초록 ▼

A method and a system are disclosed for measuring the baseline vector b between a pair of survey marks on the ground by radio interferometry using radio signals broadcast from the earth orbiting satellites of the NAVSTAR Global Positioning System (GPS), the radio signals broadcast by the satellites

A method and a system are disclosed for measuring the baseline vector b between a pair of survey marks on the ground by radio interferometry using radio signals broadcast from the earth orbiting satellites of the NAVSTAR Global Positioning System (GPS), the radio signals broadcast by the satellites being double-sideband modulated with their carriers suppressed. An antenna is positioned at each survey mark. The signals received by one antenna during a predetermined time span are separated into upper and lower sideband components. These separate components are filtered, converted to digital form, and then multiplied together. Their product is analyzed digitally by means of correlation with quadrature outputs of a local oscillator to determine the power, and the phase relative to that local oscillator, of the carrier wave that is implicit in the double-sideband signal being received from each satellite. Differences in Doppler shift are utilized to distinguish the carriers of different satellites. The signals received at the same time by the other antenna are processed in the same manner. Thus, the powers and carrier phases of the signals from a plurality of satellites are measured simultaneously and numerical data representing the measurement results are obtained at each survey mark. The measurements are performed in real time at each mark without reference to signals that are received at any other place and without knowledge of any of the coded signals that modulate the GPS carriers. The data from the measurements performed simultaneously but independently at the two survey marks.

대표청구항 ▼

A system for use in measuring position using radio signals broadcast from a plurality of earth orbiting satellites, and including a terminal adapted to be positioned at a point on earth, comprising: a. an upward looking omni-directional antenna assembly for concurrently receiving radio signals from

A system for use in measuring position using radio signals broadcast from a plurality of earth orbiting satellites, and including a terminal adapted to be positioned at a point on earth, comprising: a. an upward looking omni-directional antenna assembly for concurrently receiving radio signals from a plurality of satellites, said antenna assembly including an antenna, and b. an electronic assembly for converting received carrier-suppressed signals into carrier phase data, said electronics assembly including: i. a receiver unit for receiving signals from the antenna assembly and outputting signals, representing the upper sideband component of the received signals, the lower sideband of the received signals, and the output of a reference oscillator; ii. a digital electronics unit for converting the output signals from the receiver unit into carrier phase data, and iii. a computer for processing said carrier phase data to determine position.