A method for monitoring leakage in the aeronautical band of a high split HFC includes providing an apparatus for use in a patrol vehicle, the apparatus including a leak signal receiver coupled to a processor; setting a plurality of coefficients for an OUDP matched filter for a current location of the patrol vehicle; detecting peaks over a detection threshold at an output of the OUDP matched filter; and determining a presence of a leak based on a time stamp and a level of each detected peak. An upstream leak detection system is also described.