Notation

Symbol	Description
\(\psi_{x}^{i}\)	Wrapped phase at pixel \(x\) in SLC \(i\)
\(\psi_{x}^{ij}\)	Wrapped phase at pixel \(x\) in interferogram \(ij\)
\(\phi_{x}^{ij}\)	Unwrapped phase at pixel \(x\) in interferogram \(ij\)
\(\Delta \psi_{xy} ^{ij}\)	Double difference wrapped phase between pixels \(x\) and \(y\) in interferogram \(ij\)
\(\Delta \phi_{xy}^{ij}\)	Double difference unwrapped phase between pixels \(x\) and \(y\) in interferogram \(ij\)

Wrapped phases are assumed to be in the range \(\left[ -\pi, \pi \right)\). When working with phase linked data, the phase data in inherently referenced to a particular acquisition in the stack.