TWI706638B - Antennas control method and terminal device for mimo communication - Google Patents

Abstract

Antennas control method for MIMO communication is used for a terminal device having N receiving antennas. The method comprises selecting n receiving antennas having higher RSSI as executing receiving antennas by the terminal device; selecting k executing receiving antennas among the n executing receiving antennas to establish a plurality of receiving antennas configurations, and using one of the plurality of receiving antennas configurations to receive wireless signals from a remote device by the terminal device; changing radiation statuses of the k executing receiving antennas of the plurality of receiving antennas configurations by the terminal device to establish a plurality of communication performances, wherein the communication performances represent the receiving data rate of the selected k executing receiving antennas with determined radiation statuses; for each of the plurality of communication performances, setting a middle value of RSSI, obtaining a difference of the absolute values of the k executing receiving antenna’s RSSI; among the plurality of communication performances, selecting one communication performance having the smallest difference of the absolute values to perform the optimized MIMO communication. Thus, data rate can be improved.

Description

Antenna control method and terminal device for multiple input multiple output communication

The present invention relates to a multiple-input multiple-output communication, and in particular to an antenna control method and terminal device for multiple-input multiple-output communication.

The creation of wireless networks and mobile communication devices with high-speed transmission capabilities has always been the goal of related industries. The evolution of various wireless transmission standards has been continuously increasing the data transmission rate (abbreviated as data rate, or data rate, data rate). For example, today In the IEEE 802.11 standard of Wireless Local Area Network (WLAN), the maximum raw data transmission rate of the early 802.11a standard was 54 Mbps, and the 802.11ac standard, which has been widely used, has increased the single channel rate to at least 500 Mbps. In terms of mobile communication, the future popular fifth-generation mobile communication system (5G) standard defines the required target of an amazing data transmission rate of 1Gbps.

However, the formulation of wireless transmission standards requires not only a digital chip with sufficient computing and processing capabilities to perform signal encoding and decoding, but also a correspondingly improved radio frequency circuit with an antenna (or antenna system) with sufficient bandwidth and high efficiency. In fact, the upper limit of the actual data transmission rate of wireless products provided by wireless product suppliers is not only limited by the respective performance limitations of various radio frequency components, analog modules and digital modules, but also a large part of the reason All components and module hardware cooperate with the integration of software algorithms. Traditionally, in the wireless transmission process, the wireless data transmission rate The increase or decrease is mainly determined by the control of the wireless chip and the channel state (external transmission environment), while the radio frequency components and antenna components are in a passive position and have no control. There are still many limitations in finding a solution to increase the data transmission rate from the point of view of the wireless chip.

In order to solve the aforementioned prior art problems, embodiments of the present invention provide an antenna control method for multiple-input multiple-output communication, which is used for a terminal device with N receiving antennas. The method includes: Select n receiving antennas with higher signal strength indicators as the receiving antennas, where N is greater than n, both N and n are positive integers, and n is greater than 2. The terminal device arbitrarily selects k among the n receiving antennas To form a plurality of receiving antenna configurations, and use one of the plurality of receiving antenna configurations to receive wireless signals from the remote device, where n is greater than k, and k is a positive integer greater than or equal to 2; the terminal device changes everything State the radiation status of the k receiving antennas of the plurality of receiving antenna configurations to establish a plurality of communication performances, where each communication performance is the received data rate of the k receiving antennas of the selected and determined radiation status; For each communication performance, set an intermediate value of the received signal strength indicator to obtain the absolute value difference of the received signal strength indicators of the k receiving antennas; and among the plurality of communication performances, select the one with the smallest absolute value difference The communication performance is optimized for multiple input multiple output communication.

