Microwave quantum detection method based on environmental noise fine perception

Abstract

A microwave quantum detection method based on environmental noise fine perception comprises the following steps: step 1, constructing a parallel link of environmental noise perception and signal detection, adding an antenna and a low-temperature switch at the front ends of the environmental noise perception link and the signal detection link, connecting the two links in parallel, and switching between the environmental noise perception and the signal detection; step 2, acquiring environment noise distribution by using an environment noise sensing link: operating a low-temperature switch, selecting the environment noise sensing link, testing internal noise of the environment noise sensing link by adopting a cold and hot load method, and measuring external environment noise by using the environment noise sensing link; and step 3, pointing to a target orientation by using a signal detection link, and performing signal detection: operating a low-temperature switch, selecting the signal detection link, determining an antenna pointing angle, obtaining environment noise of the angle, setting attenuation of an adjustable attenuator according to the external environment noise, and detecting signals by using a microwave quantum detection device.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of radar detection, and particularly relates to a quantum detection technology. BACKGROUND

[0002] Quantum radar is a new radar combining radar technology and quantum technology, which fully utilizes the quantum characteristics of electromagnetic waves to break through the performance limit of classical detection, and has broad application prospects.

[0003] An important feature of quantum radar superior to traditional radar is higher sensitivity, which can detect a farther distance under the same transmitting power and antenna size.

[0004] The document "Development Status and Trends of Quantum Radar Technology" recorded in the 44th volume of the 4th issue of National Defense Science and Technology discusses different technical branches and practicalization processes of quantum radar. The quantum radar in the optical band, especially the single-photon detection quantum radar, has achieved a target detection result of more than 100 kilometers.

[0005] The quantum radar in the microwave band is still in the laboratory demonstration and verification stage, because: 1. The quantum device technology in the microwave band is difficult and has harsh working conditions; 2. The thermal noise in the microwave band is large, and the microwave quantum system working in an open environment faces complex environmental background noise. SUMMARY

[0006] The application adopts a microwave quantum amplifier to construct a receiving link, measures and senses the external environmental noise in different directions, and establishes an environmental noise spectrum; based on the environmental noise spectrum, an adjustable attenuator and a microwave quantum detector are used to construct a detection link, which simultaneously suppresses environmental noise and detects signals, and improves the adaptability of the microwave quantum radar to the environment.

[0007] Step one: Construct a parallel link for environmental noise sensing and signal detection.

[0008] A microwave quantum amplifier, a post-amplifier and a signal reading device are used to construct an environmental noise sensing link; the microwave quantum amplifier amplifies the signal with ultra-low noise, so that the noise of the environmental noise sensing link reaches the quantum limit, and the sensitivity of the environmental noise sensing is improved; the post-amplifier amplifies the signal again to meet the requirements of conventional signal detection devices; the signal reading device reads and analyzes the signal obtained by the environmental noise sensing link, and generates output power information to provide data for environmental noise analysis and calculation.

[0009] A signal detection link is constructed using an adjustable attenuator, a microwave quantum detector, a post-amplifier, and a signal readout device. The adjustable attenuator controllably attenuates the signal containing noise, keeping the input noise at a level that has no impact on the microwave quantum detector. The microwave quantum detector detects the echo signal and outputs the detection result. The post-amplifier amplifies the detection result from the microwave quantum detector. The signal readout device reads and analyzes the amplified detection result.

[0010] Furthermore, the signal reading equipment employs analog-to-digital converters, data processing computers, spectrum analyzers, and oscilloscopes.

[0011] Antennas and cryogenic switches are added to the front end of the environmental noise sensing link and the signal detection link, and the two links are connected in parallel to switch between environmental noise sensing and signal detection.

[0012] Step 2: Use the environmental noise sensing link to obtain the environmental noise distribution.

[0013] Manipulate the cryogenic switch to select the environmental noise sensing link: Apply a high / low level, switch the cryogenic switch, and connect the antenna to the environmental noise sensing link.

