CN104467922B

CN104467922B - Tempest device

Info

Publication number: CN104467922B
Application number: CN201410829258.2A
Authority: CN
Inventors: 李大庆
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-12-29
Filing date: 2014-12-29
Publication date: 2019-03-15
Anticipated expiration: 2034-12-29
Also published as: CN104467922A

Abstract

The present invention provides a kind of Tempest device, belongs to field of information security technology.Tempest device provided by the invention includes noise-producing equipment, and for generating white noise, the white noise is coupled on power supply line the noise-producing equipment by coupler.The present invention uses wide band power filter, filters out the useful information loaded on electrical equipment power supply line, while broadband white noise source is added, interferes space radiation information, to realize the information screen in cable and space.White noise sound source punctures circuit using triode, then by amplification, becomes middle power white noise signal, it is filtered using low-pass filter, the white noise of certain bandwidth is generated, can effectively interfere the radiation signal of electrical equipment and influences the normal operation of other equipment.The configuration of the present invention is simple, it is small in size, by test, leakage of information problem caused by electrical equipment ELECTROMAGNETIC RADIATION SIGNATURE can be efficiently solved.

Description

Tempest device

Technical field

The present invention relates to a kind of Tempest device more particularly to a kind of anti-power supply line leakage of information devices, belong to letter Cease security technology area.

Background technique

With the high speed development of social informatization, electronic information equipment also constantly improves, to meet the daily life of people The needs that information interconnects in work.But electronic information equipment will generate certain electromagnetic radiation while information exchange, from And cause two kinds of results: the leakage of electromagnetic wave interfered with each other with installation electromagnetical information, wherein electromagnetic wave interferes with each other problem The problem of being people's extensive concern, the time that it is found is more early, and electromagnetic compatibility (EMC) technology is exactly to solve electromagnetic wave It interferes with each other problem and generates, there now have been the theory and technical foundation of comparative maturity.The problem of electromagnetic information leakage Just be taken seriously and pay close attention in recent decades, with electromagnetic wave interfere with each other problem compared with, electromagnetic information leakage processing technique It is more focused on information security field, it causes serious threat to the security work of information.

Although electromagnetic information leakage protection and detection technique and electromagnetic compatibility technology are all to be with the radiation problem of electromagnetic wave Basis, but it again there are difference with general electromagnetic compatibility technology.Electromagnetic information leakage protection and detection technique are compared with general Electromagnetic compatibility problem, it is more focused on leakage of information caused by the weak electromagnetic wave radiation of electronic information technology equipment, and General electromagnetic compatibility problem focuses on the microwave radiation at work of electronic equipment and does to other electronic equipments It disturbs, it is indifferent to information entrained by electromagnetic wave.In addition, the protection of processing electromagnetic information leakage and test problems are asked than electromagnetic compatibility Topic more requires the detection and test equipment of profession.Also, electromagnetic information leakage protection will follow TEMPEST mark with detection It is quasi-.In short, electromagnetic information leakage protection and detection technique are compared with the electromagnetic interference problem of electronic equipment, its technical requirements are more Height, electromagnetic environment is more complicated, testing standard is stringenter.

With the continuous development of internet, computer has become a part indispensable in people's life.But it counts A kind of equipment of the calculation machine as information processing and exchange, it can constantly radiate a large amount of electromagnetic wave signals when working into space. This electromagnetic wave signal given off is possible to carry the important information that computer is being handled, to give information security issue band Carry out huge hidden danger.At work, its mainboard, display and all kinds of interface data wires, cable etc. can all be sent out computer Project the different degrees of electromagnetic radiation of intensity.From the angle of electromagnetic radiation theory, these useful informations given off all may be used It can be received and restore.

For relating computer, its same radiated electromagnetic wave at work, and confidential information therein be possible to by The leakage of this mode to decoding is received, the firewall of computer and a series of anti-including hardware isolated has been bypassed Shield measure.In this case, even if computer does not connect the data that can similarly be stolen with any other equipment, so not having Computer by special electromagnetic information safety and Protection is difficult that channel of divulging a secret is truncated.In general, computer Primary radiation source concentrate on cable part, if its cable cannot provide effective shielding or filtering, the spoke of electromagnetic leakage Penetrating intensity will greatly enhance.

