Radar systems for tracking low-flying unmanned aircraft and objects.

Abstract

A radar system is provided for tracking UAVs and other low-altitude flying objects using a wireless network device. The system is implemented as a distributed low-altitude radar system, wherein a transmitting antenna is coupled to a wireless network device to radiate signals toward the sky. A receiving antenna or array receives the signals radiated from the transmitting antenna, particularly signals or echoes reflected from objects in the sky detection area. One or more processing components are electronically coupled to the wireless network device and the receiving antenna to receive and manipulate signal information, thereby providing identification and tracking of low-altitude flying objects and their movement within the coverage area. The system can provide detection of objects across multiple areas via network area nodes, and aggregate this information as they move within the detection area to detect and track UAVs and other low-altitude flying objects.

Description

[0001] This application is a divisional application of application number 201780044315.8, filed on May 30, 2017, entitled "Radar System for Tracking Low-Altitude Unmanned Aircraft and Objects". Technical Field

[0002] This invention relates to the field of unmanned aerial vehicles (UAVs), and more particularly to systems, methods and apparatus for tracking UAVs and low-flying objects. Background Technology

[0003] The current challenge is verifying the location of beyond-visual-range (BVR) unmanned aerial vehicles (UAVs). When UAVs are beyond their operator's line of sight, or when they are operating autonomously or under the control of an autonomous air traffic control system, they typically operate at altitudes far below what conventional air traffic control radars can "see." Radar (or RADAR) is an acronym for radio detection and ranging. Furthermore, while UAVs can self-report their locations via communication networks, there are numerous instances where their reported locations are inaccurate or temporarily unavailable. Additionally, because low-altitude UAVs often operate in close proximity to each other, and may also be in the same airspace as birds, balloons, or even other manned aircraft, and these do not report their locations to UAV air traffic control systems, a method for independently mapping objects in low-altitude airspace is needed.

[0004] This function is typically handled by radar systems, but for mapping low-altitude UAV airspace, special considerations apply to low-altitude radar: distinguishing it from conventional radar. First and foremost, radar covering low altitudes cannot inherently be long-range. Ground clutter is a significant problem for radars attempting to cover low altitudes at distances typically associated with air traffic control radar. Furthermore, the size of UAVs and other low-altitude groups (such as birds) makes their radar cross-sections too small for long-range observation associated with air traffic control radar. Therefore, short-range radar systems capable of "seeing" small radar cross-section targets and avoiding ground clutter problems are needed. Summary of the Invention

[0005] A radar system for tracking UAVs and other low-flying objects is provided. According to a preferred embodiment, the system is implemented as a distributed low-altitude radar system. The system is designed to track objects using a wireless network device to generate RF signals. A transmitting antenna, preferably multiple transmitting antennas, is coupled to the wireless network device for radiating signals in a skyward direction. The transmitting antennas of the system are preferably cellular antennas, such as those on cell phone towers, configured for cellular signal communication. A receiving antenna receives signals radiated from the transmitting antennas, particularly signals reflected from low-flying objects such as UAVs and other objects (e.g., birds, balloons, etc.). According to a preferred embodiment, the receiving antenna is a separate antenna for receiving transmissions or echoes reflected from the object. Multiple receiving antennas are provided, and preferably, the receiving antennas are located at or near each transmitting antenna. Multiple transmitting antennas can be provided at a single location, and one or more receiving antennas can also be provided at or near the location of the transmitting antennas. The presence, direction, and speed of an object can be determined by utilizing the RF transmissions broadcast from the transmitting antennas, which are configured to transmit communication to sky objects, such as UAVs operating within the antenna's broadcast range. The RF transmission is preferably for relaying datagrams, voice, or other information transmitted towards the sky generated by wireless network communication components. The associated RADAR antenna receives the echo of the RF transmission based on objects within the transmission area. The radar antenna is connected to provide a signal to a radar processor, which can be a computing unit, such as a computer providing software containing instructions for processing the information from the radar antenna. Embodiments of the system are also configured to have a copy of the transmitted signal broadcast into the sky, which is provided to the radar processor. Thus, the radar processor receives the signal from the transmitter and receives the echo as the signal is broadcast into the sky (and may be reflected by objects). The radar processor can be configured to minimize the possibility of strong signals, which may be the result of back transmission from nearby mountains or other objects.

[0006] Embodiments of this system preferably utilize multiple radar receiving antennas arranged at or near the location of a sky transmitter. The radar receiving antennas are preferably arranged to provide radar detection information to a computing component (e.g., a computer) that aggregates radar reception responses. According to some embodiments, where the radar antenna associated with the radar processor is close to multiple transmitters broadcasting sky signals, the radar processor can receive a copy of the signal from each of those transmitters.

[0007] Embodiments of this system are preferably configured to utilize codes transmitted for sky communication between transceivers. RF transmissions from transmitting antennas may include codes from RF communication transmissions, and these codes are part of RF communication with the UAV (e.g., datagrams broadcast to the UAV), which can be used by a radar processor to provide detection of objects in the sky. The codes may be transmitted to the sky or as part of a copy of the transmission to the relevant radar processor. According to some embodiments, an aggregator may further process radar detection information from multiple radar processors to provide detection of objects that may be within range broadcast by multiple transmitters. According to some embodiments, the aggregator may be a computer that receives and processes radar information from multiple radar processors to provide detection of objects as they move across the entire sky area.

[0008] This system can be implemented as a distributed network, where nodes are configured to detect signals generated by objects within a zone or area covered by that node. In a preferred embodiment, a radar processor is electronically coupled to a wireless network device to receive signals. A receiving antenna is provided to receive transmitted signals, including RF transmission signals reflected from low-flying objects (e.g., UAVs, birds, or other objects in the sky) for detection (e.g., within the monitored area or elevation level). The radar processor is preferably electronically coupled to the receiving antenna to receive signals from it. The radar processor can manipulate the signals through various signal processing applications, including beamforming operations and signal conditioning. Detected signals are processed, and preferably, the system manipulates signal information and aggregates detected signals from network nodes. A computational component is coupled to receive information from the radar processor in the network or network area, aggregates the information, and tracks objects as they move through the sky area of ​​the network. Objects can be identified by signals, and the radar processor can determine the type of object by comparative identification of object patterns through comparison with object profile data. Processing of signal information can also determine object attributes such as object movement, speed, size, and flight path. When an object moves through the detection area in the sky, its movement can be tracked. The computing unit is configured to receive information from radar processors distributed throughout the network and aggregate that information to detect low-flying objects over the coverage area.

