Filter Banks
Cheap, reliable
Difficult to get very narrow channels
Variable gains introduces systematics
Poorly matched gains of two polarisation causes systematics
Fine for slow pulsars
Figure 37: A logical signal path for observations at 1400 MHz
Autocorrelators
Overcome above systematics
Flexible but expensive
All or nothing approach
Frequency sweeping
Swept local oscillator follows frequency drift of pulse
Very precise
Inflexible
Limited to a few pulsars with suitable DMs
Coherent dedispersion
Record base-band voltages
Apply inverse transform in software
Best way to remove dispersion
Recording data is difficult 
MB/sec
Now becoming possible with DLT tapes