chicago radio

I've been looking at the listings for Chicago railroads, and have noticed some things. 1. The frequency 160.305 is not just for Amtrak operations. All of the railroad ops into and out of the south gates/south concourse at Union Station happen there. 2. The frequency for the Metra Milwaukee...

Hello, what type of radios do Chicago Police and fire use? What is that squawk that I here at the end of transmissions on CPD zones? And finally how come you here the squawk on the zones and not the city wides? Please let me know thank you.