An electromagnetic pulse detection circuit

Abstract

The present invention discloses an electromagnetic pulse detection circuit, comprising a signal acquisition circuit, a signal amplification circuit, a signal shaping circuit and a signal differential transmission circuit connected in sequence; wherein the signal acquisition circuit is used to acquire an electromagnetic pulse signal and clamp and limit the high voltage signal generated by the electromagnetic pulse signal; the signal amplification circuit is used to amplify the signal processed by the signal acquisition circuit; the signal shaping circuit is used to perform pulse shaping on the signal processed by the signal amplification circuit; and the signal differential transmission circuit is used to output the signal difference shaped by the signal shaping circuit into multiple channels. The present invention has a simple circuit structure, uses fewer components, has a low manufacturing cost, and has high detection efficiency and accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic pulse detection, and in particular to an electromagnetic pulse detection circuit. Background Art

[0002] When lightning or a nuclear weapon explodes, an electromagnetic pulse will be generated, which will have a destructive effect on electronic equipment. In order to detect the electromagnetic pulse in time and provide a basis for subsequent electromagnetic protection, a circuit system that can accurately and safely detect electromagnetic pulse signals is needed.

[0003] Electromagnetic pulses are electromagnetic waves generated by alternating changes in electric and magnetic fields. Based on the generation mechanism and characteristics of electromagnetic pulses, some detection devices have appeared on the market. For example, Chinese patent application CN101871977A discloses a high-voltage transient electromagnetic pulse detector, comprising a probe (1), a receiving unit (3), and a connecting component connecting the probe (1) and the receiving unit (3), wherein the connecting component is an optical fiber (6). The probe (1) comprises an antenna (2), a cylindrical sealed shielding shell (5), and a signal processing unit (4) arranged in the shielding shell (5). The invention solves the technical problems that the existing electric field tester is easily burned by the strong electric field when working in a strong electric field, and is disturbed by the strong electric field, resulting in serious distortion of the test waveform. The invention has the advantages of strong anti-interference, preventing circuit distortion, and preventing the signal processing circuit from being burned by the strong electric field.

[0004] However, the existing technology includes filtering circuits, amplifying circuits, antenna loops, impedance conversion circuits, driving amplifying circuits, optical exciters, power supply circuits, etc., which use many components. Therefore, there are problems such as complex circuit structure and high production cost. In addition, due to the complexity of the circuit, it is easy to cause serious signal attenuation, low detection efficiency, and high false alarm rate. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is to provide an electromagnetic pulse detection circuit, which solves the problems of complex circuits, high production costs, low detection efficiency, and high false alarm rate in the prior art.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An electromagnetic pulse detection circuit comprises a signal acquisition circuit, a signal amplification circuit, a signal shaping circuit and a signal differential transmission circuit which are connected in sequence; wherein the signal acquisition circuit is used to acquire the electromagnetic pulse signal and clamp and limit the high voltage signal generated by the electromagnetic pulse signal; the signal amplification circuit is used to amplify the signal processed by the signal acquisition circuit; the signal shaping circuit is used to perform pulse shaping on the signal processed by the signal amplification circuit; and the signal differential transmission circuit is used to output the signal difference shaped by the signal shaping circuit into multiple channels.

[0008] As an optimization, the signal acquisition circuit adopts a saturation circuit, including an antenna, the signal output end of the antenna is connected to one end of the resistor R5, the other end of the resistor R5 is connected to one end of the capacitor C5, and the other end of the capacitor C5 is connected to the signal amplification circuit; it also includes multiple diodes, wherein the anode of the diode D2 and the cathode of the diode D3 are connected between the resistor R5 and the capacitor C5, the anode of the diode D5 is connected to the cathode of the diode D2, the cathode of the diode D6 is connected to the anode of the diode D3, and the cathode of the diode D5 and the anode of the diode D6 are connected and grounded.

