Probabilistic signal, detection, and track processing architecture and system

• US 10,054,668 B2
• Filed: 02/26/2016
• Issued: 08/21/2018
• Est. Priority Date: 02/26/2015
• Status: Active Grant

• Current Assignee: SRC, Inc.
• Original Assignee: SRC, Inc.
• Inventors: Culkin, Daniel R.
• Primary Examiner(s): Brainard, Timothy A
• Application Number:
  US15/055,022
• Publication Number:
  US 20180164406A1
• Time in Patent Office: 907 Days
• Field of Search: 342115
• CPC Class Codes: G01S 13/20 whereby multiple time-around echoes are used or eliminated
• CPC Class Codes: G01S 13/522 using transmissions of interrupted pulse modulated waves
• CPC Class Codes: G01S 13/582 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/726 Multiple target tracking
• CPC Class Codes: G01S 7/04 Display arrangements
• CPC Class Codes: G01S 7/2923 based on data belonging to a number of consecutive radar periods
• CPC Class Codes: G01S 7/2926 by integration
• CPC Class Codes: G01S 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers
• CPC Class Codes: G06F 3/147 using display panels

Abstract

A radar system and method is provided for increasing the search volume, detection range, and/or update rate of a search radar without requiring an increase of the radar transmit power or antenna aperture size. This is accomplished by using a target response calculation that uses signal energy that is thrown away by conventional systems. A probability of target presence and target behavior (P_pb) is calculated based on the retained signal energy to thus improve the radar'"'"'s ability to detect the presence of a target. The invention processes multiple CPIs either coherently or incoherently via the P_pb methodology to further improve the radar'"'"'s detection abilities.

Claims

1. A radar system comprising:

a RF receiver configured to convert at least one RF signal obtained from an environment into at least one downconverted analog signal having main lobe signal energy and sidelobe signal energy components, the at least one downconverted analog signal corresponding to at least one digital baseband signal; and

a radar signal processor arrangement including,

at least one filter coupled to the RF receiver, the at least one filter being configured to correlate the at least one digital baseband signal with a predetermined filter signal, the at least one filter applying substantially no complex weighting to the at least one digital baseband signal to thus provide unweighted signal samples corresponding to the at least one digital baseband signal, the unweighted signal samples substantially retaining signal energy information corresponding to the main lobe signal energy and sidelobe signal energy components,

a range-Doppler processor element configured to extract frequency data from the unweighted signal samples to obtain range-Doppler data, the range-Doppler processor element being further configured to populate a range-Doppler Table with the range-Doppler data, and

a target response processor element configured to calculate a target response value for each cell in the range-Doppler Table, each target response value corresponding to a probability of target presence (P_pb).

2. The system of claim 1, wherein the radar signal processor arrangement is configured as a distributed heterogeneous processing arrangement that includes processing components selected from a group of processing components including application specific integrated circuits (ASICs), field-programmable gate array devices (FPGAs), reduced instruction set computers (RISC), graphics processing units (GPUs), or multi-purpose processor devices.

3. The system of claim 1, wherein the radar signal processor arrangement is configured to convert the at least one downconverted analog signal corresponding to at least one digital baseband signal substantially in accordance with a Nyquist sampling rate.

4. The system of claim 1, further comprising:

at least one radar display device coupled to the radar signal processor arrangement, the at least one radar display device being configured to represent data corresponding to the probability of target presence (P_pb) as human-readable indicia; and

at least one radar control device coupled to the at least one radar display device and the radar system, the at least one radar control device being configured provide control data or radar search parameters to the radar system.

5. The system of claim 1, wherein the target response value is substantially equal to:

Response(a,b)=Σ

_i=1^AΣ

_j=1^BM(i,j)I(i,j,a,b),

wherein, M corresponds to the range-Doppler table, A×

B corresponds to a size of the range-Doppler table (M), a,b represent an ordered pair corresponding to a location in the range-Doppler table, and I corresponds to an Ideal Response Table.

6. The system of claim 5, wherein the target response value corresponds to a signal-to-noise ratio (SNR), a noise portion of the SNR being based on at least the RF receiver.

7. The system of claim 1, wherein the target response value corresponds to a received signal strength representing the signal energy information, the target response processor being configured to evaluate the target response value over a plurality of cells to determine a multi-cell target response pattern, the plurality of cells corresponding to substantially all or a portion of the range-Doppler table.

8. The system of claim 1, further comprising a target probability processing element configured to arrange the target response values in a Target Response Table having a dimensionality substantially corresponding to the range-Doppler Table.

9. The system of claim 8, wherein each target response value in the Target Response Table is converted into a corresponding probability of target presence (P_pb) to thus populate a Target Probability Table having a dimensionality substantially corresponding to the Target Response Table.

10. The system of claim 9, further comprising a multi-CPI tracker element configured to compile a plurality of Target Probability Tables over a plurality of coherent processing intervals (CPIs) to form a three-dimensional probability matrix of probability of target presence (P_pb) values, the three-dimensional probability table having a range axis, a Doppler axis, and a time axis indexed by CPI.

