摘要:
A method for processing a signal modulated with information symbols to account for an additive offset and slope is disclosed. First, an initial estimate of offset and slope is made and hypotheses of all possible values of a sequence of one or more information symbols are then made. For each of said hypotheses, the associated data symbol sequence is used to make an improved estimate of offset and slope and the improved estimate of offset and slope are stored against each of the hypotheses. For each hypothesis, the improved estimate of offset and slope is used in calculating an expected signal value and a mismatch between a sample of the modulated signal and the expected value is computed. The hypotheses are then sequentially extended by one symbol, the slope and offset estimates are updated and the mismatches are accumulated to form a path metric value for each extended hypothesis, and resolving between said hypotheses based on said path metric values using a Viterbi Sequential Maximum Likelihood Sequence Estimation process to produce a most likely hypothesis of said modulated information symbols substantially unimpaired by said additive slope and offset.
摘要:
A test transmitter for verifying the positioning of antennas in a mobile telecommunications system and a method for manufacturing such a test transmitter that is particularly suited for indoor use are presented. A mobile terminal is modified so that it can transmit in the downlink frequency band, and preferably so that it can transmit one or more of the signal types used for downlink signalling in the mobile telecommunications system.
摘要:
A communications terminal having a receiver and a method therefor is provided that substantially removes a known interferer from a digitally translated intermediate frequency signal. More specifically, the receiver includes an antenna for receiving a signal, and at least one combination of a mixer and filter for translating in the analog domain the signal to the intermediate frequency signal while maintaining separation from baseband. The receiver also includes a digitizer for digitally translating the intermediate frequency signal containing the known interferer from the analog domain into the digital domain, and an interference cancellation system for removing the known interferer from the digitally translated intermediate frequency signal by utilizing either a DC offset compensator or a correlator compensator.
摘要:
A method for determining location of a mobile terminal includes repetitively switching power-on and power-off to a GPS receiver circuit which determines location of the mobile terminal using GPS signals. The power-on to power-off duty cycle of the GPS receiver circuit is regulated in response to distance that the mobile terminal has moved from a previously determined location. The power-on to power-off duty cycle can be regulated in response to identifying GPS isolation, in response to an acceleration-determined distance from previous GPS-determine location, an acceleration-determined velocity of the mobile terminal, availability of position assistance information from a cellular system, presence/absence of signals from a WLAN/Bluetooth device, and/or detection of a new cellular base station ID.
摘要:
A receiver section recovers the in-phase and quadrature components of a linear modulated data signal. The in-phase signal is sampled and quantized producing an in-phase sample stream, and the quadrature phase signal is sampled and quantized producing a quadrature sample stream. The in-phase sample stream and the quadrature sample stream are both over-sampled at a rate of N times a symbol rate of the data signal. A decimation section filters the quantized in-phase sample stream and the quantized quadrature sample stream to produce a reduced in-phase sample stream and a reduced quadrature sample stream at a rate of M times the symbol rate, wherein M is less than or equal to N. A decision component calculates the magnitude of a combination of an in-phase sample and a quadrature sample at M corresponding sample points in the reduced in-phase sample stream and the reduced quadrature sample stream, respectively, and then forms an in-phase symbol stream and a quadrature symbol stream using the in-phase sample and the quadrature sample, respectively, associated with the sample point having a largest magnitude.
摘要:
There is disclosed a phase detector which triggers on both rising and falling edges of an input pulse signal. This effectively doubles the frequency of the input signal. When the phase detector is used in a phase locked loop, the doubled frequency means that a lower division ratio can be used, thereby reducing any noise contribution introduced thereby.