[0009] As an optimization, the antenna uses an external whip antenna with a diameter of 5 mm and a length of 0.5 meters, and the antenna capacitive reactance is calculated by the following formula:

[0010]

[0011] Where Ca is the antenna capacitive reactance; L is the antenna length; d is the antenna diameter; K is the correction coefficient, which ranges from 0.133 to 0.44.

[0012] As an optimization, the forward conduction voltage drop of the diodes D2, D3, D5, and D6 is 0.7V.

[0013] As an optimization, the signal amplification circuit adopts an inverting proportional amplification circuit, including an operational amplifier, the inverting input terminal of the operational amplifier is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the signal acquisition circuit; the non-inverting input terminal of the operational amplifier is connected to one end of the resistor R14, the other end of the resistor R14 is grounded and connected to one end of the capacitor C8, the other end of the capacitor C8 is connected to one end of the resistor R9, and the other end of the resistor R9 is connected to the signal acquisition circuit; the output terminal of the operational amplifier is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the signal shaping circuit; and also includes a resistor R1, one end of the resistor R1 is connected between the resistor R6 and the inverting input terminal of the operational amplifier, and the other end is connected between the resistor R8 and the output terminal of the operational amplifier.

[0014] As an optimization, the positive power supply terminal of the operational amplifier is connected to the positive electrode of the power supply, and is respectively connected to one end of the capacitor C1 and the capacitor C2, and the other ends of the capacitor C1 and the capacitor C2 are grounded; the negative power supply terminal of the operational amplifier is connected to the negative electrode of the power supply, and is respectively connected to one end of the capacitor C9 and the capacitor C10, and the other ends of the capacitor C9 and the capacitor C10 are grounded; the two TRIM terminals of the operational amplifier are respectively connected to the two ends of the adjustable resistor R19, and the adjustment end of the adjustable resistor R19 is connected to the negative electrode of the power supply.

[0015] As an optimization, the signal shaping circuit adopts a complementary monostable circuit, including an NPN transistor V3, and PNP transistors V1 and V2. The base of the transistor V3 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to the cathode of the diode D4, the anode of the diode D4 is connected to one end of the capacitor C7, the other end of the capacitor C7 is connected to the signal amplification circuit, the collector of the transistor V3 is connected to one end of the resistor R4 and the capacitor C6 respectively, the other end of the resistor R4 is connected to the positive electrode of the power supply, the other end of the capacitor C6 is connected to the base of the transistor V2 through the resistor R10, and the emitter of the transistor V3 is grounded;

[0016] The emitter of the transistor V2 is connected to the positive electrode of the power supply, the collector is connected between the diode D4 and the resistor R13, and is grounded through the resistor R17;

[0017] The emitter of the transistor V1 is connected to the positive electrode of the power supply, the base is connected between the resistor R4 and the collector of the transistor V3 through the resistor R7, the collector is connected to one end of the resistor R12 and the resistor R15 respectively, the other end of the resistor R12 is connected to the signal differential transmission circuit, and the other end of the resistor R15 is grounded;

[0018] It also includes resistors R2, R3 and R16, one end of the resistor R3 is connected to the positive electrode of the power supply, the other end is connected between the resistor R10 and the capacitor C6, and is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the signal amplification circuit through the capacitor C4; one end of the resistor R2 is connected to the positive electrode of the power supply, and the other end is connected between the capacitor C4 and the diode D1; one end of the resistor R16 is connected between the capacitor C7 and the diode D4, and the other end is grounded.

[0019] As an optimization, the signal differential transmission circuit includes a TD501D485 module, whose VCC pin is respectively connected to the positive pole of the power supply and grounded through a capacitor C11; its GND pin is grounded; its TXD pin is grounded through a resistor R21; its RXD pin is connected to the VCC pin and to the anode of a diode D7, and the cathode of the diode D7 is connected to the signal shaping circuit; its CON pin is connected to the RXD pin; its RGND pin is connected to the power ground; its two output pins are used to output differential signals, and a resistor R20 is connected in parallel between the two output pins.

