Patent ID: 11968011
Assignee: JUN TANG
Field: Telecommunications (Electrical engineering)
Classification: CPC H  Y | IPC H

Claim 0:
1. A multi-channel multi-phase digital beamforming method, comprising following steps:
S1: pre-configuring a delay filtering coefficient storage table;
wherein the delay filtering coefficient storage table comprises a plurality of delay filter parameters;
each of the plurality of delay filter parameters comprises a filter delay and a corresponding delay filtering coefficient; and
the filter delay is in units of a quantity of sampling points, and the filter delay ranges from −0.5*sPath sampling points to 0.5*sPath sampling points, wherein the sPath represents a preset maximum quantity of signal phases;
S2: determining a filter coefficient and a weighting coefficient;
wherein after the delay filtering coefficient storage table is determined in step S2, a quantity of signal phases is first determined, and the weighting coefficient and the delay filter coefficient are configured, which specifically comprises:
S201: assuming that a processing clock frequency is fclk, when a sampling rate fs of an input signal exceeds the processing clock frequency fclk, dividing the signal into a plurality of phases, and determining the quantity of signal phases:

quantity of signal phases=fs/fclk 

wherein the sampling rate fs of the signal is an integer multiple of the clock frequency fclk;
S202: assuming that an entire array of a phased-array antenna contains a plurality of subarrays, and each of the plurality of subarrays contains a plurality of array elements, calculating a delay based on a subarray arrangement of the phased-array antenna, and selecting a corresponding filter coefficient from the delay filtering coefficient storage table, wherein step S202 specifically comprises:
A1: for any subarray, calculating a delay t1 from a reference point of the subarray to a reference point of the entire array, wherein
a rectangular coordinate system with the reference point of the entire array as an origin is established, and a calculation formula of the delay t1 is as follows:

t1=(cos θ cos φ d0,1+sin θ cos φ d0,2+sin φ d0,3)/c 

the reference point of the subarray is any point in the subarray, and the reference point of the entire array is at a center of the phased-array antenna;
d0,1, d0,2, and d0,3 represent x, y, and z coordinates of the reference point of the subarray respectively, c represents a speed of light, θ represents an azimuth of a beam direction, and φ represents a pitch angle of the beam direction;
the delay t1 is decomposed into following three items:

t1=N/fclk+τ1+δt 

wherein N=floor(t1*fclk), and floor represents downward rounding;
τ1=floor(t1*fclk)/Δτ, wherein Δτ is calculated according to a following formula: Δτ=sPath/N_filter, and N_filter represents a quantity of stored delay filters; and
δt=t1−N/fclk−τ1; and
the delay filtering coefficient storage table is searched for a delay filtering coefficient corresponding to the filter delay τ1 as a delay filtering coefficient configured for the current sub array; and
A2: repeatedly performing step A1 for each subarray to configure a delay filtering coefficient for each sub array; and
S203: calculating the weighting coefficient based on the beam direction, an array antenna arrangement, the quantity of signal phases, and a calibration channel phase, wherein step S203 specifically comprises:
B 1: first calculating a delay t2 from an ith array element on the entire array to the reference point of the entire array, establishing the rectangular coordinate system with the reference point of the entire array as the origin, and calculating the delay t2 according to a following formula:

t2=(cos θ cos φ d1,1+sin θ cos φ d1,2+sin φ d1,3)/c 

wherein
d1,1, d1,2, and d1,3 represent x, y, and z coordinates of an array element point respectively, c represents the speed of light, θ represents the azimuth of the beam direction, and φ represents the pitch angle of the beam direction;
calculating a filter delay τ2 according to the following formula:

τ2=t2−N/fclk−τ1 

calculating a phase p according to the following formula:

p=2πfτ2 

wherein f represents a carrier frequency; and
calculating a weighting coefficient of the ith array element according to the following formulas:

ωi=REi+j(IMi)

REi=cos[−p−ϕi]

IMi=sin[−p−ϕi]

wherein ϕi represents a known channel phase of the ith array element, which is also referred to as a calibration channel phase of the ith array element; and
B2: when i=1, 2, . . . , K, repeatedly performing step B1 to obtain weighting coefficients ω1, ω2, . . . , and ωK of various array elements, wherein K represents a quantity of array elements; and
S3: performing weighted synthesis and filtering processing on a multi-phase signal to form a multi-phase digital beam;
wherein step S3 comprises:
S301: dividing a signal of each phase in the multi-phase signal into signals of K channels by using a power divider, which are denoted as x1, x2, . . . , and xK, wherein xi represents a signal of an ith channel, and multiplying the signals x1, x2, . . . , and xK of the K channels by weighting coefficients ω1, ω2, . . . , and ωK to obtain weighting results x1*ω1, x2*ω2, . . . , and xK*ωK of the signals of the K channels;
S302: taking out a weighting result xi*ωi of the ith channel in the signal of each phase, adding up weighting results that are taken out to obtain a multi-phase digital beam of the ith channel, and then performing delay filtering on the multi-phase digital beam of the ith channel based on a delay filtering coefficient of a subarray in which an array element corresponding to the weighting coefficient ωi is located; and
S303: when i=1, 2, . . . , K, repeating step S302 to obtain a total of K delay-filtered multi-phase digital beams.