  The Canadian Hydrogen Intensity Mapping Experiment (CHIME) has become a
leading facility for detecting fast radio bursts (FRBs) through the CHIME/FRB
backend. CHIME/FRB searches for fast transients in polarization-summed
intensity data streams that have 24-kHz spectral and 1-ms temporal resolution.
The intensity beams are pointed to pre-determined locations in the sky. A
triggered baseband system records the coherent electric field measured by each
antenna in the CHIME array at the time of FRB detections. Here we describe the
analysis techniques and automated pipeline developed to process these
full-array baseband data recordings. Whereas the real-time FRB detection
pipeline has a localization limit of several arcminutes, offline analysis of
baseband data yields source localizations with sub-arcminute precision, as
characterized by using a sample of pulsars and one repeating FRB with known
positions. The baseband pipeline also enables resolving temporal substructure
on a micro-second scale and the study of polarization including detections of
Faraday rotation.