[0020] Compared with the prior art, this application has the following beneficial effects:

[0021] The present invention uses an external antenna to receive electromagnetic pulse signals, amplifies the signals through an amplifier, and then shapes them into useful square wave signals. Among them, a saturation circuit is used in the signal acquisition circuit, low-range and small signals are not processed, and high voltages are clamped and limited to ensure the safety of subsequent amplification circuits. The amplification circuit uses an inverting proportional amplification circuit, and its amplification factor matches the trigger threshold of the signal shaping circuit. The signal shaping circuit uses a complementary monostable circuit, which can be triggered by both positive and negative polarity signals. The pulse signal is output from the collector of the transistor V3 instead of the collector of the transistor V2, and can better utilize the trailing edge of the pulse signal with a longer duration to control the following transistor V1, and perform level conversion and pulse shaping through the transistor V1. The signal differential transmission circuit is differentially output into two paths through the TD501D485 module, has a strong anti-interference ability, and a long transmission distance. The circuit structure of the present invention is simple, the components used are few, the production cost is low, and the detection efficiency and accuracy are high. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a block diagram of the composition of the present invention;

[0023] Figure 2 Get a circuit diagram for the signal;

[0024] Figure 3 This is the signal amplification circuit diagram;

[0025] Figure 4 It is a signal shaping circuit diagram;

[0026] Figure 5 This is the circuit diagram for signal differential transmission. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0028] For specific implementation: see Figure 1-Figure 5 ,

[0029] An electromagnetic pulse detection circuit comprises a signal acquisition circuit, a signal amplification circuit, a signal shaping circuit and a signal differential transmission circuit which are connected in sequence.

[0030] The signal acquisition circuit is used to acquire the electromagnetic pulse signal and clamp the high voltage signal generated by the electromagnetic pulse signal. Specifically, the dynamic range of electromagnetic pulse detection is -20000V / m to 20000V / m, and tens of volts or even very high voltages will be induced on the antenna, which will bring hidden dangers to the safety of subsequent circuits. Therefore, a saturation circuit is used in this embodiment, and low-range and small signals are not processed, and high voltages are clamped and limited. The circuit is composed of four diodes, including an antenna, the signal output end of the antenna is connected to one end of the resistor R5, the other end of the resistor R5 is connected to one end of the capacitor C5, and the other end of the capacitor C5 is connected to the signal amplification circuit; it also includes a plurality of diodes, wherein the anode of the diode D2 and the cathode of the diode D3 are connected between the resistor R5 and the capacitor C5, the anode of the diode D5 is connected to the cathode of the diode D2, the cathode of the diode D6 is connected to the anode of the diode D3, and the cathode of the diode D5 is connected to the anode of the diode D6 and grounded.

[0031] The antenna is a whip antenna with a diameter of 5 mm and a length of 0.5 m. The antenna capacitive reactance is calculated by the following formula:

[0032]

[0033] Where, Ca is the antenna capacitive reactance; L is the antenna length; d is the antenna diameter; K is the correction factor, which ranges from 0.133 to 0.44. Calculate according to formula 1: Ca = 5.57pF, based on the distributed capacitance of the antenna base, lead wires, etc. to the ground and changes in environmental conditions.

[0034] The forward voltage drop of the diode used in the circuit is about 0.7V, so the output signal is clamped between -1.4V and +1.4V to ensure the safety of the subsequent amplification circuit.

[0035] The signal amplification circuit is used to amplify the signal processed by the signal acquisition circuit. Specifically, the signal amplification circuit adopts an inverting proportional amplification circuit, including an operational amplifier, the inverting input end of the operational amplifier is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the signal acquisition circuit; the in-phase input end of the operational amplifier is connected to one end of the resistor R14, the other end of the resistor R14 is grounded and connected to one end of the capacitor C8, the other end of the capacitor C8 is connected to one end of the resistor R9, and the other end of the resistor R9 is connected to the signal acquisition circuit; the output end of the operational amplifier is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the signal shaping circuit; and also includes a resistor R1, one end of the resistor R1 is connected between the resistor R6 and the inverting input end of the operational amplifier, and the other end is connected between the resistor R8 and the output end of the operational amplifier.

