BEagle:
The trouble with the F4 was it had 2 bloody noisy engines. The British engines were even louder on CW radar than the US Weasels. However, I kid you not that the Harrier was the most prominent on a CW scope/aural. After a couple of years operating Bloodhound (like any other system I suppose) I could identify most AC types on aural alone - the display always told you how many engines though.