Geometric delay
= Geometric delay
{title2=$\tau_g=\mathbf b\cdot\mathbf s/c$}
The difference in plane-wave propagation time between two <antennas> is the projected baseline along the source direction divided by the <speed of light>. Its sign depends on the ordering of the receivers. A monochromatic signal acquires relative phase $2\pi\nu\tau_g$; its change with Earth rotation is compensated by <fringe stopping> for the chosen reference direction.