The embodiment of the present invention provides a terminal device for multiple input multiple output communication, including N receiving antennas, an application unit, and a control unit. N receiving antennas are connected to the wireless chip. The application unit is connected to the wireless chip, and the received signal strength of the plurality of receiving antennas received by the wireless chip indicates the receiving data rate of the multiple input multiple output communication, wherein the application unit selects the higher signal strength among the N receiving antennas The indicated n receiving antennas are used as execution receiving antennas, where N is greater than n, both N and n are positive integers, and n is greater than 2. Among them, the application unit arbitrarily selects k from the n execution receiving antennas to form a plurality of receiving antennas Configuration, and use one of the plurality of receiving antenna configurations to receive wireless signals from the remote device, where n is greater than k, and k is a positive integer greater than or equal to 2; wherein, the application unit changes the plurality of The radiation state of the k receiving antennas configured by the receiving antenna is used to establish a plurality of communication performances, each of which is the received data rate of the k receiving antennas with the selected and determined radiation status; where for each Communication performance, set an intermediate value of the received signal strength indicator, and the application unit obtains the absolute value difference of the received signal strength indicators of the k receiving antennas; wherein, among the plurality of communication performances, the application unit selects the smallest absolute value The differential communication performance is used as optimized multiple input multiple output communication. The control unit connects the application unit and the N receiving antennas, and is controlled by the application unit to control the radiation state of the k executing receiving antennas among the N receiving antennas.

To sum up, the embodiments of the present invention provide an antenna control method and terminal device for multiple input multiple output communication, which cooperate with the control of the radiation state of the antenna and minimize the difference in the absolute value of the received signal strength indicator of each antenna to Further improve the data rate of multiple input and multiple output communication, which has high industrial application value.

In order to further understand the features and technical content of the present invention, please refer to the following detailed descriptions and drawings about the present invention, but these descriptions and accompanying drawings are only used to illustrate the present invention, not the rights to the present invention The scope is subject to any restrictions.

S110, S120, S130, S140, S150, S131, S132: steps

1, 21, 22, 31, 3N: execute receiving antenna

11: reflection unit

111, 112: Half-wavelength reflector

111a, 112a: Diode

111b, 112b: extension circuit

111c, 112c: capacitance

211: Ground current control unit

211a, 211b: Earth current part

212a, 212b: switch

G: Ground

213a, 213b: ground capacitance

221: Ground Current Control Unit

221a, 221b: earth current part

222a, 222b: switch

223a, 223b: ground capacitance

4: Application unit

5: Control unit

6: wireless chip

Fig. 1 is an antenna for multiple input multiple output communication provided by an embodiment of the present invention Flow chart of the control method.

Fig. 2 is a flowchart including sub-steps of step S130 of Fig. 1.

Fig. 3 is a schematic diagram of a receiving antenna and its reflection unit provided by an embodiment of the present invention.

Fig. 4 is a schematic diagram of a receiving antenna according to another embodiment of the present invention.

Fig. 5 is a block diagram of a terminal device for multiple input multiple output communication provided by an embodiment of the present invention.

Referring to FIG. 1, this embodiment provides an antenna control method for multiple-input multiple-output communication, which is used in a terminal device with N antennas. The method is stored in the firmware or software in the terminal device and executed by the operating system of the terminal device itself. The terminal device is, for example, a notebook computer, a laptop computer, a tablet computer, an all-in-one computer, a smart TV, a small base station or a wireless router, but it is not limited thereby. The method includes the following steps. First, in step S110, the terminal device selects n receiving antennas with higher signal strength indication (RSSI) from the N receiving antennas as the receiving antennas, where N is greater than n, and both N and n are positive integers, and n Greater than 2. In step S110, an absolute signal strength indicator threshold value can be set, or a floating relative threshold value based on the signal strength indicators of all N receiving antennas, or the N receiving antennas can be classified into two groups, one group is the signal strength indicator In the higher group, the other group is the group with the lower signal strength indicator, and the antenna in the group with the higher signal strength indicator is selected as the receiving antenna. The specifications for applying multiple input multiple output (MIMO) transmission communication are, for example, 802.11n, 802.11ac, or the existing fourth-generation mobile communication specifications, or the future fifth-generation mobile communication specifications.

Then, in step S120, the terminal device arbitrarily selects k among the n executing receiving antennas to form a plurality of receiving antenna configurations, and receives wireless signals from the remote device in one of the plurality of receiving antenna configurations , Where n is greater than k, and k is a positive integer greater than or equal to 2. That is, according to the number k of the required antennas among all the n execution receiving antennas that have been selected, k of them are used as the antenna configuration to perform the substantial operation of receiving data.

