Method for reducing inter-frequency bias effects in a receiver
AssigneeNovAtel Inc.
InventorsJanet Brown Neumann, Marcia Bates, Robert S. Harvey
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Abstract
A calibration procedure for reducing frequency-dependent bias effects in a fixed satellite-based ground-positioning receiver is disclosed, the receiver having the capability to receive both GPS and GLONASS satellite signals. The calibration procedure removes satellite dynamics by utilizing the respective satellite ephemeris data, estimates the change in receiver clock offset by means of GPS measurements, and acquires a set of two or more GLONASS pseudorange measurements while cycling a local oscillator in the receiver through a predetermined sequence of different frequencies.
Claims16
A method for reducing frequency-dependent bias effects in a fixed satellite-based ground-positioning receiver having the capability to receive both pseudorandom noise (PRN) encoded signals such as transmitted by GPS satellites, and frequency division multiple access (FDMA) signals such as transmitted by GLONASS satellites, said method comprising the steps of:
- obtaining pseudorange measurements from the PRN signals at times t0, t1, and t2;
- computing theoretical PRN satellite range measurements at times t0, t1, and t2;
- determining PRN satellite clock offsets at times t0, t1, and t2;
- deriving a PRN correction value at time t2 from said PRN pseudorange measurements, said theoretical PRN range measurements, and said PRN satellite clock offsets;
- obtaining FDMA pseudorange measurements (i) at time t0 and at a reference frequency fREF, (ii) at time t1 and at a first frequency f1, and (iii) at time t2 and at said reference frequency fREF;
- computing theoretical FDMA satellite range measurements at times t0, t1, and t2;
- determining FDMA satellite clock offsets at times t0, t1, and t2;
- and
- obtaining a bias correction value at time t2 for said first frequency f1 from said PRN correction value at time t2, said FDMA pseudorange measurements, said theoretical FDMA satellite range measurements, and said FDMA satellite clock offsets.
A method for reducing frequency-dependent bias effects in a fixed satellite-based ground-positioning receiver having the capability to receive both pseudorandom noise (PRN) encoded signals such as transmitted by GPS satellites, and frequency division multiple access (FDMA) signals such as transmitted by GLONASS satellites, said method comprising the steps of:
- obtaining pseudorange measurements from the PRN signals at times t0 and t1;
- computing theoretical PRN satellite range measurements at times t0 and t1;
- determining PRN satellite clock offsets at times t0 and t1;
- deriving a PRN correction value at time t1 from said PRN pseudorange measurements, said theoretical PRN range measurements, and said PRN satellite clock offsets;
- obtaining FDMA pseudorange measurements (i) at time t0 and at a first frequency fREF, and (ii) at time t1 and at a second frequency f1;
- computing theoretical FDMA satellite range measurements at times t0 and t1;
- determining FDMA satellite clock offsets at times t0 and t1;
- and
- obtaining a bias correction value at time t1 for said second frequency f1 from said PRN correction value at time t1, said FDMA pseudorange measurements, said theoretical FDMA satellite range measurements, and said FDMA satellite clock offsets.
A method for reducing frequency-dependent bias effects in a fixed satellite-based ground-positioning receiver having the capability to receive both pseudorandom noise (PRN) encoded signals such as transmitted by GPS satellites, and frequency division multiple access (FDMA) signals such as transmitted by GLONASS satellites, said method comprising the steps of:
- deriving PRN source positional data by using the PRN encoded signals;
- deriving receiver clock correction data using said PRN source positional data;
- deriving FDMA source positional data at a reference frequency by using the FDMA encoded signals;
- deriving FDMA source positional data at a first frequency by using the FDMA encoded signals;
- and
- calculating a correction term for said first frequency from said derived data, said correction term for reducing the frequency-dependent bias effects.
Dependencies are inferred from the claim text.