[0036] The positive power supply terminal of the operational amplifier is connected to the positive electrode of the power supply, and is respectively connected to one end of the capacitor C1 and the capacitor C2, and the other ends of the capacitor C1 and the capacitor C2 are grounded; the negative power supply terminal of the operational amplifier is connected to the negative electrode of the power supply, and is respectively connected to one end of the capacitor C9 and the capacitor C10, and the other ends of the capacitor C9 and the capacitor C10 are grounded; the two TRIM terminals of the operational amplifier are respectively connected to the two ends of the adjustable resistor R19, and the adjustment end of the adjustable resistor R19 is connected to the negative electrode of the power supply.

[0037] Since the duration of the leading edge of the first half cycle of the electromagnetic pulse is about 0.3 to 0.5 microseconds, it can be regarded as a signal with a frequency of f = 1Mhz, then:

[0038]

[0039] Where:

[0040] L——antenna length;

[0041] Ca——antenna capacitive reactance;

[0042] Cb——input capacitance;

[0043] EL——minimum electric field strength.

[0044] The trigger threshold required for electromagnetic pulse detection is no more than 15V / m. Take EL = 10V / m, Ca ≈ 5.6pF, Cb = 100pF, L = 0.5m, and calculate by formula (2):

[0045] Vin=0.5×5.6÷100×0.5×10=0.14(V)

[0046] Since the trigger threshold of the subsequent signal shaping circuit is 1V, the amplifier's gain K is required to be ≥8. Considering that a certain working margin should be left, K is taken to be ≥20. The gain is determined by resistors R6 and R1.

[0047] The signal shaping circuit is used to perform pulse shaping on the signal processed by the signal amplification circuit. Specifically, the signal shaping circuit adopts a complementary monostable circuit, which can be triggered by both positive and negative polarity signals, including an NPN transistor V3, and PNP transistors V1 and V2. The base of the transistor V3 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to the cathode of the diode D4, the anode of the diode D4 is connected to one end of the capacitor C7, the other end of the capacitor C7 is connected to the signal amplification circuit, the collector of the transistor V3 is connected to one end of the resistor R4 and the capacitor C6 respectively, the other end of the resistor R4 is connected to the positive electrode of the power supply, the other end of the capacitor C6 is connected to the base of the transistor V2 through the resistor R10, and the emitter of the transistor V3 is grounded;

[0048] The emitter of the transistor V2 is connected to the positive electrode of the +12V power supply, the collector is connected between the diode D4 and the resistor R13, and is grounded through the resistor R17;

[0049] The emitter of the transistor V1 is connected to the positive electrode of the +5V power supply, the base is connected between the resistor R4 and the collector of the transistor V3 through the resistor R7, the collector is connected to one end of the resistor R12 and the resistor R15 respectively, the other end of the resistor R12 is connected to the signal differential transmission circuit, and the other end of the resistor R15 is grounded;

[0050] It also includes resistors R2, R3 and R16, one end of the resistor R3 is connected to the positive electrode of the power supply, the other end is connected between the resistor R10 and the capacitor C6, and is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the signal amplification circuit through the capacitor C4; one end of the resistor R2 is connected to the positive electrode of the power supply, and the other end is connected between the capacitor C4 and the diode D1; one end of the resistor R16 is connected between the capacitor C7 and the diode D4, and the other end is grounded.

