Patent ID: 7778356

Claim:
A modulator comprising: a direct modulation synthesizer circuit for producing a modulated signal to be inputted to a transmitter; a reference frequency oscillator for providing an input reference signal to the direct modulation synthesizer circuit for locking a carrier frequency to a stable frequency; and a pre-emphasis unit for receiving data bits and for producing a modulating signal for direct modulation by the direct modulation synthesizer circuit, the modulating signal having data bit dependent voltage levels; wherein the pre-emphasis unit is a digital-to-analog converter and wherein each voltage level of the modulating signal is a function of the bit values of a given data bit and of at least one data bit preceding the given data bit; wherein the modulating signal has at least four voltage levels; wherein the at least four voltage levels are: V 0 , if the given data bit is “ 0 ” and the preceding data bit is “ 0 ”; V 0 −δV, if the given data bit is “ 0 ” and the preceding data bit is “ 1 ”; V 1 , if the given data bit is “ 1 ” and the preceding data bit is “ 1 ”; and V 1 +δV, if the given data bit is “ 1 ” and the preceding data bit is “ 0 ”.