Abstract: A method including receiving a waveform, identifying the presence of a pulse in the waveform, and subtracting a reflection template from the received waveform when a pulse is present in the waveform to obtain a corrected waveform, is presented. The method may further include reading the corrected waveform using a digital processing protocol and adjusting a drilling parameter according to the reading. A device configured to perform a method as above is also provided. A method as above, further including modifying a drilling parameter in a wellbore based on the reading of a pulse sequence including the waveform is also provided.

Abstract: A system for channel sounding and initializing an equalizer using a frequency hopping sounder signal. The system identifies a frequency range for sounding a channel between a first device at a first location within a wellbore and a second device at a second location within the wellbore. Center frequencies, bandwidths, and timeframes are assigned to each of a plurality of sounding sequences, such that an entirety of the frequency range is assigned to the plurality of sounding sequences, and wherein when played in order according to the timeframe assigned to each sounding sequence in the plurality of sounding sequences, a sounding signal having a non-contiguous frequency is produced. By comparing an attenuated sounding signal based on the sounding signal to the sounding signal, the system estimates a transfer function of the channel. The system also initializes the equalizer based on the comparison.

Abstract: A method including receiving a waveform, identifying the presence of a pulse in the waveform, and subtracting a reflection template from the received waveform when a pulse is present in the waveform to obtain a corrected waveform, is presented. The method may further include reading the corrected waveform using a digital processing protocol and adjusting a drilling parameter according to the reading. A device configured to perform a method as above is also provided. A method as above, further including modifying a drilling parameter in a wellbore based on the reading of a pulse sequence including the waveform is also provided.

Abstract: A system for channel sounding and initializing an equalizer using a frequency hopping sounder signal. The system identifies a frequency range for sounding a channel between a first device at a first location within a wellbore and a second device at a second location within the wellbore. Center frequencies, bandwidths, and timeframes are assigned to each of a plurality of sounding sequences, such that an entirety of the frequency range is assigned to the plurality of sounding sequences, and wherein when played in order according to the timeframe assigned to each sounding sequence in the plurality of sounding sequences, a sounding signal having a non-contiguous frequency is produced. By comparing an attenuated sounding signal based on the sounding signal to the sounding signal, the system estimates a transfer function of the channel. The system also initializes the equalizer based on the comparison.

Abstract: A downlink telemetry system providing improved apparatus and methods for communicating instructions via pressure pulses from surface equipment to a downhole assembly. The apparatus comprises a surface transmitter for generating pressure pulses, a control system, and a downhole receiver for receiving and decoding pulses. In operation, a bypass valve is opened and closed to create a series of pressure pulses received and decoded by a downhole receiver. The method significantly reduces the time required for downlink communication without interrupting drilling and without interrupting uplink communications such that simultaneous, bi-directional communication is achievable if the uplink and downlink signals are sent at different frequencies. The telemetry scheme and algorithm provide an inventive method for filtering and decoding the downlink signals. The algorithm determines the time intervals between pulse peaks and decodes the intervals into an instruction.

Abstract: A downlink telemetry system providing improved apparatus and methods for communicating instructions via pressure pulses from surface equipment to a downhole assembly. The apparatus comprises a surface transmitter for generating pressure pulses, a control system, and a downhole receiver for receiving and decoding pulses.