Abstract:
A phase locked loop is disclosed having a frequency controlled oscillator (42), a feedback path, a time to digital converter (10) and a memory. The frequency controlled oscillator (42) comprises a first control input (135, 136) for varying the frequency of the output (106) of the frequency controlled oscillator (42) so as to track a reference frequency (101) and a second control input (139) for modulating the frequency of the output signal (106) so as to produce a chirp. The feedback path is configured to provide an input signal (107) to the time to digital converter (10), and comprises modulation cancelling module (14) operable to remove the frequency modulation resulting from the second control input (139) from the output signal (106). The memory stores second control input values that each correspond with a desired chirp frequency and which compensate for non-linearity in the response of the frequency controlled oscillator to the second control input (139). The phase locked loop is operable in a chirp mode, in which the second control input (139) is produced by determining a value for the second control input (139) corresponding with a desired chirp frequency based on the stored second control input values in the memory, and in which the phase locked loop is configured to determine the first control input (135, 136) based on the feedback path from which the modulation cancelling module (14) has removed the frequency modulation resulting from the second control input (139).
Abstract:
A system and method of extracting data from data packets transmitted over a wireless network includes receiving a data packet having a preamble portion and a payload portion. The preamble portion is cross correlated with a first known spreading sequence to generate a first timing signal and the preamble portion is cross correlated with a second known spreading signal to generate a frame timing signal. An impulse is detected in the first timing signal and a first timing parameter is set based upon the detected impulse in the first timing signal. An impulse is detected in the frame timing signal and a frame timing parameter is set based upon the detected impulse in the frame timing signal. Data is extracted from the received payload portion according to the first timing parameter and the frame timing parameter.
Abstract:
Systems and methods are described for determining position of a receiver, The positioning system comprises a transmitter network including transmitters that broadcast positioning signals. The positioning system comprises a remote receiver that acquires and tracks the positioning signals and/or satellite signals. The satellite signals are signals of a satellite-based positioning system, A first mode of the remote receiver uses terminal-based positioning in which the remote receiver computes a position using the positioning signals and/or the satellite signals. The positioning system comprises a server coupled to the remote receiver. A second operating mode of the remote receiver comprises network-based positioning in which the server computes a position of the remote receiver from the positioning signals and/or satellite signals, where the remote receiver receives and transfers to the server the positioning signals and/or satellite signals
Abstract:
A system and method of extracting data from data packets transmitted over a wireless network includes receiving a data packet having a preamble portion and a payload portion. The preamble portion is cross correlated with a first known spreading sequence to generate a first timing signal and the preamble portion is cross correlated with a second known spreading signal to generate a frame timing signal. An impulse is detected in the first timing signal and a first timing parameter is set based upon the detected impulse in the first timing signal. An impulse is detected in the frame timing signal and a frame timing parameter is set based upon the detected impulse in the frame timing signal. Data is extracted from the received payload portion according to the first timing parameter and the frame timing parameter.