WARNING! LONG POST AHEAD
I know that a topic about Indianapolis (Marion County)'s system was posted a while back, but since that thread is outdated and not all of the info on it is 100% accurate, I figured I'd go ahead and start a new thread, since I do live in Indy and probably know more about their system than a lot of people do.
Let's start with the general testing policy. Indianapolis used to test every Friday at 11:00 for 50 seconds and sound the sirens off for Severe Thunderstorm Warnings with a Tornado Watch on it as well as for Tornado Warnings for 3 minutes, up in till about July of 2011. People started to become "desensitized" to the sirens because they were sounded so often, thus the policy was changed so that now the sirens are sounded ONLY for tornado warnings. The testing policy is as follows: 50 second alert on the first Friday of every month at 11:00 and a weekly growl test on other Fridays. The sirens used to be controlled via WiFi, however the signals kept on getting blocked due to new buildings being put up and whatnot. So come last September Emergency Management has been in the process of switching to RHF to activate their sirens with. The sirens are now activated via 3 FSK outbursts, and even have FSK Parties every 3 hours, starting at 12:00 A.M..
Now let's move on to the actual system itself. (Note that the numbers might be a little off). Indianapolis's old system consisted of 154 total sirens, which included 38 Model 7s/7Ts; 40 Thunderbolt 1000Ts; 7 Thunderbolt 1003s; 64 2001-SRNs; 3 SD-10s (one of which was replaced by a Model 2 or vice versa); a Model 2; and an RSH-10. In 2007, it became clear that the majority of the old sirens had hit their limit. so from 2007-2009 the system was upgraded to a system of 168 Federal Signal 2001 sirens, which includes 54 2001-SRNs (2nd Gen. with the small motor housing and 3rd Gen. with the large motor housing); 4 2001-SRNBs (one of which is not marked on the map but is at Butler University); and 110 2001-130s. Quite a system right there!