If you're that close to the tower, monitoring THAT specific site, and still having trouble with reception/locking onto the control channel, I'm betting the system is other than Motorola.
There may not be all that much you can do to improve things with your scanner but that depends on at least two major questions (that have already been asked):
- what model scanner are you using?
- what system and sites are we talking about?
For more details on what others have said, read this over (assuming you haven't already):
https://wiki.radioreference.com/index.php/Simulcast_digital_distortion
However, the issues potentially go beyond what this discusses --
EDIT: Looking at other threads, I now suspect you have a bcd325p2 and are trying to monitor
Middlesex County (RRDB says is a single simulcast site 700/800Mhz system) - is that the case? Middlesex DOES appear to be a non-Motorola system (it appears to be a Harris system) and most of my scanners have a terrible time receiving these systems. My PSR-500 won't hold the control channel at all and others only do slightly better. In contrast, my Unication G5 has no problem receiving the exact same systems from the exact same location (and actually do well from most any location in the area).
The other possibility looks like
Somerset County - which seems to be a two site (500Mhz and 700Mhz) Motorola simulcast system.
