A method for driving a lamp (2) comprises the steps of: generating a lamp current (ICONST) having a constant magnitude; defining a commutation period having a duration TCOMM; defining a time base of original commutation moments, having fixed mutual intervals of 0.5*TCOMM; receiving data to be embedded in the light output; commutating the lamp current at commutation moments; wherein individual commutations are time-modulated in order to encode said received data. Preferably, a commutation moment is: either equal to an original commutation moment if there are no data to embed; or advanced over a modulation distance (Δ) with respect to the corresponding original commutation moment in order to encode data having a first value (“0”); or delayed over said modulation distance (Δ) with respect to the corresponding original commutation moment in order to encode data having a second value (“1”).