Testing system and method for radiation emission of electromagnetic signals in weak space

Abstract

The invention discloses a test system and method for radiation and emission of electromagnetic signals in a weak space, and relates to the field of electromagnetic compatibility testing, and the system comprises a computer, a real-time spectrum analyzer, a low-noise amplifier, a high-gain directional antenna combination, an antenna frame, a radio frequency cable, a general purpose interface bus (GPIB), a network cable, and a semi-anechoic chamber. The test system can test background noise and electromagnetic signals under the background noise by using the test system consisting of a real-time spectrum analyzer, a low-noise amplifier, a high-gain directional antenna combination, a radio frequency cable and the like on the premise of no stray interference in a darkroom; through a background noise separation method, an accurate weak electromagnetic signal generated by the tested equipment is obtained.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic compatibility testing, and in particular to a testing system and method for weak space radiation emission electromagnetic signals. Background Art

[0002] In the fields of radio astronomy observation and medical instrument testing, the amplitude of the electromagnetic signal emitted by space radiation that needs to be tested is very small. Sometimes the energy of the weak signal needs to be tested and is even close to the background noise. In this way, the background noise itself will have a significant impact on these weak signals. At present, there is no standard method for testing weak electromagnetic signals emitted by space radiation, and conventional electromagnetic compatibility test methods cannot accurately test these weak electromagnetic signals. Therefore, R&D and testing personnel are in urgent need of a system and method for accurately testing weak electromagnetic signals emitted by radiation that can solve the influence of noise.

[0003] As mentioned above, the energy of the radiated emission signal in traditional electromagnetic compatibility testing is much higher than the background noise and will not be affected by the background noise. However, for the radiated emission signal with an amplitude lower than -50dBμV / m, traditional testing is difficult to meet the test requirements. It is necessary to analyze the impact of noise on the test and design a new test system and method. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a testing system and method for weak space radiation emission electromagnetic signals. The present invention can remove the influence of background noise on weak signals and measure accurate weak radiation emission electromagnetic signals.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A test system for weak space radiation emission electromagnetic signals, used for measuring weak space radiation emission electromagnetic signals of a device under test, comprising a computer, a real-time spectrum analyzer, a low noise amplifier, a high-gain directional antenna combination, an antenna stand, a radio frequency cable, a general GPIB interface bus, a network cable, and a semi-anechoic chamber; wherein:

[0007] The high-gain directional antenna assembly, antenna stand, and low-noise amplifier are arranged in the semi-anechoic chamber;

[0008] The computer, the general GPIB interface bus, the network cable, and the real-time spectrum analyzer are arranged outside the semi-anechoic chamber;

[0009] The radio frequency cable is divided into two parts, one part is arranged inside the semi-anechoic chamber, and the other part is arranged outside the semi-anechoic chamber, and connected by a through-wall radio frequency connector integrated in the semi-anechoic chamber;

[0010] The semi-anechoic chamber is used to shield external radiation and simulate an open test site; the device under test is located in the semi-anechoic chamber;

[0011] The high-gain directional antenna assembly is fixed on the antenna frame and connected to the low-noise amplifier;

[0012] The low noise amplifier is connected to the real-time spectrum analyzer via the radio frequency cable;

[0013] The computer is connected to the real-time spectrum analyzer via a general GPIB interface bus and a network cable;

[0014] The weak space radiation emission electromagnetic signal of the device under test is received by the high-gain directional antenna combination, amplified by the low-noise amplifier and transmitted to the real-time spectrum analyzer. The computer controls the real-time spectrum analyzer through the general GPIB interface bus to test it. The test raw data file of the real-time spectrum analyzer is transmitted to the computer through the network cable for storage.

[0015] Furthermore, the real-time spectrum analyzer has a time domain test function, and the file name suffix of the test raw data file generated by the time domain test is tar.

