| 摘要 |
A telemetry system using four-level positive pulses is provided to transmit data over a logging cable. More particularly, method and apparatus are provided for using multi-level positive pulses that may have variable width for communication from up hole to down hole, self-clocking modulation and a synchronization circuit to obtain more efficient downlinks and transmission of data to the surface via electric wireline. A peak detector circuit avoids the requirement for very high-speed analog-to-digital converters and a synchronization circuit allows knowing when a pulse is ready to be processed, thus reducing the requirements for processing.
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