摘要:
Predistorting an input signal prior to amplification in an RF power amplifier (206) includes isolating a plurality sub-band signals, each representing a portion of the input signal s(t). The method includes independently modifying an amplitude and a phase of each of the plurality of sub-band signals. The modification of the amplitude and/or phase is performed using a set of signal weighting parameters (weights) w and W, controlling linear and nonlinear modifications respectively, which are determined in an adaptive process by an adaptive controller (224). After modification, each of the sub-bands are summed together to obtain a predistorted input signal for an RF power amplifier (206).
摘要:
RF amplifier system (200) incorporating feedforward linearization. The system includes a digital waveform source (202) generating digital data s(t) representative of at least one analog signal. The system also includes a feedforward linearization circuit for reducing a distortion of an RF power amplifier (212). The feedforward linearization circuit includes a differential amplifier (230) arranged for generating an error signal. The error signal is determined based on a difference between the distorted RF output signal and an analog RF reference signal (229) generated from the digital data.
摘要:
RF amplifier system (200) incorporating feedforward linearization. The system includes a digital waveform source (202) generating digital data s(t) representative of at least one analog signal. The system also includes a feedforward linearization circuit for reducing a distortion of an RF power amplifier (212). The feedforward linearization circuit includes a differential amplifier (230) arranged for generating an error signal. The error signal is determined based on a difference between the distorted RF output signal and an analog RF reference signal (229) generated from the digital data.
摘要:
Method (500) and system (402) for actively detecting and determining a range of a remotely located radio receiver (100). The invention also provides a method and system to determine whether a remote receiver (100) is receiving a transmitted signal (418) and the minimum necessary transmitter power required to establish a communication link to the receiver (100). Finally, the invention also provides a method and system to resolve directional ambiguities due to multipath.
摘要:
Method (500) and system (402) for actively detecting and determining a range of a remotely located radio receiver (100). The invention also provides a method and system to determine whether a remote receiver (100) is receiving a transmitted signal (418) and the minimum necessary transmitter power required to establish a communication link to the receiver (100). Finally, the invention also provides a method and system to resolve directional ambiguities due to multipath.
摘要:
A communications device includes at least one memory device for storing complex exponential functions as approximations of sine and cosine basis waveforms. A logic circuit adds and subtracts the complex exponential functions to generate an Orthogonal Frequency Division Multiplexed (OFDM) communications signal as a plurality of N data subcarriers that carry communications data. The logic circuit provides efficient and accurate implementation of the IFFT for use as an OFDM modulator using additions of stored complex exponentials and modulation of the integer-valued QAM data symbols using logic shifts and sign changes (2's complement).
摘要:
A communications device includes at least one memory device for storing complex exponential functions as approximations of sine and cosine basis waveforms. A logic circuit adds and subtracts the complex exponential functions to generate an Orthogonal Frequency Division Multiplexed (OFDM) communications signal as a plurality of N data subcarriers that carry communications data. The logic circuit provides efficient and accurate implementation of the IFFT for use as an OFDM modulator using additions of stored complex exponentials and modulation of the integer-valued QAM data symbols using logic shifts and sign changes (2's complement).
摘要:
A device and system communicates data and includes a modulation and mapping circuit that modulates and maps data symbols into a plurality of multiple subcarrier frequencies that are orthogonal to each other to form an Orthogonal Frequency Division Multiplexed (OFDM) communications signal based on a fixed or variable OFDM symbol rate. A pseudo-random signal generator operative with the modulation and mapping circuit generates pseudo-random signals to the modulation and mapping circuit based on an encryption algorithm for frequency hopping each subcarrier at an OFDM symbol rate to lower any probability of interception and detection, reduce power per frequency (dB/Hz/sec), and lower any required transmission power while maintaining an instantaneous signal-to-noise ratio A frequency domain spreader circuit is operatively connected to the modulation and mapping circuit for spreading the multiple subcarriers over the frequency domain.
摘要:
A communications device includes a signal input that receives an orthogonal frequency division multiplexed (OFDM) communications signal. A demodulator is connected to the signal input for receiving the OFDM communications signal and demodulating the OFDM communication signal. It includes at least one memory element for storing the at least one sine/cosine basis waveform approximation as complex exponential functions. A logic circuit performs logical shifts in additions and multiples of +/−2n and extracts amplitude and phase values from a plurality of N data subcarriers within the OFDM communications signal. The demodulator includes efficient implementation of the FFT for use as an OFDM demodulator where the complex exponentials are approximated by multi-level complex sinusoids and optionally oversampled to increase SNR of the FFT output.
摘要:
A wireless ranging system for determining a range of a remote wireless device may include a wireless transmitter and a wireless receiver. The wireless ranging system may also include a ranging controller to cooperate with the wireless transmitter and receiver to generate a multi-carrier base waveform, transmit a sounder waveform to the remote wireless device including concatenated copies of the multi-carrier base waveform, and receive a return waveform from the remote wireless device in response to the sounder waveform. The ranging controller may also generate time domain samples from the return waveform, convert the time domain samples into frequency domain data, and process the frequency domain data to determine the range of the remote wireless device.