Originally Posted by
aterpster
This is a fun review.
Do we have a participant who can explain the interrogator/reply details of Mode A and the similarities to DME interrogators?
Main difference is with SSR Mode A, the interrogator is on the ground and the aircraft's transponder replies to its interrogation. With DME (trying to remember my 'radar for controllers' course some 45 years ago) the ground based equipment transmits 'squitter' pulses and the aircraft equipment picks up this signal and locks on to pairs of these pulses to which the ground equipment replies, each DME being capable of handling about 200 aircraft. NB: I may have got this wrong!! I seem to remember the squitter pulses are transmitted in a rotating field called a 'romecon' or 'limecon' shape?; would that sound right?
Don't ask me how TACAN works though!!