Method, a computer program product, an apparatus and a frequency-modulated continuous-wave radar system

A non-transitory computer-readable medium storing computer-readable instructions which, when executed on a processing unit, will cause the processing unit to perform a method for producing an interference reduced radar image, the method comprising:

• receiving a measured sequence of beat signals, each beat signal comprising a number of segments, each segment being a beat signal time sample and having an amplitude representing the beat signal time amplitude at a time of recording the beat signal time sample, wherein the i:th segment of the j:th beat signal is identifiable as a segment i,j with amplitude Ai,j, wherein i=1, . . . , a, j=1, b;
• wherein a and b are integers greater than or equal to two;
• identifying one or more interference segments within the measured sequence of beat signals, an interference segment being a segment subject to an interference;
• doctoring the measured sequence of beat signals by creating a doctored representation segments of the measured sequence of beat signals in the form of a matrix Y with elements yi,j:
• Y
• =
• [
• y
• 1
• ,
• 1
• …
• y
• 1
• ,
• b
• ⋮
• ⋱
• ⋮
• y
• a
• ,
• 1
• …
• y
• a
• ,
• b
• ]
• ,
• wherein yi,j=mi,j×Ai,j, wherein mi,j is a masking value, the masking value being dependent on whether segment i,j is identified as an interference segment or not, the masking value being set to a lower value if segment i,j is an interference segment compared to if it is not an interference segment;
• creating a doctoring mask representing the doctoring of the measured sequence of beat signals, the doctoring mask being a matrix M with elements mi,j:
• M
• =
• [
• m
• 1
• ,
• 1
• …
• m
• 1
• ,
• b
• ⋮
• ⋱
• ⋮
• m
• a
• ,
• 1
• …
• m
• a
• ,
• b
• ]
• ;
• and
• estimating a reconstructed range-doppler image {circumflex over (X)} from Y and M, wherein the reconstructed range-doppler image is a range-doppler image of Y which is deconvolved using M, a range-doppler image being a time-frequency transform of a representation of a sequence of beat signals;
• such that doctoring the measured sequence of beat signals at least partially removes interference effects and estimating a reconstructed range-doppler image at least partially removes image artefacts created by the doctoring.

An apparatus for producing an interference reduced radar image, the apparatus comprising a control circuit configured to:

• receive a measured sequence of beat signals, each beat signal comprising a number of segments, each segment being a beat signal time sample and having an amplitude representing the beat signal time amplitude at a time of recording the beat signal time sample, wherein the i:th segment of the j:th beat signal is identifiable as a segment i,j with amplitude Ai,j, wherein i=1, . . . , a, j=1, b;
• wherein a and b are integers greater than or equal to two;
• identify at least one interference segment within the measured sequence of beat signals, the interference segment being a segment subject to an interference;
• doctor the measured sequence of beat signals by creating a doctored representation of segments of the measured sequence of beat signals in the form of a matrix Y with elements yi,j:
• Y
• =
• [
• y
• 1
• ,
• 1
• …
• y
• 1
• ,
• b
• ⋮
• ⋱
• ⋮
• y
• a
• ,
• 1
• …
• y
• a
• ,
• b
• ]
• ,
• wherein yi,j=mi,j×Ai,j, wherein mi,j is a masking value, the masking value being dependent on whether segment i,j is identified as an interference segment or not, the masking value being set to a lower value if segment i,j is an interference segment compared to if it is not an interference segment;
• create a doctoring mask representing the doctoring of the measured sequence of beat signals, the doctoring mask being a matrix M with elements mi,j:
• M
• =
• [
• m
• 1
• ,
• 1
• …
• m
• 1
• ,
• b
• ⋮
• ⋱
• ⋮
• m
• a
• ,
• 1
• …
• m
• a
• ,
• b
• ]
• ;
• estimate a reconstructed range-doppler image {circumflex over (X)} from Y and M, wherein the reconstructed range-doppler image is a range-doppler image of Y which is deconvolved using M, a range-doppler image being a time-frequency transform of a representation of a sequence of beat signals which transforms the representation of the sequence of beat signals from a time domain to a frequency domain;
• whereby doctoring the measured sequence of beat signals at least partially removes interference effects and estimating a reconstructed range-doppler image at least partially removes image artefacts created by the doctoring.

A frequency-modulated continuous-wave, FMCW, radar system, comprising:

• a radar unit;
• an apparatus for producing an interference reduced radar image, the apparatus comprising:
• a control circuit configured to:
• receive a measured sequence of beat signals, each beat signal comprising a number of segments, each segment being a beat signal time sample and having an amplitude representing the beat signal time amplitude at a time of recording the beat signal time sample, wherein the i:th segment of the j:th beat signal is identifiable as a segment i,j with amplitude Ai,j, wherein i=1, . . . , a, j=1, b;
• wherein a and b are integers greater than or equal to two;
• identify at least one interference segment within the measured sequence of beat signals, the interference segment being a segment subject to an interference;
• doctor the measured sequence of beat signals by creating a doctored representation of segments of the measured sequence of beat signals in the form of a matrix Y with elements yi,j:
• Y
• =
• [
• y
• 1
• ,
• 1
• …
• y
• 1
• ,
• b
• ⋮
• ⋱
• ⋮
• y
• a
• ,
• 1
• …
• y
• a
• ,
• b
• ]
• ,
• wherein yi,j=mi,j×Ai,j, wherein mi,j is a masking value, the masking value being dependent on whether segment i,j is identified as an interference segment or not, the masking value being set to a lower value if segment i,j is an interference segment compared to if it is not an interference segment;
• create a doctoring mask representing the doctoring of the measured sequence of beat signals, the doctoring mask being a matrix M with elements mi,j:
• M
• =
• [
• m
• 1
• ,
• 1
• …
• m
• 1
• ,
• b
• ⋮
• ⋱
• ⋮
• m
• a
• ,
• 1
• …
• m
• a
• ,
• b
• ]
• ;
• estimate a reconstructed range-doppler image {circumflex over (X)} from Y and M, wherein the reconstructed range-doppler image is a range-doppler image of Y which is deconvolved using M, a range-doppler image being a time-frequency transform of a representation of a sequence of beat signals which transforms the representation of the sequence of beat signals from a time domain to a frequency domain;
• whereby doctoring the measured sequence of beat signals at least partially removes interference effects and estimating a reconstructed range-doppler image at least partially removes image artefacts created by the doctoring;
• and
• wherein the radar unit comprises:
• a transmit antenna configured to transmit a first sequence of signals;
• a receive antenna configured to receive a second sequence of signals in response to the first sequence of signals transmitted by the transmit antenna;
• and
• a mixer configured to mix the first sequence of signals and the second sequence of signals to generate a sequence of beat signals;
• the radar unit being configured to deliver the sequence of beat signals to the apparatus as a measured sequence of beat signals, such that the apparatus produces the interference reduced radar image.