As has been suggested, suggested, suggested, identify them by their call signs.
If these are police agencies in the United States, and are operating on 424 mhz, they are operating illegally. If that is the case, most likely the police agency is not aware of it, as very few police officers know what actual frequency their radios are on. They just know channel numbers. But the service agency that sets up their radios, and certifies them, should know.
Not doubting your word, but you need more than "I hear them." Identify them. It is possible, though not awfully likely, that some police agency has decided to 'cut corners' and has purchased some ham gear and is using that illegally. That actually has happened a few times, but it is not very common.
Your next step is to identify the agencies. Then file a complaint with the FCC.
Since you are in Michigan, that most likely puts you north of Line A. Hams may not use 420-430MHz if they are north of line A because Canada uses that frequency range for land mobile allocations and they are a primary user.
It turns out that, since hams can not use this frequency range, that the FCC is assigning channels in this range to land mobile licensees.
A quick search of the FCC data base shows numerous LMR licensees. For instance, the first one to show up is the City of Dearborn with assigned frequencies at 423.300 MHz, 423.400 MHz, etc.
Any one in the northern US states needs to check to see where they are relative to Line A before operating in the 420-430 MHz range.
You need to take a look at 47 CFR Part 90 Sections 90.273, 90.275, and 90.279. There are definitely frequencies in the following frequency ranges within the 70 cm band that can be licensed to commercial two-way users in the Detroit, Michigan, Cleveland, Ohio, and Buffalo, New York, area.
The frequency ranges 422.1875 MHz to 425.4875 MHz and 427.1875 MHz to 429.9875 MHz are available to the Detroit and Cleveland areas. The frequency ranges 423.8125 MHz to 425.4875 MHz and 428.8125 MHz to 429.9875 MHz are available in the Buffalo area.
Mobile operations are generally confined to within a 50 mile radius of the geographic center of the cities referenced.
WA9ZZZ beat me to the answer. Amateurs do not have 420 to 430 MHz near the Canadian border (see line A). Certain American cities have been allowed LMR operations in this frequency range for quite a number of years.
Frank
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AC0FP first licensed 1973________________________________
I do "Ignore" those who consistently make outrageous or erroneous posts, you know who you are.
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