An engine has a fueling system that uses hydraulic fluid to force fuel into engine combustion chambers via fuel injectors. The Viterbi decoder includes a traceback processor having a traceback engine that tracks a state of a traceback operation in response to the survivor information. Also provided are a corresponding encryption method, a storage unit suitable for storing the correspondence table generated by the above generation method, a device for physically implementing such a correspondence table, a decryption device including such a storage unit, and a computer program product suitable for implementing the above generation method. Measurements are made on the volatile hydrocarbons andor pyrolytic hydrocarbons and one or more formation properties are inferred based on the measurements. A time window is defined on either side of the picked arrival times and the azimuthal direction is determined by maximizing the energy of the horizontal components within this time window.