[0014] The internal noise of the environmental noise sensing link was tested using the hot and cold load method: the antenna aperture was covered with absorbing material at room temperature (Th) and low temperature (Tc) respectively, and the output power Ph and Pc of the environmental noise sensing link were obtained under the two conditions. The internal noise Tsi of the environmental noise sensing link was calculated using the formulas Y = Ph / Pc and Tsi = (Th-Y×Tc) / (Y-1).

[0015] Measuring external ambient noise using an ambient noise sensing link: Divide the detection angle range into several regions, point the antenna to the corresponding angle of each region, obtain the output power Pa of the ambient noise sensing link, and calculate the external ambient noise Ta at that angle using the formulas Ya = Pa / Pc and Ta = Ya×(Tc+Tsi)-Tsi, forming a data table of angle-external ambient noise.

[0016] Step 3: Use the signal detection link to point to the target location and perform signal detection.

[0017] Operate the cryogenic switch to select the signal detection link: Apply a high / low level, switch the cryogenic switch, and connect the antenna to the signal detection link.

[0018] Determine the antenna pointing angle and obtain the environmental noise at that angle: The servo turntable reports the antenna pointing angle, and the external environmental noise corresponding to the antenna pointing angle is obtained by using an interpolation fitting method based on the distribution of external environmental noise data obtained in step two.

[0019] Based on the external ambient noise, set the attenuation of the adjustable attenuator using the formula: Calculate the attenuation L of the adjustable attenuator, where Pfa is the false alarm probability, k is the Boltzmann constant, Ta is the external ambient noise, B is the bandwidth, τ is the signal pulse width, h is Planck's constant, f is the frequency, and Cd is the dark count rate of the microwave quantum detector.

[0020] The signal is detected using a microwave quantum detector: if the detection result of the microwave quantum detector is 1, the target is determined to exist; if the detection result is 0, the target is determined to not exist. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a parallel link. Detailed Implementation

[0022] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] An environmental noise sensing link is constructed using a microwave quantum amplifier, a post-amplifier, and a signal readout device. A signal detection link is constructed using an adjustable attenuator, a microwave quantum detector, a post-amplifier, and a signal readout device. Antennas and cryogenic switches are added to the front ends of both the environmental noise sensing and signal detection links. The two links are then connected in parallel. Figure 1 As shown.

[0024] The antenna aperture was covered at room temperature (Th=300K) and liquid nitrogen cryogenic temperature (Tc=77K) respectively. The output power of the environmental noise sensing link was obtained as Ph=-42.15dBm and Pc=-48.01dBm under these two conditions. Using the formula Y = Ph / Pc = 5.86dB = 3.855 Tsi = (Th-Y×Tc) / (Y-1) = 1.11K calculates the internal noise Tsi of the environmental noise sensing link.

[0025] The detection angle ranges of azimuth [10°, 30°] and elevation [30°, 60°] are divided into several regions in 5° increments, as shown in the table below:

[0026] The external noise corresponding to each angle is shown in the table below:

[0027] The antenna is set to an azimuth angle of 22° and an elevation angle of 45°.

[0028] With Ta as the dependent variable and azimuth angle y and elevation angle x as independent variables, the interpolation fitting [x,y] = ndgrid(30:5:60,10:5:30) is performed using the griddedInterpolant function in MATLAB as follows: Ta = [30.08 29.49 33.03 30.86 28.52; 26.60 26.22 26.54 23.70 26.41; 24.34 23.76 23.03 23.59 22.92; 21.78 22.00 21.47 22.37 22.48; 16.22 16.62 18.06 17.89 17.75; 14.95 15.17 14.80 14.84 15.47; 12.72 12.94 12.94 12.22 13.10] The interpolation function F = griddedInterpolant(x, y, Ta) is obtained. For a position with an azimuth angle of 22° and an elevation angle of 45°, F(45, 22) = 21.83.

[0029] Based on the external environmental noise, the following parameters were set: false alarm probability Pfa = 10⁻³, Boltzmann constant k = 1.38 × 10²³ J / K, external environmental noise Ta = 21.83 K, bandwidth B = 1 MHz, signal pulse width τ = 5 μs, Planck constant h = 6.63 × 10³⁴ J·s, frequency f = 10 GHz, and dark count rate of the microwave quantum detector Cd = 1 Hz. The formula was used... Calculation yields .

