Figure 2.

This paper assumes a standard setup, which is simplified to one dimension here. The two receivers read the transmitter’s signals after they have traveled the two distances L + Δx and L − Δx. Thus, the time difference Δt = t₁ − t₂ = 2Δx/c is a result of the transmitter’s off-center position Δx. The system indirectly determines Δt = Δφ/(2πf) by estimating the phase shift Δφ between the two incoming signals r₁(t) and r₂(t).