Print Email Facebook Twitter An uncertainty assessment of the effect of using FM pulses on MBES depth measurements Title An uncertainty assessment of the effect of using FM pulses on MBES depth measurements Author Mohammadloo, Tannaz H. (TU Delft Aircraft Noise and Climate Effects) Snellen, M. (TU Delft Aircraft Noise and Climate Effects; Deltares) Simons, D.G. (TU Delft Aircraft Noise and Climate Effects) Date 2017 Abstract The most recent generation multi-beam echosounders (MBES) allows to transmit Frequency Modulated (FM) signals, in addition to the more conventional Continuous Wave (CW) pulses. In this contribution, the effect of using these FM pulses for bathymetric measurements is investigated. Advantage of using FM signals is that measurements can be taken at long ranges, due to the use of long pulse lengths combined with matched filtering at reception. However, it is found that using FM pulses results sometimes in a loss of the quality of the depth measurements. An important contributor to the errors when using FM signals is the Doppler frequency shift of the received signal, inducing errors in the matched filtering and beamsteering. The latter, however, also holds when using CW signals. A second contributor is the baseline decorrelation, resulting from not having an infinitely small footprint. Due to the larger pulse lengths of the FM signals, also the footprint is larger and consequently the effect of baseline decorrelation is more pronounced for FM signals. Here, we consider a situation of relevance for measurements in the Dutch North Sea (water depth of 50 m and ship dynamics corresponding to a typical winter season sea state). For this case, the uncertainty induced by the Doppler frequency shift, both for CW and FM signals, is found to contribute significantly to the MBES total error budget. The effect of baseline decorrelation depends fully on the signal shape and parameters. Subject multibeam echosounderbaseline decorrelationbathymetric uncertaintyDoppler effect To reference this document use: http://resolver.tudelft.nl/uuid:aa05e977-cef0-469e-8291-0fcdd6a18786 Source Proceedings of the 4th Underwater Acoustics Conference and Exhibition, Skiathos, Greece, 3-8 September 2017 Event 4th Underwater Acoustics Conference and Exhibition, 2017-09-03 → 2017-09-08, Skiathos, Greece Part of collection Institutional Repository Document type conference paper Rights © 2017 Tannaz H. Mohammadloo, M. Snellen, D.G. Simons Files PDF AN_UNCERTAINTY_ASSESSMENT ... EMENTS.pdf 539.31 KB Close viewer /islandora/object/uuid:aa05e977-cef0-469e-8291-0fcdd6a18786/datastream/OBJ/view