|In this thesis, timing-based methods of multipath mitigation and detection are developed.
GPS pseudorange measurements are used to calculate a receiver's position and timing
bias, which is a measurement of the di erence between the GPS satellite clocks and receiver
clock. The timing bias will be monitored while the receiver is disciplined with a chip-scale
atomic clock (CSAC), which has exceptional stability and accuracy, and has recently been
made available to the public at an a ordable cost. The CSAC controls the receiver's timing
bias drift rate, allowing for the use of the timing bias to detect multipath and spoo ng. Under
normal operation, the clock in a GPS receiver drifts too rapidly to be used for multipath
detection, and must the timing bias must always be solved for as a nuisance parameter.
Di erent grades of clocks will be examined in a benign environment to attain accurate
models of the speci c clocks being used, and to determine what the clock drifts are without
uences. The clock models will then be used to detect multipath in a dynamic test.
After detection, an algorithm to remove faulty GPS signals will be implemented, creating
an accurate, multipath-free position solution. In addition to detecting multipath, the clock
model will provide a reasonable estimate of the clock drift when there are fewer than four
satellites available. This allows for a reduction from four to three satellites needed to solve
for position, as well as the ability to predict clock drift during a GPS outage. Finally, a
spoo ng simulation will be outlined and simulated using a low-cost ublox receiver. The
ublox clock is not as good as a CSAC, but performs acceptably for determining whether or
not the receiver is being spoofed.