[0051] The signal differential transmission circuit is used to convert the signal difference after the signal shaping circuit into multiple outputs. Specifically, the signal differential transmission circuit includes a TD501D485 module. The main components of the module are a 485 chip and a peripheral protection circuit. The main function is to convert the TTL level signal of the serial port into two differential signal A and B outputs. Due to the use of differential transmission, it has a strong anti-interference ability, so the transmission distance is long. Its VCC pin is respectively connected to the positive pole of the power supply and grounded through a capacitor C11; its GND pin is grounded; its TXD pin is grounded through a resistor R21; its RXD pin is connected to the VCC pin, and is connected to the anode of a diode D7, and the cathode of the diode D7 is connected to the signal shaping circuit; its CON pin is connected to the RXD pin; its RGND pin is connected to the power ground; its two output pins are used to output the differential signal, and a resistor R20 is connected in parallel between the two output pins.

[0052] The present invention uses an external antenna to receive electromagnetic pulse signals, amplifies the signals through an amplifier, and then shapes them into useful square wave signals. Among them, a saturation circuit is used in the signal acquisition circuit, low-range and small signals are not processed, and high voltages are clamped and limited to ensure the safety of subsequent amplification circuits. The amplification circuit uses an inverting proportional amplification circuit, and its amplification factor matches the trigger threshold of the signal shaping circuit. The signal shaping circuit uses a complementary monostable circuit, which can be triggered by both positive and negative polarity signals. The pulse signal is output from the collector of the transistor V3 instead of the collector of the transistor V2, and can better utilize the trailing edge of the pulse signal with a longer duration to control the following transistor V1, and perform level conversion and pulse shaping through the transistor V1. The signal differential transmission circuit is differentially output into two paths through the TD501D485 module, has a strong anti-interference ability, and a long transmission distance. The circuit structure of the present invention is simple, the components used are few, the production cost is low, and the detection efficiency and accuracy are high.

[0053] Although the embodiments of the present invention have been shown and described, it is apparent to those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and basis of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Therefore, the embodiments of the present invention are merely illustrative examples of the present invention. The embodiments of the present invention do not constitute limitations on the present invention from any point of view.

Claims

1. An electromagnetic pulse detection circuit, characterized in that: It comprises a signal acquisition circuit, a signal amplification circuit, a signal shaping circuit and a signal differential transmission circuit which are connected in sequence; wherein the signal acquisition circuit is used to acquire an electromagnetic pulse signal and clamp and limit the high voltage signal generated by the electromagnetic pulse signal; the signal amplification circuit is used to amplify the signal processed by the signal acquisition circuit; the signal shaping circuit is used to perform pulse shaping on the signal processed by the signal amplification circuit; the signal differential transmission circuit is used to output the signal difference shaped by the signal shaping circuit into multiple channels; The signal shaping circuit adopts a complementary monostable circuit, including an NPN transistor V3, and PNP transistors V1 and V2. The base of the transistor V3 is connected to one end of a resistor R13, the other end of the resistor R13 is connected to the cathode of a diode D4, the anode of the diode D4 is connected to one end of a capacitor C7, the other end of the capacitor C7 is connected to a signal amplification circuit, the collector of the transistor V3 is connected to one end of a resistor R4 and a capacitor C6 respectively, the other end of the resistor R4 is connected to the positive electrode of a power supply, the other end of the capacitor C6 is connected to the base of the transistor V2 through a resistor R10, and the emitter of the transistor V3 is grounded; The emitter of the transistor V2 is connected to the positive electrode of the power supply, the collector is connected between the diode D4 and the resistor R13, and is grounded through the resistor R17; The emitter of the transistor V1 is connected to the positive electrode of the power supply, the base is connected between the resistor R4 and the collector of the transistor V3 through the resistor R7, the collector is connected to one end of the resistor R12 and the resistor R15 respectively, the other end of the resistor R12 is connected to the signal differential transmission circuit, and the other end of the resistor R15 is grounded; It also includes resistors R2, R3 and R16, one end of the resistor R3 is connected to the positive electrode of the power supply, the other end is connected between the resistor R10 and the capacitor C6, and is connected to the anode of the diode D1, and the cathode of the diode D1 is connected to the signal amplification circuit through the capacitor C4; one end of the resistor R2 is connected to the positive electrode of the power supply, and the other end is connected between the capacitor C4 and the diode D1; one end of the resistor R16 is connected between the capacitor C7 and the diode D4, and the other end is grounded.