[0009] The key feature of the disclosed radar system is its distributed nature, as it relies on a distributed network of ground-based communication transmitters, such as cellular UAV command and control systems disclosed in other pending patent applications (i.e., U.S. Patent Application Serial No. 62 / 214,053, filed September 3, 2015, and U.S. Patent Application Serial No. 62 / 323,957, filed April 18, 2016, the entire contents of which are incorporated herein by reference). This distributed network enables the disclosed radar system to bring its signal source portion relatively close to the target it seeks to detect and track.

[0010] Another feature of the disclosed radar system is that the signal used for detection propagates primarily upwards over a small area of ​​the sky, rather than horizontally, allowing the system to significantly avoid reflections from buildings, trees, and other ground clutter. Therefore, the detection signal can be directed towards the sky within a specific monitored area.

[0011] Another feature of the disclosed radar system is that it relies on communication signals transmitted for the initial purpose of communicating with aircraft or UAVs; therefore, new spectrum and new transmission devices are not necessary according to the preferred embodiment of the system. Embodiments of the detection system can be implemented in conjunction with a UAV communication system, and some or all of the network components of that system can be used.

[0012] Furthermore, because the duration of the communication signal is typically longer than that of the conventional linear frequency modulated signal associated with conventional radar, a longer integration time can be employed in the detection and ranging algorithms, which improves the performance of the disclosed system relative to more conventional radar systems. By using a pseudo-random coded (PRC) continuous wave bistatic radar system, the effects of range ambiguity reduction and detection enhancement can be enhanced using methods well-known in radar science. By employing a bistatic configuration with a conventional communication signal that can potentially naturally simulate PRC codes to some extent, the disclosed system achieves similar gains to a fully PRC-coded bistatic radar system.

[0013] According to some embodiments of the distributed low-altitude radar system of this application, the distributed low-altitude radar system includes: a wireless network device for generating RF signals; at least one transmitting antenna coupled to the wireless network device for radiating signals in a skyward direction; at least one receiving antenna for receiving signals reflected from low-altitude flying objects; a radar processor electronically coupled to the wireless network device to receive signals therefrom and coupled to the receiving antenna to receive signals therefrom; and a computing unit coupled to the radar processor to receive information therefrom; wherein the computing unit is configured to receive information from multiple radar processors distributed throughout the coverage area, and wherein the computing unit aggregates the information to detect and track low-altitude flying objects over the coverage area.

[0014] In some embodiments, the wireless network device includes a transceiver, a power supply, and a processor for processing communications transmitted and received over the network.

[0015] In some embodiments, at least one of the transmitting antenna and the receiving antenna includes an antenna array.

[0016] In some embodiments, at least one of the transmitting antenna and the receiving antenna includes a phased array.

[0017] In some embodiments, the system is configured to detect reflected RF radiation from the corner reflector of the UAV.

[0018] In some embodiments, the transceiver is configured to generate a transceiver signal polarized in a circumferential direction, and wherein the receiving antenna is polarized in a circumferential direction opposite to the communication transceiver signal to reduce direct interference from the communication transceiver signal and improve response to object reflections.

[0019] In some embodiments, the wireless network device is configured to communicate with a UAV.

[0020] In some embodiments, multiple wireless network devices are provided to form multiple nodes.

[0021] In some embodiments, the nodes are configured to provide signals indicating the presence of objects within the area of ​​each node.

[0022] In some embodiments, a plurality of transmitting antennas are coupled to a plurality of corresponding wireless network devices for radiating signals from the transmitting antennas toward the sky; each of the plurality of transmitting antennas is configured to provide a sky area with signal coverage; wherein a plurality of corresponding receiving antennas are provided for receiving reflected signals generated from the respective plurality of transmitting antennas; wherein each receiving antenna is located near a respective associated transmitting antenna, and wherein the transmitting antenna and the respective associated receiving antenna define a detection area through their respective signal radiation and signal reception; wherein the system includes a plurality of detection areas; and wherein the computing unit detects and tracks objects within the detection areas.

[0023] In some embodiments, each of the transmitting antennas transmits a signal polarized in a circumferential direction, and each associated receiving antenna is polarized in the opposite circumferential direction of its respective associated transmitting antenna.

[0024] In some embodiments, the distributed low-altitude radar system further includes a UAV air traffic control system configured to have at least one processor for processing information, and the processor being electronically coupled to the radar processor to receive tracking information of low-altitude flying objects within the detection area, and to manage UAV operations by controlling one or more UAVs to minimize potential collisions with other UAVs and other objects within the detection area detected by the system.

[0025] In some embodiments, the distributed low-altitude radar system further includes a UAV air traffic control system configured to have at least one processor for processing information, and the processor being electronically coupled to the radar processor to receive tracking information of low-altitude flying objects within the detection area, and to manage UAV operations by controlling one or more UAVs to minimize potential collisions with other UAVs and other objects within the detection area detected by the system.

[0026] In some embodiments, the transmitting antenna provides RF communication for communicating with one or more UAVs, the wireless network device including at least one transmitter, wherein the RF communication includes RF signals generated by the transmitter; and wherein the receiving antenna is configured to receive echoes of RF signals transmitted from reflected objects.

[0027] In some embodiments, the transmitter that generates the RF signal provides a copy of the signal to the radar processor.

[0028] In some embodiments, the radar signal includes a communication signal transmitted from the at least one transmitting antenna to the UAV.

[0029] In some embodiments, the RF signal includes coded modulation.

[0030] In some embodiments, the code of the coded modulated RF signal includes code from signal communication between the at least one transmitting antenna and the UAV.

[0031] In some embodiments, the code is provided from the transmitter to the at least one transmitting antenna and the radar processor.

[0032] In some embodiments, the transmitter is coupled to provide the code to the radar processor.

[0033] In some embodiments, the transmitter is coupled to provide the code to multiple radar processors within the transmitter's transmission and echo range.

[0034] In some embodiments, the distributed low-altitude radar system includes a sky communication system for RF communication from multiple transmitters, and multiple corresponding antennas radiating RF signals from the respective multiple transmitters; wherein multiple radar processors with corresponding receiving antennas are provided for receiving signals reflected from sky objects from the respective multiple transmitters.

[0035] In some embodiments, the plurality of radar processors receive copies of the transmitted RF signals from the transmitter.

[0036] In some embodiments, the radar processor is configured to process the phase difference between a reflected signal detected by the radar processor's associated antenna and a copy of the signal received from the transmitter.

[0037] In some embodiments, codes are applied to the transmitter frequency carrier.

[0038] In some embodiments, a code is applied to the transmitter frequency carrier, the code including a pseudo-random code.

[0039] In some embodiments, the pseudo-random code is generated as an L-bit code, which is based on multiple N-level shift register stages that are periodically repeated, wherein for the number of N-level shift register stages, the expression for determining the L-bit code is L = 2^N–1.

[0040] In some embodiments, the wireless network device includes a transmitter for transmitting RF transmissions broadcast from the transmitting antenna, and wherein the wireless network device provides a copy of the RF transmissions to the radar processor.

[0041] In some embodiments, a code is applied to the transmitter frequency carrier, the code including a pseudo-random code.

[0042] These and other advantages of the present invention are described herein and illustrated in conjunction with exemplary embodiments. Attached Figure Description

[0043] Figure 1 This is an illustration depicting an exemplary embodiment of the system of the present invention for tracking low-flying objects.

[0044] Figure 2 yes Figure 1 An exemplary embodiment of the nodes of the system depicted in the illustration.

[0045] Figure 3 This is a diagram illustrating an example of a passive radar processor system that can be used in conjunction with the system of the present invention. Detailed Implementation

[0046] See Figures 1 to 3This document describes exemplary embodiments of a system for tracking low-flying objects, particularly for tracking low-flying unmanned aerial vehicles (UAVs) and other objects. The system can be implemented according to the methods disclosed herein, and means for implementing the system and methods can be provided and configured. According to a preferred embodiment, the system can be implemented in conjunction with existing cell phone towers. Alternatively, the system can be implemented using existing cell phone towers and some additional components, or, according to some other alternative embodiments, it can be implemented using separately provided towers, transmitters, and other components dedicated to UAV / RPV communication. According to other embodiments, the system can be implemented using a separate distributed network of ground-based communication transmitters.

[0047] An exemplary embodiment of the system according to the invention is illustrated, wherein components are arranged to track low-flying aerial objects, such as UAVs and other objects. Figure 1 In the exemplary depiction, a bird 1060 or UAV 1051 can be tracked by the system as it flies over an area covered by a "cell-type" grid of communication datagram transceivers. This network is depicted as including nodes 1000', 1000", 1000"' (and may include many additional nodes, not shown). Each node 1000', 1000", 1000"' contains associated communication equipment and its own local antenna array or phased array antenna for receiving reflections from objects within the coverage area, and has radar processing capabilities. Its network connects to other nodes and returns data to a central aggregation tracking computer 280, providing area tracking of objects across multiple nodes deployed across the region.

[0048] like Figure 1As shown, an arrangement of cell phone towers 120, 130, and 140 is provided to represent a segment of a distributed network for tracking UAVs and other low-flying objects. In this exemplary embodiment, a network communication system 1000 is shown, and three nodes 1000', 1000”, and 1000”' are depicted (other similar nodes comprising the distributed network are provided throughout the detection area). Each node 1000', 1000”, and 1000”' is shown, represented by a corresponding tower 120, 130, and 140, and associated with wireless network communication devices (WNEs) 261, 271, and 281 and a radar detection component, respectively. The wireless network communication devices (WNEs) 261, 271, and 281 preferably include transceivers, which may include transceivers coupled to one or more antennas (e.g., 121, 131, and 141). Towers 120, 130, and 140 are preferably equipped with one or more associated antennas (e.g., 121, 131, 141) and may include an antenna array supported thereon. The system can be implemented using a communication system disclosed in my U.S. patent application cited herein, such that the transceivers and transmitting antennas of those sky UAV communication systems can be used in conjunction with a radar detection system, and preferably with a radar detection assembly.

[0049] Towers 120, 130, and 140 are preferably equipped with or associated with corresponding communication equipment, such as transceivers, antennas, power supplies, and other equipment for generating and receiving cellular communications. Figure 1 In the exemplary depiction shown, each tower 120, 130, 140 is configured with an RF generating device, such as a wireless network datagram RF transceiver (WNE) 261, 271, 281 associated with each corresponding antenna (or antenna array) 121, 131, 141. The wireless network datagram RF transceiver (WNE) preferably includes a means for transmitting data over a communication network (e.g., Figure 1 Network 1000, and Figure 2 The device (part 1000') includes components for generating and receiving signals, and devices for network communication (e.g., UAV 1051, configured with its own transceiver equipment to enable it to receive and / or transmit signals and datagrams). Wireless network datagram RF transceiver (WNE) (see, for example, 261, 271, 281) preferably includes signal processing and generation components and provides signals to multiple associated antennas 121, 131, 141 radiating signals upwards in a skyward direction for communication with UAV 1051. The signals are preferably radiated in a conical pattern towards the sky, and the sky-conical beams 220, 230, and 240 are depicted to represent the signal coverage area. The radiated signal is generated to provide continuous coverage of the airspace above the ground 2000. This can be achieved by positioning or tuning the antennas to generate the desired coverage area. Figure 1The area between arrows A and B represents a continuous radar coverage area 2000, positioned at an elevated level relative to the ground, and is shown in an exemplary embodiment formed by conical beams 220, 230, and 240 (particularly by the overhead regions of these cones). The overhead region 2000 is preferably positioned within the area representing the radar coverage area (between arrows A and B in the figure), where the presence of low-flying objects can be detected.

