METHOD AND DEVICE FOR MEASURING ALTITUDE AND VELOCITY COMPONENTS FROM SIGNALS OF TWO-CHANNEL COHERENT RADIO ALTIMETER Russian patent published in 2025 - IPC G01S13/42 G01S13/58 G01S13/60 

FIELD: radio navigation.

SUBSTANCE: invention relates to radio navigation and can be used to measure altitude and speed components of an aircraft. Disclosed method includes probing the earth's surface with a radar signal through a wide directional transmitting-receiving antenna (TRA); simultaneous reception of an echo signal by two antennae: TRA and receiving wide directional (RA) coherent radio altimeter, spaced apart along the Z axis in the associated with the aircraft coordinate system to the interferometer base, equal to the wavelength of the radiation source, Z axis is located perpendicular to aircraft lengthwise axis towards right wing. Further, two complex range-Doppler portraits (RDP) are formed based on the received RA1 and RA2 signals. Two maximum contrast curves (MCC) are formed for each RDP, the first curve is obtained by enumeration of hypotheses by Doppler frequency at each range n, the second curve is obtained by enumeration of hypotheses by a pair of Doppler frequencies at each range n, which give maximum logarithm of likelihood. Vector of maximum contrast is formed based on the results of combining the first and second MCC and the refinement algorithm. Vector of weighted average coordinates of the MCC echo signal is calculated. Aircraft altitude and speed parameters are hypothesized X_i=[H_i,V_gi,V_vi]^T, where H_i,V_gi,V_vi – altitude, ground and vertical speeds of aircraft for i-th hypothesis. Vectors describing the curves of maximum contrast for the i-th hypothesis are formed. Optimal estimate of the error of the vector X_i relative to the true value is found by the least squares method and new i+1 hypotheses are formed X_i+1 = X_i + ΔX_i. Then iterations of vector X_i parameters refinement are repeated until error vector is reduced to permissible values. Further, for each coordinate of the vector of the weighted average coordinates of the curve of the maximum contrast of the echo signal, the angular coordinates of each resolvable element of the MCC are determined from the two complex RDP, calculating a weighted estimate of the drift angle of the aircraft for all polar coordinates of the resolvable elements of the MCC, estimation of longitudinal and transverse components of aircraft speed is calculated according to expressions relating measured ground speed to drift angle.

EFFECT: measurement of altitude and three components of aircraft speed from signals of a two-channel coherent radio altimeter with reduced dimensions of the antenna system.

2 cl, 6 dwg, 1 apps