Downhole telemetry system using discrete multi-tone modulation having repeated symbols

摘要

A downhole telemetry system and method using discrete multi-tone modulation having repeated symbols. The system includes a surface receiver, a cable, and a downhole transmitter coupled to the surface receiver via the cable. The transmitter communicates a time-domain signal to the receiver. The time-domain signal has a cyclic prefix for a symbol at least as long as the length of the symbol. The system may alternatively include the time-domain signal having a symbol followed immediately by a copy of the symbol. The method includes receiving a time-domain signal carrying desired information at specific frequencies. The signal has at least one symbol. The method includes prepending a cyclic prefix having first length to the beginning of the symbol. The cyclic prefix has a second length no longer than the first length. The method may alternatively include appending a copy of the at least one symbol to the end of the at least one symbol.