For continuum measurements observers can use either the Digital
Continuum Receiver (DCR) or the Analog-to-Digital (A/D) Converters.
The pointing is typically done with the A/D's while the DCR is used
for more sensitive continuum measurements.
For spectral line observations there are two choices: the NRAO Model IV
correlator or the spectral processor. A brief overview of each system
is given in the following links:
NRAO Model IV Autocorrelator
A more complete description of the spectral processor can be found here:
An estimate of radiometer sensitivity is given in the following link: