Somebody send me this question via email and I thought I would answer it here.
saw a thread on the Van's Forum and thought I would ask a question:
I know each transponder has I believe what is called an S-Code? Can you trace a transponder back to an individual airplane with no other information other than what you see on the radar? Also, I fly from an airport under the outer layer of class C. How closely do you pay attention to those type of airplanes like mine that are going from their aiport away from the Class C airport. for example, I am to stay below 2300MSL until out of the Class C, but I am actually at 2500.
I am not very familiar with an s-code... I think you are referring to transponder types. All I really know about that is mode c and mode s transponders are capable of transmitting altitude. i.e. "Squawk altitude" is what we say when we want you to turn your mode c or s ON. As in, you flip your transponder button to ALT.
Transponders are considered "secondary radar". I can see your target on my scope with or without a transponder but the transponder allows a certain code (1200, 7700, 7600 or any assigned code), usually with altitude to be interigated by my radar equipment. This allows me to see your altitude and squawk code, ie 1200
As far as airpace violators, I see them on occasion. If they interfere with my operation I will certainly track that target and find out who they are. Sometimes I will see them approaching a local airport to land, I will have someone at the airport give me the tail number and track you down. Most times, if it isn't that bad, then all we want to do is talk to you via phone. We explain what we saw and how it could be dangerous and urge you to be more cognisent of what you are doing. In the worse cases we will pass on the info to FSDO and let them handle it.
In your example, a couple hundred feet will get my attention and we will complain about it to other controllers in the room but if they didn't interfere with my operation I usually don't do anything unless it becomes habitual.
As far as some sort of equipment to identify your plane squawking 1200....no. You are just another VFR aircraft and we don't/won't know who you are. BUT...if you have a major violation, we will track you, even up to hundreds of miles away We may even scramble fighter jets to intercept you depending upon the severity. For example, if you want to see fighter jets up close...penetrate the prohibited area (P40) over Camp David. You will QUICKLY get an escort!!