ATC History Squawk Ident
Hello,
I am an aviation student and the proud owner of 32 hours. A retired British ATC visitor attended at my flight school recently, and I asked him about squawk idents. He started to explain why there are no 8's and 9's used in squawk idents. He then said that in the early days, he would count four strokes on the radar screen, to a maximum of seven.
I note this comment earlier,
"Prior to this they showed as a single bar before identification, then a two bar once identified and during the squawk ident process (20 secs duration) there was a third bar flashing."
I would appreciate further explanation of the early four stroke system, up to 7 and what this means.
Thank you