For fun add this line to compare between MODULATE and the formal equation:
a1 modulation 0 0 0 0 0 fm2 0 modulator mark={FC+DEVIATION} space={FC}
Compare node FM to FM2.? With 1nS max time step I get less than 100 microvolt difference between the two.? No doubt the MODULATE device is more accurate since it is no doubt implemented internally in source code (C or C++).
Dan
