A process and an apparatus determines the position of an object by triangtion. In order to determine the location of an object, two illumination light beams coming from different directions are aimed at a reflector attached to the object and the reflected beams are detected by a location-sensitive sensor. In order also to detect the rotation position of the object, the reflector is partially mirrored so that a part of the illumination light beams striking thereon pass through it. The laser beams passing through the retro-reflector are detected in a sensor plane, which is spaced at a distance from the center of the reflector.
The invention relates to a method and an apparatus for determining the distance (h) between a base (1) and a specular surface (2) of an object (3). The method is based on the measurement of the direct reflection of radiation of a first light source (4) by a first detector (5) and the measurement of radiation of a second light source (6), located at least approximately at the location of the first detector (5), by a second detector (7), located at least approximately at the location of the first light source (4), in order then to determine with the known geometry of the setup and the measured values obtained for the angles of appearance (.gamma., .alpha.) of the virtual images of the light sources (4, 6) the position with respect to the base (1) of the specular surface (2) to be measured.
In a method, the light beams of two separated optical radar units (each of which are capable of emitting light pulses in a direction and receiving light pulses from the same direction) are directed to a point. The first optical radar unit emits a light pulse to the point and the second optical radar unit detects the light pulse reflected from the object at the point. After a time interval, the second optical radar unit emits a light pulse to the point and the first optical radar unit detects the light pulse reflected from the object at the point. If there is an object at the point, the time difference of the two detected signals from the two optical radar units is the switching time interval. By comparing the two detected signals from the two optical radar units, one can determine whether an object is at the point.
A method and apparatus for estimating the changing frequency of a signal received by a satellite receiver from, illustratively, positioning system satellites is disclosed that enables a more accurate measurement of the change in frequency of that signal due to movement of the satellite receiver relative to those satellites. The system includes a PLL having a numerically controlled oscillator (NCO) and a filter of frequency estimates (FFE). In operation, an analog signal is received at the satellite receiver and the PLL tracks the changing signal frequency and outputs non-smoothed frequency estimates into the FFE. The FFE then smoothes noise in the signal to produce a more accurate smoothed frequency estimate of the input signal. Comparing multiple estimates over time allows Doppler shift of the signal frequency received by the satellite receiver to be calculated more precisely, thus resulting in more accurate satellite receiver velocity vector determinations and, hence, position measurements.
