System and method for target detection

1. A sonar based sensor for localization of a target in air, the sensor comprising:

a wide or ultra-wide band emitter for emitting a wide or ultra-wide band signal; and

a set of spatially randomly or irregularly positioned receivers for receiving the wide or ultra-wide band signal after reflection at the target

wherein the wide or ultra-wide band emitter is adapted for emitting a wide or ultra-wide band signal having a bandwidth spanning at least one octave, and

wherein the sensor comprises a processor programmed for processing the received signals thereby applying a matched filter and applying spatial bandpass filtering by beamforming processing.

2. A sensor according to claim 1 , wherein the spatially randomly or irregularly positioned receivers are spatially randomly or irregularly arranged in two directions for allowing three dimensional localization.

3. A sensor according to claim 1 , wherein the sensor is arranged for sensing sonar signals and wherein the emitter is arranged for emitting a sound wave.

4. A sensor according to claim 1 , wherein the receivers are distributed sparsely.

5. A sensor according to claim 1 , wherein a receiver density is less than 0.5 receivers/λ max 2 , whereby λ max is the maximum wavelength in the wide or ultra-wide band signal.

6. A sensor according to claim 1 , the sensor furthermore comprising a processor for processing the received signals, the processor being configured for determining an azimuth angle and an elevation angle.

7. A sensor according to claim 6 , wherein the processor is configured for processing the set of receiver signals by

extracting an envelope for the signal, for deriving a location of a target.

8. A sensor according to claim 1 , wherein the set of receivers are positioned in a fixed configuration with respect to each other.

9. A sensor according to claim 1 , wherein the sensor comprises only a single emitter.

10. A processor for processing sonar based sensor signals, the processor comprising:

an input means arranged for receiving signals from a set of spatially randomly or irregularly positioned receivers, the signals being in reply to the wide or ultra-wide band signal after reflection at a target in air, the wide or ultra-wide band signal having a bandwidth spanning at least one octave; and

a calculating means arranged for calculating a location of a target in air, the calculating means being configured for calculating taking into account an azimuth angle and an elevation angle,

wherein the processor is furthermore adapted for processing the received signals thereby applying a matched filter and applying spatial bandpass filtering by beamforming processing.

11. A processor according to claim 10 , wherein the calculating means is configured for

extracting an envelope for the signal, for deriving a location of a target.

12. A method for locating a target in air based on sonar, the method comprising

obtaining a set of receiver signals, received in response to a wide or ultra-wide band signal after reflection at the target in air, using a set of spatially randomly or irregularly positioned receivers, the wide or ultra-wide band signal having a bandwidth spanning at least one octave;

deriving a location of the target in air based on the obtained set of receiver signals,

wherein said deriving a location of the target comprises processing the received signals thereby applying a matched filter and applying spatial bandpass filtering by beamforming processing.

13. A method according to claim 12 , the method furthermore comprising, prior to said obtaining, generating the wide or ultra-wide band signal,

wherein said generating comprises generating a wide or ultra-wide band signal having a bandwidth spanning at least an octave.

14. A method according to claim 12 , wherein the method furthermore comprises, outputting derived location information.

15. A method according to claim 12 , wherein the deriving comprises applying a matched filter, applying spatial bandpass filtering and extracting an envelope signal.

16. A method according to claim 12 , the method being implemented as a set of instructions on a non-transitory computer-readable medium for, when executing on a processing means, carrying out the method.

17. A non-transitory computer-readable medium for storing a set of instructions for, when executing on a processing means, performing a method for locating a target in air based on sonar, the method comprising:

obtaining a set of receiver signals, received in response to a wide or ultra-wide band signal after reflection at the target, using a set of spatially randomly or irregularly positioned receivers, the wide or ultra-wide band signal having a bandwidth spanning at least one octave;

deriving a location of the target in air based on the obtained set of receiver signals,

wherein said deriving a location of the target comprises processing the received signals thereby applying matched filtering and applying spatial bandpass filtering by beamforming processing.

18. A sonar based sensor for localization of a target in air, the sensor comprising:

a wide or ultra-wide band emitter for emitting a wide or ultra-wide band signal being a bat-like hyperbolic FM-sweep; and

a set of spatially randomly or irregularly positioned receivers for receiving the wide or ultra-wide band signal after reflection at the target

wherein the wide or ultra-wide band emitter is adapted for emitting a wide or ultra-wide band signal having a bandwidth spanning at least one octave, and

wherein the sensor comprises a processor programmed for processing the received signals thereby applying a matched filter and applying spatial bandpass filtering by beamforming processing.