A method and system generates a modulated chirp signal in accordance with the present invention. A phase-locked loop output signal is generated, together with a sampled feedback signal from a voltage controlled oscillator. The sampled feedback signal is received within a quadrature I/Q phase modulator. I/Q quadrature signals are generated from an I/Q generator circuit to the quadrature I/Q phase modulator to produce a desired modulation of a sampled feedback signal as a string of +/−90 degree phase shifts to create a desired offset at the voltage controlled oscillator. The I/Q quadrature signals are chirp modulated and the resultant phase-locked loop output signal is chirp modulated by the chirp signal that comprises a sequence of chirps having a reference chirp followed by a plurality of data chirps.