Next, proceed to step S130, the terminal device changes the radiation status of the k receiving antennas of the plurality of receiving antenna configurations to establish a plurality of communication performances, where each communication performance is selected and the radiation status is determined. The receiving data rate of the receiving antenna. Under general application conditions, according to the reciprocity theorem, the radiation state is equal to the receiving state, and usually R&D personnel can analyze the radiation state as a research and development method. The present invention is based on the purpose of making multiple-input multiple-output communication play better performance (increasing the data rate), using antennas with multiple radiation states, it can also be said that the antenna is used to control its operating state to achieve multiple radiation field patterns (Each operating state has a different radiation field pattern). For example, the first performing receiving antenna ATA has multiple radiation states RA1, RA2, RA3..., the second performing receiving antenna ATB has multiple radiation states RB1, RB2, RB3..., and the third performing receiving antenna ATC There are multiple radiation states RC1, RC2, RC3..., and so on. When the terminal device is in operation, when any two receiving antennas are selected to form a receiving antenna configuration (ie k=2), the first one to perform receiving antenna ATA is selected for a radiation state (such as RA1, RA2 or RA3) and the first A radiation state of the two receiving antennas ATB (such as RB1, RB2 or RB3) to obtain a corresponding communication performance P11, and then continue to change the radiation state of the first receiving antenna ATA and the second receiving antenna ATB, And make selective combination, you can get multiple communication tables Now, for example, communication performances P11, P12, P13..., P21, P22, P23... and so on can be obtained. In other embodiments, for 4x4 MIMO, k=4; for 8x8 MIMO, k=8, but the digital value of k is not limited to this. In addition, the implementation of changing the radiation state of the receiving antenna will be further described in FIG. 2 below.

Next, proceed to step S140, for each communication performance, set a received signal strength indicator (RSSI) intermediate value, and obtain the absolute value difference of the received signal strength indicator of the k receiving antennas. That is, each communication performance will have an absolute value difference, this difference is the difference of the received signal strength indicator (RSSI) of each receiving antenna used, for example, when k=4, four receiving antennas The received signal strength indicators are -65dbm, -65dbm, -66dbm and -64dbm. When the intermediate value is -65dbm, -66dbm causes a difference of 1, and -64dbm causes another difference of 1, so the absolute difference is 2 . Or, when k=8, the received signal strength indicators of the 8 receiving antennas are -55dbm, -54dbm, -56dbm, -57dbm, -55dbm, -53dbm, -57dbm and -55dbm, when the middle value is- At 55dbm, -53dbm causes a difference of 2, -54dbm causes a difference of 1, -56dbm causes a difference of 1, and two -57dbm causes a difference of 2, so the absolute difference is 6. The smaller the difference between the received signal strength indications of the selected receiving antennas, the more favorable the multiple-input multiple-output data transmission (including stability). Then, step S150 is performed, among the plurality of communication performances, the communication performance with the smallest absolute value difference is selected as the optimized multiple input multiple output communication. When selecting the communication performance with the smallest absolute value difference, regardless of whether the communication environment is good or bad, on the whole it means that the selected execution receiving antennas are selected to the best or better radiation state at the same time, which is most conducive to multiple inputs and multiple outputs Transmission. Conversely, the greater the difference between the received signal strength indicators of the selected receiving antennas, the more unstable transmission or the change of the data transmission rate for multiple input multiple output communications. The float is likely to be large, which is quite unfavorable for multiple input and multiple output transmission. In step S150 of the present invention, the communication performance with the smallest absolute value difference is selected as the optimized multiple-input multiple-output communication, and the instability or uncertainty parameters of the transmission process are avoided as much as possible, and there is no need for multiple-input multiple-output communication. The output matrix is used for complex data calculation processing, and the optimization scheme can be proposed in a more convenient way (reducing cost and reducing operation time). Moreover, in the transmission process of multiple input multiple output, if the transmission environment or transmission distance is changed, the steps S120, S130, S140 and S150 can also be continuously performed dynamically, so as to avoid affecting the normal transmission status. Try to find a better communication performance suitable for the situation.

In addition, the above steps S110 to S150 may further include a judgment step: the remote device has m transmitting antennas to transmit wireless signals to the terminal device, m is a positive integer greater than or equal to 2, when the terminal device knows The m transmitting antennas of the remote device have been changed, and the terminal device changes the radiation state of the k receiving antennas of the plurality of receiving antenna configurations to re-establish the plurality of communication performances. In other words, the terminal device can monitor whether the antenna state of the remote device has changed from the received data (for example, the original transmitting antenna is changed to another antenna, or the state of the original transmitting antenna itself changes). If there is a change, Therefore, the terminal device can update the radiation status of the receiving antenna in a timely manner to respond to changes in the status of the wireless signal source, avoid a significant drop in the received data rate, and thereby update a better receiving antenna configuration.

