Weather also plays a role in this too. Prevailing winds and atmospheric conditions do have effects on reception, especially an simulcast P25. I noticed with an PRO-96, that in winterish weather, and strong storm fronts... Reception in certain areas sucked maximum nasty, but in milder weather that area was fine.... IDPSC is one of the really weird systems for reception... Not only is it LSM P25, they literally make small tweaks almost every time you turn around. The tweaks make things better for the guys using the system, but confound scanner users. Your feed sometimes has almost perfect reception... then there comes a weather change, or system tweak. And it can throw it off for a day or two til you can play with your antenna, or a setting, etc. Then the cycle starts all over. Ahh the joys of LSM systems.. and weird weather effects too.