circuit according to an embodiment of the present invention.

[0029] like Figure 3 As shown, the antenna tuning and matching circuit includes a first tuning circuit, a second tuning circuit, a third tuning circuit, an antenna coordinator, and a single-pole four-throw switch SP4T.

[0030] In one embodiment, the single-pole, four-throw switch SP4T is a HMC241ALP3E chip. The HMC241ALP3E is a general-purpose, non-reflective, 100MHz to 4GHz single-pole, four-throw (SP4T) switch manufactured using a gallium arsenide (GaAs) process. The switch provides up to 43dB of isolation at 2GHz, as low as 0.7dB of insertion loss at 2GHz, and has on-chip termination of the isolated ports.

[0031] The first tuning circuit further includes a first inductor L1, a first capacitor C1 and a first varactor diode VD1, one end of the first inductor L1 is grounded, the other end of the first inductor L1 is connected to pin 4 of the HMC241ALP3E chip, the anode of the first varactor diode VD1 is grounded, and the cathode of the first varactor diode VD1 is connected to pin 4 of the HMC241ALP3E chip through the first capacitor C1.

[0032] Furthermore, the second tuning circuit also includes a second inductor L2, a second capacitor C2 and a second varactor diode VD2, one end of the second inductor L2 is grounded, the other end of the second inductor L2 is connected to pin 9 of the HMC241ALP3E chip, the anode of the second varactor diode VD2 is grounded, and the cathode of the second varactor diode VD2 is connected to pin 9 of the HMC241ALP3E chip through the second capacitor C2.

[0033] Furthermore, the first tuning circuit also includes a third inductor L3, a third capacitor C3, and a third varactor diode VD3. One end of the third inductor L3 is grounded, and the other end of the third inductor L3 is connected to pin 12 of the HMC241ALP3E chip. The anode of the third varactor diode VD3 is grounded, and the cathode of the third varactor diode VD2 is connected to pin 12 of the HMC241ALP3E chip through the third capacitor C3.

[0034] In one embodiment, for an external antenna suitable for a LoRa_433M wireless module, it is known that its operating frequency band is 410-490MHz, and its operating frequency band is divided into a low frequency band: 410-435MHz, a medium frequency band: 435MHz-460MHz, and a high frequency band: 460-490MHz, and a tuning circuit is determined according to the frequency of the radio frequency signal received by the LoRa_433M wireless module, wherein the first tuning circuit corresponds to the high frequency band, the second tuning circuit corresponds to the medium frequency band, and the third tuning circuit corresponds to the low frequency band. In this embodiment, the capacity of the first capacitor C1 is Ch, where Ch=9pF, and the inductive reactance of the first inductor L1 is Lh, where Lh=15nH; the capacity of the second capacitor C2 is Cm, where Cm=12pF, and the inductive reactance of the second inductor L2 is Lm, where Lm=18nH; the capacity of the third capacitor C3 is Cl, where Cl=15pF, and the inductive reactance of the third inductor L3 is Ll, ​​where Lm=24nH.

[0035] Further, the tuning circuit connected to the LoRa_433M wireless module is taken as the connected tuning circuit, The MCU applies a reverse voltage to the varactor diode of the connected tuning circuit according to the frequency of the RF signal received by the LoRa_433M wireless module, so as to minimize the difference between the resonant frequency of the connected tuning circuit and the frequency of the RF signal. f The formula is: , C 1 is the capacitance value of the varactor diode, C 2 is the capacitance value of the capacitor in the connected tuned circuit, L 0is the inductive reactance of the inductor in the connected tuned circuit.

[0036] In one embodiment, the first varactor diode, the second varactor diode, and the third varactor diode are all of model 1SV305. For the varactor diode of model 1SV305, when the reverse voltage VR of the varactor diode is 1V, its capacitance value C is 18.3pF; when the reverse voltage VR of the varactor diode is 1V, its capacitance value C is 18.3pF, and the capacitance ratio of the varactor diode is 3.

[0037] Figure 4 Schematically shows a characteristic curve diagram of reverse voltage and capacitance value of a 1SV305 type varactor diode according to an embodiment of the present invention.

[0038] In one embodiment, when it is determined that the wireless communication module is connected to the connected tuning circuit, the frequency of the radio frequency signal received by the wireless communication module is the desired resonant frequency of the connected tuning circuit. For the connected tuning circuit, the MCU obtains the desired resonant frequency of the circuit, the capacitance value of the capacitor in the circuit and the inductance reactance of the inductor, and then calculates the desired capacitance value of the varactor diode of the circuit, and then the MCU calculates the desired capacitance value of the varactor diode of the circuit. Figure 4 The reverse voltage to be applied to the varactor connected to the tuned circuit is determined from the graph in (Characteristic graph of reverse voltage and capacitance of the varactor type 1SV305).

[0039] Figure 5 FIG. 4 is a diagram schematically showing the structure of a wired headset according to an embodiment of the present invention.

[0040] like Figure 5 As shown, the limited earphone of the embodiment of the present invention includes an earphone interface 5 and an earphone cable 6.

[0041] The earphone cable 6 is a spiral structure, so the antenna 4 is also a spiral structure. The spiral structure of the antenna 4 increases the size of the antenna without increasing the length of the earphone cable (the earphone cable remains in a spiral state), thereby satisfying the antenna 4 to receive electromagnetic waves with a longer wavelength.