[0030] The above are embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A microwave quantum probing method based on fine perception of environmental noise, characterized in that, The application relates to a microwave quantum noise sensing and signal detection device. Step one: constructing a parallel link of environmental noise sensing and signal detection: constructing an environmental noise sensing link by using a microwave quantum amplifier, a post-amplifier and a signal reading device; constructing a signal detection link by using an adjustable attenuator, a microwave quantum detector, a post-amplifier and a signal reading device; adding an antenna and a cryogenic switch at the front end of the environmental noise sensing link and the signal detection link, connecting the two links in parallel and switching between the environmental noise sensing and the signal detection; Step two: obtaining environmental noise distribution by using the environmental noise sensing link: operating the cryogenic switch to select the environmental noise sensing link; testing the internal noise of the environmental noise sensing link by using a cold-hot load method; measuring external environmental noise by using the environmental noise sensing link; Step three: directing the target direction by using the signal detection link and performing signal detection: operating the cryogenic switch to select the signal detection link; determining the antenna pointing angle and obtaining the environmental noise at the angle; setting the attenuation amount of the adjustable attenuator according to the external environmental noise; and detecting the signal by using the microwave quantum detection device.

2. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The environmental noise sensing link comprises a microwave quantum amplifier which amplifies the signal with ultra-low noise, so that the noise of the environmental noise sensing link reaches the quantum limit and the sensitivity of the environmental noise sensing is improved; the post-amplifier performs secondary amplification on the signal and meets the requirements of conventional signal detection devices; and the signal reading device reads and analyzes the signal obtained by the environmental noise sensing link and generates output power information to provide data for environmental noise analysis and calculation.

3. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The signal detection link comprises an adjustable attenuator which controllably attenuates the signal containing noise and controls the input noise to a magnitude which has no influence on the microwave quantum detector; the microwave quantum detector detects the echo signal and outputs the detection result; the post-amplifier amplifies the detection result of the microwave quantum detector; and the signal reading device reads and analyzes the amplified detection result.

4. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The signal reading device adopts an analog-to-digital converter, a data processing computer, a spectrum analyzer and an oscilloscope.

5. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The operation of the cryogenic switch to select the environmental noise sensing link comprises applying a high / low level to switch the cryogenic switch and connecting the antenna to the environmental noise sensing link; and the operation of the cryogenic switch to select the signal detection link comprises applying a high / low level to switch the cryogenic switch and connecting the antenna to the signal detection link.

6. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The cold-hot load method for testing the internal noise of the environmental noise sensing link comprises covering the antenna port surface with wave-absorbing materials at normal temperature Th and low temperature Tc respectively, obtaining the output power Ph and Pc of the environmental noise sensing link in the two states, and calculating the internal noise Tsi of the environmental noise sensing link by using the formula Y = Ph / Pc and Tsi = (Th-Y*Tc) / (Y-1).

7. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The method comprises the following steps: dividing a detection angle range into several regions, pointing an antenna to a corresponding angle of each region, obtaining an output power Pa of an environmental noise sensing link, and calculating an external environmental noise Ta of the angle by using a formula Ya = Pa / Pc and Ta = Ya×(Tc+Tsi)-Tsi to form a data table of angle-external environmental noise.

8. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The method comprises the following steps: reporting an antenna pointing angle by a servo turntable, and obtaining an external environmental noise corresponding to the antenna pointing angle by using an interpolation fitting method according to the external environmental noise data distribution obtained in step two.

9. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The setting of the attenuation amount of the adjustable attenuator according to the external environment noise comprises the following steps The attenuation amount L of the adjustable attenuator is calculated, wherein Pfa is the false alarm probability, k is the Boltzmann constant, Ta is the external environment noise, B is the bandwidth, τ is the signal pulse width, h is the Planck constant, f is the frequency, and Cd is the dark count rate of the microwave quantum detector.

10. The microwave quantum probing method based on fine perception of environmental noise according to claim 1, characterized in that, The method comprises the following steps: if a detection result of the microwave quantum detector is 1, it is determined that the target exists; and if the detection result is 0, it is determined that the target does not exist.

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