Radio frequency electromagnetic field signal frequency test circuit and method

Abstract

The invention discloses a radio frequency electromagnetic field signal frequency test circuit and method. The radio frequency electromagnetic field signal frequency test circuit comprises an amplifying and shaping circuit, a differentiating circuit, a high-speed electronic switch, an RC charging circuit, an integrating circuit and an isolation output circuit, and the amplifying and shaping circuit is used for shaping a received radio frequency electromagnetic field signal into an approximate square wave signal; the differentiating circuit is used for converting the square wave signal into a narrow pulse signal; the high-speed electronic switch performs on-off control through narrow pulse signals and is connected with the RC charging circuit to control the RC charging circuit to output sawtooth waves; the integrating circuit is used for integrating, smoothing and converting the sawtooth waves and outputting approximate direct-current voltage; the isolation output circuit is used for outputting the approximate direct-current voltage, the approximate direct-current voltage is in negative correlation with the frequency of the radio frequency electromagnetic field signal, and the frequency of the radio frequency electromagnetic field signal is determined according to the approximate direct-current voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of broadband high-frequency electromagnetic wave frequency measurement, and more specifically, to a radio frequency electromagnetic field signal frequency testing circuit and method. Background Art

[0002] In the environment of strong electromagnetic interference, the metering performance of smart electric energy meters will be seriously affected, and even the whole machine will not work or crash. Therefore, in some occasions where serious electromagnetic interference may occur, electric energy meters with electromagnetic interference monitoring function will be used to record relevant information when the electric energy meter is subjected to electromagnetic interference, which is used to provide auxiliary evidence for disputes caused by abnormal measurement. The electromagnetic interference monitoring function is realized by the electromagnetic interference monitoring module, which mainly has the ability to judge the type of electromagnetic interference, including constant magnetic field, power frequency magnetic field, pulse magnetic field, radio frequency electromagnetic field, etc. The impact of radio frequency electromagnetic field interference on smart electric energy meters is related to the frequency and amplitude of radio frequency electromagnetic field. The amplitude detection of radio frequency electromagnetic field can be composed of receiving antenna, high frequency detector, filter, analog-to-digital converter, etc., which is relatively easy to implement; while the frequency detection of radio frequency electromagnetic field is difficult to implement due to cost, power consumption and other restrictions. Therefore, the general electromagnetic interference monitoring module only has the amplitude detection function of radio frequency electromagnetic field, but in fact, the frequency of radio frequency electromagnetic field is different, and the amplitude threshold that can cause abnormal operation of electric energy meter varies greatly. Therefore, the electromagnetic interference monitoring module that only has the amplitude detection function of radio frequency electromagnetic field lacks important frequency information in its data record. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a radio frequency electromagnetic field signal frequency testing circuit and method.

[0004] According to one aspect of the present invention, a radio frequency electromagnetic field signal frequency test circuit is provided, comprising: an amplification and shaping circuit, a differential circuit, a high-speed electronic switch, an RC charging circuit, an integration circuit, and an isolation output circuit, wherein

[0005] The shaping amplifier circuit is used for shaping the received radio frequency electromagnetic field signal into an approximate square wave signal;

[0006] Differentiator circuit is used to convert square wave signal into narrow pulse signal;

[0007] The high-speed electronic switch is controlled by a narrow pulse signal and is connected to the RC charging circuit to control the RC charging circuit to output a sawtooth wave;

[0008] The integration circuit is used to integrate, smooth and transform the sawtooth wave and output an approximate DC voltage;

[0009] The isolated output circuit is used to output an approximate DC voltage, wherein the approximate DC voltage is negatively correlated with the frequency of the radio frequency electromagnetic field signal, and the frequency of the radio frequency electromagnetic field signal is determined according to the approximate DC voltage.

[0010] Optionally, the radio frequency electromagnetic field signal frequency test circuit further includes: a limiting circuit connected to the high-speed electronic switch, and used for limiting the amplitude of a negative pulse signal in the narrow pulse signal.

