FULL DUPLEX DMT MODULATION IN WELL-LOGGING APPLICATIONS

摘要

A communication protocol based upon the Asymmetric Digital Subscriber Line (ADSL) protocol developed for telephone communications is used for two way transmission of data between a downhole logging device and a surface device. The total available bandwidth for a pair of conductors is determined by the length of the conductors and the choice of conductors ( operational mode) of a conventional 7 conductor wireline. The available bandwidth is partitioned in to channels with a bandwidth of 4.3125kHz, each of the channels carrying a portion of the data. A contiguous subset of the channels is used for downwar d communication (Down channel) and another subset is used for upward communication (Up channel). The bit loading is dynamically determined based upon monitoring of the noise level. Optionally, more than one mode of the 7 conductor wireline may be used.