Summary of the invention

To overcome disadvantage existing in the prior art, goal of the invention of the invention is to provide a kind of Tempest device, The device can effectively prevent leakage of information caused by power supply beta radiation and conduction.

To realize that the goal of the invention, the present invention provide a kind of Tempest device comprising noise-producing equipment, institute Noise-producing equipment is stated for generating white noise, the white noise is coupled on power supply line by coupler.

Preferably, Tempest device further includes power-supply filter, and the power-supply filter is for filtering out power supply line Power line carrier wave information.

Preferably, Tempest device further includes AC/DC amplifier, and the AC/DC amplifier is used for from power supply line Part alternating current source is taken out, and is converted to DC power supply.

Preferably, Tempest device further includes amplifier, and the amplifier is produced for amplifying noise-producing equipment Raw white noise acoustic intelligence.

Preferably, Tempest device further includes low-pass filter, and the low-pass filter is for putting amplifier Big white noise acoustic intelligence is filtered.

Preferably, Tempest device further includes working state monitoring and display device, the working state monitoring with Display device is used to monitor operating current and the working time of Tempest device, and is shown.

Preferably, the stopband operating frequency range of power-supply filter is 150KHz to 400MHz.

Preferably, the cutoff frequency of low-pass filter is 300MHz.

Preferably, the coupler is capacity coupler or inductive coupler.

Compared with prior art, Tempest device provided by the invention can effectively prevent power supply beta radiation and conduction institute Caused leakage of information.

Detailed description of the invention

Fig. 1 provides the composition block diagram of Tempest device for the present invention；

Fig. 2 is the circuit diagram of noise generating device provided by the invention；

Fig. 3 is the composition block diagram of working state monitoring provided by the invention and display device；

Fig. 4 is the circuit diagram of amplifier provided by the invention；

Fig. 5 is the circuit diagram of working state monitoring circuit provided by the invention；

Fig. 6 is the circuit diagram of low-pass filter provided by the invention.

Specific embodiment

The invention will now be described in detail with reference to the accompanying drawings.

Fig. 1 provides the composition block diagram of Tempest device for the present invention.As shown in Figure 1, anti-information provided by the invention Leakage device, including power-supply filter, AC/DC converter, noise-producing equipment, amplifier, low-pass filter and working condition Monitoring and display device, the power-supply filter is for filtering out power line carrier wave information on power supply line, it is preferable that power-supply filter Stopband operating frequency range be 150KHz to 400MHz；AC/DC converter is used for from the taking-up AC power source on power line simultaneously It is converted into DC power supply, main generation+5V and+7V DC power supply, is subsequent noise-producing equipment, amplifier, work shape State and display device provide DC power supply.The noise-producing equipment is for generating white noise；The amplifier is made an uproar for amplifying White noise acoustic intelligence produced by generating device；The white noise acoustic intelligence that the low-pass filter is used to amplify amplifier is filtered Wave, it is preferable that the passband operating frequency range of low-pass filter is 0MHz to 300MHz；The white noise is coupled by coupler Onto power supply line, the coupler is inductive coupler or capacity coupler.

Fig. 2 is the circuit diagram of noise generating device provided by the invention.As shown in Fig. 2, noise provided by the invention generates Device includes low-pass filter and white noise generator, and the low-pass filter is by inductance L5, capacitor C9, capacitor C15 and capacitor C16 composition, the cathode output end of+7V direct current supply line connect the first end of the inductance L5, and the second end of inductance L5 is all connected with The first end of capacitor C9, capacitor C15 and capacitor C16, the second end ground connection of capacitor C9, capacitor C15 and capacitor C16；Inductance L5's Second end is connected to the first end of resistance R3, and the second end of resistance R3 is connected to the transmitting of the transistor Q1 in white noise generator Pole, that is to say, that the low-pass filtered device of+7V power supply filters out ripple and then provides electric energy to white noise generator.The inductance L5 Logical direct current is exchanged for hindering.The present invention uses the capacitor C9 an of large capacity and the capacitor C15 and capacitor of two low capacities The mode that C16 is in parallel substantially increases the filtering characteristic of ripple.White noise sound generation device is made of transistor Q1, transistor Q1 Base earth, collector is hanging, and emitter connects the second end of current-limiting resistance R3, while being connected to the first of coupled capacitor C17 End, i.e., be provided out white noise acoustic intelligence by coupled capacitor C17.White noise generator generates wideband using the breakdown characteristics of PN junction The white noise of band.

