The way the Birdog meter works is you go to the Birdog homepage here
Horizon Satellite Meters and download the configuration files for whatever satellites you want to locate. I think the meters memory limit is about 60 different satellites at one time.
With the dish mounted, you connect the Birdog and go to the meters internal menu and select the satellite you're looking for. The Birdog then sends a DiSEqC switch command to the lnb, switching to the correct lnb for the satellite you selected. You then swing the dish in the general direction of the satellite and when the meter locates the correct satellite using the satellites
Unique Satellite Information Data, it locks on and displays a peaking meter, allowing you to maximise the signal.
A new Birdog goes for about $500, so it's probably not worth it if you only use it a couple of times a year, but if you're setting up a dish in an RV a few times a week it can sure make life easier.