# US 2020/0067550 A1 · Method for cancelling multi-path signals for frequency-modulated radio signal receiver > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0067550 A1 - Document ID: US20200067550A1 - Status: Published application - Kind: A1 - Application number: 16/489,742 - Filed: 2018-05-29 - Published: 2020-02-27 - Earliest claimed: 2017-06-01 - Assignees: Continental Automotive France; Continental Automotive GmbH - Applicants: Continental Automotive France; Continental Automotive GmbH - Inventors: Gérald Soulier; Chao Lin - Web page: https://patentgrep.com/patent/US20200067550A1 ## CPC - H04B 1/1081: {Reduction of multipath noise (by equalising H04B7/005)} - H03H 21/0043: {Adaptive algorithms} - H04B 1/082: {to be used in vehicles (H04B1/086 takes precedence; holding or mounting accessories B60R11/02)} - H04L 27/14: Demodulator circuits; Receiver circuits - H03H 2021/0054: {Affine projection} - H04B: TRANSMISSION - H03H: IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS (waveguides, resonators, lines or other devices of the waveguide type H01P) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A method for decreasing multi-path interference, for the implementation thereof in a vehicle radio receiver including a radio reception antenna that receives a plurality of radio signals corresponding to an emitted radio signal, the plurality of signals received by the antenna being composed of time-shifted radio signals, the plurality of signals being intended to be combined in order to deliver a combined radio signal zn to be played, with zn WnTYn, the method aiming to determine the complex components of the vector of complex weights and including: introducing a temporal correlation, between the real and imaginary parts of the complex weights, that is dependent on the time shift between said received signals, by the expression of the complex weights in polar coordinates, implementing an iterative adaptation algorithm in order to determine the gains and delays of said complex weights able to keep constant over time the modulus of zn. ## Claims ### Claim 1 A method for decreasing multi-path interference, for implementation thereof in a vehicle radio receiver, said radio receiver being intended to receive an emitted radio signal and comprising a radio reception antenna that receives a plurality of radio signals corresponding to said emitted radio signal, said plurality of signals received by said antenna being composed of time-shifted radio signals resulting from a multi-path effect, said plurality of radio signals being intended to be combined in order to deliver a combined radio signal zn to be played, with zn=WnTYn at the time n, where Yn is a vector the components of which correspond to the plurality of received signals, expressed in complex baseband, and Wn is a vector the components of which correspond to complex weights intended to be attributed to each of the radio signals of said plurality of received radio signals, respectively, in order to form the combined radio signal zn in which a set of secondary radio signals resulting from the multi-path effect are canceled out, said method aiming to determine said complex components of said vector of complex weights and comprising: Introducing a temporal correlation between the real and imaginary parts of said complex weights, said correlation being dependent on the time shift between said signals of said plurality of received radio signals, by means of the expression of said complex weights in polar coordinates, so that Wn = [ g o  exp  ( j   θ o ) g 1  exp  ( j   θ 1 ) ⋮ ⋮ g K - 1  exp  ( j   θ K - 1 ) ] , so as to incorporate an interdependence between the real and imaginary parts of said complex weights, and Implementing an iterative adaptation algorithm in order to determine the g0, g1, . . . , gk−1 and θ0, θ1, . . . , θk−1 able to keep constant over time the modulus of zn. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein said iterative adaptation algorithm is a constant-modulus adaptation algorithm. ### Claim 3 (depends on 1) The method as claimed in claim 1, comprising determining a constant H corresponding to the modulus of the envelope of the frequency-modulated radio signal emitted, the implementation of the iterative adaptation algorithm consisting in determining Gn, Θn able to minimize over time the cost function characterized by the following instantaneous gradient: ∇ J CMA = 2  (  z n  2 - R 2 )  [ 2   Re  [ z n  exp  ( jΘ n ) · Y n _ ] - 2   Im  [ z n  G n · exp  ( j   Θ n ) · Y n _ ] ] where Gn is a vector composed of the complex gains of each of the complex weights of the vector of complex weights at the time n, Θ, is the vector composed of the complex delays of each of the complex weights of the vector of complex weights of the time n and the operator “∘” is defined as performing the multiplication of two vectors, component by component, the resultant being a vector. ### Claim 4 (depends on 3) The method as claimed in claim 3, wherein the respective variations in Gn, and Θn over time are computed by means of the following formulae: Gn+1=Gn−μg(|zn|2−R2)Re[zn exp(jΘn)∘Yn] Θn+1=Θn−μθ(|zn|2−R2)Im[znGn∘exp(jΘn)∘Yn] where Gn is a vector composed of the complex gains of each of the complex weights of the vector of complex weights at the time n, and where Θn is the vector composed of the complex delays of each of the complex weights of the vector of complex weights at the time n, and where μg and μθ are the iterative steps chosen for the update of the gains and phases of each of the complex weights and where the operator “∘” is defined as performing the multiplication of two vectors, component by component, the resultant being a vector. ### Claim 5 (depends on 1) A radio receiver comprising a microcontroller configured to implement the method as claimed in claim 1. ### Claim 6 (depends on 5) A motor vehicle comprising a radio receiver as claimed in claim 5. ### Claim 7 (depends on 2) The method as claimed in claim 2, comprising determining a constant R corresponding to the modulus of the envelope of the frequency-modulated radio signal emitted, the implementation of the iterative adaptation algorithm consisting in determining Gn, Θn able to minimize over time the cost function characterized by the following instantaneous gradient: ∇ J CMA = 2  (  z n  2 - R 2 )  [ 2   Re  [ z n  exp  ( j   Θ n ) · Y n _ ] - 2   Im  [ z n  G n · exp  ( j   Θ n ) · Y n _ ] ] where Gn is a vector composed of the complex gains of each of the complex weights of the vector of complex weights at the time n, Θn is the vector composed of the complex delays of each of the complex weights of the vector of complex weights of the time n and the operator “∘” is defined as performing the multiplication of two vectors, component by component, the resultant being a vector.