[0016] A method for testing electromagnetic signals emitted by weak space radiation is implemented based on a test system for electromagnetic signals emitted by weak space radiation as described in any one of the above items, and specifically comprises the following steps:

[0017] Step 1: Turn off the device under test, control the real-time spectrum analyzer in the time domain working mode, test the background noise of the space where the device under test is located, and convert the test raw data corresponding to the background noise into x noise (t) stored in a computer;

[0018] Step 2: Turn on the device under test, control the real-time spectrum analyzer in the time domain working mode, test the weak space radiation emission electromagnetic signal plus background noise emitted by the device under test, and convert the corresponding test raw data x RFI+NF (t) stored in a computer;

[0019] Among them, x noise (t) and x RFI+NF (t) are all IQ data;

[0020] Step 3: Calculate x by Fourier transform noise (t) The corresponding received power P rsa , and x RFI+NF (t) The corresponding received power P' rsa :

[0021]

[0022] Where: P rsa and P' rsa The units of are all dBm; R is the signal input impedance of the real-time spectrum analyzer; the parameter 1000 in the formula is the conversion parameter that makes the final unit dBm;

[0023] Step 4: Calculate x noise (t) The corresponding electromagnetic intensity NF E , and x RFI+NF (t) The corresponding electric field strength E rfi+NF :

[0024]

[0025] Where: NF E and E rfi+NF The unit is dBμV / m; f is the test frequency, unit Hz; G rx is the antenna gain in dB; G lna is the gain of the low noise amplifier, in dB; L cable is the RF line loss, in dB; Z0 is the spatial wave impedance; c is the speed of light.

[0026] Step 5: Calculate the electric field strength E of the weak space radiation electromagnetic signal emitted by the device under test rfi :

[0027]

[0028] Where: E rfi The unit is dBμV / m.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention uses time domain testing technology to perform radiation emission testing. The time domain testing technology can improve the dynamic range of the resolution bandwidth and make the resolution bandwidth reach the sub-hertz level.

[0031] 2. The present invention can use a test system composed of a real-time spectrum analyzer, a low-noise amplifier, a high-gain directional antenna combination, a radio frequency cable, and a computer to test the background noise and the weak electromagnetic signal radiated by the device respectively, and adopts a method of separating the background noise to obtain the accurate weak electromagnetic signal emitted by the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of a testing system for transmitting electromagnetic signals of weak space radiation according to an embodiment of the present invention;

[0033] Figure 2The present invention is a flowchart of a method for testing electromagnetic signals emitted by weak space radiation in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] To make the technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0035] A test system for weak space radiation emission electromagnetic signals includes a computer, a real-time spectrum analyzer, a low-noise amplifier, a high-gain directional antenna combination, an antenna stand, a radio frequency cable, a universal GPIB interface bus, a network cable, and a semi-anechoic chamber. The output end of the high-gain directional antenna combination is connected to the input end of the low-noise amplifier, and the output end of the low-noise amplifier is connected to the input end of the real-time spectrum analyzer through a radio frequency cable. The computer controls the real-time spectrum analyzer through the universal GPIB bus and transmits the original data through the network cable. The high-gain directional antenna combination receives the signal, and after amplification by the low-noise amplifier, the real-time spectrum analyzer is controlled by the computer for testing and the radiation emission test results are displayed in the computer.

[0036] Specifically, the high-gain directional antenna combination includes a plurality of high-gain directional antennas with different operating frequencies;

[0037] Specifically, the high-gain directional antenna combination, antenna stand, and low-noise amplifier are arranged in the semi-anechoic chamber; the high-gain directional antenna combination is used to receive signals, and the high-gain directional antenna combination is fixed on the antenna stand; the low-noise amplifier is used to amplify the signal received by the receiving antenna, and the noise coefficient of the low-noise amplifier is recommended to be below 2dB and the gain is above 35dB; the semi-anechoic chamber is used to shield external radiation and simulate an open test site; the computer, general GPIB interface bus, real-time spectrum analyzer, and radio frequency cable are arranged outside the semi-anechoic chamber; the radio frequency cable is used to transfer the amplified signal to the real-time spectrum analyzer in the form of current; the real-time spectrum analyzer is used to collect signals in the time domain and transfer data to the computer; the computer is a high-performance computer, which is used to calculate the effective value of noise in the entire test frequency band, and at the same time store and process a large amount of data collected by the real-time spectrum analyzer.

