Thanks for that explanation ferpe still just a few queries if you could help
"Imagine that the beam would be 10° wide, you would have a begin and end of the target return over a 10° sector. If it was not for a multipath phenomenon called target fading one could guess the target would lie in the middle of this arc but given that fading makes the return echo go up and down in strenght when the painting takes place you need to make this arch as short as possible to get precision."
How come you would guess the target would lie in the middle of the arch if it was not for target fading? i am guessing that it is better then for the beam width to be narrow because that way it will not cover as much i.e. the unwanted area to the left/right of the aircraft?
"So how god is 0.6°. Well sinus for 0.6° is 0.01 so you would have a 10 m blip at 1000 m range, just about the maximum uncertainty you want at that range because then you are at some 50m above threshold if your are on a 3° glideslope like for a standard ILS."
Does 0.01 mean seconds yes? could you tell me how you calulated that and i am presuming that a blip is basically a scan cycle refreshed on the PAR controllers screen?
Thanks again for helping