Peaking meters for installers simply look at aggregate signal strength in the satellite IF band from the LNB(s) and for DirecTV may have the option of the 22Khz tone to switch to another satellite and maybe up the voltage to change polarization. Some have a voltage pass through to allow the receiver to change the polarization.
Then you've got higher end meters which can actually read the digital identifier which tells the meter or satellite box what satellite it is looking at so you don't accidentally peak on the wrong birds. Channel Master, Bird Dog, and Promax come to mind.
Truly high end meters will choose specific transponders to look at.
A dual LNB peaker is ideal because then you can peak two at once. If you get maximum on both 101 and 119 with DirecTV, then you know 110 right between them will be fine, simple matter of geometery. Just remember to take legacy LNBs with you for Dish as those with built-in switches won't work with most meters as they don't generally have the ability to give the digital signals that tell their system to change to another satellite unlike DirecTV which uses the 22Khz signal.
Sonora Designs has a PDF file with a frequency break-down of transponders which with a spectrum analyzer would allow you to check for what any given transponder is doing.
