  Slow noise processes, with characteristic timescales ~1s, have been studied
in planar superconducting resonators. A frequency locked loop is employed to
track deviations of the resonator centre frequency with high precision and
bandwidth. Comparative measurements are made in varying microwave drive,
temperature and between bare resonators and those with an additional dielectric
layer. All resonators are found to exhibit flicker frequency noise which
increases with decreasing microwave drive. We also show that an increase in
temperature results in a saturation of flicker noise in resonators with an
additional dielectric layer, while bare resonators stop exhibiting flicker
noise instead showing a random frequency walk process.
