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US 5,515,057 AGranted
GPS receiver with N-point symmetrical feed double-frequency patch antenna
AssigneeTrimble Navigation Limited
InventorsGary R. Lennen, Wilfred Hand, Brian Westfall
Life of this patent
Estimating the term…
Abstract
Apparatus and method for eliminating the time delay variation associated with the satellite signal propagating within an antenna for a GPS receiver (or GLONASS receiver). The antenna is an n-point symmetrical feed double-frequency feed antenna which has the reduced electrical center error ellipsoid as compared with the single point antenna. The angular dependence of the time delay variation on the azimuth and the angle of elevation of the incoming satellite signal is reduced in case of n-feed point symmetrical antenna. The GPS receiver with n-point antenna can be used for differential GPS, both static and dynamic, and for absolute GPS positioning.
Claims9
An apparatus for the precise survey measurements comprising:
- an n-point feed double-frequency double-patch antenna, n being a positive integer, said antenna receiving the right-hand circular-polarized L1 and L2 carrier waves from at least four satellites located above the horizon;
- said first patch having dimensions equal to one-half of the wavelength of said L1 carrier wave, said second patch having dimensions equal to one-half of wavelength of said L2 carrier wave;
- an amplifying circuit, said circuit being conductively connected to said antenna, said circuit amplifying said modulated right-hand circular- polarized L1 and L2 carrier waves and converting their electromagnetic energy into an equivalent electric current containing the appropriate C/A-code, P(Y)-code, and data stream modulations;
- a code-tracking loop, said code-tracking loop being conductively connected to said amplifying circuit, said code-tracking loop measuring the pseudorange of said apparatus by tracking the C/A-code and P(Y)-code pulse trains from each of said satellites;
- a phase-lock loop, said phase-lock loop being conductively connected to said code-tracking loop, said phase-lock loop measuring carrier phase of said apparatus by tracking the carrier wave from each of said four relevant satellites;
- a navigation processor, said navigation processor being connected to said phase-lock loop, said navigation processor processing said pseudorange and said carrier phase of said apparatus to determine the instantaneous position coordinates, the clock-offset, and the velocity components of said apparatus;
- and
- a display module conductively connected to said navigation processor for displaying the position coordinates, the clock-offset, and the velocity components of said apparatus;
- wherein the electrical center error ellipsoid of said n-point feed antenna is reduced as compared to the electrical center error ellipsoid of a GPS receiver with a single-point feed antenna;
- wherein the dimensions of the electrical center error ellipsoid for a code-phase derived single point antenna is 50 cm, and wherein the dimensions of the electrical center error ellipsoid for a carrier-phase derived single point antenna is 3-4 mm;
- and wherein the measurement error resulting from the time delay variation of the satellite signal propagating within the n-point antenna itself is significantly reduced as compared with the measurement error resulting from the time delay variation of the satellite signal propagating within the single-point antenna;
- and wherein the measurement error resulting from the azimuth and elevation angular dependencies of the incoming satellite signal is significantly reduced as compared with the measurement error resulting from the azimuth and elevation angular dependencies of the satellite signal incoming into a SPS receiver with a single-point antenna.
9 more elements
A method of survey measurement using an apparatus comprising a double frequency double-patch n-point feed antenna, n being a positive integer, an amplifying circuit, a code-tracking loop, a phase-lock loop, a navigation processor, a power supply, and a display module, said method comprising the steps of:
- supplying said apparatus by said power supply;
- receiving the right-hand circular-polarized L1 and L2 carrier waves from at least four satellites located above the horizon by said n-point feed double-frequency symmetrical antenna;
- amplifying said modulated right-hand circular- polarized L1 and L2 carrier waves and converting their electromagnetic energy into an equivalent electric current containing the appropriate C/A-code, P(Y)-code, and data stream modulations by said amplifying circuit;
- measuring the pseudorange of said apparatus by tracking the C/A - and P(Y)-code pulse trains from each of said at least four satellites by said code-tracking loop;
- measuring the carrier phase of said apparatus by tracking the carrier wave from each of said at least four satellites by said phase-lock loop;
- processing said pseudorange and said carrier phase of said apparatus to determine the instantaneous position coordinates, the clock-offset, and the velocity components of said apparatus by said navigation processor;
- and
- displaying the position coordinates, the clock-offset, and the velocity components of said apparatus by said display module;
- wherein the electrical center error ellipsoid of said n-point feed antenna is significantly reduced as compared to the electrical center error ellipsoid of a GPS receiver with a single-point feed antenna;
- wherein the dimensions of the electrical center error ellipsoid for a code-phase derived single point antenna is 50 cm, and wherein the dimensions of the electrical center error ellipsoid for a carrier-phase derived single point antenna is 3-4 mm;
- and wherein the measurement error resulting from the time delay variation of the satellite signal propagating within the n-point antenna itself is significantly reduced as compared with the measurement error resulting from the time delay variation of the satellite signal propagating within the single-point antenna;
- and wherein the measurement error resulting from the azimuth and elevation angular dependencies of the incoming satellite signal is significantly reduced as compared with the measurement error resulting from the azimuth and elevation angular dependencies of the satellite signal incoming into a SPS receiver with a single-point antenna.
9 more elements
Dependencies are inferred from the claim text.