Passive positioning and identification system for civil unmanned aerial vehicles

A civilian unmanned aerial vehicle, passive positioning technology, applied in the field of passive positioning and identification systems, can solve the problems of easy interference with radio equipment, high transmission power, weak radar echo, etc., and achieves good ability to detect low-altitude slow-speed small targets , reduce complexity and cost, and improve the effect of distance

Active Publication Date: 2018-02-09

芜湖华创光电科技有限公司

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AI-Extracted Technical Summary

Problems solved by technology

Consumer drones fly at low altitudes, slow speeds, and small target reflection areas. Their radar echoes are not only weak, but also mixed with background clutter signals and are not easy to distinguish. Using conventional radars for detection is not effective; When the rad...

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Method used

Most of UAV's remote control telemetry distance is 2km, but its remote control end antenna gain is less, no more than 3dB, in order to reach the signal detection distance of 10km, need our receiving antenna gain to increase 25% than the remote control antenna gain Here we choose the gain of the signal detection antenna as 18dB, which is 15dB larger than the gain of the remote control antenna, which can meet the detection and target recognition requirements of the WIFI remote control telemetry signal of the UAV beyond 10km.

The present invention adopts passive radar to detect and locate the unmanned aerial vehicle of low-altitude slow-speed flight, and passive radar possesses better detection low-altitude slow-speed small target ability, and is good to unmanned aerial vehicle detection effect; System adopts unmanned aerial vehicle Human-machine remote control telemetry signal detection and analysis method to identify UAVs, because the characteristics of different types of UAV remote control telemetry signals are quite different, so it is better to use this signal to identify UAV targets; the reception of remote control telemetry signals is affected The inf...

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Abstract

The present invention belongs to the aerial vehicle positioning, tracking and identification technical field and relates to a passive positioning and identification system for civil unmanned aerial vehicles. The system is composed of three parts, namely, a passive radar, a signal detection and receiving part and a fusion processing part. According to the passive positioning and identification system for the civil unmanned aerial vehicles of the present invention, the passive radar is adopted to detect and position an unmanned aerial vehicle at a low altitude and a low velocity; since the passive radar has a good capability of detecting small targets at low altitudes and low velocities, and therefore, a good unmanned aerial vehicle detection effect can be realized; since the characteristicsof different types of unmanned aerial vehicle remote control and telemetry signals have large differences, so that an unmanned aerial vehicle remote control and telemetry signal detection and receiving analysis method can be adopted to identify unmanned aerial vehicles; the passive radar is adopted to guide the system of remote control and telemetry signal detection and receiving, and therefore,a signal detection and receiving acting distance can be prolonged, and the complexity and cost of signal detection and receiving can be improved; and during work, the entire system does not need to radiate out signals, and therefore, the system is free of electromagnetic pollution and environmentally friendly.

Application Domain

Radio wave reradiation/reflection

Technology Topic

Telemetry EquipmentLow altitude +11

Image

Examples

Experimental program(1)

Example Embodiment

[0025] Implementation case one:

[0026] Passive radar uses an analog FM radio station as an external radiation source, and is mainly composed of three parts: a direct receiving signal receiving part, a target signal receiving part, and a signal processor. The direct signal receiving part is composed of a direct signal receiving antenna with good directivity and a frequency conversion receiver. The target signal receiving part is composed of an 8-unit array antenna and an 8-channel frequency conversion receiver. The signal processor is composed of 9-channel AD acquisition, digital down conversion and It is composed of high-speed digital signal processor. The direct signal and the target echo signal are received by the antenna and converted into a fixed intermediate frequency signal after being converted into a fixed intermediate frequency signal. After the quantization and acquisition are completed by the AD collection, they are converted into a digital baseband signal through digital down conversion. Among them, the multi-channel target echo signal is formed by digital beams to form multiple digital beams covering the detection airspace at the same time. Each digital beam is combined with the direct baseband signal to complete strong direct and multipath clutter suppression, correlation processing, target detection, and parameters After measurement, positioning and target tracking, the target track is formed. The whole system works on the working frequency band of 88~108MHz FM radio station.

[0027] The signal detection part adopts the interferometer system, the antenna gain is 18dB, and it works on two WIFI signal frequency bands of 2.4GHz and 5.5GHz. Three antennas are used to form two baselines. While ensuring good direction finding accuracy, avoiding direction finding ambiguity. The signal detection part is specifically composed of 3 antennas, 3 frequency conversion channels and 3-channel AD acquisition, and a fast signal detection processor based on FPGA. Among them, the instantaneous bandwidth of the channel is 50MHz, which can realize the requirement of fast coverage of the working frequency.

[0028] Assuming that the noise figure of the passive radar receiver is 5dB, the accumulation time is 100ms, and the minimum detection signal-to-noise ratio is 13dB, the receiver sensitivity is

[0029]

[0030] In the above formula, K is Boltzmann's constant, T is the temperature expressed in absolute temperature scale Kelvin (abbreviated as K), and the normal temperature is 290K, N f Is the noise figure, SNR min Is the minimum detection signal-to-noise ratio.

[0031] Suppose the equivalent radiation power of the FM radio station is 10KW, the unit antenna gain of the passive radar target signal receiving array antenna is 3dB, and the radar reflection area of the civilian consumer UAV is 0.01m 2 , The receiving array antenna gain is 11dB (the unit antenna is 3dB plus the array gain is 9dB, and the beam synthesis loss of 1dB is removed), and the distance between the radio and the drone is 10km, and the distance between the drone and the passive radar is 10km. The power of the echo signal received is

[0032]

[0033] In the above formula, ERP is the equivalent radiation power of the FM radio station, σ is the UAV radar reflection area, G r Is the gain of the array antenna, λ is the wavelength, here the center frequency is 100MHz, the wavelength is 3m, R t Is the distance from the radio to the drone, R r Is the distance from the UAV to the passive radar, L s Is the system loss, which is 6dB. Obviously, it is calculated that the reflected echo of the UAV exceeds the sensitivity of the receiver and can be detected. The passive radar can reach a distance of more than 10km on the UAV.

[0034] The remote control telemetry distance of most UAVs is 2km, but the antenna gain of the remote control end is small, no more than 3dB. In order to reach the signal detection distance of 10km, we need our receiving antenna gain to be more than 25 times larger than the remote control antenna gain. Here we choose the signal reconnaissance antenna gain to be 18dB, which is 15dB larger than the remote control antenna gain, which can meet the requirements for reconnaissance and target recognition of UAV WIFI remote control telemetry signals beyond 10km.

[0035] The above example uses a combination of passive radar illuminated by FM radio stations and WIFI signal detection, which can realize the detection, positioning and identification of consumer-grade UAVs beyond 10km.

[0036] The present invention uses passive radar to detect and locate low-altitude slow-flying drones. The passive radar has a better ability to detect low-altitude slow-speed small targets and has a good detection effect on the drone; the system adopts remote control of the drone The method of detection and analysis of telemetry signals is used to identify UAVs. Because different types of UAV remote-control telemetry signals have different characteristics, it is better to use this signal to identify UAV targets; the reception of remote-control telemetry signals is greatly affected by the weather. It is small and can work day and night. Compared with visible light camera and infrared camera, it can work all day long. The system adopts a system in which passive radar guides the signal reconnaissance part, which increases the range of the signal reconnaissance part while reducing the complexity and cost of signal reconnaissance. The whole system does not need to radiate signals when working, no electromagnetic pollution, environmental protection and green.

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