Patent ID: 7742542

Claim:
A method of transmitting base band binary data contained in respective successive time cells using a digital communication system, the base band binary data being transmitted in the form of a signal obtained by amplitude modulation and frequency modulation of a wireless carrier wave with a 0 bit data having a 0 bit mean amplitude and a 0 bit mean frequency and a 0 bit duration and a 1 bit data having a 1 bit mean amplitude and a 1 bit mean frequency and a 1 bit duration the improvement wherein the amplitude and frequency are modulated with the same binary base band signal whereby to decrease a spectral width of the resulting modulated signal below the spectral width of the binary base band signal; wherein a product of the 0 bit duration and a frequency excursion between the 1 bit mean frequency and the 0 bit mean frequency is equal to ½ such that the frequency excursion produces a π phase shift between 1 bits having an odd number of 0 bits therebetween.