[0050] like Figure 1 and Figure 2 As shown, the RF signal is directed upwards towards the sky. In the example shown, radiated signals 220, 230, and 240 propagate from associated antennas (or antenna arrays) 121, 131, and 141, respectively, which in this depiction originate from a mobile phone tower system including corresponding mobile phone towers 120, 130, and 140. The signals are radiated upwards and are preferably controllable to provide suitable signal strength for communication with and / or reflection by devices in area 2000.

[0051] A radar detection mechanism is illustrated in conjunction with a cellular network communication system. The illustrated cellular communication system is used for communication with a UAV and preferably includes a sky-projected cellular system. The sky-projected cellular communication system can provide a separate frequency or band for communication of the UAV's command, control, and / or navigation functions (as well as another frequency or frequency range for other types of UAV communication, such as camera operation and feeds). Figure 1 The illustration shows a radar detection mechanism integrated with a cellular communication setup. The radar detection mechanism is preferably configured with an antenna or antenna array for receiving signals, and a radar processor for processing the signals. Figure 1 An exemplary embodiment of the system is shown, including a radar detection mechanism 210 for detecting sky objects such as UAVs and other objects. The radar detection mechanism 210 is shown in conjunction with a first communication tower (e.g., cell phone tower 120), where a signal detection receiving antenna 221 and an associated radar processor 222 are provided. The signal detection receiving antenna 221 preferably includes an RX antenna or antenna array (e.g., receiving antenna 221a or antenna array 221b) that receives RF signals generated by WNE 261 and transmitted from one or more antennas 121, and includes reflected signals or echoes from objects. Preferably, antenna 221 is dedicated to radar detection functionality. The RX antenna or antenna arrays 221a, 221b (for radar functionality only) may be located on or near the same structure (e.g., tower 120) used for WNE antennas or planar phased array antennas. Antenna 221 may be located on or near a tower used for wireless networks (WNE). For example, in Figure 1In this system, the system is used in conjunction with a wireless communication network. Tower 120 is shown having multiple antennas 121 or antenna arrays for wireless communication over the network (e.g., between the network and communication devices), and also has a radar antenna 221 supported on tower 120. Additional antennas 231, 241 on each tower 130, 140 are shown together with corresponding associated radar processors 232, 242, which are preferably configured to operate in conjunction with corresponding WNEs 271, 281. The radar mechanism is configured to detect UAVs and low-flying objects. According to a preferred embodiment, the radar tracking system utilizes network 1000 to transmit signals to provide radar functionality. Radar antennas 221, 231, and 241 can be supported on cell towers 120, 130, and 140 and configured to operate in conjunction with associated cellular communication components (e.g., WNE 261, 271, and 281), which relay signals for communication exchange between transmission and / or reception components of a communication network 1000 (e.g., according to some embodiments, a communication network for communicating with UAVs and command and control computers).

[0052] In addition to the WNE and radar antennas 221, 231, and 241, the radar detection mechanism preferably includes associated radar processors 222, 232, and 242, respectively. The radar processors may be configured with instructions for monitoring signals transmitted from the associated WNE (e.g., WNE wireless transceivers). According to a preferred configuration, the radar processors (222, 232, 242) are associated with cell phone towers (120, 130, 140) and provide detection within the tower's range, for example, in the propagation area represented by the corresponding signal cones 220, 230, and 240 generated by the tower antenna arrangements 121, 131, and 141 (see [link to tower antenna arrangement]). Figure 1 Each radar processor 222, 232, 242 is configured to generate or monitor data transmitted through transceiver-related antennas (e.g., Figure 1 The signal propagated by the antenna 121 on the central tower 120 is represented by dashed line 300 and, as shown, reflected upon encountering an object, such as UAV 1051 in the exemplary depiction. The reflected wave, also referred to as an echo (represented by dashed line 301), is collected by antenna 221, which in this embodiment is a receiving antenna configured to receive the reflected signal (shown as reflected from UAV 1051). UAV 1051 may be configured with reflectors, such as corner reflectors, to enhance the reflected signal by amplifying its return to the radar node. Radar processor 222 receives the reflected signal or echo 301. Radar processor 222 is preferably configured with a computing unit capable of receiving, storing, and processing data to detect objects (e.g., low-flying objects) in the airspace monitored by the radar agency.

[0053] exist Figure 1The diagram illustrates a cellular communication network 1000 (or a portion thereof) configured to provide communication to low-flying objects (e.g., UAVs) via a sky system. A radar system is distributed across a network of ground-based communication transmitters, which preferably include components of network 1000. The signal source components of the radar system can be configured to effectively approach targets such as UAVs and other low-flying objects to be detected by the system. A sky radar detection system is shown in an exemplary illustration configured with a coverage area 2000. Objects within this area can be tracked. For example, in… Figure 1 In the illustration, an object, represented as bird 1060, is shown in a continuous coverage area 2000, located within a conical beam 230 generated by a wireless network datagram RF transceiver (WNE) 271, associated with a tower 130 and an arranged antenna 131. An associated radar processor 232 is shown, which receives data, preferably including a copy of the signal transmitted by the WNE 271. The system is preferably configured to generate a signal within a transmission area; for example, the area represented by the cone 230 may include brief communication bursts, recorded by a receiving antenna 231 located near the periphery, and monitored by processing and / or monitoring components (e.g., radar processor 242). In the illustrated embodiment, a signal 302 is transmitted from a transmitter (e.g., the transmitter of WNE 251) and encounters bird 1060 in area 2000. Signal 302 contacts bird 1060, and signal or echo 303 is reflected by bird 1060. The reflected signal 303 is collected by the receiving antenna 231 and can be used by the radar processor 232. The radar processor now has copies of the signal transmitted from WNE 251 and the echo signal 303.

