  The Galaxy And Mass Assembly (GAMA) survey has obtained spectra of over
230000 targets using the Anglo-Australian Telescope. To homogenise the redshift
measurements and improve the reliability, a fully automatic redshift code was
developed (autoz). The measurements were made using a cross-correlation method
for both absorption-line and emission-line spectra. Large deviations in the
high-pass filtered spectra are partially clipped in order to be robust against
uncorrected artefacts and to reduce the weight given to single-line matches. A
single figure of merit (FOM) was developed that puts all template matches onto
a similar confidence scale. The redshift confidence as a function of the FOM
was fitted with a tanh function using a maximum likelihood method applied to
repeat observations of targets. The method could be adapted to provide robust
automatic redshifts for other large galaxy redshift surveys. For the GAMA
survey, there was a substantial improvement in the reliability of assigned
redshifts and in the lowering of redshift uncertainties with a median velocity
uncertainty of 33 km/s.
