I would like to thank everyone who responded to my post. In fact this frequency (in my area, Central New Jersey) is part of a NYC Federal system. All the frequencies people supplied were confirmed. Most of the activity I hear is from the USPS Police, primarily in Staten Island. The system is: 413.700, 415.150, 415.550, 415.950, 416.950, 418.350 Thanks to everyone, Michael