[0038] The following is a specific example:

[0039] like Figure 1 As shown, a testing system for weak space radiation emission electromagnetic signals, the system comprising:

[0040] High-gain directional antenna combination 1, antenna stand 2, low-noise amplifier 3, radio frequency cable 4, radio frequency cable 5, real-time spectrum analyzer 6, general GPIB interface bus 7, network cable 8, computer 9, semi-anechoic chamber 10;

[0041] The high-gain directional antenna assembly 1, the antenna frame 2, and the low-noise amplifier 3 are arranged in a semi-anechoic chamber 10;

[0042] The real-time spectrum analyzer 6, the general GPIB interface bus 7, the network cable 8, and the computer 9 are arranged outside the semi-anechoic chamber 8;

[0043] A high-gain directional antenna assembly 1 is fixedly mounted on an antenna stand 2, with the center of the antenna kept 1.2 m above the anti-static floor, and connected to a low-noise amplifier 3;

[0044] The low noise amplifier 3 is connected to the real-time spectrum analyzer 6 via the radio frequency cable 4 and the radio frequency cable 5;

[0045] The computer 9 is connected to the real-time spectrum analyzer 6 via the GPIB interface bus 7 and the network cable 8;

[0046] The semi-anechoic chamber 10 is used to shield the interference of the external environment of the anechoic chamber and simulate an open test site.

[0047] The high-gain directional antenna assembly 1 is used to receive signals and convert the signal field strength into voltage.

[0048] The low noise amplifier 3 is used to reduce the effective value of the test system noise and amplify the signal amplitude.

[0049] The real-time spectrum analyzer 6 is used for time domain testing to obtain signal time domain data.

[0050] The computer 9 is used to control the real-time spectrum analyzer to store and process signal data.

[0051] like Figure 2 As shown, a test method for weak space radiation emission electromagnetic signal, the method comprising:

[0052] Step S1, testing background noise and storing raw data;

[0053] In the specific implementation, it should be noted that the computer 9 controls the real-time spectrum analyzer 6 to work in the time domain mode, and the original data obtained by the test is stored in the computer 9 .

[0054] Step S2, testing the space radiation emission electromagnetic signal under the same background noise, and storing the original data;

[0055] In the specific implementation, it should be noted that the computer 9 controls the real-time spectrum analyzer 6 to work in the time domain mode, and the original data obtained by the test is stored in the computer 9 .

[0056] Step S3, processing the test data to obtain the field strength of the electromagnetic signal emitted by the weak space radiation;

[0057] Specifically, the background noise raw data x obtained in step S1 and step S2 is noise (t) and the original data x of the weak space radiation emission electromagnetic signal plus background noise RFI+NF (t) is IQ data, and the received power of the real-time spectrum analyzer is calculated by Fourier transform, and the formula is as follows:

[0058] Unit: [dBm]

[0059] Unit: [dBm]

[0060] Where: P rsa and P' rsa is the received power of the real-time spectrum analyzer, in dBm; x(t) is the time domain raw data of the IQ mode tested by the real-time spectrum analyzer; R is the signal input impedance, which is 50 ohms for the real-time spectrum analyzer; where parameter 1000 is the conversion parameter that makes the final unit dBm.

[0061] Calculate the electromagnetic intensity NF of the background noise respectively E And the electric field strength E of the weak space radiation emission signal measured under the same background noise rfi+NF , the calculation formula is as follows:

[0062]

[0063] Unit: [dBμV / m]

[0064] Where: P rsa and P' rsa is the received power of the real-time spectrum analyzer, in dBm; f is the test frequency, i.e. the frequency range requirement of the electromagnetic compatibility test, in Hz; G rx is the antenna gain in dB; G lna is the gain of the low noise amplifier, in dB; L cable is the RF line loss, in dB; Z0 is the spatial wave impedance, approximately equal to 120π; c is the speed of light. rfi+NF The weak space radiation emission electromagnetic signal emitted by the device under test plus the background noise, unit: dBμV / m; NF E is the background noise signal, unit is dBμV / m.

[0065] Specifically, G. rx is the antenna gain of the high-gain directional antenna corresponding to the working frequency in the current test process; the calculation of the value of the electric field strength only focuses on the calculation of the values ​​of each symbol in the formula under the corresponding unit;

[0066] The electric field strength of the weak space radiation emission electromagnetic signal is obtained by subtracting the background noise from the above-mentioned test weak signal, and the formula is:

[0067] Unit: [dBμV / m]

[0068] Where: E rfi The weak space radiation emitted electromagnetic signal is finally tested without the influence of background noise; E rfi+NF The weak space radiation emitted by the device under test plus the background noise; NF E is the background noise signal.

