Temperature Compensated Clock Correction for Autonomous Ocean Bottom Nodes

The Ocean Bottom Node (OBN) seismic method is unique in the seismic industry in that the recorder is not fed a highly accurate GPS timing measurement while measuring the earth reflections. Instead the method relies on an internal clock which will drift over the dive time of the node. Initially the standard for OBN’s was the Cip Scale Atomic Clock (CSAC) which uses a quantum feedback loop to discipline the clock during the dive. More recently contractors have adopted crystal oscillators for practical reasons. This paper will compare the benefits of the two clock types and propose a method to correct for the main deficiency of the crystal oscillator.