Please refer to Figure 1 and Figure 2 at the same time. In the following, with k=2, the number of receiving antennas selected to receive data is two, as an example of determining the radiation status. In step S130, steps S131 and S132, step S131 and step S122 are parallel, because the first one of the multiple input multiple output communication performs the receiving antenna and the second The two receiving antennas are simultaneously operating to transmit data. In step S131, at least one reflection unit or at least one ground current control unit that executes the receiving antenna first is controlled. In step S132, at least one reflection unit or at least one ground current control unit of the second receiving antenna is controlled.

For step S131 and step S132, the method of controlling the reflection unit belongs to one control method, and the control of the current element belongs to another control method. For the way to control the reflection unit, please refer to the antenna and reflection unit structure in Figure 3. The reflection unit is for example a half-wavelength reflector. The implementation of the receiving antenna takes a half-wavelength dipole antenna as an example. It is preferable that there are at least one or more reflection units 11 implementing the receiving antenna 1. For example, one half-wave reflector 111 in FIG. 3 is on the left and the other half-wave reflector 112 is on the right to produce the receiving antenna 1. Plural kinds of radiation states. The control method of the embodiment in FIG. 3 includes: for the half-wavelength reflector 111 on the left, selecting the diode 111a to conduct the half-wavelength reflector 111 so that the half-wavelength reflector 111 realizes the half-wavelength reflection function. Alternatively, the diode 111a is selected to be non-conducting and the extension circuit 111b uses the capacitor 111c to extend the path of the half-wavelength reflector 111 so that the half-wavelength reflector 111 does not produce a half-wavelength reflection function. For the half-wavelength reflector 112 on the right, the diode 112a is selected to conduct the half-wavelength reflector 112, so that the half-wavelength reflector 112 realizes the half-wavelength reflection function. Alternatively, the diode 112a is selected to be non-conducting and the extension circuit 112b uses the capacitor 112c to extend the path of the half-wavelength reflector 112, so that the half-wavelength reflector 112 does not produce a half-wavelength reflection function.

For an exemplary implementation of controlling the ground current control unit, please refer to FIG. 4, assuming that when k=2, the ground current control unit 211 and the ground current control unit 221 are used to connect the ground G, and the receiving antenna 21 is executed first. With the second execution receive The antenna 22 takes an inverted F-shaped panel antenna (PIFA) as an example. In the manner of controlling the ground current control unit 211 of the first receiving antenna 21, the ground current control unit 211 of the first receiving antenna 21 preferably needs There are at least one or more components, such as one ground current part 211a and the other ground current part 211b of FIG. 4, which can generate a plurality of types of the first receiving antenna by changing the ground current close to the first receiving antenna 21 21 radiation status. The control method of the embodiment of FIG. 4 includes: for the ground current portion 211a, selecting the switch 212a to conduct the ground current portion 211a to the ground G, or selecting the non-conductive switch 212a and connecting the ground capacitor 213a to the ground current portion 211a and the ground G Meanwhile, the ground current portion 211a in FIG. 4 not only uses the ground capacitor 213a, but also uses the ground capacitor 213b to connect to the ground G. Furthermore, for the ground current portion 211b, the switch 212b is selected to conduct the ground current portion 211b to the ground G, or the switch 212b is selected to be non-conductive and the ground capacitor 213b is connected between the ground current portion 211b and the ground G.

Continuing to refer to FIG. 4, for the second receiving antenna 22, the ground current control unit 221 preferably needs to have at least one or more components, such as one ground current part 221a and another ground current part 221b in FIG. The ground current close to the second receiving antenna 22 is changed to generate a plurality of radiation states of the second receiving antenna 22. Similar to the control method of the ground current control unit 211, the control method of controlling the ground current control unit 221 includes: selecting the switch 222a to conduct the ground current portion 221a to the ground G, or selecting the non-conductive switch 222a and connecting the ground capacitor 223a to the ground current Between the portion 221a and the ground G, the ground current portion 221a in FIG. 4 not only uses the ground capacitor 223a, but also uses the ground capacitor 223b to connect to the ground G. Furthermore, the switch 222b is selected to conduct the ground current portion 221b to the ground G, or the switch 222b is selected to be non-conductive and the ground capacitor 223b is connected between the ground current portion 221b and the ground G. However, the structure of the second receiving antenna 22 and the structure of the first receiving antenna 21 are unnecessary. Similarly, the ground current control unit 221 and the ground current control unit 211 are not necessarily the same. In addition, the above-mentioned switches 212a, 212b, 222a, and 222b are realized by, for example, diodes, but are not limited thereto.

