초록 ▼

A signal y is received by a radar, the signal y being the reflection of a signal s emitted by the radar, the signal s having been reflected by a target. A filter w is estimated and applied to the signal y, in which the filter w compensates for an unwanted and beforehand unknown distortion d in the e

A signal y is received by a radar, the signal y being the reflection of a signal s emitted by the radar, the signal s having been reflected by a target. A filter w is estimated and applied to the signal y, in which the filter w compensates for an unwanted and beforehand unknown distortion d in the emitted signal s.

대표청구항 ▼

1. A method for use in a radar for filtering a received signal, the received signal being a signal emitted by the radar and reflected by a target, the target being at a location corresponding to an nth range resolution cell of the radar, the method comprising the following steps: transmitting a samp

1. A method for use in a radar for filtering a received signal, the received signal being a signal emitted by the radar and reflected by a target, the target being at a location corresponding to an nth range resolution cell of the radar, the method comprising the following steps: transmitting a sampled signal s=[s0 . . . sN−1]T containing N samples in a range dimension, N being an integer greater than or equal to 1, the sampled signal s satisfying s=z+d where z=[z0 . . . zN−1]T is a reference template signal and d=[d0 . . . dN−1]T is unwanted distortion;using the radar to receive a signal y, the signal y being a sampled signal {tilde over (y)}(n)=[y(n) . . . y(n+N−1)]T containing N samples corresponding to a measurement of the signal y in N consecutive resolution cells following the nth cell; andapplying a filter w to the signal y, w being a set of N weighting factors, wherein w is applied to y by calculating the convolution wH{tilde over (y)}(n);wherein determining the filter w comprises performing the following steps M times, M being an integer greater than or equal to 1 and p being an integer ranging from 1 to M:a step S1 of calculating, based on an estimated distortion d(p−1), a reference signal s(p);a step S2 of calculating, based on s(p), an estimated filter w(p); anda step S3 of calculating, based on w(p), an estimated distortion d(p); the Mth iteration of S3 providing w(M)=w. 2. A method according to claim 1, wherein during the step S1, d(0)=0, s(0)=s and s(p)=s(p−1)−d(p−1) if 1≦p≦M. 3. A method according to claim 1, wherein the sampled signal {tilde over (y)}(n) satisfies {tilde over (y)}(n)=AT(n)s+{tilde over (b)}(n), where {tilde over (b)}(n)=[b(n) . . . b(n+N−1)]T is a hypothetical sampled signal representing a thermal noise b collected from N consecutive resolution cells following the nth cell and A(n) is an N×N matrix representing how objects located in resolution cells between the (n−N+1)th cell and the (n+N−1)th cell reflect the signal s, the matrix A(n) being defined as: A⁡(n)=[x⁡(n)⁢⁢…⁢⁢x⁡(n+N-1)⋱x⁡(n-N+1)⁢⁢…⁢⁢x⁡(n)]where x(n) is a hypothetical true profile of the target located in the nth resolution cell, the method being characterized in that the step S2 comprises the following steps: a step S21 of calculating, based on w(p−1), an estimated profile {circumflex over (x)}(p)(n) of the target located in the nth resolution cell; anda step S22 of calculating, based on s and {circumflex over (x)}(p)(n), the estimated filter w(p). 4. A method according to claim 3, wherein during the step S21, {circumflex over (x)}(0)(n)=sH{tilde over (y)}(n) and {circumflex over (x)}(p)(n)=w(p−1)H(n){tilde over (y)}(n) if 1≦p≦M. 5. A method according to claim 3, wherein during the step S22, the estimated filter is calculated as follows: w(p+1)(n)=(Ĉ(p)(n)+B(n))−1s {circumflex over (ρ)}(p)(n)where {circumflex over (ρ)}(p)(n)=E{|{circumflex over (x)}(p)(n)|2}=|{circumflex over (x)}(p)(n)|2, E{.} being the expected value;where C.^(p)⁡(n)=∑m=-N+1N-1⁢ρ^(p)⁡(n+m)⁢sm⁢smH, sm containing the elements of s right-shifted by m samples, the m first elements being zero-filled; andwhere B(n)=E{{tilde over (b)}(n){tilde over (b)}H(n)}. 