  Group delay fringe tracking using spectrally-dispersed fringes is suitable
for stabilising the optical path difference in ground-based astronomical
optical interferometers in low light situations. We discuss the performance of
group delay tracking algorithms when the effects of atmospheric dispersion,
high-frequency atmospheric temporal phase variations, non-ideal path
modulation, non-ideal spectral sampling, and the detection artifacts introduced
by electron-multiplying CCDs (EMCCDs) are taken into account, and we present
ways in which the tracking capability can be optimised in the presence of these
effects.
