A low-cost, solid-state position sensor system suitable for making precise
code and carrier phase measurements in the L1 and L2 bands of GPS uses an
ordinary, low-cost OEM card single-frequency carrier phase tracking C/A
code receiver and includes low-cost hardware for sensing the L1 and L2
components of GPS carrier phase. Such measurements are suitable for
general use in a variety of fields, including surveying. They are also of
sufficient quality to be used in controlling heavy machinery, such as
aircraft, farm tractors, and construction and mining equipment. A C/A code
continuous tracking GPS receiver is used to produce GPS positioning fixes
and real-time L1 carrier phase measurements. This C/A code receiver
generates timing and reference information for a digital sampling
component. This sampling component processes the L1 and L2 signals from
the GPS signals in view. A digital signal processing component coupled to
this sampling component processes the raw samples in synchronous, batch
form including a step to precisely unwrap the P(Y) carrier phase to
baseband. The receiver outputs synchronous, carrier phase measurements
associated with each ranging source and signal observable. The synchronous
raw carrier phase measurements from the continuous tracking C/A code
receiver and the digital sampling component may be used to resolve the
cycle ambiguities to each ranging source with respect to a reference
station at a known location. Within a short interval typically tens of
seconds from initial turn on, continuous, synchronous raw measurements are
provided by the GPS receiver and processed into precise position fixes.
