Why would the OP need to try to listen to the "input" unless it is a split Duplex system? A split system has the option of not repeating the mobile, only the dispatcher hears the mobile.Just curious are you near Weehawkeen when you try to listen to them? Input frequencies usually don't have a lot of power
It would appear then that the 156.0075 frequency listed in the FCC files may be the input frequency.Just outside the Lincoln Tunnel listening on a Uniden BCD396XT heard a close call hit on 156.010mhz DPL-131.
Sounded like ambulance #214. possibly the new input frequency for 159.090mhz but unconfirmed.