Patent ID: 7680421

Claim:
An optical transmitter unit for connection to a multimode optical fibre transmission link, comprising: a data input for receiving an input data signal; a data signal processing circuit and a source of optical radiation, the data signal processing circuit being arranged to receive the input data signal from the data input and to provide a processed data signal to the source of optical radiation and the source of optical radiation being arranged to generate therefrom an optical signal for transmission by a multimode optical fibre, the data signal processing circuit comprising: a first variable delay line and an associated control input for applying a first controllable delay in accordance with the control signal; a second variable delay line and an associated control input for applying a second controllable delay in accordance with the control signal; a first variable gain stage and an associated control input for applying a first controllable gain in accordance with the control signal; a second variable gain stage and an associated control input for applying a second variable gain in accordance with the control signal; wherein the data signal processing circuit is arranged to: provide from the input data signal a non-inverted data signal and an inverted data signal; receive a control signal for controlling the generation of the processed data signal; apply a controllable delay in accordance with the control signal to at least one of said non-inverted and inverted data signals; apply a controllable gain factor in accordance with the control signal to at least one of said non-inverted and inverted data signals; and combine the non-inverted and inverted signals after the application of the controllable delay(s) and gain factor(s) to generate the processed data signal.