[0054] According to the preferred embodiment shown, the system is configured to operate over a communication network, and preferably over a distributed cellular communication network. The system preferably includes an aggregation computing component, such as an aggregation tracking computer 280. The aggregation tracking computer 280 is preferably electronically connected to receive data, which may be in the form of signals associated with the propagation and reception of detection signals, or byproducts of such signals. The aggregation tracking computer 280 is preferably configured to function as a central computing resource among multiple nodes in the network communication system. For example, the aggregation tracking computer 280 may be associated with multiple nodes in a region to provide area tracking of objects, such as UAVs and other low-flying objects. The aggregation tracking computer 280 receives and manages detection information through network 1000, and, as shown, provides signal data from network nodes 1000', 1000", and 1000"'.

[0055] refer to Figure 2An exemplary embodiment is illustrated, depicting a node 1000' of a radar detection system 1000 for detecting and monitoring UAVs and other low-flying objects in a sky area or region. In the depicted system, a communication system for communicating with UAVs by radiating signals upwards from an antenna system is shown. Node 1000' is shown, comprising a tower 120 configured with an antenna 121 and a wireless network datagram RF transceiver (WNE) 261. The WNE 261 is preferably part of the communication network 1000 and is electronically coupled to exchange information, such as communications and other data on the communication network 1000. Node 1000' is shown as part of a tracking system. Figure 1 The diagram illustrates three nodes: a first node 1000', a second node 1000"", and a third node 1000"'". Nodes 1000', 1000"", and 1000"' comprise a communication network 1000 and are preferably arranged to provide coverage over a designated or desired coverage area. Preferably, the nodes are arranged such that coverage of the sky area 2000 exists in the area to be monitored. Figure 1 The image depicts three regions formed by corresponding cones 120, 130, and 140. The system is preferably configured to include additional towers and WNEs to provide extensions on the network (in addition to those provided by...). Figure 1 (Outside the areas covered by the three nodes in the system). A computing unit preferably arranged with a transceiver (which may be part of or associated with WNE 261) is configured to generate RF communication signals transmitted from antenna 121 and propagating in a skyward direction. This can be implemented as part of a cellular communication network, and more specifically, as the skyward directional communication system disclosed in my prior application cited herein. The radar detection system can be implemented by incorporating components of an existing cellular system (and a cellular system configured to communicate over a skyward communication area).

[0056] The system is configured to monitor signals transmitted from antennas. Transmitting antennas 121, 131, and 141 preferably provide RF signals from corresponding associated WNEs 261, 271, and 281. The signals propagate upwards in a skyward direction. Preferably, a signal cone is generated to provide multiple narrow areas of skyward directional coverage, which avoid or can operate around structures. Preferably, the signal is propagated to provide detection coverage of multiple smaller areas, which can be aggregated to provide extended coverage. Preferably, a signal of suitable strength is generated to reach the area where the UAV operates (and where other objects that need to be detected may be present). A transmission signal is generated. The transmission signal is transmitted to antenna 121 to radiate the signal upwards, and a copy of the signal is also transmitted to radar processor 222. Therefore, radar processor 222 receives the signal and provides the signal generation time. In practice, numerous signals and signal copies (including their generation time, frequency, modulation data (and other attributes)) are generated and monitored by radar processor 222. Radar processor 222 is preferably connected to receive signals from receiving antenna 221. A receiving antenna 121 is configured to receive signals generated by the receiving antenna 121, including signals that can be reflected from an object (e.g., UAV 1050 (or other objects within the detection area)). The reflected signal 301 is processed and compared with a generated copy of the signal (provided to the radar processor (e.g., from WNE 261)). The reflected signal received at the receiving antenna can be received along with other signals. The signals received from the receiving antenna (e.g., antenna 221) are processed to distinguish the reflected signals or echoes expected to be generated by the presence of a flying object within the detection zone. For example, a copy of the signal is provided to the radar processor with consecutive time frames (even when no reflected signal is received (or no signal indicating the presence of an object is received), e.g., for a specific duration), or for a given signal frequency, the radar processor continues its monitoring state. However, in the case of receiving a reflected signal from a sky object, the radar processor identifies the object detection and can further process that signal along with other signals used to indicate the object's position and movement. Even when processing the detection of reflected signals and identifying detected objects, the radar detection system is preferably configured to continue monitoring the signal. The radar processor can identify more than one object within the sky area covered by the node (or other areas covered by the designated radar processor). According to some embodiments, the system can be configured to use the same frequency as the communication to the UAV. For example, when preparing to transmit communication from antenna 121 to UAV 1051 operating within area 2000 in the sky direction (e.g., on a subband for payload applications (e.g., imaging, transmission, etc.), or on another designated subband reserved for critical UAV operational communications (e.g., command, control, and navigation functions), the radar processor can also receive a copy of the signal.The signal is generated by a wireless network device (WNE) and is preferably radiated from antenna 121 at a specific frequency and as a copy of the signal provided to radar processor 222. Radar processor 222 is preferably a passive radar processor and can be configured to process the signal information according to any of a variety of well-known methods. Embodiments of the radar processor (such as radar processor 222) may include computing components, such as processors, microprocessors, controllers, microcontrollers, microchips, or other processing circuitry, and storage media, such as flash memory or other memory chips, hard disk drives, etc., for storing processing instructions used to instruct the processor to execute the processing of the signal received by the receiving antenna. Radar processor 222 is preferably configured to store raw or processed signal information and / or transfer such information to another computing component for further processing or for storage. For example, ... Figure 1 The illustration shows three radar processors 222, 232, and 242, associated with nodes and WNEs of the sky network. The radar processors 222, 232, and 242 are connected for communication with a computer identified as an aggregation tracking computer 280. The tracking computer 280 can receive raw data from the radar processors 222, 232, and 242, or, according to some embodiments, processed or partially processed signal data. The aggregation tracking computer 280 is preferably capable of identifying sky objects, such as UAVs and other low-flying objects within the sky area of ​​the monitored network. The aggregation computer 280, either alone or in conjunction with another computing component, can manage airspace to provide alerts when potential hazards are encountered (e.g., when objects are close to each other; see also UAV 1051 approaching bird 1060, see also UAV 1051). Figure 1 Radar tracking systems can operate in conjunction with UAV traffic control systems and can be integrated with automated air traffic control systems that control or manage the operation of autonomous UAVs. Radar systems can be configured to process radar signals to provide alerts or management of UAVs, which may include manipulating or controlling UAV operations (e.g., flight path, direction, speed, etc.), including the detection of potential threats or risks (e.g., nearby balloons or birds). For example, when it is determined that a UAV's flight path coincides with another nearby object (which may be moving or stationary within the UAV's flight area), UAV air traffic control may hover it.

