Mud pulse telemetry preamble for sequence detection and channel estimation
AssigneeHalliburton Energy Services, Inc.
InventorEhud Barak
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Abstract
A method and system of mud pulse telemetry uses a preamble having a number of periods of a synchronization sequence followed by a single period of a channel estimation sequence. The synchronization may be characterized by a generally flat frequency spectrum, and the channel estimation sequence may be characterized by a low cross-correlation with said synchronization sequence. The sequences may be generated from a set of nonrepeating discrete sequences. The preamble may be suitable for both sequence detection and channel estimation, satisfy all the physical and/or electronic constraints of the system, and allow for fast convergence of an adaptive channel tracking or equalization system.
Claims17
A method of telemetry, comprising:
- defining a synchronization sequence of pulses separated by varying pulse intervals, said synchronization sequence characterized by a generally flat frequency spectrum, said synchronization sequence defining a period length P;
- defining a channel estimation sequence of pulses separated by varying pulse intervals, said channel estimation sequence characterized by a low cross-correlation with said synchronization sequence;
- defining a preamble having a number Np−1 of serially repeated periods of said synchronization sequence followed by an instance of said channel estimation sequence;
- and
- transmitting said preamble by a transmitter across a communication channel.
A telemetry system, comprising:
- a transmitter;
- a receiver;
- and
- a communication channel coupling said transmitter with said receiver;
- said transmitter designed and arranged to transmit a signal including preamble having a number Np−1 of serially repeated periods of a synchronization sequence followed by an instance of a channel estimation sequence, said synchronization sequence characterized by a generally flat frequency spectrum, said channel estimation sequence characterized by a low cross-correlation with said synchronization sequence;
- said receiver designed and arranged to receive and autocorrelate said signal to identify said serially repeated periods of said synchronization sequence and estimate an endpoint of said channel estimation sequence.
Dependencies are inferred from the claim text.