RADAR SYSTEM

• US 20100265122A1
• Filed: 05/29/2008
• Published: 10/21/2010
• Est. Priority Date: 05/29/2007
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Aveillant Limited (Thales SA)
• Inventors: Oswald, Gordon Kenneth Andrew
• Granted Patent: US 8,860,604 B2
• Time in Patent Office: Days
• US Class Current: 342/136
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/951 ground based
• CPC Class Codes: G01S 2013/0263 Passive array antenna
• CPC Class Codes: G01S 7/414 Discriminating targets with respect to background clutter
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
• CPC Class Codes: Y02B 10/30 Wind power

Abstract

A radar system comprising a transmitter to transmit radar signals into a region, a receiver to receive return signals of said radar signals reflected from within the region wherein the transmitter and receiver are adapted for location on a structure at a wind farm, and a processor to process the return signals to extract wind farm associated data for said region.

Claims

1-157. -157. (canceled)

158. A radar system comprising:

a transmitter adapted to transmit radar signals into a region of a cluttered environment to illuminate said region with a signal modulated as a regular sequence of pulses at a given pulse rate;

a receiver adapted to receive return signals, of said radar signals, reflected from within said region, and representing observations;

and a processor adapted to process the return signals to extract data, including clutter related data, for said region;

wherein said processor is operable to integrate said return signals subject to a limit on the range and range rate associated with the observations that the return signals represent, within which limit said radar operates substantially unambiguously in range and range rate at said pulse rate.

159. A radar system as claimed in claim 158 wherein said receiver is operable to limit the delays at which said return signals are received thereby to limit said range in accordance with said limit on the range and range rate.

160. A radar system as claimed in claim 158 wherein the range and range rate are each limited:

in inverse proportion to an operating frequency of the radar system; and

/or in proportion to the square of the speed of light; and

/or in inverse proportion one another, in accordance with said limit on the range and range rate.

161. A radar system as claimed in claim 158 wherein said limit on the range and range rate is expressed by the inequality:

162. A radar system as claimed in claim 158 wherein said transmitter has a first aperture and said receiver has a second aperture, wherein said first aperture is smaller than said second aperture, for example wherein said receiver has a substantially larger total aperture than said transmitter.

163. A radar system as claimed in claim 162 wherein said receiver comprises a plurality of sub-arrays each of which has a sub-aperture of substantially equal size and shape to the first aperture.

164. A radar system as claimed in claim 158 wherein said transmitter comprises a static transmitter and/or wherein said transmitter is configured to do at least one of the following:

persistently illuminate said region;

persistently illuminate said region without being sequentially scanned or directed;

form multiple receiving beams;

illuminate said whole region with a broad beam;

illuminate a whole volume of interest simultaneously;

illuminate said region with a coherent signal modulated to permit range resolution; and

/or

illuminate targets in the region at a rate sufficient to exceed the Nyquist limit for Doppler shifts associated with the targets.

165. A radar system as claimed in claim 158 wherein said processor is configured to do at least one of the following:

assess the significance of an observation represented by a return signal only after data relating to the observation has been extracted, stored, and analysed;

classify a target represented by an observation only after data relating to the observation has been extracted, stored, and analysed;

identify observations of interest from said extracted data and to store historical data for said identified observations;

store extracted data representing an observation in process pixels each of which represents a unique set of attributes;

store a characteristic of a return signal representing an observation in an associated pixel;

form a plurality of beams by combining different signal channels with suitable amplitude and/or phase weightings;

determine the amplitude, frequency, delay and/or phase of said return signals using a signal which is coherent with the transmitted radar signal; and

/or

process signals received b a plurality of sub-arrays of receiving elements in a first data stream and a second data stream in parallel.

166. A radar system as claimed in claim 158 wherein said processor is configured to identify observations of interest from said extracted data and to store historical data for said identified observations, wherein said historical data comprises phase and/or amplitude histories.

167. A radar system as claimed in claim 158 wherein said processor is configured to identify observations of interest from said extracted data and to store historical data for said identified observations, wherein said historical data comprises a Doppler history.

168. A radar system as claimed in claim 167 wherein said processor is operable to discriminate between observations representing moving clutter (for example a wind turbine blade) and other observations, based on the Doppler history.

169. A radar system as claimed in claim 167 wherein said processor is operable to discriminate between observations representing moving targets (for example an aircraft) and other observations, based on the Doppler history.

170. A radar system as claimed in claim 167 wherein said processor is operable to discriminate between observations representing a surface wave, and other observations, based on the Doppler history.

171. A radar system as claimed in claim 158 wherein said processor is configured to identify observations of interest from said extracted data and to store historical data for said identified observations, wherein:

said processor is configured to form tracks for said targets based on processing and interpretation of said historical data; and

/or

said processor is configured to discriminate between significant and insignificant observations (and/or targets representing one class or another) based on said historical data.