11. The system of claim 10, wherein the multi-CPI tracker is configured to calculate a multi-CPI probability of target presence based on the three-dimensional probability matrix, the multi-CPI probability of target presence being calculated in accordance with a coherent tracker, a non-coherent tracker, a probabilistic multi-model tracker, or a multi-hypothesis tracker.

12. The system of claim 1, wherein the radar signal processor arrangement is further configured to perform a target probability determination, the target probability determination including a converse-Swerling operation, the converse-Swerling operation that converts the target response value into the probability of target presence (P_pb).

13. The system of claim 12, wherein the target response processor element is configured to covert each cell in the range-Doppler Table into a corresponding target response value to populate a Target Response Table substantially corresponding to the range-Doppler Table.

14. The system of claim 12, wherein the converse-Swerling operation is performed by retrieving the probability of target presence (P_pb) for each target response value from a look-up table to form a Target Probability Table having a dimensionality substantially corresponding to the range-Doppler Table, the Target Probability Table including probability of target presence (P_pb) values obtained over one coherent processing interval (CPI).

15. The system of claim 14, further comprising a multi-CPI probability tracker configured to evaluate target probability trends over a plurality of CPIs by evaluating a plurality of Target Probability Tables obtained over a plurality of CPIs.

16. The system of claim 1, wherein the radar system is characterized by an effective search volume, an effective detection range, or an effective update rate that are functions of the signal energy information.

17. A method comprising:

providing a radar system having an RF receiver configured to convert at least one RF signal obtained from an environment into at least one downconverted analog signal having main lobe signal energy and sidelobe signal energy components, the at least one downconverted analog signal corresponding to at least one digital baseband signal;

correlating the at least one digital baseband signal with a predetermined filter signal so that substantially no complex weighting is applied to the at least one digital baseband signal to thus provide unweighted signal samples corresponding to the at least one digital baseband signal, the unweighted signal samples substantially retaining signal energy information corresponding to the main lobe signal energy and sidelobe signal energy components, the radar system being characterized by an effective search volume, an effective detection range, or an effective update rate that are functions of the signal energy information;

extracting frequency data from the unweighted signal samples to obtain range-Doppler data;

populating a range-Doppler Table with the range-Doppler data; and

calculating a target response value for each cell in the range-Doppler Table, each target response value corresponding to a probability of target presence (P_pb).

18. The method of claim 17, further comprising the step of converting the at least one downconverted analog signal into at least one digital baseband signal in accordance with a Nyquist sampling rate.

19. The method of claim 17, further comprising:

representing data corresponding to the probability of target presence (P_pb) as human-readable indicia; and

providing control data or radar search parameters to the radar system.

20. The method of claim 17, wherein the target response value is substantially equal to:

Response(a,b)=Σ

_i=1^AΣ

_j=1^BM(i,j)I(i,j,a,b),

wherein, M corresponds to the range-Doppler table, A×

B corresponds to a size of the range-Doppler table (M), a,b represent an ordered pair corresponding to a location in the range-Doppler table, and I corresponds to an Ideal Response Table.

21. The method of claim 20, wherein the target response value corresponds to a signal-to-noise ratio (SNR), a noise portion of the SNR being based on at least the RF receiver.

22. The method of claim 17, wherein the target response value corresponds to a received signal strength representing the signal energy information, the target response processor being configured to evaluate the target response value over a plurality of cells to determine a multi-cell target response pattern, the plurality of cells corresponding to substantially all or a portion of the range-Doppler table.

23. The method of claim 17, further comprising the step of arranging the target response values in a Target Response Table having a dimensionality substantially corresponding to the range-Doppler Table.

24. The method of claim 23, wherein each target response value in the Target Response Table is converted into a corresponding probability of target presence (P_pb) to thus populate a Target Probability Table having a dimensionality substantially corresponding to the Target Response Table.

25. The method of claim 24, further comprising the step of compiling a plurality of Target Probability Tables over a plurality of coherent processing intervals (CPIs) to form a three-dimensional probability matrix of probability of target presence (P_pb) values, the three-dimensional probability table having a range axis, a Doppler axis, and a time axis indexed by CPI.

26. The method of claim 25, further comprising the step of calculating a multi-CPI probability of target presence based on the three-dimensional probability matrix, the multi-CPI probability of target presence being calculated in accordance with a coherent model, a non-coherent model, a probabilistic multi-model tracker, or a multi-hypothesis tracker.

27. The method of claim 17, further comprising the step of performing a target probability determination, the target probability determination including a converse-Swerling operation, the converse-Swerling operation that converts the target response value into the probability of target presence (P_pb).

28. The method of claim 27, further comprising the step of converting each cell in the range-Doppler Table into a corresponding target response value to populate a Target Response Table substantially corresponding to the range-Doppler Table.

29. The method of claim 27, wherein the converse-Swerling operation is performed by retrieving the probability of target presence (P_pb) of the corresponding target response value from a look-up table stored in a memory to form a Target Probability Table having a dimensionality substantially corresponding to the range-Doppler Table, the Target Probability Table including probability of target presence (P_pb) values for one coherent processing interval (CPI).

30. The method of claim 29, further comprising the step of evaluating target probability trends over a plurality of CPIs by evaluating a plurality of Target Probability Tables obtained over a plurality of CPIs.