Join Xtera at ECOC2017 in Gothenburg where Maria Ionescu will be presenting her studies on the Dynamic Range of Coherent Optical Time-Domain Reflectometer with Golay Coded ASK Probes. Join her in the poster session on Tuesday 19th September for more details; The Golay-coded ASK-based COTDR eases the trade-off between dynamic range and spatial resolution, whilst maintaining an accurate loss measurement, as well as relaxing the implementation constraints in terms of laser linewidth and measurement time. This benefit is maximised when sidelobe suppression is sufficiently high. By applying offline DSP techniques for tracking the laser frequency drift and correcting for jitter and amplitude noise of the fibre end reflection, the sidelobe noise was reduced by 12 dB. This ensured that only 400 backscatter signal measurements were sufficient to obtain a dynamic range as high as 17.1 dB for code lengths of 256-bits and 200 m spatial resolution. This technique benefits from the improved sensitivity of coherent detection, giving an extra 3 dB dynamic range improvement compared to its IM/DD counterpart, when reducing the measurement time and when the pulse width and code length are limited by the fibre length.