The Letter Modulation Codes

Using the above definition the FM angle is converted to a character by a function such as the one below written in C++.

char FMCode(double C)

{

char charOut;

int Num;

char BaseChr;

Num = abs((int)(C * 10.0));

if (Num > 16) Num = 16;

if (C >= 0.0) BaseChr = 'A';

else BaseChr = 'a';

charOut = BaseChr + Num;

return charOut;

}

This is a graphic representation of the slope codes for increasing frequency:

This is a graphic representation of the slope codes for decreasing frequency: