An accuracy verification device for current method conducted disturbance measurement system

Abstract

The present invention discloses an accuracy verification device for a current method conducted disturbance measurement system, which is characterized by comprising a trapezoidal pulse generation module, a coaxial radio frequency connector 1, a coaxial radio frequency connector 2, a transmission conductor 1, a transmission conductor 2, a coaxial radio frequency load and an insulating support washer. The present invention outputs a trapezoidal pulse with a repetition period less than the minimum measurement dwell time of the current method conducted disturbance measurement system and a repetition frequency less than the minimum measurement intermediate frequency bandwidth of the current method conducted disturbance measurement system through the trapezoidal pulse generation module, and transmits it to two transmission conductors and a coaxial radio frequency load through a coaxial radio frequency cable and a coaxial radio frequency connector to form a fixed structure transmission line. Finally, the current loop clamped on the transmission conductor can measure a radio frequency current spectrum with a relatively flat and continuous amplitude in the full frequency band, and compare it with the theoretical calculated value, so as to realize a full-band and rapid accuracy verification of the current method conducted disturbance measurement system.

Description

Technical Field

[0001] The invention relates to an accuracy checking device for a current method conducted disturbance measurement system, belonging to the technical field of electromagnetic compatibility testing. Background Art

[0002] The purpose of electromagnetic compatibility testing is to examine the ability of systems and equipment to work in coordination with external systems, equipment or electromagnetic environments without interfering with each other. The current method conducted disturbance measurement test is one of the key items in electromagnetic compatibility testing. It uses a current loop clamped on the wiring harness of the device under test (DUT) to electromagnetically sense the electromagnetic disturbance signal level of the DUT wiring harness to the outside world.

[0003] According to the relevant requirements of the national standard GB / T 18655 (corresponding to the international standard CISPR 25), the frequency range of the current method conducted disturbance measurement is 150kHz~108MHz, which contains a wealth of interference signals such as radio and television signals. The current loop in the current method conducted disturbance measurement system measures the electromagnetic disturbance signal of the DUT harness to the outside world through spatial electromagnetic induction, which is very susceptible to interference signals. Therefore, in the current method conducted disturbance measurement test, the DUT system and the current loop and other measurement parts need to be placed in the electromagnetic shielding room or darkroom, and the data reading parts such as the receiver and the control computer are usually placed outside the electromagnetic shielding room or darkroom; the measurement part and the data reading part are connected by a coaxial RF cable and at least one RF interface board, which makes the current method conducted disturbance measurement system complex. In the current method conducted disturbance measurement system, the degradation of the RF performance of any interface or coaxial RF cable, the change of the RF characteristics of the current loop itself, and the change of the gain of the easily damaged preamplifier will affect the accuracy of the measurement data. It can be seen that it is essential to periodically check the accuracy of the current method conducted disturbance measurement system.

[0004] At present, the separable modules such as current loop, coaxial RF cable, receiver and preamplifier in the current method conducted disturbance measurement system are periodically calibrated separately, but there is no mature verification method or device for the complete measurement system formed by the combination and connection of each module. This is because under the existing technical conditions, usually only two types of methods can be used for accuracy verification, and both methods have great limitations, poor operability and low utilization rate. Specifically, first, a vector network analyzer is used to verify the current method conducted interference measurement system. Since the measurement part and data reading part of the system are respectively placed inside and outside the electromagnetic shielding room or darkroom, the system verification using a vector network analyzer requires multiple high-performance, long-length RF coaxial RF cables to connect the system ports inside and outside the electromagnetic shielding room or darkroom, and it is necessary to transport the vector network analyzer, calibration fixture and other equipment to the test site. The process is complicated, time-consuming, and has high requirements on equipment conditions; second, a point frequency signal source is used to verify the current method conducted interference measurement system. This method uses a point frequency signal source and a calibration fixture to generate a point frequency signal of a certain amplitude, and then the system measures the amplitude of the point frequency signal for verification. Although the operation is relatively simple, it can only realize the verification of the system at a limited frequency point, and the time required increases exponentially with the increase in the number of frequency points. Therefore, this method is time-consuming and it is difficult to realize the system accuracy verification of the entire frequency band. Summary of the invention

[0005] The purpose of the present invention is to provide a current method conducted disturbance measurement system accuracy verification device with higher accuracy and convenience, so as to realize full-band and rapid verification of the current method conducted disturbance measurement system.