Based on the above method, this embodiment also provides a terminal device for multiple-input multiple-output communication. The mid-end device is, for example, a notebook computer, a laptop computer, a tablet computer, and an all-in-one device that can realize multiple-input multiple-output communication. Computer, smart TV, small base station or wireless router. Referring to FIG. 5, the terminal device of this embodiment includes N receiving antennas (in the figure, the first receiving antenna 31 and the N-th receiving antenna 3N are briefly shown), an application unit 4, and a control unit 5. The receiving antenna (31 to 3N) is connected to the wireless chip 6. The application unit 4 is connected to the wireless chip 6, and the wireless chip 6 receives the received signal strength of the receiving antenna (31 to 3N) to indicate the received data rate of the multiple input multiple output communication. The application unit 4 selects n receiving antennas (31 to 3N) with higher signal strength indication among the N receiving antennas (31 to 3N) as the executing receiving antenna, where N is greater than n, and both N and n are positive integers , N is greater than 2; wherein, the application unit 4 arbitrarily selects k among n executing receiving antennas to form a plurality of receiving antenna configurations, and receives from the remote device in one of the plurality of receiving antenna configurations A wireless signal, where n is greater than k, and k is a positive integer greater than or equal to 2; wherein, the application unit 4 changes the radiation state of the k receiving antennas of the plurality of receiving antenna configurations to establish a plurality of communication performances, where Each communication performance is the received data rate of the k receiving antennas that have been selected and the radiation status has been determined; for each communication performance, an intermediate value of the received signal strength indicator is set, and the application unit 4 obtains the data rate of the k receiving antenna The absolute value difference indicated by the received signal strength; wherein, among the plurality of communication performances, the application unit 4 selects the communication performance with the smallest absolute value difference as the optimized multiple-input multiple-output communication. The control unit 5 connects the application unit 4 with N receiving antennas (31 To 3N), controlled by the application unit 4 to control the radiation state of the k receiving antennas out of the N receiving antennas (31 to 3N). For N receiving antennas (31 to 3N), please refer to the embodiment of Fig. 3 or Fig. 4 and related descriptions. Simply put, the control unit 5 is controlled by the application unit 4 to control at least one reflection unit or at least one reflection unit of each receiving antenna. One ground current control unit.

When the control unit 5 controls and executes at least one reflection unit of the receiving antenna, it is analogous to the embodiment of FIG. 3. The control unit 5 controls the diode to selectively turn on the half-wavelength reflector, or choose not to turn on the diode and make the extension The loop uses capacitors to extend the path of the half-wavelength reflector. When the control unit 5 controls the execution of at least one ground current control unit of the receiving antenna, analogous to the embodiment of FIG. 4, the control unit 5 controls the switch to select the conduction of the ground current to the ground, or select the non-conduction switch and connect the grounding capacitor to the ground. Between ground current and ground.

In addition, when the remote device has m transmitting antennas to send wireless signals to the terminal device, m is a positive integer greater than or equal to 2. When the terminal device learns that the m transmitting antennas of the remote device have changed, the terminal device changes everything. The k execution receiving antenna configurations of the plurality of receiving antenna configurations are used to re-establish the plurality of communication performances.

To sum up, the embodiments of the present invention provide an antenna control method and terminal device for multiple input multiple output communication, which cooperate with the control of the radiation state of the antenna and minimize the difference in the absolute value of the received signal strength indication of each antenna to Further improve the data rate of multiple input and multiple output communication, which has high industrial application value. The radiation status of the antenna can be controlled by reflector or ground current control.

The above are only the embodiments of the present invention, and they are not intended to limit the patent scope of the present invention.

