Chromatic dispersion measurement system

The chromatic dispersion of an optical system (22) having physically separated access points is measured, wherein a modulation signal (23) at a local access point (LAP) of the optical system (11) and a reference signal at a remote access point (RAP) of the optical system are generated and the signals are synchronised via timing signals (19) derived from global positioning satellites (GPS). The signal (23) modulates optical test signals (25) having predetermined optical wavelengths and the modulated optical test signals (27) are applied to the local access point of the optical system (22) and transmitted to the remote access point where the signals are demodulated. The time delay of the demodulated signal relative to the reference signal is measured at the remote access point by a phase comparison or alternatively by measuring the relative time delay directly. The relative time delay through the optical system (22) as a function of optical wavelength provides a measure of chromatic dispersion of the optical system between the local and remote access points.