Radar system and method

• US 9,372,263 B2
• Filed: 12/03/2008
• Issued: 06/21/2016
• Est. Priority Date: 05/29/2007
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Cambridge Solutions Limited (DXC Technology Company)
• Inventors: Webster, Craig Duncan, Oswald, Gordon Kenneth Andrew, Smithson, Allan Geoffrey
• Primary Examiner(s): Sotomayor, John B
• Assistant Examiner(s): WINDRICH, MARCUS E
• Application Number:
  US12/995,169
• Publication Number:
  US 20110241928A1
• Time in Patent Office: 2,757 Days
• Field of Search: 342/90, 342107-109, 342/114, 342/159, 342/160
• US Class Current: 1/1
• 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 for discriminating between sources of radar interference and targets of interest. The system includes a transmitter for transmitting radar signals into a region, a receiver for receiving return signals of the radar signals returned from within the region, and a processor for processing the return signals to discriminate between return signals returned from a first object and return signals returned from a second object where the return signals from the second object comprise both zero and non-zero Doppler components and interfere with the return signals from the first object. The radar system is operable for discriminating between the return signals when the return signals are received at a distance from the second object which is less than a proximity limit based on the geometry of the object.

Claims

1. A radar system for discriminating between sources of radar interference and targets of interest, the system comprising:

a transmitter operable to transmit radar signals into a region;

a receiver operable to receive return signals of said radar signals returned from within said region; and

a processor operable to process the return signals to discriminate between return signals returned from a first object comprising a target of interest and return signals returned from a second object comprising a source of radar interference wherein said return signals from said objects comprise Doppler components;

wherein said processor is operable for transforming said return signals from a time domain into a frequency domain and for discriminating between said return signals in dependence on the manner in which a spectral spread of Doppler components, including both phase and amplitude of each Doppler component, exhibited by said return signals from either targets of interest or from radar interference changes, in said frequency domain, progressively with time; and

wherein said processor is operable to process said signals at a resolution, of at least 100 Doppler bins to be sufficient, when at least one of said first object and said second object comprises a rotating element, to characterize the manner in which the spectral spread of Doppler components exhibited by return signals from said rotating element changes progressively, and cyclically, within each period of rotation thereby discriminating between said first and second objects.

2. A radar system according to claim 1, wherein said processor is operable to determine that said return signals are returned from said second object if said Doppler components comprise a plurality of components at a plurality of locations across a pre-defined Doppler spectrum.

3. A radar system according to claim 1, wherein said processor is operable to determine that said return signals are returned from said first object if said Doppler components comprise a localised part of a pre-defined Doppler spectrum.

4. A radar system according to claim 1, wherein said processor is operable to place at least one of said Doppler components into at least one of a plurality of discrete Doppler bins and to discriminate between said return signals in dependence on the or each Doppler bin in which said at least one of said Doppler components is located.

5. A radar system according to claim 4, wherein said processor is operable to determine that said return signals are returned from said second object if said at least one of Doppler components of said return signal comprises a plurality of Doppler components located in a number of said plurality of Doppler bins which is not less then a first predetermined threshold.

6. A radar system according to claim 5, wherein said number of Doppler bins and said first threshold are each a proportion of said Doppler bins.

7. A radar system according to claim 6, wherein said first threshold comprises a threshold between 5% and 100% of the plurality of Doppler bins.

8. A radar system according to claim 4, wherein said processor is operable to determine that said return signals are returned from said first object if said at least one of Doppler components of said return signal is located in a number of Doppler bins which does not exceed a second predetermined threshold.

9. A radar system according to claim 8, wherein said number of Doppler bins and said second threshold are each a proportion of said Doppler bins.

10. A radar system according to claim 9, wherein said second threshold comprises any of a single Doppler bin to 1%, 2%, 5% or up to 25% of the plurality of Doppler bins.

11. A radar system according to claim 8, wherein said number of Doppler bins represents a target of interest comprising an environmental target.

12. A radar system according to claim 1, wherein said processor is operable to discriminate between said return signals in dependence on the conformity of said manner in which a spectral spread of Doppler components exhibited by said return signals changes progressively with a model or function.

13. A radar system according to claim 12, wherein said model or function comprises a sinusoidal, exponential, quadratic, and/or logarithmic model or function.

14. A radar system according to claim 1, wherein said system comprises a range determiner for determining a range of said objects based on said return signals, and wherein said processor is further operable to discriminate between said return signals in dependence on a change in said determined range of the objects over time.

15. A radar system according to claim 14, wherein said processor is operable to determine that said return signals are returned from said first object if said range changes over a time period.

16. A radar system according to claim 14, wherein said processor is operable to determine that said return signals are returned from said second object if said range remains substantially constant over a time period.

17. A method of discriminating between sources of radar interference and targets of interest, the method comprising:

transmitting radar signals into a region;

receiving return signals of said radar signals returned from within said region; and

processing the return signals to transform said return signals from a time domain into a frequency domain and to discriminate between return signals returned from a first object comprising a target of interest and return signals returned from a second object comprising a source of radar interference wherein said return signals from said objects comprise Doppler components;

wherein said processing comprises discriminating between said return signals in dependence on the manner in which a spectral spread of Doppler components, including both phase and amplitude of each Doppler component, exhibited by said return signals from either targets of interest or from radar interference changes, in said frequency domain, progressively with time; and

wherein said processing step comprises processing said signals at a resolution, of at least 100 Doppler bins to be sufficient, when at least one of said first object and said second object comprises a rotating element, to characterize the manner in which the spectral spread of Doppler components exhibited by return signals from said rotating element changes progressively, and cyclically, within each period of rotation thereby discriminating between said first and second objects.