An attitude angle detecting apparatus receives radio waves transmitted from
a plurality of position-fixing satellites with multiple antennas located
at specific positions of a mobile unit, determines relative positions of
the antennas and detects the heading and attitude of the mobile unit by
determining carrier phase ambiguities quickly and accurately. When it is
needed to redetermine integer ambiguities after recovery from an
interruption of the radio waves from the position-fixing satellites or as
a result of a change in combination of the position-fixing satellites, for
example, the attitude angle detecting apparatus redetermines the integer
ambiguities by using attitude angles and an attitude angle error
covariance obtained from previous observation. This enables the attitude
angle detecting apparatus to uninterruptedly obtain information on the
heading and attitude of the mobile unit.