[0006] In order to achieve the above-mentioned purpose, the technical solution of the present invention is to provide an accuracy verification device for a current method conducted disturbance measurement system, characterized in that: it includes a trapezoidal pulse generating module, a coaxial RF connector 1, a coaxial RF connector 2, a transmission conductor 1, a transmission conductor 2, a coaxial RF load and an insulating support washer, the trapezoidal pulse generating module is used to output a trapezoidal pulse with a duration, a rise time and a fall time in the nanosecond level, and form a broadband spectrum with a wide frequency range, a flat amplitude and a continuous frequency in the frequency domain, so as to provide a reference signal for the full-band verification of the current method conducted disturbance measurement system;

[0007] One end of the coaxial RF connector 1 is connected to the output end of the trapezoidal pulse generating module, and the other end is connected to one end of the coaxial RF connector 2 through the transmission conductor 1 and the transmission conductor 2 respectively, and the other end of the coaxial RF connector 2 is connected to the coaxial RF load;

[0008] The two ends of the transmission conductor 1 are respectively connected to the core conductor of the coaxial RF connector 1 and the core conductor of the coaxial RF connector 2, and the two ends of the transmission conductor 2 are respectively connected to the outer conductor of the coaxial RF connector 1 and the outer conductor of the coaxial RF connector 2;

[0009] The insulating support washer is sleeved on the transmission conductor one, and a current loop of a current method conducted disturbance measurement system is sleeved on the insulating support washer for measuring the radio frequency current on the transmission conductor one.

[0010] Preferably, the duration of the trapezoidal pulse is 8 ns or less, and the rise time and fall time of the trapezoidal pulse are both 5 ns or less.

[0011] Preferably, the repetition period of the trapezoidal pulse is less than or equal to the minimum measurement dwell time of the current method conducted disturbance measurement system.

[0012] Preferably, the repetition frequency of the trapezoidal pulse is less than the minimum measurement intermediate frequency bandwidth of the current method conducted disturbance measurement system.

[0013] Preferably, it also includes a vector network analyzer, which is used to measure the transmission loss value of the transmission conductor through the current loop and compensate the measured data to evaluate the difference between the actual measured data and the theoretical calculated data.

[0014] Preferably, the transmission conductor 1 is sleeved on the central axis of the current ring through an insulating support washer.

[0015] Preferably, the coaxial radio frequency load exhibits 50Ω in the full frequency band of the current method conducted disturbance measurement system.

[0016] Preferably, the coaxial RF connector 1 is connected to the output end of the trapezoidal pulse generating module through a coaxial RF cable.

[0017] Preferably, the dielectric constant of the insulating support gasket is less than 1.4.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention uses a trapezoidal pulse generation module to output a trapezoidal pulse with a duration, rise time and fall time of nanoseconds, a repetition period less than the minimum measurement dwell time of the current method conducted disturbance measurement system, and a repetition frequency less than the minimum measurement intermediate frequency bandwidth of the current method conducted disturbance measurement system, and transmits it to two transmission conductors and a coaxial RF load through a coaxial RF cable and a coaxial RF connector to form a fixed structure transmission line. The current loop of the current method conducted disturbance measurement system is clamped on the transmission conductor wrapped by an insulating support washer to measure the RF current passing through the transmission conductor. Finally, the current loop can measure a relatively flat and continuous RF current spectrum with a full-band amplitude, and compare it with the theoretical calculated value, so as to realize a full-band and rapid accuracy verification of the current method conducted disturbance measurement system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a device for checking the accuracy of a current method conducted disturbance measurement system according to the present invention;

[0021] Figure 2 It is a waveform diagram of a trapezoidal pulse;

[0022] Figure 3 This is an example diagram of verification data of an accuracy verification device for a current method conducted disturbance measurement system according to the present invention. DETAILED DESCRIPTION

[0023] In order to make the present invention more clearly understood, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0024] See also Figure 1 The present invention provides an accuracy verification device for a current method conducted disturbance measurement system, comprising a trapezoidal pulse generating module 1, a coaxial radio frequency cable 2, two coaxial radio frequency connectors (coaxial radio frequency connector one 3 and coaxial radio frequency connector two 6), two transmission conductors (transmission conductor one 4 and transmission conductor two 5), a coaxial radio frequency load 7, an insulating support washer 8 and a vector network analyzer.

[0025] like Figure 2 As shown, the trapezoidal pulse generating module 1 outputs a trapezoidal pulse with a duration (τ0+τ / 2), a rise time (τ-τ0) / 2 and a fall time (τ-τ0) / 2, all of which are in the nanosecond (ns) level. The purpose is to form a broadband spectrum with a wide frequency range, a relatively flat amplitude and continuity in the frequency domain, so as to provide a reference signal for the full-frequency band verification of the current method conducted disturbance measurement system.

[0026] The duration of the trapezoidal pulse (τ0+τ / 2) is 8ns or less, and the (τ-τ0) / 2 and fall time (τ-τ0) / 2 of the trapezoidal pulse are both 5ns or less, thereby forming a relatively flat and continuous broadband spectrum in the full frequency band of the current method conducted disturbance measurement system.

[0027] The repetition period (T) of the trapezoidal pulse should be less than or equal to the minimum measurement dwell time of the current method conducted disturbance measurement system, that is, ≤5ms, to avoid the amplitude collapse of the broadband spectrum.

[0028] The repetition frequency (1 / T) of the trapezoidal pulse should be less than the minimum measurement intermediate frequency bandwidth of the current method conducted disturbance measurement system to maintain the broadband characteristics of the pulse signal as a single pulse at the measurement frequency.

