The Michigan State Police APCO-25 9600 BAUD System
What is the MPSCS System?
The MPSCS system is a group of towers that are Motorola APCO-25 9600 BAUD trucking systems towers. Law enforcement or non profit agencies that run under the system can travel anywhere (covering about 95% of the state of Michigan) and communicate with their dispatch or law enforcement. Under the old convention system, if a unit traveled too far away from the tower, about 50 miles they where unable to communicate. But with these new trunking systems, each tower is connected to other towers like a big cell phone network.
The MPSCS system is a trunked system. Difference is in the old convention system, you had one frequency, and all traffic is on the frequency and nothing else. Companies then realized, they could take 6 or so frequencies and have as many as 10 or more different organizations use those 6 frequencies because not everyone talks at the same time. To hear the traffic you only need to program in the one control channel and make sure you have a APCO 25 9600 Baud scanner and have that bank trunked to MOT. Some towers like in the Detroit area may have as many as 10 or 15 frequencies because of so many agencies using them. Plus those frequencies are used not only for voice, but data in the cars or referred to as MDCs. Those are the computers or laptops in the patrol cars.
A talk group is a special channel of talking. Some agencies use only one talk group for traffic, some larger area must separate their traffic into two or three areas, like North and South. When you monitor a certain tower, anytime a unit that is on that talk group talks you will hear all traffic. For example, if someone from Kent county is near the Barry County Nashville tower and you are listing to the Nashville tower, you will hear everything from that Kent County unit, till they move out of the area. That is why you might hear an agency 50 or 100 miles away. I have heard traffic from D.O.C. from the UP on the Ionia tower because they where transferring some prisoners from the UP to Ionia County Prison. If course when they left the Ionia area and went back up north I then was not able to hear them anymore. A tower will only broadcast that talk group when a unit on that talk group is on that tower.
What is Encryption?
With the Motorola system, agencies are able to digitally encrypted their traffic, making almost impossible to decrypt. Example of what you will hear will be posted here soon ---->
If an agency wishes to talk to another agency that does not use the same encryption, they must turn their encryption off for the agency to hear them. Sometimes they will then forget to turn their radio encryption back on when they switch back to their original talk group, so sometimes you might be able to hear non encryption talk. Eventually they will realize it and turn the encryption on. With the Pro 96 by Radio Shack (made by GRE), they will not block the encryption noise which is very annoying. The new GRE scanners and the Uniden scanners will block this notice, you will only hear about 1/2 of a second of noise.
More info to come.
This is just quick info but I will include more explains soon.