Personally when I'm able to pick up the system from the Montco, PA side across the river from Roxborough section of Philly, I'm able to get a reliable decode with filter on my SDS100 set to "off" with 3 to 4 bars and RSSI about -101 INDOORS at that!
Set filter to Wide Invert. Then set Attenuator to ON. Thats how I hear it when I pass through the area daily. And my SDS 100 almost never drops a transmission that way. I believe you must be near the antenna farm which is causing interference with the attenuator off.