many thanks everyone for your time
let's see if i have gotten it right this time
the CVOR transmist a carrier and the allocated frequency.
The carrier is FM at 30Hz. Why does it need to be FM?
FM refers to how often the signal repeats itself, complete a full cycle, for lack of better word, within one second 30Hz, 30 times per second.
This carrier carries a subcarrier amplitude modulated at 9960Hz and frequency modulated at 30Hz consisting of the variable signal.
AM means that there is another wave having an amplitude, vertical displacement from the position of rest, different than the carrier and carried by the carrier.
The receiver measures the phase difference between the reference signal and the 9960 hz variable signal and detremines the position of the aircraft related to the navaid.
now why do we need to FM the carrier and the subcarrier, wouldnt inserting the 9960 hz signal be enough? and i do beg your pardon for the sillyness of this question, but for the mortals like me having a mental picture of this stuff is pretty hard!!
i am still working on understaanding the DVOR but i will come back to you as soon as i have a clue of what i am talking about!!!
baobab72