The Gre600C the canadian model
Multi-System Trunking - Scans most common trunked radio
system signaling formats, including Motorola, EDACS, LTR and
P25 trunked radio networks. Both talkgroup and individual call
monitoring are supported.
GRE's Exclusive Automatic Adaptive Digital Tracking - When
monitoring P25 digital systems, instantly adapts the digital
decoder to the digital modulation format of the transmitted signal,
then analyzes the signal over 50 times each second and adapts
to any subtle changes caused by multipath or fading. No
cumbersome manual adjustments are required.
P25 NAC Functionality - Much like CTCSS and DCS with
analog signals, P25 Network Access Code (NAC) is used to
provide selective squelch operation on conventional digital
channels. Your PSR-600C will detect the NAC that is being used
on a P25 conventional digital channel, and allow you to program
NAC codes to block transmissions that do not have a matching
NAC, including analog traffic on the same frequency.
This is from the GRE600 owners manual