[0057] Radar processing of signal information received from receiving antennas 221, 231, and 241 can be performed according to known methods for radar signal processing. According to an exemplary embodiment, a passive radar processor (such as any of those radar processors 222, 232, and 242) is configured to receive signal information from antennas (such as...) Figure 1 and Figure 2The radar system (221a or 221b, 231, 241) receives signals and manipulates the information to generate information about the position, size, and movement of objects within a monitored sky area. This information provides object detection and also provides object tracking as the object moves within the area. The motion of sky objects, including their direction and speed, can be determined by the radar detection system. The detection system can also be used to provide information about the objects themselves and to differentiate and / or identify the type of object or possible object types. For example, a signal pattern can be identified to correspond to a UAV, while other signal patterns can identify the object as a bird. The system is preferably configured to process signal information and can be set with patterns corresponding to expected objects to be detected, such as UAVs, birds, balloons, etc. One or more identification patterns can be stored as references for specific objects. A database of signal patterns can be generated based on expected or previous detections of known objects within the area. When the radar system receives reflected signals from the receiving antenna, it can query the database for matching. Preferably, this is performed by a processing component, such as a radar processor (e.g., 222, 232, 242) or an aggregation tracking computer 280.

[0058] Figure 3 An example of a method that can be implemented by combining radar processing with signals received by the receiving antenna is shown. For example... Figure 3 As shown, the antenna array (box 400) is illustrated to represent multiple antennas. For example, the multiple antennas may be combined. Figure 1 The system depicts antennas such as receiving antennas 221, 231, 241 (and) Figure 2The receiving antenna or array 221a, 221b is shown in the diagram. According to some embodiments, the antenna array can be a simple array consisting of several antenna elements and element-level digitization. Digital beamforming (block 401) is performed to determine the direction of arrival of the received signal. Standard radar beamforming techniques can be used to calculate the direction of arrival of the reflected signal or echo. Although multiple antenna elements are shown, according to some embodiments, a pair of antenna elements can be used, and the phase difference of arrival is used to determine the direction of arrival of the echo. According to some embodiments, a phased array antenna can be used. The received signal preferably undergoes signal conditioning (block 402). Furthermore, a copy of the transmitted signal can also be conditioned (block 403). Signal conditioning can be performed before cross-correlation processing to manipulate certain portions of the signal (block 406). Signal conditioning (blocks 402, 404) can be performed to improve the signal-to-interference ratio (SIR). Although the beamformer (block 401) is depicted separately, it can include a portion of the signal conditioning. The radar processor is preferably configured with an adaptive filter. Preferably, the adaptive filter is used to manipulate the signal to remove direct signals. Adaptive filtering can also be referred to as adaptive cancellation (block 405). According to some embodiments, adaptive filtering is performed, for example, by examining the correlation characteristics of received data across channels. In this way, the presence of interference and clutter entering the antenna pattern sidelobes can be identified. Channels can be combined according to a set of weights to provide the antenna with a high-gain main lobe and generally low sidelobes. Adaptive filtering can also combine channels and provide weights to generate nulls in the antenna pattern at the jammer's angle of arrival. In the radar processing example shown, the processing may include cross-correlation processing (block 406). Cross-correlation processing (block 406) is designed to measure the similarity of two series as a function of hysteresis relative to the other. In the radar processing example, cross-correlation (block 406) provides estimates of the bistatic range and bistatic Doppler shift of each target echo. Cross-correlation acts as a matched filter. This can be achieved by providing a set of matched filters, each matched to a different target Doppler shift. Small unit average constant false alarm rate (CAFR) algorithm processing is implemented (block 407). CAFR detection (block 407) is designed to detect targets. An adaptive threshold is applied to detect targets on the cross-correlated surface. The radar processor can be configured to implement CFAR detection, such that all echoes above the cross-correlated surface are considered detected targets. Preferably, targets (such as UAVs and other low-flying objects) are tracked throughout the entire time, thus allowing information about their motion, direction, and velocity to be determined. For example, in cases where objects such as UAVs, birds, or balloons are moving within the monitored sky area, frequency shifts (e.g., Doppler effect) in echoes reflected from these moving objects can be observed and detected.This information can provide the location of low-flying objects, such as UAVs, birds, etc., as well as the direction and speed at which the object is moving. Preferably, for each transmitter in the system, or the aggregation of each transmitter in a portion of the monitored network area, line tracing is performed by a line tracker (blocks 408a, 408b, 408c (representing the line tracker for the respective transmitter)). See, for example, reference. Figure 1 Transmitters 261, 271, and 281 preferably provide signals associated with the respective line trackers 408a, 408b, and 408c. The radar processor can be configured to perform line tracking of target returns from the respective targets. This is preferably performed over time in a range-Doppler space generated by cross-correlation processing (box 406). Tracking association and trajectory estimation (box 409) are performed to determine the position of a UAV or other low-flying object. Tracking association can be performed using a single transmitter and a single receiver, or, according to some embodiments, multiple receivers can be used to perform tracking association, where an object (such as a UAV or other object) may be detected by each receiver and associated with one or more transmitters. Although an exemplary embodiment is shown with multiple nodes and references are made to a transmitter associated with each depicted receiver node, the system can be configured such that multiple receivers are used to receive signals propagated and reflected from a single tower antenna by the transmitter and to process the received signals to determine which targets returned by one transmitter correspond to those signals on the other receivers. The associated signal returns are used to determine the object's position by using signal information provided by the reflected signals received from one or more receivers. The processed signal data generates a target track (box 310) and provides indications of the direction, velocity, and position of the UAV (or other object). This is thus an example of radar processing, and other radar processing methods can be used to process signal data generated from a network system and provide UAV localization and tracking.

