Potential accuracy of the delay measurement of a signal that has passed through a dispersively nonuniform ionospheric layer

Relationships are derived for the potential accuracy of the delay-time measurement of signals that have passed through a dispersively nonuniform ionospheric layer and are additively mixed with normal white noise. The ionosphere is modeled as an equivalent linear filter whose unknown parameters are constant during the time period of the measurements. Signals with known phase and random phase are considered, and the case of a narrow-band signal is examined. The results have reference to the conditions of space-ground communications.