I've got him on the......

[gismo]

When I was 121 (it is ten years ago now)

I had no idea you were that old. And to think you still have your medical at 131!

Lastly, if you are looking at what amounts to a repeater of the what the controller is seeing you are subject to the same errors and inaccuracies that the controllers are subject to. I imagine there is a substantial component to radar controller training that examines the inherent inaccuracies in radar data and why they result in fairly large seperation standards.

I've been amused at the same thing (someone reporting to ATC about their TIS repeated (and delayed) version of what the controller sees) and I can almost hear the controller thinking "You idiot, I know the radar shows you in close proximity, I told you about it so you would look outside for the traffic!"

And you are right about limitations on RADAR accuracy affecting separation standards, close in with ASR (approach) the rule is "green between" IIRC and at the outer limits of center coverage it's something like 5 miles. There are many things that affect surveillance RADAR's accuracy such as the carrier wavelength, pulse length and spacing, antenna rotation speed, antenna position measurement, and there are inaccuracies in the electronics that process and display the results as well.