The signal-to-noise ratio (SNR) enhancement using a coded pulse in Brillouin Optical Time Domain Analysis (BOTDA) is studied theoretically and experimentally and compared with the one pulse case. This new technique is based on simplex coding and provides a theoretical SNR enhancement of 3.6 dB. We find that the experimental SNR improvement is around 3.8 dB, which is in good accordance with the theory. We also observe that the Differential Pulsewidth Pair - Brillouin Optical Time Domain Analysis (DPP-BOTDA) method can be applied. This allows to combine high spatial and frequency resolutions1 and higher SNR.© (2009) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.