[0042] In addition, the terms "first" or "second" used in this specification to refer to numbers or ordinals are only used for descriptive purposes and cannot be understood as explicitly or implicitly indicating relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this specification, the meaning of "plurality" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically defined.

[0043] Although this specification has shown and described a number of embodiments of the present invention, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Those skilled in the art will conceive of many modifications, changes and alternatives without departing from the ideas and spirit of the present invention. It should be understood that in the practice of the present invention, various alternatives to the embodiments of the present invention described herein may be employed.

Claims

1. A communication device based on an external antenna, characterized in that: include: A headphone interface, comprising a left channel interface, a right channel interface, a MIC interface and an ANT interface, wherein the ANT interface is used to connect to an external antenna 4 for wireless communication, or the ANT interface is also used for grounding, and when the MCU wirelessly communicates with the ANT interface through a wireless communication module, the ANT is wirelessly connected to the wireless communication module; when the MCU receives a second digital signal or outputs a first digital signal, the ANT interface is grounded; an audio circuit, which receives a first audio signal output by the MIC interface and converts the first audio signal into a first digital signal, receives a second digital signal output by the MCU, converts the second digital signal into a second audio signal, and then outputs the second audio signal to the left channel interface and the right channel interface; an MCU, which performs wireless communication with the ANT interface via a wireless communication module, wherein the wireless communication module is used to receive a radio frequency signal and convert the radio frequency signal into the second digital signal; An antenna tuning and matching circuit, comprising an antenna coordinator, a single-pole four-throw switch (SP4T), and three modulation circuits, wherein any modulation circuit comprises a varactor diode, and the three modulation circuits comprise: a first tuning circuit, a second tuning circuit, and a third tuning circuit; The antenna coordinator selects a tuning circuit according to the frequency of the RF signal to make the tuning circuit conductive with the wireless communication module, and enables the modulation circuit to perform frequency selection on the RF signal input to the wireless communication module, wherein the frequency domains for frequency selection of each tuning circuit are different.

2. A communication device based on an external antenna according to claim 1, characterized in that: The MCU is also connected to the cathode of the varactor diode of each tuning circuit. The MCU determines the frequency of the radio frequency signal according to the second digital signal, and transmits a control voltage signal to the cathode of the varactor diode of the modulation circuit connected to the wireless communication module according to the frequency of the radio frequency signal.

3. A communication device based on an external antenna according to claim 1, characterized in that: The single-pole four-throw switch (SP4T) is a HMC241ALP3E chip.

4. A communication device based on an external antenna according to claim 3, characterized in that: The first tuning circuit also includes a first inductor (L1), a first capacitor (C1) and a first varactor (VD1), one end of the first inductor (L1) is grounded, the other end of the first inductor (L1) is connected to pin 4 of the HMC241ALP3E chip, the anode of the first varactor (VD1) is grounded, and the cathode of the first varactor (VD1) is connected to pin 4 of the HMC241ALP3E chip through the first capacitor (C1).

5. A communication device based on an external antenna according to claim 3, characterized in that: The second tuning circuit also includes a second inductor (L2), a second capacitor (C2) and a second varactor (VD2), one end of the second inductor (L2) is grounded, the other end of the second inductor (L2) is connected to pin 9 of the HMC241ALP3E chip, the anode of the second varactor (VD2) is grounded, and the cathode of the second varactor (VD2) is connected to pin 9 of the HMC241ALP3E chip through the second capacitor (C2).

6. A communication device based on an external antenna according to claim 3, characterized in that: The first tuning circuit also includes a third inductor (L3), a third capacitor (C3), and a third varactor diode (VD3). One end of the third inductor (L3) is grounded, and the other end of the third inductor (L3) is connected to pin 12 of the HMC241ALP3E chip. The anode of the third varactor diode (VD3) is grounded, and the cathode of the third varactor diode (VD2) is connected to pin 12 of the HMC241ALP3E chip through the third capacitor (C3).

7. A communication device based on an external antenna according to claims 4-6, characterized in that: The first varactor diode, the second varactor diode and the third varactor diode are all of model 1SV305.

8. A communication device based on an external antenna according to claim 1, characterized in that: The external antenna 4 is arranged on the headphone cable of the wired headset, and the headphone cable includes a left channel audio cable 2, a right channel audio cable 1, a MIC audio cable 3 and an external antenna 4, one end of the left channel audio cable 2 is configured with the left channel interface, and the other end of the left channel audio cable 2 is connected to the left channel speaker, one end of the right channel audio cable 1 is configured with the right channel interface, and the other end of the right channel audio cable 1 is connected to the right channel speaker, one end of the MIC audio cable 3 is configured with the MIC interface, and the other end of the MIC audio cable 3 is connected to the MIC, and one end of the external antenna 4 is connected to the ANT interface.

9. A communication device based on an external antenna according to claim 8, characterized in that: The headphone cable also includes a plastic jacket, in which the left channel audio cable 2, the right channel audio cable 1, the MIC audio cable 3 and the external antenna 4 are arranged, and the plastic jacket separates the left channel audio cable 2, the right channel audio cable 1, the MIC audio cable 3 and the external antenna 4 respectively.

10. A communication device based on an external antenna according to claim 1, characterized in that: The wireless communication module is a LoRa_433M wireless module.

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