Chevvron - But the little blobby target on your magnificent video screen is obtained from a radar pulse and that pulse may not be as accurate as my satellite obtained position (note I do not use the G?S word
).
I'm sure you're right, your video screen may have the CAS lines and things nicely and accurately depicted theron it but that does not mean the moving 'blob' is absolutely correct - That 'blob' does depend on pulse length and beam width of the radar (s) used - An electronics bloke (and I ain't one) Iwould be able to indicate to you the inbuilt positional 'errors' due to the fundemental machinations of the radar emission (eg a conservative beam's width of say 0.5deg will produce a pretty accurate position at 1 naut.mile. but that same beam width, after 'fanning out' for 20 or 60 or whatever nautical miles will produce a rather more inaccurate result. The same goes for the pulse length (but due to the nature of the beast, is normally more accurate).
How many times have I heard Jersey Radar calling "You're crossing 50 North now - Squawk 7000, Change to xxx.xxx"? When, in fact, we've still got 3 miles to run?
PLEASE, please, please don't force me to go have to climb into my attic to root out my Ladybird Book on "How a Radar works" with it's associated mystical radar block diagrams, and circuitry stuff - PLEASE! my age won't allow!
