A system for adjusting a reference constellation for demodulating an optical signal comprising: a coherent electro-optical receiver configured to convert a received optical signal to a plurality of electrical signals; an array of analog-to-digital convertors configured to digitize the plurality of electrical signals; and processor logic configured to: process the digitized plurality of electrical signals using a reference constellation to yield a plurality of decoded signals and a signal quality measurement, the reference constellation including: an inphase component equal to an ideal inphase component plus an inphase offset, the inphase offset initially set to zero, and a quadrature component equal to an ideal quadrature component plus a quadrature offset, the quadrature offset initially set to zero; determine an optimal inphase offset for the entire reference constellation by adjusting the inphase offset over a first range of values while monitoring the signal quality measurement and keeping the quadrature offset constant; determine an optimal quadrature offset for the entire reference constellation by adjusting the quadrature offset over a second range of values while monitoring the signal quality measurement and keeping the inphase offset constant; and update the reference constellation by setting the inphase offset for the entire reference constellation to the determined optimal inphase offset and the quadrature offset for the entire reference constellation to the determined optimal quadrature offset. a coherent electro-optical receiver configured to convert a received optical signal to a plurality of electrical signals; an array of analog-to-digital convertors configured to digitize the plurality of electrical signals; and processor logic configured to: process the digitized plurality of electrical signals using a reference constellation to yield a plurality of decoded signals and a signal quality measurement, the reference constellation including: an inphase component equal to an ideal inphase component plus an inphase offset, the inphase offset initially set to zero, and a quadrature component equal to an ideal quadrature component plus a quadrature offset, the quadrature offset initially set to zero; determine an optimal inphase offset for the entire reference constellation by adjusting the inphase offset over a first range of values while monitoring the signal quality measurement and keeping the quadrature offset constant; determine an optimal quadrature offset for the entire reference constellation by adjusting the quadrature offset over a second range of values while monitoring the signal quality measurement and keeping the inphase offset constant; and update the reference constellation by setting the inphase offset for the entire reference constellation to the determined optimal inphase offset and the quadrature offset for the entire reference constellation to the determined optimal quadrature offset. process the digitized plurality of electrical signals using a reference constellation to yield a plurality of decoded signals and a signal quality measurement, the reference constellation including: an inphase component equal to an ideal inphase component plus an inphase offset, the inphase offset initially set to zero, and a quadrature component equal to an ideal quadrature component plus a quadrature offset, the quadrature offset initially set to zero; an inphase component equal to an ideal inphase component plus an inphase offset, the inphase offset initially set to zero, and a quadrature component equal to an ideal quadrature component plus a quadrature offset, the quadrature offset initially set to zero; determine an optimal inphase offset for the entire reference constellation by adjusting the inphase offset over a first range of values while monitoring the signal quality measurement and keeping the quadrature offset constant; determine an optimal quadrature offset for the entire reference constellation by adjusting the quadrature offset over a second range of values while monitoring the signal quality measurement and keeping the inphase offset constant; and update the reference constellation by setting the inphase offset for the entire reference constellation to the determined optimal inphase offset and the quadrature offset for the entire reference constellation to the determined optimal quadrature offset.