Back to results
US 6,727,841 B1Granted
Position-adaptive UAV radar for urban environments
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorAtindra Mitra
Life of this patent
Estimating the term…
Abstract
Bistatic/multistatic radar system concept for purposes of interrogating difficult and obscured targets in urban environments via the application of low-altitude “smart” or “robotic-type” unmanned air vehicle platforms. A significant aspect of the invention is the formulation of a unmanned air vehicle system concept that implements self-adaptive positional adjustments based on sensed properties such as phase discontinuities of the propagation channel.
Claims12
A multi-mode, radar method for detecting targets in urban environments comprising the steps of:
- transmitting an electromagnetic signal from a high altitude unmanned air vehicle to an urban environment including between buildings;
- receiving by a low altitude unmanned air vehicle a plurality of electromagnetic rays from said electromagnetic signal from said transmitting step, said electromagnetic signal diffracting and reflecting off buildings in said urban environment, an electric field at said low altitude unmanned air vehicle defined as E r = E t A t ∑ s = 1 S ( ∏ m s M s A R R _ ) ( ∏ n s N s A D D _ ) exp ( - jkd s )
- Er is the received electric field
- Et is the transmitted electric field
- S is the number of signal paths from transmitter to receiver
- {overscore (R)} is the reflection coefficient at Ms reflection points in the s_th signal path
- {overscore (D)} is the diffraction coefficient at Ns diffraction points in the s_th signal path
- At is the spatial attenuation factor from transmitter to first reflection point
- AR is the spatial attenuation factor for reflection points
- AD is the spatial attenuation factor for diffraction points
- ds is the length of s_th signal path;
- compensating for phase deviation in said electromagnetic signal transmitted from said high altitude unmanned air vehicle and received by said low altitude unmanned air vehicle;
- determining signal differential path lengths by measuring the phase difference between high altitude unmanned air vehicle electromagnetic signals and electric field phase measurements at said low altitude unmanned air vehicle, said signal differential path lengths indicating an obstruction embedded within said urban environment;
- and
- monitoring said signal differential path lengths and said low altitude unmanned air vehicle converging to a vicinity of said obstruction.
12 more elements
A multi-mode radar device for detecting targets in urban environments comprising:
- a high altitude unmanned air vehicle for transmitting an electromagnetic signal to an urban environment including between buildings;
- a low altitude unmanned air vehicle receiving a plurality of electromagnetic rays resulting from said electromagnetic signal diffracting and reflecting off urban buildings;
- means for phase deviation determination between said electromagnetic signal transmitted from said high altitude unmanned air vehicle and received by said low altitude unmanned air vehicle;
- means for determining signal differential path lengths by measuring the phase difference between high altitude unmanned air vehicle electromagnetic signals and electric field phase measurements at said low altitude unmanned air vehicle, said signal differential path lengths indicating an obstruction embedded within said urban environment;
- and
- means for processing said signal differential path lengths whereby said low altitude unmanned air vehicle converges to a vicinity of said obstruction.
3 more elements
A multi-mode, radar method for detecting targets in urban environments comprising the steps of:
- transmitting an electromagnetic signal from a high altitude unmanned air vehicle to an urban environment including between buildings;
- receiving by a low altitude unmanned air vehicle a plurality of electromagnetic rays from said electromagnetic signal from said transmitting step, said electromagnetic signal diffracting and reflecting off buildings in said urban environment, an electric field at said low altitude unmanned air vehicle defined as E r = E t A t ∑ s = 1 S ( ∏ m s M s A R R _ ) ( ∏ n s N s A D D _ ) exp ( - jkd s )
- Er is the received electric field
- Et is the transmitted electric field
- S is the number of signal paths from transmitter to receiver
- {overscore (R)} is the reflection coefficient at Ms reflection points in the s_th signal path
- {overscore (D)} is the diffraction coefficient at Ns diffraction points in the s_th signal path
- At is the spatial attenuation factor from transmitter to first reflection point
- AR is the spatial attenuation factor for reflection points
- AD is the spatial attenuation factor for diffraction points
- ds is the length of s_th signal path;
- compensating for phase deviation in said electromagnetic signal transmitted from said high altitude unmanned air vehicle and received by said low altitude unmanned air vehicle;
- determining signal differential path lengths by measuring the phase difference between high altitude unmanned air vehicle electromagnetic signals and electric field phase measurements at said low altitude unmanned air vehicle, said signal differential path lengths indicating an obstruction embedded within said urban environment;
- monitoring said signal differential path lengths and said low altitude unmanned air vehicle converging to a vicinity of a channel embedded with an obstruction;
- close range interrogating of said obstruction by said low altitude unmanned air vehicle with on-board low power active radar;
- generating a signal signature from said embedded obstruction as a function of said high altitude unmanned air vehicle transmitter angle by said high altitude unmanned air vehicle flying a fast trajectory, and
- computing electric field at said low altitude unmanned air vehicle based on said signal signature.
14 more elements
Dependencies are inferred from the claim text.