[0011] Optionally, the operation of controlling the RC charging circuit to output a sawtooth wave includes: when a narrow pulse signal controls a high-speed electronic switch to turn on, the charge on the capacitor C of the RC charging circuit is quickly discharged to the ground; when the high-speed electronic switch is turned off, the RC charging circuit is charged through the resistor R, and a sawtooth wave on the output capacitor C is output.

[0012] Optionally, the high-speed electronic switch is a high-speed electronic switch composed of a radio frequency triode.

[0013] Optionally, the isolated output circuit is a follower isolation composed of an operational amplifier.

[0014] According to another aspect of the present invention, a method for testing the frequency of a radio frequency electromagnetic field signal is provided, comprising:

[0015] The received radio frequency electromagnetic field signal is shaped into an approximate square wave signal through an amplifying and shaping circuit;

[0016] The square wave signal is converted into a narrow pulse signal through a differential circuit;

[0017] The high-speed electronic switch is controlled by a narrow pulse signal, so that the RC charging circuit connected to the high-speed electronic switch outputs a sawtooth wave;

[0018] The sawtooth wave is integrated and smoothly transformed through an integration circuit to output an approximate DC voltage;

[0019] The frequency of the RF electromagnetic field signal is determined based on the approximate DC voltage.

[0020] Therefore, the present invention provides a frequency testing method for radio frequency electromagnetic field signals applied to electromagnetic interference monitoring modules of smart electric energy meters, including an amplifying and shaping circuit, a differential circuit, a limiting circuit, a high-speed electronic switch, an RC charging circuit, an integrating circuit, and an isolated output circuit. The present invention uses common low-cost components and common operational amplifiers to implement frequency testing of radio frequency signals. The problem of frequency detection of radio frequency interference sources by electromagnetic interference monitoring modules of smart electric energy meters is solved, and the power consumption and cost of detection circuits are effectively reduced, which is more conducive to the promotion and application of electromagnetic interference monitoring modules and improves the application effect of electromagnetic interference monitoring modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0022] Figure 1 It is a schematic diagram of a radio frequency electromagnetic field signal frequency test circuit provided by the first aspect of an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the structure of a broadband high-frequency electromagnetic wave frequency measurement circuit provided by the first aspect of an embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of key waveforms of a wide-band high-frequency electromagnetic wave frequency measurement circuit provided by the first aspect of an embodiment of the present invention;

[0025] Figure 4 It is a flow chart of a method for testing the frequency of a radio frequency electromagnetic field signal provided in the second aspect of an embodiment of the present invention. DETAILED DESCRIPTION

[0026] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0027] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0028] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0029] It should also be understood that, in the embodiments of the present invention, “plurality” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0030] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0031] In addition, the term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0032] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0033] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0034] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0035] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0036] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0037] Exemplary Methods

[0038] Figure 1 FIG. 1 is a schematic diagram of a radio frequency electromagnetic field signal frequency test circuit provided by an exemplary embodiment of the present invention. Figure 1 As shown, the radio frequency electromagnetic field signal frequency test circuit includes: an amplification and shaping circuit, a differential circuit, a high-speed electronic switch, an RC charging circuit, an integration circuit, and an isolation output circuit, wherein

[0039] The shaping amplifier circuit is used for shaping the received radio frequency electromagnetic field signal into an approximate square wave signal;

[0040] Differentiator circuit is used to convert square wave signal into narrow pulse signal;

[0041] The high-speed electronic switch is controlled by a narrow pulse signal and is connected to the RC charging circuit to control the RC charging circuit to output a sawtooth wave;

[0042] The integration circuit is used to integrate, smooth and transform the sawtooth wave and output an approximate DC voltage;

[0043] The isolated output circuit is used to output an approximate DC voltage, wherein the approximate DC voltage is negatively correlated with the frequency of the radio frequency electromagnetic field signal, and the frequency of the radio frequency electromagnetic field signal is determined according to the approximate DC voltage.