S110, S120, S130, S140, S150‧‧‧Step

Claims (8)

An antenna control method for multiple-input multiple-output communication is used for a terminal device with N receiving antennas. The method includes: the terminal device selects n of the N receiving antennas with higher signal strength indicators The receiving antenna is used as an executing receiving antenna, where N is greater than n, both N and n are positive integers, and n is greater than 2. The terminal device arbitrarily selects k among the n executing receiving antennas to form a plurality of receiving antenna configurations, And use one of the receiving antenna configurations to receive a wireless signal from a remote device, where n is greater than k, and k is a positive integer greater than or equal to 2; the terminal device changes k of the receiving antenna configurations The radiation status of the receiving antenna is used to establish a plurality of communication performances, each of which is the received data rate of the k receiving antennas for which the selected and the radiation status has been determined; for each communication performance, set A received signal strength indicator intermediate value, obtaining k absolute value differences of the received signal strength indicators of the receiving antenna; and among the communication performances, the communication performance with the smallest absolute value difference is selected as the optimized Multiple-input multiple-output communication; wherein the remote device has m transmitting antennas to transmit wireless signals to the terminal device, and m is a positive integer greater than or equal to 2, when the terminal device learns the m number of the remote device The transmitting antenna has been changed, and the terminal device changes the radiation status of the k receiving antenna configurations of the receiving antennas to re-establish the communication performance. The antenna control method for multiple input multiple output communication according to claim 1, wherein the step of changing the radiation state of the receiving antenna configuration of the k receiving antennas in the terminal device to establish the communication performance includes : At least one reflection unit or at least one ground current control unit of each receiving antenna is controlled. The antenna control method for multiple-input multiple-output communication according to claim 2, wherein the method of controlling the reflecting unit of each receiving antenna includes: selecting a diode to conduct a half-wavelength reflector, or selecting not The diode is turned on and an extension loop utilizes a capacitor to extend the path of the half-wavelength reflector. The antenna control method for multiple input multiple output communication according to claim 2, wherein the method of controlling each of the ground current control units of the receiving antenna includes: selecting a switch to conduct a ground current part to a ground, Or choose not to turn on the switch and connect a grounding capacitor between the ground current part and the ground. A terminal device for multiple-input multiple-output communication, including: N receiving antennas connected to a wireless chip; an application unit connected to the wireless chip, and the wireless chip receives the received signal strength indicator and multiple input of the receiving antennas The receiving data rate of multi-output communication, where the application unit selects n receiving antennas with higher signal strength indication from the N receiving antennas as the executing receiving antenna, where N is greater than n, and both N and n are positive Integer, n is greater than 2; wherein, the application unit arbitrarily selects k among the n receiving antennas to form a plurality of receiving antenna configurations, and uses one of the receiving antenna configurations from a remote device Receive a wireless signal, where n is greater than k, and k is a positive integer greater than or equal to 2; wherein, the application unit changes the radiation state of the receiving antenna configuration k of the receiving antennas to establish a plurality of communication performances, where Each communication performance is the received data rate of the k receiving antennas that have been selected and the radiation status has been determined; for each communication performance, a received signal strength indicator intermediate value is set, and the application unit obtains k Execute receiving antenna The absolute value difference indicated by the received signal strength; wherein, among the communication performances, the application unit selects the communication performance with the smallest absolute value difference as the optimized multiple input multiple output communication; and a control unit, The application unit is connected with the N receiving antennas, and the application unit is controlled by the application unit to control the radiation status of the receiving antennas of the N receiving antennas; wherein, the remote device has m transmitting antennas to transmit When the wireless signal arrives at the terminal device, m is a positive integer greater than or equal to 2. When the terminal device learns that the m transmitting antennas of the remote device have changed, the terminal device changes the k receiving antenna configurations. Receive the radiation state of the antenna to re-establish these communication performance. The terminal device for multiple input multiple output communication according to claim 5, wherein the control unit is controlled by the application unit to control at least one reflection unit or at least one ground current control unit of each receiving antenna. The terminal device for multiple-input multiple-output communication according to claim 6, wherein the control unit controls a diode to selectively turn on a half-wavelength reflector, or choose not to turn on the diode and make an extension loop use a The capacitor extends the path of the half-wave reflector. The terminal device for multiple-input multiple-output communication according to claim 6, wherein the control unit controls a switch to selectively conduct a ground current part to a ground, or choose not to conduct the switch and connect a grounding capacitor to the Between the ground current section and the ground.

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