....and when approaching another aircraft with only mode C (S not required) you should receive an RA.....had a few bugs in the beginning...but now works good.
Another nice piece of equipment that was invented in America....along with GPS, INS, VOR, LORAN, ILS...well the list goes on. But just to show that the British came up with a few good ideas...RADAR, turbine engines, and oh yes, the Comet.