Abstract: This invention is designed for use in transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides an apparatus for receiving data signals from a telemetry module comprising first and second adaptive equalisers, and in which in a first modulation mode the coefficients of the first adaptive equaliser are updated until an error signal falls below a predetermined threshold and in a second modulation mode the coefficients of the first adaptive equaliser are locked and coefficients of the second adaptive equaliser are updated to continually minimise an error signal in which the number of bits encoded by the symbols of the first signal in an initial modulation mode is fewer than the number of bits encoded by the symbols of the second signal in a subsequent modulation mode.

Abstract: An inspection apparatus for use in wellbores in the oil and gas industries relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method and apparatus for determining analog filter parameters for an analog front end comprising a plurality of filter stages receiving signals from a telemetry module, by repeating the steps of; receiving a signal of a known frequency and processing said signal by determining the magnitude of the frequency of the received signal until a plurality of signals have been received and processed; calculating an optimum set of filter parameters in dependence upon the measured frequency magnitudes and a predefined set of filter stage frequency responses.

Abstract: This invention is designed for use in transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides an apparatus for receiving data signals from a telemetry module comprising first and second adaptive equalisers, and in which in a first modulation mode the coefficients of the first adaptive equaliser are updated until an error signal falls below a predetermined threshold and in a second modulation mode the coefficients of the first adaptive equaliser are locked and coefficients of the second adaptive equaliser are updated to continually minimise an error signal in which the number of bits encoded by the symbols of the first signal in an initial modulation mode is fewer than the number of bits encoded by the symbols of the second signal in a subsequent modulation mode.

Abstract: An inspection apparatus for use in wellbores in the oil and gas industries relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method and apparatus for determining analogue filter parameters for an analogue front end comprising a plurality of filter stages receiving signals from a telemetry module, by repeating the steps of; receiving a signal of a known frequency and processing said signal by determining the magnitude of the frequency of the received signal until a plurality of signals have been received and processed; calculating an optimum set of filter parameters in dependence upon the measured frequency magnitudes and a predefined set of filter stage frequency responses.

Abstract: The present invention relates to inspection apparatus for use in wellbores in the oil and gas industries. In particular the invention relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method and apparatus for determining analog filter parameters for an analog front end comprising a plurality of filter stages receiving signals from a telemetry module, by repeating the steps of; receiving a signal of a known frequency and processing said signal by determining the magnitude of the frequency of the received signal until a plurality of signals have been received and processed; calculating an optimum set of filter parameters in dependence upon the measured frequency magnitudes and a predefined set of filter stage frequency responses.

Abstract: The present invention relates to inspection apparatus for use in wellbores in the oil and gas industries. In particular the invention relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method an apparatus for receiving data from a telemetry module, the data being modulated according to a quadrature amplitude modulation coding scheme, in which a receiver has a carrier recovery circuit comprising a phase detector, a loop filter and a signal synthesizer generating an inphase and a quadrature demodulation signal. The method comprises receiving a preamble sinusoidal signal representing a symbol; determining the cross product of the received inphase and quadrature components and ideal inphase and quadrature components; indexing a look up table with said cross product to determine a phase adjustment and adjusting the phase of the demodulation signals in accordance with said determined phase adjustment.

Abstract: The present invention relates to inspection apparatus for use in wellbores in the oil and gas industries. In particular the invention relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method and apparatus for determining analogue filter parameters for an analogue front end comprising a plurality of filter stages receiving signals from a telemetry module, by repeating the steps of; receiving a signal of a known frequency and processing said signal by determining the magnitude of the frequency of the received signal until a plurality of signals have been received and processed; calculating an optimum set of filter parameters in dependence upon the measured frequency magnitudes and a predefined set of filter stage frequency responses.

Abstract: The present invention relates to inspection apparatus for use in wellbores in the oil and gas industries. In particular the invention relates in general to the field of transmission of data between downhole module in a wellbore and a controlling module at the surface. The invention provides a method an apparatus for receiving data from a telemetry module, the data being modulated according to a quadrature amplitude modulation coding scheme, in which a receiver has a carrier recovery circuit comprising a phase detector, a loop filter and a signal synthesiser generating an inphase and a quadrature demodulation signal. The method comprises receiving a preamble sinusoidal signal representing a symbol; determining the cross product of the received inphase and quadrature components and ideal inphase and quadrature components; indexing a look up table with said cross product to determine a phase adjustment and adjusting the phase of the demodulation signals in accordance with said determined phase adjustment.