172. A radar system as claimed in claim 158 wherein said processor is configured to store extracted data representing an observation in process pixels each of which represents a unique set of attributes, and wherein said attributes for each pixel comprise at least one of the following:

a combination comprising at least two of time, range, range rate and/or Doppler frequency for the associated observation; and

/or

at least one of beam number, sub-array number and/or element number for the associated observation.

173. A radar system as claimed in claim 158 wherein the processor is configured to store a characteristic of a return signal representing an observation in an associated pixel wherein:

said characteristic comprises at least one of amplitude, phase and frequency; and

/or

the observation represents one of a target, an item of clutter, or a ‘

null’

.

174. A radar system as claimed in claim 158 wherein the receiver comprises at least one array comprising a plurality of receiving elements (or sub-arrays), each receiving element being configured to receive signals from substantially a whole volume of interest, thereby forming an associated signal channel.

175. A radar system as claimed in claim 174 wherein the receiver comprises a plurality of said arrays (or sub-arrays).

176. A radar system as claimed in claim 158 wherein said processor is configured for at least one of the following:

forming a plurality of beams by combining different signal channels with suitable amplitude and/or phase weightings;

forming a plurality of beams having substantially a different look direction; and

/or

forming a plurality of apertures with beams having substantially the same look direction.

177. A radar system as claimed in claim 176 wherein said beams are formed for each of a plurality receiving elements and/or for each of a plurality of sub-arrays of receiving elements.

178. A radar system as claimed in claim 176 wherein said processor is configured for monopulse angular measurement using a plurality of said beams, for example wherein said monopulse angular measurement comprises phase monopulse angular measurement or amplitude monopulse angular measurement.

179. A radar system as claimed in claim 158 wherein said receiver comprises a planar array of receiving elements, or wherein said receiver comprises a non-planar array of receiving elements conformal to a known shape.

180. A radar system as claimed in claim 158 wherein said radar system is located at said wind farm and/or comprises a holographic radar.

181. A radar system as claimed in claim 158 wherein said processor is configured to process signals received by a plurality of sub-arrays of receiving elements in a first data stream and a second data stream in parallel;

and wherein each data stream is processed using different amplitude and/or phase weightings, for example;

wherein said amplitude and/or phase weightings used for the first data stream are configured to provide a null in a direction of a land or sea surface thereby to reject surface targets;

or

wherein said amplitude and/or phase weightings used for the first data stream are configured to provide a null in the direction of raised objects thereby to reject such objects in favour of surface targets.

182. A method of obtaining information by a radar system, the method comprising:

transmitting radar signals into a region of a cluttered environment to illuminate said region with a signal modulated as a regular sequence of pulses at a given pulse rate;

receiving return signals, of said radar signals, reflected from within said region, and representing observations; and

processing the return signals to extract data, including clutter related data, for said region, said processing step comprising integrating said return signals subject to a limit on the range and range rate associated with the observations that the return signals represent, within which limit said radar operates substantially unambiguously in range and range rate at said pulse rate.

183. A radar system comprising:

a transmitter adapted to transmit radar signals into a region of a cluttered environment, which cluttered environment comprises a wind farm, to illuminate said region and said wind farm with a signal modulated as a regular sequence of pulses at a given pulse rate;

a receiver adapted to receive return signals, of said radar signals, reflected from within said region, and representing observations; and

a processor adapted to process the return signals to extract data, including wind farm related data, for said region, whereby to discriminate between observations representing targets of interest such as aircraft and observations representing moving clutter such as wind turbine blades;

wherein said processor is operable to process said return signals, subject to a limit on the range and range rate associated with the observations that the return signals represent, within which limit said radar operates substantially unambiguously in range and range rate at said pulse rate.

184. A radar system comprising:

a transmitter adapted to transmit radar signals into a region of a cluttered environment to illuminate said region with a signal modulated as a regular sequence of pulses;

a receiver adapted to receive return signals, of said radar signals, reflected from within said region, and representing observations; and

a processor adapted to process the return signals to extract data, including clutter related data, for said region;

wherein said processor is adapted to identify observations of interest from said extracted data and to store historical data for said identified observations, said historical data including a Doppler history.

185. A radar system as claimed in claim 184 wherein said processor is adapted to discriminate between observations representing moving clutter (for example a wind turbine blade) and other observations, based on said Doppler history.

186. A radar system as claimed in claim 184 wherein said processor is adapted to discriminate between observations representing moving targets (for example an aircraft) and other observations, based on said Doppler history.

187. A radar system as claimed in claim 184 wherein said processor is adapted to discriminate between observations representing surface waves and other observations, based on said Doppler history.