In at least one illustrative embodiment, a guided wave radar (GWR) level transmitter may comprise a timing circuit including a first oscillator circuit and a second oscillator circuit, a coincidence circuit configured to generate a coincidence signal indicative of phase shifts created by a difference between first and second frequencies of the first and second oscillator circuits, and a microcontroller configured to (i) determine a stretching factor based on the coincidence signal and at least one of the oscillator signals, (ii) calculate, when the stretching factor is within a first range, a distance to a media surface using the stretching factor, and (iii) adjust, when the stretching factor is outside of a second range, at least one of the first and second oscillator circuits to adjust the difference between the first and second frequencies.