[0044] Specifically, the purpose of the present invention is to provide a frequency testing method for radio frequency electromagnetic field signals applied to electromagnetic interference monitoring modules of smart electric energy meters, including an amplifying and shaping circuit, a differential circuit, a limiting circuit, a high-speed electronic switch, an RC charging circuit, an integrating circuit, and an isolated output circuit. Through this method, the frequency test of radio frequency signals is realized using ordinary low-cost components and ordinary operational amplifiers. Figure 1 As shown, the RF electromagnetic field signal is transmitted to the signal pre-amplifier circuit through the receiving antenna, and the RF signal is amplified and shaped into an approximate square wave. The square wave signal is transformed into a narrow pulse signal through the differential circuit. The narrow pulse signal controls a high-speed switch. The high-speed switch is connected to an RC charging circuit. When the switch is turned on, the charge on the capacitor C can be quickly discharged to the ground. When the switch is turned off, the capacitor C is charged through the resistor R. When there is no RF signal input, the voltage on the capacitor C will charge the resistor R to the power supply VCC. When there is an RF signal input, the capacitor C is periodically discharged through the high-speed electronic switch, forming a sawtooth wave on the capacitor C. The peak voltage of the sawtooth wave depends on the frequency of the RF signal. The higher the frequency, the lower the peak voltage. The sawtooth wave on the capacitor C is integrated and smoothed by the two-stage integration circuit and transformed into an approximate DC voltage. Finally, it is driven and output by the isolation follower circuit. The output voltage value is negatively correlated with the input RF signal frequency value. The higher the frequency, the lower the voltage. Conversely, the lower the frequency, the higher the voltage.

[0045] Further, Figure 2 The invention discloses a radio frequency electromagnetic field signal frequency test circuit diagram designed according to the method proposed in the present invention. The radio frequency electromagnetic field signal is inputted by the SIN terminal, coupled to the emitter of the amplifier U1 through the capacitor C1, and the amplified and shaped signal is outputted by the C pole of U1. The signal outputted by the C pole forms a narrow pulse signal on the resistor R5 through the differential capacitor C3, and the narrow pulse signal is connected to the high-speed electronic switch tube U3 through R6. Under the control of the positive pulse, the C pole and the E pole of the electronic switch tube U3 are forwardly conducted. The function of U2 is to limit the negative pulse signal to avoid damaging U3 when the negative pulse is too high. The C pole of U3 is connected to the capacitor C5 of the RC charging circuit. When the switch is turned on, the charge on the capacitor C5 can be quickly discharged to the ground. When the switch is turned off, the capacitor C5 is charged through the resistor R7. The signal on the capacitor C5 is smoothed and filtered by a two-stage integration circuit composed of R8, C6, R9, and C7, and then output after isolation by the operational amplifier U4. SOUT is the signal output terminal.

[0046] Further, Figure 3 It is a signal waveform schematic diagram of key points of the radio frequency electromagnetic field signal frequency test circuit designed according to the present invention. Figure 3 The A, B, C, D, E, and F waveforms in the figure are respectively Figure 2The test points A, B, C, D, E, and F are located in the middle. Waveform A is the RF input sinusoidal signal; waveform B is the square wave signal after amplification and shaping; waveform C is the narrow pulse signal after the differential capacitor; waveform D is the waveform on the capacitor of the RC charging circuit; waveform E is the signal waveform on the integrating capacitor after the first-level integration; waveform F is the signal waveform on the integrating capacitor after the second-level integration.

[0047] Therefore, the present invention realizes the frequency test of radio frequency electromagnetic field signal through an amplifying and shaping circuit, a differential circuit, a limiting circuit, a high-speed electronic switch, an RC charging circuit, an integration circuit, and an isolation output circuit. By using ordinary discrete components, the cost and power consumption of the test circuit are effectively reduced, which is more conducive to the promotion and application of the electromagnetic interference monitoring module and improves the application effect of the electromagnetic interference monitoring module.

