US 12,146,981 B2
Resolving doppler unambiguity in TDM-MIMO radars based on spatial phase change rate
Anders Lloyd, Lund (SE); Anders Mannesson, Lund (SE); Bertil Roslund, Lund (SE); Mattias Simonsson, Lund (SE); and Stefan Adalbjörnsson, Lund (SE)
Assigned to AXIS AB, Lund (SE)
Filed by Axis AB, Lund (SE)
Filed on Jul. 25, 2023, as Appl. No. 18/358,215.
Claims priority of application No. 22196744 (EP), filed on Sep. 21, 2022.
Prior Publication US 2024/0103128 A1, Mar. 28, 2024
Int. Cl. G01S 7/35 (2006.01); G01S 7/03 (2006.01); G01S 13/02 (2006.01); G01S 13/58 (2006.01)
CPC G01S 7/354 (2013.01) [G01S 7/03 (2013.01); G01S 13/584 (2013.01); G01S 2013/0263 (2013.01)] 14 Claims
OG exemplary drawing
 
1. A method for resolving a phase ambiguity between subarrays in a virtual array of a time-division multiplexing (TDM), multiple-input multiple-output (MIMO), frequency-modulated continuous-wave (FMCW), radar,
wherein the TDM MIMO FMCW radar comprises an array of physical receivers including at least one row of physical receivers with a first spacing in a first direction, and further comprises a plurality of physical transmitters arranged with a second spacing in said first direction,
wherein each of the subarrays in the virtual array is generated by a combination of the array of physical receivers and one of the physical transmitters, the method comprising:
obtaining a virtual array signal of a range-Doppler bin relating to a scene with a moving object, each element of the virtual array signal corresponding to one virtual antenna element of the virtual array;
compensating a velocity-induced phase shift of the virtual array signal using a phase compensation method, which introduces a phase ambiguity between the subarrays if the moving object's velocity exceeds a threshold, thereby obtaining a compensated virtual array signal;
computing, based on elements of the compensated virtual array signal corresponding to one subarray at a time, a spatial phase change rate with respect to the first direction;
from the spatial phase change rate with respect to the first direction and the second spacing, predicting a spatial phase shift between a pair of the subarrays;
determining a residual phase shift between said pair of subarrays by comparing an actual phase shift of the compensated virtual array signal and the spatial phase shift; and
applying an inverse of the residual phase shift to the compensated virtual array signal.