A petroleum well has an electronic module and a number of sensors which communicate with the surface using the tubing string and casing as conductors. Induction chokes at the surface and downhole electrically impede AC flow through the (tubing or casing if so configured) with the resulting voltage potential useful for power and communication. A high bandwidth, adaptable spread spectrum communications system is used to communicate between the downhole electronics module and a surface master spread spectrum modem. Downhole sensors, such as pressure, temperature, acoustic and seismic sensors accurately assess downhole physical conditions. In a preferred form, the electronics module and sensors are wireline insertable and retrievable into a side pocket mandrel in the tubing string. Permanent downhole sensors that can communicate with the surface allow such diverse applications as optimizing well and field performances, monitoring and assessing the geophysics of the fomrations around the well, assessing well and reservoir reserves, assessing reservoir conditions.

Petroleum well having downhole sensors, communication and power

The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation. Amplitude modulation may be achieved by directly or effectively varying the operating voltage on the power amplifier while simultaneously achieving high efficiency in the conversion of primary DC power to the amplitude modulated output signal. High efficiency is enhanced by allowing the switch-mode DC-to-DC converter to also vary its output voltage such that the voltage drop across the linear regulator is kept at a low and relatively constant level. Time-division multiple access (TDMA) bursting capability may be combined with efficient amplitude modulation, with control of these functions being combined. In addition, the variation of average output power level in accordance with commands from a communications system may also be combined within the same structure.

High-efficiency modulating RF amplifier

A system and method of communicating among devices via a piping structure using at least one induction choke about the piping structure to route a time-varying current carrying communication signals between the devices. A communications system comprises a piping structure, a first communication device, a second communication device, and an induction choke. The piping structure comprises a first location, a second location, and an electrically conductive portion extending between the first and second locations. The first and second locations are distally spaced along the piping structure. The first and second communication devices are each electrically connected to the electrically conductive portion of the piping structure along the first location and second location, respectively, and each is adapted to send and receive communication signals via time-varying current. The induction choke is located about an electrically choked portion of the electrically conductive portion of the piping structure, such that the induction choke is adapted to route time-varying current within the piping structure between the electrical connection location for the first communication device and the electrical connection location for the second communication device, and such that the first communication device can communicate with the second communication device via the piping structure. A preferred application of the present invention is a well for producing petroleum products (e.g., oil, natural gas), comprising a communication system as described above.

Permanent downhole, wireless, two-way telemetry backbone using redundant repeaters

An amplifier system is provided that switches between a linear mode of operation, an envelope tracking mode of operation and a polar mode of operation. The amplifier system switches between modes of operation based upon a characteristic of an input signal relative to a first threshold level and a second threshold level. A mode selector selects the operation mode by transmitting an amplitude modulated signal plus a variable headroom voltage to a supply terminal of a power amplifier during the envelope tracking mode, an amplitude modulated signal to the supply terminal and phase modulated input signal during the polar mode and a substantially constant amplitude signal to the supply terminal during the linear mode.

Multi-mode amplifier system

An amplifier arrangement comprising an amplifier for amplifying an input radio frequency (RF) signal to generate an output RF signal. A linear function processor generates a linear function correction signal which is a linear function of previous samples of the input signal in order to compensate for distortion effects of the amplifier related to the history of the input signal. A non-linear function processor generates a non-linear function of the input signal in order to compensate for instantaneous distortion effects of the amplifier. Then a pre-distortion processor distorts the current input signal in accordance with the linear and non-linear function correction signals in order to compensate for both types of distortion in the output signal.

A linear amplifier arrangement

A method (200) and device (100) provide an efficient linear power amplifier that generates a variable-envelope radio frequency RF signal. The method includes the steps of: A) using an efficient envelope-following unit to output a supply voltage in accordance with a variable envelope of an input baseband signal, wherein using the efficient envelope-following unit includes: 1) using a bandwidth-limiting mapping unit to determine a reference signal based on the baseband signal; and 2) using an envelope-tracking power converter to output a supply voltage, responsive to the reference signal, to the linear RF power amplifier; B) providing an RF input signal with amplitude and phase information to a linear RF power amplifier; and C) using the linear RF power amplifier to output a power-efficient amplified variable-envelope RF signal with substantially a same amplitude and phase information as the RF input signal.

Method, device, phone and base station for providing envelope-following for variable envelope radio frequency signals

The present invention provides a linearization system (100) and method (700, 800) for generating a predistorted drive signal for a nonlinear transmission path. The linearization includes: A) an analog feedback system (39), coupled to a computation unit, for determining, during a training mode, a complex error signal that linearizes the nonlinear transmission path and wherein, in an operation mode, the analog feedback system is disabled; and B) a computation unit (1), coupled to the analog feedback system and coupled to receive a complex input signal and the complex error signal, for determining, during the training mode, complex predistortion gain coefficients and, during the operation mode, generating the predistorted drive signal for the nonlinear transmission path, wherein the analog feedback system and computation unit are interconnected by interface circuitry.

Predistortion system and method using analog feedback loop for look-up table training

A voltage (Vo) is added to an envelope function and input into a switching modulator (105). The output of the switching modulator (VSUP) is input to a linear regulator (103) where amplitude compensation of VSUP takes place and is output as VPA. VPA is then used to accomplish envelope modulation of a power amplifier (101). The value chosen for Vo is chosen to be adequate to maintain VSUP(t)>VPA(t) over all time.

Method and apparatus for power modulating to prevent instances of clipping

An adaptive predistortion linearization system includes input path digital-to-analog converters (DACs), error path DACs, a digital signal processor, and a radio frequency (RF) combiner. The digital signal processor includes a look-up table storing complex gain coefficient values. The digital signal processor generates an error signal based on the complex input signal and the complex gain coefficients by using a vector decomposition calculation. Feedback from a power amplifier can be provided to a training algorithm for periodically updating the gain coefficient values stored in the look-up table. By performing separate D/A conversions, the error path and input signals can be separately filtered. This separation also permits the error signal to be decoupled from the complex input signal, which facilitates an improvement in the wide-frequency-offset noise performance of the system.

Amplifier predistortion system and method

System (100) is coupled with power amplifier (106). Generation component (166) generates error signal (110) based at least in part on an input signal (144) for the system (100). The error signal (110) includes a phase component. The input signal (144) includes an envelope component. Modification component (130) modifies the phase component of the error signal (110) in response to the envelope component of the input signal to reduce variation of a phase component of the power amplifier output signal (194).

Andrew Merritt Khan

Papers

Method, device, phone and base station for providing envelope-following for variable envelope radio frequency signals

Predistortion system and method using analog feedback loop for look-up table training

Method and apparatus for power modulating to prevent instances of clipping

Amplifier predistortion system and method

Modification of phase component of error signal to reduce variation of phase component of output signal of power amplifier