[0069] In the specific implementation of step S3, the operation of the computer can be performed using Matlab software. It should be noted that Matlab is only one programming language, including but not limited to C, C++ and Java, etc., to implement radiation emission testing, which are all within the scope of protection of this patent.

[0070] The test system of the present invention can test background noise and electromagnetic signals under the background noise under the premise of no stray interference in a dark room, based on the test system composed of a real-time spectrum analyzer, a low-noise amplifier, a high-gain directional antenna combination, a radio frequency cable, etc., and obtain the weak electromagnetic signal generated by the device under test accurately by separating the background noise.

[0071] The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, shall be covered by the protection scope of the present invention.

Claims

1. A test system for weak space radiation emission electromagnetic signals, used for measuring weak space radiation emission electromagnetic signals of a device under test, characterized in that: It includes a computer, a real-time spectrum analyzer, a low-noise amplifier, a high-gain directional antenna combination, an antenna stand, a radio frequency cable, a universal GPIB interface bus, a network cable, and a semi-anechoic chamber; among which: The high-gain directional antenna assembly, antenna stand, and low-noise amplifier are arranged in the semi-anechoic chamber; The computer, the general GPIB interface bus, the network cable, and the real-time spectrum analyzer are arranged outside the semi-anechoic chamber; The radio frequency cable is divided into two parts, one part is arranged inside the semi-anechoic chamber, and the other part is arranged outside the semi-anechoic chamber, and connected by a through-wall radio frequency connector integrated in the semi-anechoic chamber; The semi-anechoic chamber is used to shield external radiation and simulate an open test site; the device under test is located in the semi-anechoic chamber; The high-gain directional antenna assembly is fixed on the antenna frame and connected to the low-noise amplifier; The low noise amplifier is connected to the real-time spectrum analyzer via the radio frequency cable; The computer is connected to the real-time spectrum analyzer via the general GPIB interface bus and a network cable; The weak space radiation emission electromagnetic signal of the device under test is received by the high-gain directional antenna combination, amplified by the low-noise amplifier and transmitted to the real-time spectrum analyzer. The computer controls the real-time spectrum analyzer through the general GPIB interface bus to test it. The test raw data file of the real-time spectrum analyzer is transmitted to the computer through the network cable for storage.

2. A test system for weak space radiation emission electromagnetic signals according to claim 1, characterized in that: The real-time spectrum analyzer has a time domain test function, and the file name suffix of the test raw data file generated by the time domain test is tar.

3. A test method for weak space radiation emission electromagnetic signal, characterized in that: A test system for weak space radiation emission electromagnetic signals according to claim 1 or 2 is implemented, specifically comprising the following steps: Step 1: Turn off the device under test, control the real-time spectrum analyzer in the time domain working mode, test the background noise of the space where the device under test is located, and convert the test raw data corresponding to the background noise into x noise (t) stored in a computer; Step 2: Turn on the device under test, control the real-time spectrum analyzer in the time domain working mode, test the weak space radiation emission electromagnetic signal plus background noise emitted by the device under test, and convert the corresponding test raw data x RFI+NF (t) stored in a computer; Among them, x noise (t) and x RFI+NF (t) are all IQ data; Step 3: Calculate x by Fourier transform noise (t) The corresponding received power P rsa , and x RFI+NF (t) The corresponding received power P' rsa : Where: P rsa and P' rsa The units of are all dBm; R is the signal input impedance of the real-time spectrum analyzer; the parameter 1000 in the formula is the conversion parameter that makes the final unit dBm; Step 4: Calculate x noise (t) The corresponding electromagnetic intensity NF E , and x RFI+NF (t) The corresponding electric field strength E rfi+NF : Where: NF E and E rfi+NF The unit is dBμV / m; f is the test frequency, unit Hz; G rx is the antenna gain in dB; G lna is the gain of the low noise amplifier, in dB; L cable is the RF line loss, in dB; Z0 is the spatial wave impedance; c is the speed of light. Step 5: Calculate the electric field strength E of the weak space radiation electromagnetic signal emitted by the device under test rfi : Where: E rfi The unit is dBμV / m.

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