Abstract: A telemetry system for communication in a borehole uses two spaced-apart transducers. The outputs from the two transducers are filtered to decoupled tool signals traveling in opposite directions. One of the two signals may be it telemetry signal while other signal may be pump noise.

Abstract: The transfer function of the communication channel in a mud pulse telemetry system is determined by sending a known signal through the channel and spectral analysis of the received signal. The known signal may be a chirp signal or a stepped frequency signal. Based on the determined transfer function, operating parameters of the pulser are adjusted.

Abstract: A transmitter for sending signals over wireless channels and a method of sending signals over wireless channels are described. The transmitter and the method are used to determine a transfer characteristic of an amplifier (8) in the transmitter. Symbols in the OFDM signals to be transmitted are multiplied by test signals at predefined points in time to compare the OFDM symbol, which has been multiplied by the test signal, upstream and downstream from the amplifier to determine the transfer characteristic of the amplifier (8). This transfer characteristic of the amplifier (8) is used by a predistorter (4) to predistort the signals according to this transfer characteristic. The test signal, which is generated by a signal generator (13), is input into a symbol of the fast information channel, the test signal having an amplitude which drives the multiplied symbol into the saturation range of the amplifier (8) with regard to its amplitude.

Abstract: A telemetry system for communication in a borehole uses two spaced-apart transducers. The outputs from the two transducers are filtered to decoupled tool signals traveling in opposite directions. One of the two signals may be it telemetry signal while other signal may be pump noise. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Abstract: A method of transmitting wireless signals and a transmitter for transmitting wireless signals for optimally operate an amplifier of a transmitter in its linear range, signals being transmitted in orthogonal frequency division multiplexing (OFDM). The amplitudes of the OFDM signals that lie above a predefined threshold are eliminated using an additive correction signal, the phase of the OFDM signals being impressed on the additive correction signal. Furthermore, a correction signal is formed and subtracted from the OFDM signals, until there are no more amplitudes of the OFDM signal above the predefined threshold. Gauss pulses are used as correction signals due to their simple handling. Oversampling of the OFDM signals determines the amplitude values of the OFDM signals.

Abstract: The transfer function of the communication channel in a mud pulse telemetry system is determined by sending a known signal through the channel and spectral analysis of the received signal. The known signal may be a chirp signal or a stepped frequency signal. Based on the determined transfer function, operating parameters of the pulser are adjusted.

Abstract: A transmitter for sending signals over wireless channels and a method of sending signals over wireless channels are described. The transmitter and the method are used to determine a transfer characteristic of an amplifier (8) in the transmitter. Test signals are input at preset times into OFDM signals to be transmitted, and then test signals amplified by the amplifier (8) are compared with test signals buffered in a measurement module (12) to determine the transfer characteristic of the amplifier (8). This transfer characteristic of the amplifier (8) is used by a predistorter (4) to predistort the signals according to this transfer characteristic. The test signal generated by a signal generator (13) is input into a synchronization symbol, with the amplitude of the test signal being increased incrementally or being large enough to determine the transfer properties of the amplifier (8). The test signal has an envelope which is not dependent on time.

Abstract: A transmitter for sending signals over wireless channels and a method of sending signals over wireless channels are described. The transmitter and the method are used to determine a transfer characteristic of an amplifier (8) in the transmitter. Symbols in the OFDM signals to be transmitted are multiplied by test signals at predefined points in time to compare the OFDM symbol, which has been multiplied by the test signal, upstream and downstream from the amplifier to determine the transfer characteristic of the amplifier (8). This transfer characteristic of the amplifier (8) is used by a predistorter (4) to predistort the signals according to this transfer characteristic. The test signal, which is generated by a signal generator (13), is input into a symbol of the fast information channel, the test signal having an amplitude which drives the multiplied symbol into the saturation range of the amplifier (8) with regard to its amplitude.

Abstract: A transmitter for sending signals over wireless channels and a method of sending signals over wireless channels are described. The transmitter and the method are used to determine a transfer characteristic of an amplifier (8) in the transmitter. Test signals are input at preset times into OFDM signals to be transmitted, and then test signals amplified by the amplifier (8) are compared with test signals buffered in a measurement module (12) to determine the transfer characteristic of the amplifier (8). This transfer characteristic of the amplifier (8) is used by a predistorter (4) to predistort the signals according to this transfer characteristic. The test signal generated by a signal generator (13) is input into a synchronization symbol, with the amplitude of the test signal being increased incrementally or being large enough to determine the transfer properties of the amplifier (8). The test signal has an envelope which is not dependent on time.