Explanation of the dBc/Hz unit used in noise of RF design

http://radarproblems.com/chapters/ch....dir/c06p7.htm

C stands for carrier signal
When you are measuring say Phase noise of oscillator this unit is used
it means Some X dB down with respect to carrier power at Y Hz from carrier.
When you say -100dBC/Hz at 100MHz offset means
you have measured at 100 db down from carrier power at 100MHz away from it.

dBc means the compared signal is bellow carrier(main signal),and the unit is dB