Tom and Walter:
I am not an ADS-B expert, but here us my understanding from talking with the local FAA. Go to this web site (http://www.faa.gov/nextgen/flashmap/), let it load = 100%, then click on "Click to Begin", then click on the "ADS-B" button on the left. ADS-B services can come from three sources as shown by the three buttons in the upper right - En Route, Terminal, and Surface. Mouse over each button and you will be able to read a definition of each. Seems the En Route is provided by the ARTCC's stations and from what I have read, you may need to be at least 1,000-3,000 ft agl to get the ADS- B via "En Route" stations. Clicking on this "En Route" button shows the coverage map as of 7/1/2011 (an "as of" date is in lower right of map.) Sorry, Tom, it does not look like St. Louis is in the green region, yet. Clicking on the "Terminal" button shows the TRACONs (green circles) providing ADS-B, where the coverage is line-of-sight out to about 60 mn radius typically. And "Surface" coverage?...Fuhgettaboutit! = only two test sites in Louisville and Philadelphia.
Now then, in the cockpit, as long as we are receiving an ADS-B signal we won't know or care if it is from En Route or Terminal stations. The only difference to us in using ADS-B En Route vs Terminal services is the altitude at which we will receive the respective services reliably. In a manner of speaking it will be En Route at altitude in "remote" areas, and Terminal close to major airports down to the ground. My analogy is it will be like using a cell phone - we don't know or care where the cell towers are as long as we have a signal. To us users it will all just be ADS-B. That's the way it was explained to me and I hope it is correct, given the data link for aircraft operating at or above 18,000 ft will be 1090 MHz Extended Squitter [1090 ES] in their aircraft but most of us will be using the UAT (Universal Access Transceiver = 978 MHz] for aircraft that primarily operate below FL180. If anyone out there has a different understanding, let's hear it, please.
The FAA TRACON manager at CVG told me last week that he had not seen any schedules of when the TRACONs would get ADS-B and was not informed about when we would have nationwide coverage, even though the FAA has published "by 2013." Like Walter said, "This is frustrating." ---Ralph