Fig. 3 is the composition block diagram of working state monitoring provided by the invention and display device.As shown in figure 3, working condition Monitoring and display device are made of single-chip microcontroller, liquid crystal display, clock chip, Hall element and working state monitoring circuit, can To show working time, the electric current for flowing through power-supply filter and current working condition.The Hall element is for monitoring stream The electric current of power-supply filter is crossed, and exports a voltage signal proportional to the electric current for flowing through power supply line, is then supplied to list Piece machine；Working state monitoring circuit mainly judges the quiescent potential of amplifier, sees that its DC static operating point is It is no in normal voltage range；Single-chip microcontroller mainly handles the information of Hall element output and the letter of working state monitoring circuit output Breath, and shown on liquid crystal display, clock chip is for providing current temporal information, and single-chip microcontroller is also according to clock core The temporal information that piece provides is in the current date Hour Minute Second of liquid crystal display screen display and the working time of the present apparatus.

Fig. 4 is the circuit diagram of amplifier provided by the invention.As shown in figure 4, amplifier provided by the invention includes three-level, The amplifier is for amplifying white noise acoustic intelligence caused by noise generator, and successively dialogue noise information carries out third stage amplifier Amplification.First order amplifier is supplied to the second level after amplification and puts for amplifying white noise signal caused by noise generating device Big device continues to amplify, and is made of the first amplification chip MAR-8+ and its peripheral circuit, wherein the first amplification chip MAR-8+'s 1st foot connects the second end of coupled capacitor C17, and the 2nd and 4 feet ground connection, the 3rd foot connects the first end of coupled capacitor C18, coupled Capacitor C18 provides driving signal to second level amplifier；Power supply+5V successively gives amplification core through biasing resistor R1 and inductance L6 simultaneously Piece MAR-8+ provides suitable quiescent point, and capacitor C11 and C12 play ac short circuit ground connection.Second level amplifier is used for The white noise signal that amplification first order amplifier is amplified, is supplied to third level amplifier and continues to amplify, by second after amplification Amplification chip MAR-8+ and its peripheral circuit composition, wherein the 1st foot of the second amplification chip MAR-8+ connects coupled capacitor C18 Second end, the 2nd and 4 feet ground connection, the 3rd foot connect coupled capacitor C19 first end, coupled capacitor C19 to the third level amplify Device provides driving signal；Power supply+5V is successively provided through biasing resistor R2 and inductance L7 to amplification chip MAR-8+ suitable simultaneously Quiescent point, capacitor C13 and C14 play ac short circuit ground connection, and capacitor C10 is used to filter out the ripple of+5V power supply.The third level Amplifier is supplied to rear class low-pass filter and is filtered for amplifying the white noise signal that second level amplifier is amplified after amplification Wave is made of third amplification chip MAR-8+ and its peripheral circuit, wherein the 1st foot of third amplification chip MAR-8+ connects The second end of coupled capacitor C23, the first end of capacitor C23 are connected to the second end of resistance R9, and the first end of resistance R9 is connected to The second end of capacitor C19；Resistance R9 is for controlling output power；The 2nd and 4 feet of third amplification chip MAR-8+ are grounded, the 3rd foot The first end of coupled capacitor C24 is connected, coupled capacitor C24 provides signal to low-pass filter；Power supply+5V is successively passed through partially simultaneously It sets resistance R4 and inductance L8 and provides suitable quiescent point to amplification chip MAR-8+, capacitor C21 and C22 play ac short circuit and connect Ground effect, capacitor C20 are used to filter out the ripple of+5V power supply.