[0048] According to the second aspect of the embodiment of the present application, Figure 4 The following is a flow chart of a method for testing the frequency of a radio frequency electromagnetic field signal provided by an exemplary embodiment of the present invention. Figure 4 As shown, the method 400 includes:

[0049] Step 401: shaping the received radio frequency electromagnetic field signal into an approximate square wave signal through an amplifying and shaping circuit;

[0050] Step 402: transforming the square wave signal into a narrow pulse signal through a differential circuit;

[0051] Step 403: Control the high-speed electronic switch by a narrow pulse signal, so that the RC charging circuit connected to the high-speed electronic switch outputs a sawtooth wave;

[0052] Step 404: integrating and smoothly transforming the sawtooth wave through an integration circuit to output an approximate DC voltage;

[0053] Step 405: Determine the frequency of the radio frequency electromagnetic field signal according to the approximate DC voltage.

[0054] Specifically, the specific content of the radio frequency electromagnetic field signal frequency testing method proposed in the present invention has been described in the first aspect of this embodiment and will not be repeated here.

[0055] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A radio frequency electromagnetic field signal frequency test circuit, characterized in that: include: Amplification and shaping circuit, differential circuit, high-speed electronic switch, RC charging circuit, integration circuit, isolation output circuit, among which The shaping amplifier circuit is used to shape the received radio frequency electromagnetic field signal into an approximate square wave signal; The differential circuit is used to transform the square wave signal into a narrow pulse signal; The high-speed electronic switch is switched on and off by the narrow pulse signal and is connected to the RC charging circuit to control the RC charging circuit to output a sawtooth wave; The integration circuit is used to integrate, smooth and transform the sawtooth wave to output an approximate DC voltage; The isolated output circuit is used to output the approximate DC voltage, wherein the approximate DC voltage is negatively correlated with the frequency of the radio frequency electromagnetic field signal, and the frequency of the radio frequency electromagnetic field signal is determined according to the approximate DC voltage.

2. The radio frequency electromagnetic field signal frequency test circuit according to claim 1, characterized in that: Also includes: The amplitude limiting circuit is connected to the high-speed electronic switch and is used for limiting the amplitude of the negative pulse signal in the narrow pulse signal.

3. The radio frequency electromagnetic field signal frequency test circuit according to claim 1, characterized in that: The operation of controlling the RC charging circuit to output a sawtooth wave includes: when the narrow pulse signal controls the high-speed electronic switch to be turned on, the charge on the capacitor C of the RC charging circuit is quickly discharged to the ground; when the high-speed electronic switch is turned off, the RC charging circuit is charged through the resistor R and outputs the sawtooth wave on the capacitor C.

4. The radio frequency electromagnetic field signal frequency test circuit according to claim 1, characterized in that: The high-speed electronic switch is a high-speed electronic switch composed of a radio frequency triode.

5. The radio frequency electromagnetic field signal frequency test circuit according to claim 1, characterized in that: The isolated output circuit is a follower isolation composed of an operational amplifier.

6. The radio frequency electromagnetic field signal frequency testing method implemented by the radio frequency electromagnetic field signal frequency testing circuit according to any one of claims 1 to 5, characterized in that: include: The received radio frequency electromagnetic field signal is shaped into an approximate square wave signal through an amplifying and shaping circuit; Converting the square wave signal into a narrow pulse signal through a differential circuit; Controlling a high-speed electronic switch by means of the narrow pulse signal so that an RC charging circuit connected to the high-speed electronic switch outputs a sawtooth wave; The sawtooth wave is integrated and smoothly transformed by an integration circuit to output an approximate DC voltage; The frequency of the radio frequency electromagnetic field signal is determined according to the approximate DC voltage.

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