I've noticed a data burst of some sort, every one second on 453.225 using no PL, this is the frequency for Saddle Brook FD. any idea as to what this is? my guess is it is not SBFD, and the members must hear this on their pager when monitoring.
PL-less data bursts are a possible sign of an LTR system, but not really likely in that frequency range (and to the normal human ear, LTR data sounds like a dead-key squelch burst).
Is it possible that you're actually receiving a signal being transmitted 21.7 MHz (or whatever the IF frequency is for your scanner) below 453.225?
I'm having a similar issue here with 453.850, Hawthorne Fire channel #1. I have not taken the time yet to figure out if the signal is actually on 453.850, or on a frequency IF to my scanner.