  Dual comb spectroscopy allows for high-resolution spectra to be measured over
broad bandwidths, but an essential requirement for coherent integration is the
availability of a phase reference. Usually, this means that the combs' phase
and timing errors must be measured and either minimized by stabilization or
removed by correction, limiting the technique's applicability. In this work, we
demonstrate that it is possible to extract the phase and timing signals of a
multiheterodyne spectrum completely computationally, without any extra
measurements or optical elements. These techniques are viable even when the
relative linewidth exceeds the repetition rate difference, and can tremendously
simplify any dual comb system. By reconceptualizing frequency combs in terms of
the temporal structure of their phase noise, not their frequency stability, we
are able to greatly expand the scope of multiheterodyne techniques.
