Looking at your screenshot from Sentinel that you posted
earlier in this thread, I see that apparently you are collecting warning siren channels for a number of areas, many of them in other states, and obviously out of range from your home location. I took a quick look at some of the locations, and it appears that at least a few of them (as is the case with your home area) nay be using trunked systems, not conventional channels. For any of those entries that really are from trunked systems, you need to have correct system type, as well as the corresponding site(s) and talkgroups.
For your home area, and using the SLATER trunked system, I think the best thing for you to do would be to append the system. For St Louis County, I see some conventional channels for the county OEM department,
View attachment 121756
The first frequency in that list is in Sentinel. (The others, labeled as data channels are not, since the scanner would not be able to accurately decode the data.)
In Sentinel, go to the database section at the top of the left side window of Sentinel's main screen.
Click on USA to expand the list of states
Then, in the state listing, click on Missouri.
Scroll down through the list of counties until you come to St. Louis County. Click on it to expand.
View attachment 121757
Click on the County Systems link.
Under that category, look for the entry with just the county's name:
View attachment 121758
Under that link are various departments using conventional channels.
Here you can find the county OEM.
View attachment 121759
If you click on that name, you'll see the frequency listed for it.
View attachment 121760
If you <Right><Click on that frequency, you'll get the option to append it to a Favorites list.
View attachment 121761
You can then append (add) it to your existing list, or create a new list.
If there are talkgroups on SLATER that you want to capture, you can append those as well. Just be aware that when you append the system, or only one of the listed departments, it will also append
all of the sites for the system.
The advantage of appending, as opposed to adding manually through Sentinel or the scanner's keypad, is that when appending, location data is part of what is added to a Favorites list. So, if you were to try and use your list, along with a GPS when traveling, the systems in range would be enabled. If you manually add a site or department, without location data also being manually entered, then the scanner will simply ignore any site or department without location information. Those fields would be blank, so the GPS & scanner would treat them as being at location zero degrees for both latitude & longitude, which is in the Atlantic Ocean, off the coast of Africa. Obviously, that would be treated as well out of range.
If you can be more specific on what parts of the
SLATER system that you want to include, then I could be more specific on what you need to do.