On February 18,  the first Expanded Very Large Array (EVLA) pulsar detection was  accomplished by processing phased array voltage data with coherent  de-dispersion software. This observation is a successful  proof-of-concept for the use of the EVLA as a pulsar-timing instrument.

High-precision  timing of millisecond pulsars has a number of scientific applications,  including tests of gravity, exploring nuclear physics via neutron star  mass measurements, and direct detection of ultra-low frequency  gravitational waves (see NANOGrav). These studies have traditionally  been carried out using large single-dish telescopes. However, the  excellent point source sensitivity and octave-bandwidth receivers of the  EVLA promise to make it a world-class pulsar-timing instrument as well.

This  observation builds on recent efforts to operate the EVLA in phased array  mode for very long baseline interferometry (VLBI). In this mode, the  array effectively acts as a single large dish, providing a single beam  of voltage data similar to the output of a single-dish telescope. For  VLBI, the raw data are recorded directly to disk for eventual  correlation with other station data. For pulsar timing, a coherent  de-dispersion filter is first applied to the data, then they are  detected and averaged modulo the pulse period. Coherent de-dispersion  must be done pre-detection, and is required to exactly remove the  dispersive effects of the interstellar medium from the pulsar signal and  achieve the best possible timing results.

See the website for more details.

http://science.nrao.edu/enews/4.3/#almaconstructionprogress(SY)