2. An electromagnetic pulse detection circuit according to claim 1, characterized in that: The signal acquisition circuit adopts a saturation circuit, including an external antenna, the signal output end of the antenna is connected to one end of the resistor R5, the other end of the resistor R5 is connected to one end of the capacitor C5, and the other end of the capacitor C5 is connected to the signal amplification circuit; it also includes multiple diodes, wherein the anode of the diode D2 and the cathode of the diode D3 are connected between the resistor R5 and the capacitor C5, the anode of the diode D5 is connected to the cathode of the diode D2, the cathode of the diode D6 is connected to the anode of the diode D3, and the cathode of the diode D5 and the anode of the diode D6 are connected and grounded.

3. An electromagnetic pulse detection circuit according to claim 2, characterized in that: The antenna is a whip antenna with a diameter of 5 mm and a length of 0.5 m, and the antenna capacitive reactance Ca is: Where Ca is the antenna capacitive reactance; L is the antenna length; d is the antenna diameter; K is the correction coefficient, which ranges from 0.133 to 0.

44.

4. An electromagnetic pulse detection circuit according to claim 2, characterized in that: The forward conduction voltage drop of the diodes D2, D3, D5, and D6 is 0.7V.

5. The electromagnetic pulse detection circuit according to claim 1, characterized in that: The signal amplification circuit adopts an inverting proportional amplification circuit, including an operational amplifier, the inverting input terminal of the operational amplifier is connected to one end of the resistor R6, and the other end of the resistor R6 is connected to the signal acquisition circuit; the non-inverting input terminal of the operational amplifier is connected to one end of the resistor R14, the other end of the resistor R14 is grounded and connected to one end of the capacitor C8, the other end of the capacitor C8 is connected to one end of the resistor R9, and the other end of the resistor R9 is connected to the signal acquisition circuit; the output terminal of the operational amplifier is connected to one end of the resistor R8, and the other end of the resistor R8 is connected to the signal shaping circuit; and also includes a resistor R1, one end of the resistor R1 is connected between the resistor R6 and the inverting input terminal of the operational amplifier, and the other end is connected between the resistor R8 and the output terminal of the operational amplifier.

6. An electromagnetic pulse detection circuit according to claim 5, characterized in that: The positive power supply terminal of the operational amplifier is connected to the positive electrode of the power supply, and is respectively connected to one end of the capacitor C1 and the capacitor C2, and the other ends of the capacitor C1 and the capacitor C2 are grounded; the negative power supply terminal of the operational amplifier is connected to the negative electrode of the power supply, and is respectively connected to one end of the capacitor C9 and the capacitor C10, and the other ends of the capacitor C9 and the capacitor C10 are grounded; the two TRIM terminals of the operational amplifier are respectively connected to the two ends of the adjustable resistor R19, and the adjustment end of the adjustable resistor R19 is connected to the negative electrode of the power supply.

7. The electromagnetic pulse detection circuit according to claim 1, characterized in that: The signal differential transmission circuit includes a TD501D485 module, whose VCC pin is respectively connected to the positive electrode of the power supply and grounded through a capacitor C11; its GND pin is grounded; its TXD pin is grounded through a resistor R21; its RXD pin is connected to the VCC pin and to the anode of a diode D7, and the cathode of the diode D7 is connected to the signal shaping circuit; its CON pin is connected to the RXD pin; its RGND pin is connected to the power supply ground; its two output pins are used to output differential signals, and a resistor R20 is connected in parallel between the two output pins.

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