Fig. 5 is the circuit diagram of working state monitoring circuit provided by the invention.As shown in figure 5, work provided by the invention Status monitoring circuit includes: comparator, level translator and indicator, and the comparator is respectively compared the three-level in amplifier The quiescent point voltage and threshold values of every level-one are to judge whether every grade of amplifier operation is normal, and level translator is for providing valve Threshold voltage, and comparison result is converted into high level or low level；Whether indicator is used to indicate amplifier operation normal, refers to It when showing that lamp is bright, indicates working properly, when indicator light does not work, indicates that work is abnormal.Comparator includes the first electric switch, the second electricity Switch, third electric switch, the 4th electric switch, the 5th electric switch and the 6th electric switch, wherein the first electric switch by transistor Q4, The emitter of resistance R14, resistance R16 and diode D5 composition, transistor Q4 is connected to power supply+5V, collector warp through resistance R14 Resistance R16 is connected to ground, is also attached to the cathode of diode D5, base stage is connected to the detection of the first order amplifier in amplifier Hold DT1；The anode of diode D5 is connected to the input terminal of level translator, the i.e. intermediate node of resistance R7 and resistance R10；Second Electric switch is made of transistor Q5, resistance R17, resistance R21 and diode D8, and the emitter of transistor Q5 is connected through resistance R17 In power supply+5V, collector is connected to ground through resistance R21, is also attached to the cathode of diode D8, base stage is connected in amplifier The test side DT2 of second level amplifier；The anode of diode D8 is connected to the input terminal of level translator, i.e. resistance R7 and resistance The intermediate node that R10 is connected in series；Third electric switch is made of transistor Q6, resistance R18, resistance R22 and diode D9, transistor The emitter of Q6 is connected to power supply+5V through resistance R18, and collector is connected to ground through resistance R22, is also attached to the negative of diode D9 Pole, base stage are connected to the test side DT3 of the third level amplifier in amplifier；The anode of diode D9 is connected to level translator Input terminal, i.e. the intermediate node that resistance R7 and resistance R10 are connected in series.4th electric switch is made of diode D1, diode D1 Cathode be connected to the test side DT1 of the first order amplifier in amplifier, anode is connected to the input terminal of level translator, i.e., The intermediate node of resistance R7 and resistance R10；5th electric switch is made of diode D2, and the cathode of diode D2 is connected to amplifier In second level amplifier test side DT2, anode is connected to the input terminal of level translator, i.e. resistance R7 and resistance R10's Intermediate node.6th electric switch is made of diode D3, and the cathode of diode D3 is connected to the third level amplifier in amplifier Test side DT3, anode is connected to the input terminal of level translator, the i.e. intermediate node that resistance R7 and resistance R10 are connected in series.

Level translator is by resistance R7, resistance R10, capacitor C26, transistor Q2, resistance R5, resistance R8, resistance R11, electricity Hindering R13, transistor Q3 and resistance R6 composition, wherein resistance R7 and R10 are connected in series, and are connected between power supply+5V and ground, Intermediate node is the input terminal of level translator, and capacitor C26 is simultaneously connected in the both ends resistance R10, for filtering out ripple, to prevent malfunction Make.Resistance R5 and R8 are connected in series, and are connected between power supply+5V and ground, and wherein intermediate node provides for the emitter of transistor Q2 The collector of one suitable quiescent point, transistor Q2 is grounded through resistance R13, and base stage is connected to resistance R7 and goes here and there with R10 phase The intermediate node of connection.Transistor Q3 works in switch state, and collector is connected to power supply+5V through resistance R6, and emitter is grounded, Base stage is connected to the collector of transistor Q2 through resistance R11.

The quiescent point of amplification chip MAR-8+ is in normal operating conditions, when first order amplifier in 2.8-4V When normal work, the transistor Q4 for being connected to DT1 is in the conductive state, and diode D5 is in off state, and diode D1 is in Off state, the intermediate node voltage that resistance R7 and R10 are connected in series is unaffected, and transistor Q2 is in off state, resistance R13 The voltage at both ends is zero, and transistor Q3 is also at off state, and it is one of single-chip microcontroller that R6 and R23 intermediate node voltage, which is+5V, Input terminal provides high level, while light emitting diode D13 connects electricity and shines, and indicates that first order amplifier operation is normal.When first When the quiescent point of amplifier MAR-8+ is higher than 4V, it is in abnormal operating state, the diode D1 for being connected to DT1, which is in, to be cut Only state, transistor Q4 are in off state, and diode D5 is in the conductive state, the intermediate node that resistance R7 and R10 are connected in series Voltage is influenced to become smaller than+2V by Q4 cut-off, and transistor Q2 is in the conductive state, and the voltage at the both ends resistance R13 is greater than 1V, brilliant Body pipe Q3 is in saturation conduction state, R6 and R23 intermediate node voltage is less than 1V, provides low electricity for an input terminal of single-chip microcontroller It is flat, while light emitting diode D13 power-off indicates that first order amplifier operation is abnormal without shining；When the first amplification chip When the quiescent point of MAR-8+ is lower than 2.8V, it is in abnormal operating state, the diode D1 for being connected to DT1 is on shape State, transistor Q4 is in the conductive state, and diode D5 is in off state, the intermediate node voltage that resistance R7 and R10 are connected in series It is influenced to become smaller than+3.5V by D1 conducting, transistor Q2 is in the conductive state, and the voltage at the both ends resistance R13 is greater than 1V, crystal Pipe Q3 is in saturation conduction state, R6 and R23 intermediate node voltage is less than 1V, provides low electricity for an input terminal of single-chip microcontroller It is flat, while light emitting diode D13 power-off indicates that first order amplifier operation is abnormal without shining.

