Since so many people have a hard time understanding the differences between the 2 state trunk systems, I am going to attempt here to give broad overview of the differences of the 2 systems. Part 1 will be an a very generic overview of the 2 systems, Part 2 will focus on the differences of the 2 systems and now they work together.
NJSP 800 Mhz Trunk System (Circa Late 1980's)
This is one the countries first trunk systems. It started out as a type 1 system, migrated to a type 1/type 2 hybrid in he 90's, and finally became a fully type 2 around 2002. The system has P25 capabilities, however the digital user base is quite small. Although I refer to it as 1 system, it is actually 3 trunk systems, all with different system ID's that are patched together. This is why if you take someone's Unitrunker file from the North System and try to run it on the Central or South, it does not work (unless you manually change the SysID in the xml file) As I said, there are 3 systems which split the state into North/Central/South. In addition there are a number of "Intellipeter" sites, which essentially are used to fill in small area's with lousy coverage. Those IR sites usually only have 2 frequencies associated with them, and only carried traffic from a radio that affliates to them. People ask all the time if they should monitor those, and the answer is no. The only exception would be if you don't get any signal at all from one of the main sites. Some examples of how limited these sites are and what would you hear compared to the main sites:
Montana Mountain site: 3 & 5 Comm Troopers only
Easton: DRJTBC Units only
Bedminster: 5 Comm troopers and at times NorthSTAR
Wildwood: Marine Police and at times Bass River Parkway
Some talkgroups are limited to a particular system, others will follow a user. For example, you may hear the Bass River Parkway channel on the North System for a while, then it disappears. A unit may have traveled into the North zone with that talkgroup on, or even switched over to it momentarily. Once a radio affilates with that talkgroup, it usually will stay active for about an hour before dropping off if there is no more activity and the radio leaves or logs off. There is some encryption capability, however it is rare and only used on a few NJSP talkgroups.
NJICS 700 Trunk System (Summer 2011)
The NJICS system is a P25 Phase 2/TDMA Trunk system. 100% digital, when complete, it will be a 4 slot TDMA system, which means up to 4 transmissions can take place per frequency. The currently configuration is a mixed P25 Phase 1 & 2 Slot TDMA. This will host local, state & federal agencies. With many NJ counties planning or rolling out their own 700Mhz systems, most are being setup in a way for users to roan onto each other's systems for better coverage and inter-operability.
Unlike the 800 system, this is considered 1 system statewide. You can take someone's Unitrunker file from any site and use it on another of the other sites and it will work. Instead of 3 simulcast sites, there are 6 (7 if you include Union County, which is sort of a special case). There are no IR sites per say, but about 15 additional sites that have varying degree's of coverage. For example the Meadowlands site covers about a mile around the stadium, and each of the Sussex County sites cover about half the county. Although you would hear more on the Simulcast sites, the smaller sites can very well carry traffic you won't hear anywhere else on the system. A good example of this is Sussex County, where you may hear Sussex Troopers on the Walpack & Highpoint sites, but no where else.
As with the 800 system, radio's will log onto each site they connect to, and any talkgroup they are affiliated on will carry over to that site. The hang time is minimal however, and when all the radios affiliated to a givin talkgroup all leave, the talkgroup shuts down on that site within a few minutes. This is why we often hear only 1 or 2 transmissions on a talkgroup at times.
NJSP 700 radios have become more common in recent months, and it is not uncommon to hear NJSP talkgroups active on the 700, especially during the daytime when they are more units on the air. 700 activity tends to drop off after 7pm.
Encryption is much more widely used on this system. NJSP has several encrypted talkgroups, along with Cape May County Prosecutors and Rutgers Encrypts pretty much everything.
This has been a very basic overview. If you haven't been there yet, check out the New Jersey forum on www.radioreference.com
In part 2, I will try and explain how the 2 systems work together, why you hear or don't hear certain things. If you have questions, post them in the comments and I will try and answer them in part 2.
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