[0059] like Figure 2 As shown, the signal ray trajectory 306 is illustrated. The signal or ray 305 from transmitter 121 encounters an object, namely UAV 1051 within the coverage area. Figure 2 In China, UAV 1051 has already been removed from its... Figure 1The positional movement is represented in the diagram. For reference, the UAV is within the sky area represented by signal cone 220. According to one example, ray tracing can be implemented to track the movement of an object (e.g., UAV 1051). Upon reaching UAV 1051, some portions of signal ray 305 may be absorbed or otherwise scattered. Signal ray 306 represents the signal reflected from UAV 1051 (a portion of the reflected ray 305), which can be received by receiving antennas 221a or 221b. Radar processor 222 preferably knows signal ray 305 by receiving a copy of signal 310. Although a representative signal ray 305 and a reflected signal ray 306 are shown, multiple signal rays can be emitted within area 220, each reflected signal ray trajectory can be identified, and this process can be repeated to derive the path of UAV 1051.

[0060] According to a preferred embodiment, the system is implemented in conjunction with a wireless network device for a sky communication system. For example, a transmitter may emit a transmission signal, which may include a continuous wave signal that, after being radiated onto and reflected from an object, is detected by a receiving antenna associated with a radar processor. According to a preferred embodiment, the transmission signal is an RF signal provided for cellular communication (e.g., transmission from a sky-oriented transmitter / antenna to a UAV). According to a preferred embodiment, the radar processor receives a copy of the transmission signal (which may be referred to as the direct signal) and also (via the associated receiving antenna) the signal reflected from the object. The reflected signal is not direct (and may be considered diffuse). The radar processor is configured to receive and distinguish between the signals (direct and reflected). Signal attributes (e.g., transmission time, reception time, frequency, and modulation data) are obtained by the radar processor and analyzed to provide detection results. While an object (e.g., a UAV or bird) remains within the detection area where the transmission occurs, the radar processor continues to receive the reflected signal and can monitor and track the object's movement and position. The detection area may include multiple detection areas to track objects throughout the area. A radar processor can be configured as part of a network to provide information to radar system components, which may be aggregated computers networked with the radar processor. Alternatively, several radar processors can be provided on a node, and the node's radar processors can be aggregated with those of other nodes.

[0061] According to some embodiments, the arrival time of a signal can be determined and used to provide a radar detection response. Embodiments can configure a radar processor to process the signal, thereby separating it. For example, in the case of the movement of an object such as a UAV or bird, the movement of the object can cause a Doppler frequency shift in the reflected or scattered signal from the UAV or bird. This frequency shift facilitates frequency separation of the two signals. Radar processing can be performed according to processing methods used for detecting and evaluating the signal. Signal differentiation provides a method for determining the presence of objects in a sky region.

[0062] According to embodiments of the system, transmission can utilize a transmission code applied to a radio frequency carrier of the transmitter. The code can be provided as a series of discrete transmitter phase levels. The code can be a random code of pseudo-random code, as they can be repeated after L bits. Transmission can include codewords or sequences of length L bits that are periodically repeated based on the number of N-stage shift registers. For example, for L bits, for N-stage shift registers, the expression could be L = 2^N–1. According to one embodiment, a clock pulse generator is provided and configured to feed the encoder shift registers. For example, each time a clock pulse is applied, the number of stages in the shift register can shift by one stage (e.g., shift to the right when considering a linear representation). According to a preferred embodiment, the code including the pseudo-random code is provided along with the RF transmission of the carrier from the transceiver of the WNE.

[0063] Although a radar processor is shown in the depiction, it can be provided as a standalone component or in combination with one or more distributed network hardware. Figure 3 One embodiment is shown, but the passive radar processor can be adapted to other methods besides... Figure 3 Manipulate the received signal using any of the various methods other than those shown.

[0064] Embodiments of this system utilize radiated communication transmissions to communicate with UAVs within the coverage area. According to some alternative embodiments, alternative implementations can be provided to generate information when there is no radiated communication transmission, for example, in the absence of UAVs within the coverage area. In this alternative implementation, the system can enable a sky-pointing communication system to transmit regular transmissions to the sky even when there are no regular communication transmissions to UAVs. According to alternative embodiments, the transmitter can transmit periodic or regular transmissions to the sky. These can be generated by a sky-pointing communication system. According to some embodiments, regular transmissions can be emitted if there are no UAV communication transmissions within a set time period. According to some alternative embodiments, regular transmissions can be generated when there are no communication transmissions from the transmitter within a predetermined time period. The alternative system can also be configured to receive signals from a radar detection component, for example, when a regular transmission results in a positive detection of an object in a sky area or zone by the radar processor. Once a notification signal detected by the radar processor is received, the transmitter can continue to transmit regular transmissions to monitor the detected object. Regular transmissions can be emitted, or continuous signal waves can be radiated such that the radar processor can receive echoes from the detected object as it remains within and / or moves through the detection zone. Therefore, when an object moves out of the area and there is a period of inactivity, the system can revert to periodic transmissions until another object is detected. According to these alternative implementations, a copy of the periodic transmissions can be sent to an associated radar processor. The radar processor processes the signal received from the receiving antenna and the copy of the periodic transmissions to determine the presence of an object (e.g., a bird (or other non-communication object)) in the area.