When second level normal amplifier operation, the transistor Q5 for being connected to DT2 is in the conductive state, and diode D8 is in Off state, diode D2 are in off state, and the intermediate node voltage that resistance R7 and R10 are connected in series is unaffected, transistor Q2 is in off state, and the voltage at the both ends resistance R13 is zero, and transistor Q3 is also at off state, R6 and R23 intermediate node electricity Pressure is+5V, provides high level for an input terminal of single-chip microcontroller, while light emitting diode D13 connects electricity and shines, and indicates the second level Amplifier operation is normal.When the quiescent point of the second amplification chip MAR-8+ is higher than 4V, it is in abnormal operating state, even The diode D2 for being connected to DT2 is in off state, and transistor Q5 is in off state, and diode D8 is in the conductive state, resistance The intermediate node voltage that R7 and R10 are connected in series is influenced to become smaller than+2V by Q5 cut-off, and transistor Q2 is in the conductive state, electricity The voltage for hindering the both ends R13 is greater than 1V, and transistor Q3 is in saturation conduction state, R6 and R23 intermediate node voltage is less than 1V, is single One input terminal of piece machine provides low level, while light emitting diode D13 power-off indicates second level amplifier operation without shining It is abnormal；When the quiescent point of the second amplification chip MAR-8+ is lower than 2.8V, it is in abnormal operating state, is connected to The diode D2 of DT2 is in the conductive state, and transistor Q5 is in the conductive state, and diode D8 is in off state, resistance R7 and The intermediate node voltage that R10 is connected in series is influenced to become smaller than+3.5V by D2 conducting, and transistor Q2 is in the conductive state, resistance The voltage at the both ends R13 is greater than 1V, and it is monolithic that transistor Q3, which is in saturation conduction state, R6 and R23 intermediate node voltage is less than 1V One input terminal of machine provides low level, while light emitting diode D13 power-off indicates second level amplifier operation not without shining Normally.

When third level normal amplifier operation, the transistor Q6 for being connected to DT3 is in the conductive state, and diode D9 is in Off state, diode D3 are in off state, and the intermediate node voltage that resistance R7 and R10 are connected in series is unaffected, transistor Q2 is in off state, and resistance R13 both end voltage is zero, and transistor Q3 is also at off state, R6 and R23 intermediate node voltage For+5V, high level is provided for an input terminal of single-chip microcontroller, while light emitting diode D13 connects electricity and shines, and indicates that the third level is put Big device is working properly.When the quiescent point of third amplification chip MAR-8+ is higher than 4V, it is in abnormal operating state, connection It is in off state in the diode D3 of DT3, transistor Q6 is in off state, and diode D9 is in the conductive state, resistance R7 The intermediate node voltage being connected in series with R10 is influenced to become smaller than+2V by Q6 cut-off, and transistor Q2 is in the conductive state, resistance The voltage at the both ends R13 is greater than 1V, and it is monolithic that transistor Q3, which is in saturation conduction state, R6 and R23 intermediate node voltage is less than 1V One input terminal of machine provides low level, while light emitting diode D13 power-off indicates second level amplifier operation not without shining Normally；When the quiescent point of third amplification chip MAR-8+ is lower than 2.8V, it is in abnormal operating state, is connected to DT3 Diode D3 it is in the conductive state, transistor Q6 is in the conductive state, and diode D9 is in off state, resistance R7 and R10 The intermediate node voltage being connected in series is influenced to become smaller than+3.5V by D3 conducting, and transistor Q2 is in the conductive state, resistance R13 The voltage at both ends is greater than 1V, and it is single-chip microcontroller that transistor Q3, which is in saturation conduction state, R6 and R23 intermediate node voltage is less than 1V An input terminal low level is provided, while light emitting diode D13 power-off is indicating third level amplifier operation not just without shining Often.