[0029] The coaxial RF cable 2 connects the output end of the trapezoidal pulse generating module 1 and the coaxial RF connector 3, and is used to transmit the trapezoidal pulse signal to the coaxial RF connector 3 with low loss.

[0030] The transmission conductor 1 4 and the transmission conductor 2 5 are hard-connected fixed structures, wherein the transmission conductor 1 4 connects the core conductors of the coaxial RF connector 1 3 and the coaxial RF connector 2 6, and the transmission conductor 2 5 connects the outer conductors of the coaxial RF connector 1 3 and the coaxial RF connector 2 6, thereby forming a RF transmission line. The current loop 9 of the current method conducted interference measurement system is clamped on the transmission conductor 4 to measure the RF current passing through the transmission conductor.

[0031] The transmission conductor 4 clamped by the current loop 9 for measuring the transmission RF current should be wrapped with an insulating support washer 8 with a low dielectric constant (<1.4) to place the transmission conductor 4 on the central axis of the current loop to improve the accuracy and consistency of the measurement results.

[0032] For a fixed structure where two transmission conductors are hard-connected, a vector network analyzer should be used to measure the transmission loss value of the transmission conductor 4 through the current loop 9, and the measured data should be compensated to facilitate the evaluation of the difference between the actual measurement data and the theoretical calculation data.

[0033] The coaxial RF load 7 is connected to the coaxial RF connector 2 6, and its purpose is to provide a fixed impedance within a required frequency range for the RF transmission line formed by the two transmission conductors.

[0034] The coaxial RF load 7 presents approximately 50Ω in the full frequency band of the current method conducted disturbance measurement system.

[0035] like Figure 3 As shown, the black solid line is the theoretical calculation data, and the +6dB and -6dB of the theoretical calculation value are taken as the upper limit and lower limit of the accuracy of the current method conducted disturbance measurement system. Figure 3The black curve in the middle is the measured data of the accuracy verification device for the current method conducted disturbance measurement system according to the present invention. It can be seen that the measured data is well consistent with the theoretical calculation data and meets the judgment standard of ±6dB, that is, the accuracy verification result of the current method conducted disturbance measurement system meets the requirements;

[0036] Depending on the actual situation of the measurement system, the judgment standard based on the theoretical calculated value can be adjusted, for example, to ±3dB.

Claims

1. An accuracy verification device for a current method conducted disturbance measurement system, characterized in that: The invention comprises a trapezoidal pulse generating module (1), a coaxial radio frequency connector 1 (3), a coaxial radio frequency connector 2 (6), a transmission conductor 1 (4), a transmission conductor 2 (5), a coaxial radio frequency load (7) and an insulating support washer (8), wherein the trapezoidal pulse generating module (1) is used to output a trapezoidal pulse with a duration, a rise time and a fall time all in the nanosecond level, and to form a broadband spectrum with a wide frequency range, a flat amplitude and a continuous frequency in the frequency domain, so as to provide a reference signal for the full-band verification of a current method conducted disturbance measurement system; One end of the coaxial RF connector 1 (3) is connected to the output end of the trapezoidal pulse generating module (1), and the other end is connected to one end of the coaxial RF connector 2 (6) through the transmission conductor 1 (4) and the transmission conductor 2 (5), respectively; the other end of the coaxial RF connector 2 (6) is connected to the coaxial RF load (7); The two ends of the transmission conductor one (4) are respectively connected to the core conductor of the coaxial radio frequency connector one (3) and the core conductor of the coaxial radio frequency connector two (6), and the two ends of the transmission conductor two (5) are respectively connected to the peripheral conductor of the coaxial radio frequency connector one (3) and the peripheral conductor of the coaxial radio frequency connector two (6); The insulating support washer (8) is sleeved on the transmission conductor one (4), and a current loop (9) of a current method conducted disturbance measurement system is sleeved on the insulating support washer (8) for measuring radio frequency current on the transmission conductor one (4).

2. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The duration of the trapezoidal pulse is 8 ns or less, and the rising time and falling time of the trapezoidal pulse are both 5 ns or less.

3. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The repetition period of the trapezoidal pulse is less than or equal to the minimum measurement dwell time of the current method conducted disturbance measurement system.

4. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The repetition frequency of the trapezoidal pulse is less than the minimum measurement intermediate frequency bandwidth of the current method conducted disturbance measurement system.

5. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: It also includes a vector network analyzer, which is used to measure the transmission loss value of the transmission conductor (4) passing through the current loop (9) and compensate the measured data to evaluate the difference between the actual measured data and the theoretical calculated data.

6. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The transmission conductor 1 (4) is sleeved on the central axis of the current ring (9) through an insulating support washer (8).

7. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The coaxial radio frequency load (7) exhibits 50Ω in the full frequency band of the current method conducted disturbance measurement system.

8. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The coaxial radio frequency connector 1 (3) is connected to the output end of the trapezoidal pulse generating module (1) via a coaxial radio frequency cable (2).

9. The accuracy checking device for the current method conducted disturbance measurement system according to claim 1, characterized in that: The dielectric constant of the insulating support washer (8) is less than 1.4.

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