Help monitoring a MOT trunked system that shares frequencies in the area

[DanRollman]

Hoping someone might have a tip that can help cure a problem I have monitoring a local MOT 900 MHz TRS on a 396XT.

I am monitoring the Delta Airlines TRS that is at the Atlanta Airport (Delta Air Lines (Atlanta) Trunking System, Atlanta, Georgia - Scanner Frequencies). Two of its voice frequencies (935.2125 and 935.2375) are also used by a site on the Emory University TRS (Emory University & Hospitals Trunking System, Various, Georgia - Scanner Frequencies). I am surprised these two frequencies are used by two unrelated systems in the same metro area, but the systems are about 15-20 miles apart and, by their nature, the users of each system typically stay in a pretty small geographic area, so perhaps the users don't experience interference from the other system.

My problem is that I am located roughly between the two locations, and the Emory system is much stronger. More importantly, 935.2375 is actually a regular control channel on the Emory system. Thus, when I try to monitor the Delta Airlines system and a targeted Delta conversation becomes active on 935.2375 (a Delta VOICE frequency), I hear the Emory control channel audio in lieu of the Delta voice transmission on that talkgroup. The scanner does not begin tracking the Emory system, but because the Emory control channel is constant, the scanner also never resumes scanning Delta - it's stuck as if the Emory CC audio is a never-ending Delta voice conversation.

Manual intervention (or a negative delay setting) is required. But in either case, while I can manually (or automatically after some period of time) resume tracking Delta, the problem recurs in 10 transmissions or so, when 935.2375 becomes the active Delta voice frequency again. I have removed 935.2375 from the programmed Delta system frequencies in hopes that I could at least, at a minimum, simply skip/miss all Delta conversations on 935.2375, but because it uses CC only mode the scanner trys to monitor 935.2375 for Delta voice comms regardless.

Any ideas on how to force the programmed Delta system to skip 935.2375 or otherwise improve on this issue?

Thanks,
Dan

[UPMan]

1st make sure you have End Code detect turned on. If it is and still has this problem, the interference from the control channel could be preventing end code detection...in which case the fallback is squelch control (which won't kick in since there is a signal).

Beyond that, using a directional antenna pointed away from the Emory system might help.