Fig. 6 is the circuit diagram of low-pass filter provided by the invention, as shown in fig. 6, low-pass filter provided by the invention For 7 rank Chebyshev filters, by inductance L10, inductance L11, inductance L9, inductance L12, capacitor C27, capacitor C28, capacitor C29, Capacitor C25 composition.The noise signal caused by triode punctures, broader bandwidth, if without restriction, it is likely that influence it Its signal, by it by low-pass filter, limits its bandwidth in a certain range, the present invention then after generating noise It is preferred that passband operating frequency range is 0MHz to 300MHz.

Design of the invention and example are elaborated in conjunction with attached drawing above, but those skilled in the art should recognize Know, under the premise of no disengaging present inventive concept, any modifications and variations made based on the present invention still fall within this hair Content in bright protection scope.

Claims

1. a kind of Tempest device comprising noise-producing equipment, amplifier and working state monitoring circuit, the noise Generating device is for generating white noise；The amplifier is for amplifying white noise acoustic intelligence caused by noise-producing equipment；It is described White noise is coupled on power supply line by coupler, which is characterized in that the working state monitoring circuit includes: comparator, electricity Flat turn parallel operation and light emitting diode (D13), the comparator make respectively the quiescent point voltage of every level-one in amplifier with Threshold values is compared to judge whether every grade of amplifier operation is normal, and level translator will compare for providing threshold voltage As a result be converted to high level or low level, level translator by first resistor (R7), second resistance (R10), capacitor (C26), Positive-negative-positive the first transistor (Q2), 3rd resistor (R5), the 4th resistance (R8), the 5th resistance (R11), the 6th resistance (R13), NPN Type second transistor (Q3) and the 7th resistance (R6) composition, wherein first resistor (R7) and second resistance (R10) are connected in series, and It is connected between+5V power supply and ground, the node that first resistor (R7) is connected with second resistance (R10) is the input of level translator End；Capacitor (C26) is parallel to the both ends of second resistance (R10);3rd resistor (R5) and the 4th resistance (R8) are connected in series, and even It is connected between+5V power supply and ground, the emitter of the first transistor (Q2) is connected to 3rd resistor (R5) and the 4th resistance (R8) phase Node even, the collector of the first transistor (Q2) are grounded through the 6th resistance (R13), and the base stage of the first transistor (Q2) is connected to The node that first resistor (R7) is connected with second resistance (R10);The collector of second transistor (Q3) connects through the 7th resistance (R6) It is connected to+5V power supply, the emitter ground connection of second transistor (Q3), the base stage of second transistor (Q3) connects through the 5th resistance (R11) It is connected to the collector of the first transistor (Q2);The 8th resistance (R23) of one end of light emitting diode (D13) is connected to the second crystalline substance The collector of body pipe (Q3), other end ground connection;Noise generating device includes low-pass filter and white noise generator ,+7V power supply Low-pass filtered device filters out ripple and then provides electric energy to white noise generator；White noise generator is by third transistor (Q1) group At the collector of the base earth of third transistor (Q1), third transistor (Q1) is hanging, the emitter of third transistor (Q1) The second end of current-limiting resistance (R3) is connected, the transmitter of third transistor (Q1) is connected to one end of coupled capacitor (C17) simultaneously, White noise acoustic intelligence is provided out by coupled capacitor (C17)；The first end of current-limiting resistance (R3) connects low-pass filter.

2. Tempest device according to claim 1, which is characterized in that it further include power-supply filter, the power supply Filter is for filtering out power line carrier wave information on power supply line.

3. Tempest device according to claim 2, which is characterized in that it further include AC/DC converter device, it is described AC/DC converter is converted to DC power supply for taking out AC power source from power supply line.

4. Tempest device according to claim 3, which is characterized in that the stopband working frequency model of power-supply filter It encloses for 150KHz to 400MHz.

5. Tempest device according to claim 1-4, which is characterized in that the coupler is capacitor coupling Clutch or inductive coupler.