The C-Band All-Sky Survey (C-BASS): Digital backend for the northern
  survey
  The C-Band All-Sky Survey (C-BASS) is an all-sky full-polarization survey at
a frequency of 5 GHz, designed to provide data complementary to the all-sky
surveys of WMAP and Planck and future CMB B-mode polarization imaging surveys.
We describe the design and performance of the digital backend used for the
northern part of the survey. In particular we describe the features that
efficiently implement the demodulation and filtering required to suppress
contaminating signals in the time-ordered data, and the capability for
real-time correction of detector non-linearity and receiver balance.
