Kongsberg Vision Meeting 2017 Abstracts

Multi-beam echo-sounder bathymetric measurements: Implications of using frequency modulated pulses

“…In contrast to the effect of Doppler on the matched filtered signals which is often taken into account in the post processing, the angular bias in the beamsteering is not corrected for. 9 This bias in the angle estimate varies from ping to ping and is as such in this research considered as a contribution to the depth uncertainty considering v r as the random variable.…”

“…With regards to the tapering value of the FM signal, Kongsberg considers a varying tapering value between 10% and 50%. 9 In this contribution, the modelling has been carried out using the smallest (nearly rectangular shape) and largest tapering values to assess the effect of signal smoothing.…”

“…With regards to the bandwidth used, the EM2040c transmits FM pulses with the effective bandwidth of a few kHz. 9 Here, we focus on an effective bandwidth of 2.615 kHz (see Table I). The length of the baseline is assumed to be 0.12 m which is one-third of the theoretical array length (based on the beam opening angle), corrected for the shading (20%).…”

“…This second effect, however, also holds for CW pulses and is in general not compensated for. 9 An uncertainty in the steering angle gives rise to uncertainties in the estimated depths which is important for the prediction of the total error budget carried out prior to a MBES bathymetric survey; an underestimation of the contribution of the Doppler effect potentially leads to an optimistic expectation of the depth uncertainties.…”