6. A method according to claim 1, wherein during the step S3, the estimated distortion d(p) is calculated as follows: d(p)=(∑n=0L-1⁢1ρ^(p-1)⁡(n)⁢F^(p-1)⁡(n)+αz2⁢I)-1⁢∑n=0L-1⁢((w(p-1)⁡(n)-1ρ^(p-1)⁡(n)⁢F^(p-1)⁡(n)⁢z))where F^(p-1)⁡(n)=∑m=-N+1N-1⁢ρ^(p-1)⁡(n-m)⁢wm(p-1)⁡(n)⁢wm(p-1)⁡(n)H, wm(p−1)(n) containing the elements of w(p−1)(n) right-shifted by m samples, the m first elements being zero-filled, α being a predefined numeral and I being the identity matrix. 7. A method for use in a radar for filtering a received signal, the received signal being a reflection of a transmitted signal off of a target, the target being located in an nth azimuth resolution cell of the radar, where n is an integer, the method comprising the following steps: transmitting a sampled pattern s=[s0 . . . sN−1]T containing N samples in the azimuth dimension, an integer greater than or equal to 1, the sampled pattern s satisfying s=z+d where z=[z0 . . . zN−1]T is a reference template pattern and d=[d0 . . . dN−1]T is unwanted distortion;using the radar to receive a signal y, the signal v being a sampled signal {tilde over (y)}(n)=[y(n) . . . y(n+N−1)]T containing N samples corresponding to the measurement of the signal y in N consecutive resolution cells following the nth cell; andapplying a filter w to the signal y, the filter w being a set of N weighting factors, wherein w is applied to y by calculating the convolution wH{tilde over (y)}(n);wherein determining the filter w comprises performing the following steps M times, M being an integer greater than or equal to 1 and p being an integer ranging from 1 to M:a step S1 of calculating, based on an estimated distortion d(p−1), a reference pattern s(p);a step S2 of calculating, based on s(p), an estimated filter w(p); anda step S3 of calculating, based on w(p), an estimated distortion d(p); the Mth iteration of S3 providing w(M)=w. 8. A method according to claim 7, wherein during the step S1, d(0)=0, s(0)=s and s(p)=s(p−1)−d(p−1) if 1≦p≦M. 9. A method according to claim 7, wherein an antenna of the radar includes a rotating antenna, and the sampled signal {tilde over (y)}(n) satisfies {tilde over (y)}(n)=AT(n)s+{tilde over (b)}(n), where {tilde over (b)}(n)=[b(n) . . . b(n+N−1)]T is a hypothetical sampled signal representing a thermal noise b collected from N consecutive resolution cells following the nth cell and A(n) is an N×N matrix representing how objects located in resolution cells between the (n−N+1)th cell and the (n+N−1)th cell reflect the pattern s, the matrix A(n) being defined as: A⁡(n)=[x⁡(n)⁢⁢…⁢⁢x⁡(n+N-1)⋱x⁡(n-N+1)⁢⁢…⁢⁢x⁡(n)]where x(n) is a hypothetical true profile of the target located in the nth resolution cell, the method being characterized in that the step S2 comprises the following steps: a step S21 of calculating, based on w(p−1), an estimated profile {circumflex over (x)}(p)(n) of the target located in the nth resolution cell; anda step S22 of calculating, based on s and {circumflex over (x)}(p)(n), the estimated filter w(p). 10. A method according to claim 9, wherein during the step S21, {circumflex over (x)}(0)(n)=sH{tilde over (y)}(n) and {circumflex over (x)}(p)(n)=w(p−1)H(n)ŷ(n) if 1≦p≦M. 11. A method according to claim 9, wherein during the step S22, the filter is calculated as follows: w(p+1)(n)=(Ĉ(p)(n)+B(n))−1s{circumflex over (ρ)}(p)(n),where {circumflex over (ρ)}(p)(n)=E{|{circumflex over (x)}(p)(n)|2}=|{circumflex over (x)}(p)(n)|2, E{.} being the expected value;where C^(p)⁡(n)=∑m=-N+1N-1⁢ρ^(p)⁡(n+m)⁢sm⁢smH, sm containing the elements of s right-shifted by m samples, the m first elements being zero-filled; andwhere B(n)=E{{tilde over (b)}(n){tilde over (b)}H(n)}. 12. A method according to claim 7, wherein during the step S3, the estimated distortion d(p) is calculated as follows: d(p)=(∑n=0L-1⁢1ρ^(p-1)⁡(n)⁢F^(p-1)⁡(n)+αz2⁢I)-1⁢∑n=0L-1⁢((w(p-1)⁡(n)-1ρ^(p-1)⁡(n)⁢F^(p-1)⁡(n)⁢z))where F^(p-1)⁡(n)=∑m=-N+1N-1⁢ρ^(p-1)⁡(n-m)⁢wm(p-1)⁡(n)⁢wm(p-1)⁡(n)H, wm(p−1)(n) containing the elements of w(p−1)(n) right-shifted by m samples, the m first elements being zero-filled, α being a predefined numeral and I being the identity matrix.