Multi-frequency pseudolites for carrier-based differential-position determination
View Patent ↗Apparatus and methods for resolving integer ambiguities in position determination. An embodiment of the invention includes a reference system, augmented with multi-frequency pseudolites using a carrier phase differential GPS implementation, and a mobile system. In one embodiment, the components of the reference system includes one or more multi-frequency pseudolites, one or more multi-frequency reference receivers, a data link standing alone or built into the pseudolites, and the associated antennae for each of these elements. The components of the reference system may be stationary. The mobile system may include a multi-frequency receiver and its associated antennae. Because the mobile systems may passively receive information, an unlimited number of mobile systems may be included in any given embodiment of the invention. A multi-frequency pseudolite uses a single frequency source to synthesize all of the multiple carrier frequencies and all of the multiple base band signals modulated onto carrier frequencies for transmission.
1. A positioning system comprising:
a plurality of pseudolite transmitters, each pseudolite transmitter capable of transmitting a plurality of GNSS-like radio-frequency (RF) signals, each signal including a carrier signal and a spreading code modulating said carrier signal; and
a receiver system, the receiver system capable of:
a) receiving said plurality of GNSS-like radio-frequency (RF) signals;
b) determining a plurality of measurements including:
a carrier phase measurement of each said carrier signal; and
a code phase measurement of each said spreading code; and
c) calculating a range between at least one of the plurality of pseudolite transmitters and the receiver system from said carrier phase and code phase measurements where the range is accurate to within one wave length of a highest frequency of the carrier signal in the absence of relative motion between the pseudolite transmitters and the receiver system;
wherein the plurality of GNSS-like radio-frequency (RF) signals includes signals whose frequencies fall within at least two different continuous ISM bands.
2. The positioning system of claim 1 wherein the receiver system is operable to determine the range in a single measurement cycle.
3. The positioning system of claim 1 wherein said receiver system comprises multiple conventional GNSS receivers.