# US 11,442,141 B2 · Systems and methods for detecting, monitoring, and mitigating the presence of a drone > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,442,141 B2 - Document ID: US11442141B2 - Status: Granted - Kind: B2 - Application number: 16/871,713 - Filed: 2020-05-11 - Published: 2020-11-12 - Granted: 2022-09-13 - Earliest claimed: 2019-05-12 - Assignees: SkySafe, Inc. - Applicants: SkySafe, Inc. - Inventors: Chun Kin Au Yeung; Brandon Lo; Scott Torborg - Web page: https://patentgrep.com/patent/US11442141B2 ## CPC - G01S 7/021: {Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals} - H04K 3/45: {characterized by including monitoring of the target or target signal, e.g. in reactive jammers or follower jammers for example by means of an alternation of jamming phases and monitoring phases, called "look-through mode"} - H04J 13/0062: {Zadoff-Chu} - H04K 3/28: {with jamming and anti-jamming mechanisms both included in a same device or system, e.g. wherein anti-jamming includes prevention of undesired self-jamming resulting from jamming} - H04K 3/65: {using deceptive jamming or spoofing, e.g. transmission of false signals for premature triggering of RCIED, for forced connection or disconnection to/from a network or for generation of dummy target signal} - H04K 3/92: {related to allowing or preventing remote control} - H04L 5/0007: {the frequencies being orthogonal, e.g. OFDM(A) or DMT} - H04K 2203/22: for communication related to vehicles - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - H04K: SECRET COMMUNICATION; JAMMING OF COMMUNICATION - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Systems and methods for detecting, monitoring, and mitigating the presence of a drone are provided herein. In one aspect, a system for detecting presence of a drone includes a radio-frequency (RF) receiver configured to receive an RF signal transmitted between a drone and a controller. The RF signal includes a synchronization signal for synchronization of the RF signal. The system can further include a processor and a computer-readable memory in communication with the processor and having stored thereon computer-executable instructions to cause the at least one processor to receive a sequence of samples from the RF receiver, obtain a double differential of the received sequence of samples, calculate a running sum of a defined number of the double differential of the received sequence of samples, and detect the presence of the drone based on the running sum. ## Claims ### Claim 1 A system for detecting presence of a drone, the system comprising: a radio-frequency (RF) receiver configured to receive an RF signal transmitted between a drone and a controller, the RF signal including a synchronization signal for synchronization of the RF signal; at least one processor; and a computer-readable memory in communication with the at least one processor and having stored thereon computer-executable instructions to cause the at least one processor to: receive a sequence of samples from the RF receiver, obtain a double differential of the received sequence of samples, calculate a running sum of a defined number of the double differential of the received sequence of samples, detect the presence of the drone based on the running sum, synchronize with the RF signal based on the running sum, determine a metric based on the running sum, wherein the metric is determined according to the following equation: γ fd ⁢ ⁢ 2 ⁡ [ k ] ⁢ = Δ ⁢ ∑ k = 2 P - 1 ⁢ Y dd ⁡ [ k ] , wherein Yfd2[k] is the metric, Ydd[k] is the double differential, and P is a length of the synchronization signal, and determine that the metric is greater than a threshold value, wherein the detecting of the presence of the drone is further based on the determination that the metric is greater than the threshold value. ### Claim 2 (depends on 1) The system of claim 1, wherein the synchronization signal comprises a Zadoff-Chu (ZC) sequence. ### Claim 3 (depends on 1) The system of claim 1, wherein the synchronization signal comprises a frequency domain sequence including guard bands. ### Claim 4 (depends on 1) The system of claim 1, wherein the computer-readable memory further has stored thereon computer-executable instructions to cause the at least one processor to estimate a root of the sequence of samples based on the metric. ### Claim 5 (depends on 4) The system of claim 4, wherein the synchronizing with the RF signal is performed using the estimated root. ### Claim 6 (depends on 1) The system of claim 1, wherein: the synchronization signal comprises a time domain sequence, and the running sum is normalized. ### Claim 7 (depends on 6) The system of claim 6, wherein the computer-readable memory further has stored thereon computer-executable instructions to cause the at least one processor to: determine that an absolute value of the normalized running sum is greater than a threshold value, wherein the detecting of the presence of the drone is further based on the determination that the absolute value of the normalized running sum is greater than the threshold value. ### Claim 8 (depends on 7) The system of claim 7, wherein the computer-readable memory further has stored thereon computer-executable instructions to cause the at least one processor to estimate a root of the sequence of samples based on the normalized running sum. ### Claim 9 A method for detecting presence of a drone, the method comprising: receiving a sequence of samples of an RF signal transmitted between a drone and a controller, the RF signal including a synchronization signal for synchronization of the RF signal; obtaining a double differential of the received sequence of samples; calculating a running sum of a defined number of the double differential of the received sequence of samples; detecting the presence of the drone based on the running sum; synchronizing with the RF signal based on the running sum; determining a metric based on the running sum, wherein the metric is determined according to the following equation: γ fd ⁢ ⁢ 2 ⁡ [ k ] ⁢ = Δ ⁢ ∑ k = 2 P - 1 ⁢ Y dd ⁡ [ k ] , wherein Yfd2[k] is the metric, Ydd[k] is the double differential, and P is a length of the synchronization signal; and determining that the metric is greater than a threshold value, wherein the detecting of the presence of the drone is further based on the determination that the metric is greater than the threshold value. ### Claim 10 (depends on 9) The method of claim 9, wherein the synchronization signal comprises a Zadoff-Chu (ZC) sequence. ### Claim 11 (depends on 9) The method of claim 9, wherein the synchronization signal comprises a frequency domain sequence including guard bands. ### Claim 12 (depends on 9) The method of claim 9, further comprising: estimating a root of the sequence of samples based on the running sum. ### Claim 13 (depends on 9) The method of claim 9, wherein: the synchronization signal comprises a time domain sequence, and the running sum is normalized. ### Claim 14 (depends on 13) The method of claim 13, further comprising: determining that an absolute value of the normalized running sum is greater than a threshold value, wherein the detecting of the presence of the drone is further based on the determination that the absolute value of the normalized running sum is greater than the threshold value. ### Claim 15 A non-transitory computer readable storage medium having stored thereon instructions that, when executed, cause a computing device to: receive a sequence of samples of an RF signal transmitted between a drone and a controller, the RF signal including a synchronization signal for synchronization of the RF signal; obtain a double differential of the received sequence of samples; calculate a running sum of a defined number of the double differential of the received sequence of samples; detect the presence of the drone based on the running sum; synchronize with the RF signal based on the running sum; determine a metric based on the running sum, wherein the metric is determined according to the following equation: γ fd ⁢ ⁢ 2 ⁡ [ k ] ⁢ = Δ ⁢ ∑ k = 2 P - 1 ⁢ Y dd ⁡ [ k ] , wherein Yfd2[k] is the metric, Ydd[k] is the double differential, and P is a length of the synchronization signal; and determine that the metric is greater than a threshold value, wherein the detecting of the presence of the drone is further based on the determination that the metric is greater than the threshold value. ### Claim 16 (depends on 15) The non-transitory computer readable storage medium of claim 15, wherein the synchronization signal comprises a frequency domain sequence including guard bands.