[0065] These and other advantages can be achieved using this invention. Although the invention has been described with reference to specific embodiments, this description is exemplary and should not be construed as limiting the scope of the invention. Various modifications and variations will occur to those skilled in the art without departing from the spirit and scope of the invention as defined herein and in the appended claims.

Claims

1. A method for detecting a low-flying object including at least one UAV, the method comprising: a) Operating a wireless network device to generate RF signals and radiate RF signals toward the sky, wherein the wireless network device includes a transmitter and at least one transmitting antenna is coupled to the wireless network device and radiates signals toward the sky; b) Receive signals reflected from low-flying objects, including at least one UAV, using at least one receiving antenna; c) Transmitting RF signals from a wireless network device to a radar processor, the radar processor being electrically coupled to the wireless network device to receive RF signals, and providing the radar processor with RF signals reflected from a low-altitude flying object including at least one UAV, received by a receiving antenna, the radar processor being electrically coupled to the receiving antenna to receive RF signals. d) Multiple radar processors are distributed throughout the network covering the entire coverage area; e) By aggregating information received from multiple radar processors distributed throughout the coverage area, the computing unit is operated to detect low-altitude flying objects over the coverage area and to detect and track the presence of low-altitude flying objects over the coverage area. f) Transmit RF signals broadcast from the transmitting antenna and radiated into the sky using the transmitter of a wireless network device, and provide copies of the RF signals to one or more of a plurality of radar processors; g) Transmitting RF signals generated by a wireless network device to at least one UAV to provide command, control, or navigation functions to at least one UAV, wherein the RF signals transmitted to at least one UAV to provide command, control, or navigation functions to at least one UAV are the same as the RF signals used as radar detection signals and are the same as the RF signals provided as a copy to the radar processor; and h) Wherein the transmitted RF signals reflected from an object include communications transmitted from a wireless network device to at least one UAV; as well as i) Using RF communication as a radar signal to command, control, or navigate at least one or more UAVs, and j) Provide a copy of the RF communications transmitted to at least one UAV to one or more of a plurality of radar processors for commanding, controlling, or navigating at least one UAV, and k) The RF communications transmitted to the UAV for commanding, controlling, or navigating the UAV are also radar signals, which are used to detect the UAV and / or other objects in the coverage area by reflection from the UAV and / or other objects in the coverage area. l) Receive echoes using a receiving antenna, wherein the echoes are RF communications transmitted to the UAV that are reflected from the UAV and / or other objects in the coverage area.

2. The method of claim 1, wherein the wireless network device includes a transceiver, a power supply, and a signal processing and generation component, the signal processing and generation component being used to process communications transmitted and received over the network.

3. The method of claim 1, wherein at least one of the transmitting antenna and the receiving antenna comprises an antenna array, and wherein the array of transmitting antennas is used to broadcast RF signals to the sky, and the array of receiving antennas receives signals reflected from a low-flying object comprising at least one UAV.

4. The method of claim 1, wherein at least one of the transmitting antenna and the receiving antenna comprises a phased array, and wherein the phased array of the transmitting antenna broadcasts RF signals to the sky, and the phased array of the receiving antenna receives signals reflected from a low-flying object comprising at least one UAV.

5. The method of claim 1, wherein at least one UAV includes a corner reflector, and the reflected RF radiation reflected from the corner reflector of at least one UAV is detected by detecting RF signals through a receiving antenna.

6. The method of claim 1 further includes polarizing the generated RF signal in a circumferential direction and polarizing the receiving antenna in a circumferential direction opposite to the generated RF signal to reduce interference and improve response capability.

7. The method of claim 1, further comprising forming a plurality of nodes to generate RF signals.

8. The method of claim 7, further comprising configuring a plurality of nodes to provide a signal to each of the plurality of nodes to indicate the presence of an object in one or more regions of the respective node.

9. The method of claim 1 further includes forming a plurality of detection regions and detecting and tracking objects within the plurality of detection regions.

10. The method of claim 9, wherein the generated RF signal is polarized in one circumferential direction, and each receiving antenna is polarized in the opposite circumferential direction.

11. The method of claim 9 further comprises operating the UAV traffic control system by tracking information of low-flying objects within the detection area, and managing the operation of one or more UAVs, including at least one UAV, by using the tracking information to reduce potential collisions with other UAVs and other objects detected within the detection area.

12. The method of claim 10 further comprises operating the UAV traffic control system by tracking information of low-flying objects within the detection area, and managing the operation of one or more UAVs, including at least one UAV, by using the tracking information to reduce potential collisions with other UAVs and other objects detected within the detection area.

13. The method according to claim 1, further comprising encoding and modulating the generated RF signal.

14. The method of claim 13, wherein the code of the encoded modulated RF signal includes code from transmission to at least one UAV for signal communication.

15. The method of claim 14, wherein the code is provided from the transmitter to at least one transmitting antenna and a radar processor.

16. The method of claim 14, further comprising connecting the transmitter to provide the code to the radar processor.

17. The method of claim 14, further comprising connecting the transmitter to provide the code to a plurality of radar processors within the transmission and echo range of the transmitter.

18. The method of claim 1, further comprising using a plurality of radar processors to receive copies of transmitted RF signals broadcast from a transmitter.

19. The method of claim 18, further comprising processing the phase difference between the detected reflected signal and a copy of the signal received from the transmitter.

20. The method of claim 1, further comprising applying a code to the transmitter frequency carrier.

21. The method of claim 1, further comprising applying a code to a transmitter frequency carrier, the code comprising a pseudo-random code.

22. The method of claim 21, wherein the method includes generating a pseudo-random code of length L bits, the pseudo-random code being periodically repeated based on a series N of multiple shift registers, wherein for the series N of multiple shift registers, the expression for determining L bits is L = 2^N–1.

23. The method of claim 20, further comprising providing the relevant radar processor with code for sky-transmission as part of a transmission copy.

24. The method of claim 1, further comprising a wireless network device supported on a tower.

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