Method and apparatus for measuring relative position of spacecraft based on GNSS difference

A method for measuring a relative position of a spacecraft based on GNSS difference, comprising:

• acquiring a first long-wave observation combination and a second long-wave observation combination;
• performing a double-difference ambiguity of whole cycles search according to a preset pseudo-range double-difference linear equation and a preset carrier double-difference equation, and determining N first ambiguities of whole cycles to be detected of the first long-wave observation combination and M second ambiguities of whole cycles to be detected of the second long-wave observation combination, wherein N and M are integers greater than 1;
• determining a first ambiguity of whole cycles from the N first ambiguities of whole cycles to be detected, and determining a second ambiguity of whole cycles from the M second ambiguities of whole cycles to be detected, wherein each of the first ambiguity of whole cycles and the second ambiguity of whole cycles satisfies a preset ambiguity of whole cycles condition;
• and
• determining, according to the first ambiguity of whole cycles and the second ambiguity of whole cycles, a short-wave double-difference ambiguity of whole cycles to measure the relative position of the spacecraft;
• wherein the first long-wave observation combination and the second long-wave observation combination satisfy a non-linear relationship;
• the first ambiguity of whole cycles is a unique correct ambiguity of whole cycles in the N first ambiguities of whole cycles to be detected that satisfies the preset ambiguity of whole cycles condition;
• and the second ambiguity of whole cycles is a unique correct ambiguity of whole cycles in the M second ambiguities of whole cycles to be detected that satisfies the preset ambiguity of whole cycles condition,
• wherein the performing the double-difference ambiguity of whole cycles search according to the preset pseudo-range double-difference linear equation and the preset carrier double-difference equation, and determining the N first ambiguities of whole cycles to be detected of the first long-wave observation combination and the M second ambiguities of whole cycles to be detected of the second long-wave observation combination comprises:
• acquiring, under a condition that original observation data is received, an initial calculated point and an ephemeris calculation based on pseudo-range single-point positioning to obtain position coordinates respectively between each of the navigation satellites of P navigation satellites and a receiver, wherein P is an integer greater than 1;
• determining elevation angles of the navigation satellites according to the position coordinates respectively between each of the navigation satellites and the receiver;
• determining a priori variance of observation values and a reference navigation satellite according to the elevation angles of the navigation satellites;
• obtaining a covariance matrix of the priori variance according to the priori variance and the reference navigation satellite,
• obtaining an observation weight matrix based on the covariance matrix;
• calculating a first baseline vector, a first channel residual and a weighted variance based on the observation weight matrix and the pseudo-range double-difference linear equation to determine a first search interval;
• and
• performing the double-difference ambiguity of whole cycles search in the first search interval according to the carrier double-difference equation, and determining the N first ambiguities of whole cycles to be detected of the first long-wave observation combination and the M second ambiguities of whole cycles to be detected of the second long-wave observation combination.