mikegilbert said:
Simple answer told by radios/systems in use:
-Mike
Like many overly simple answers, they are simply wrong.
However usually do a good job presenting the bias of the author.
mikegilbert said:
APCO 16: Mostly 800mhz Smartnet/Smartzone trunking. I belive it requires:
1. a "fail-safe" fallback option. Motorola calls is failsoft.
2. Emergency Signalling
3. Different levels of system acess priority eg. Police/Fire radios before Sewer workers.
This is basically right.
What is missing is the fact that the Project 16 was not a standard, but a functional recommendation.
Project 16 addresses trunking and only trunking.
In layman's terms, it provided a list of features that a trunked system needed to be acceptable for public safety use.
It did not specify how any of those functions were to be provided.
It was not aimed at inter-vendor compatibility in any way.
Most systems were at 800 MHz only because that is where most trunking is in general (and the only band that was trunked when it was written.
mikegilbert said:
APCO 25: Same basics as 16, but updated.
Here is where you make your first error.
P25 is nothing like Project 16. As I said earlier, there eis more different than the same.
P25 is a Standard, P16 is a recommendation
P25 is for both Trunking and Conventional, P16 is Trunking only
P25 tells "How" each feature must be implemented, P16 only says the feature has to be there.
P25 was developed from the start to be "all bands", P16 was developed for 800 MHz (only trunked band that existed)
This list can go on for a long time.
mikegilbert said:
1. P25 IMBE Digital Operation.
P25 CAI is IMBE Vocoder, C4FM/CQPSK medulation, and a specicified channel coding.
mikegilbert said:
2. Latter versions are P25 CAI (common air interface) Basically means it's no,longer limited to Motorola and EF Johnson Brand radios.
This is a common misunderstanding.
P25 allows for many system configurations. Motorola used P25 CAI on Smartnet trunked systems prior to having P25 trunked systems completed and to help system migrate.
These systems were not "earlier versions" of the standard.
mikegilbert said:
3. It was designed to promote interoperability; which is pretty much B.S...
One of the many goals was to promote interoperability and multi-vendor sourcing, and it is working quite well and getting better all the time.