why would you care about input freq's? You have to be pretty much right next to the person to hear an input Freq? You should only care about the output Freq? Those are the ones that get repeated!
Personally, I would program just the input frequencies into a bank to monitor for local activity occurring in our small town. This would spare me from having to monitor the large amount of constant radio traffic taking place throughout our entire country (a rather large one at that). At times, I have received input frequencies from over 15 miles away here in the open space of Colorado however most often they travel typically about 2-5 miles line of sight which is more than sufficient to cover the small town I live in.
Monitoring input frequencies can also assist with verifying whether an unknown talkgroup is indeed originating from an assumed location. Monitoring the input frequencies at the assumed location of an unknown talkgroup can verify whether the unknown talkgroup is indeed from that general area or not.
There are likely other reasons but these are a few.
Shawn
