摘要:
Some embodiments of the invention provide a location-determination system that includes a number of transmitters and at least one receiver. Based on a reference signal received by the receiver, this location-determination system identifies an estimated location of the receiver within a region. In some embodiments, the system selects one or more locations within the region. For each particular selected location, the system calculates a metric value that quantifies the similarity between the received signal and the signal that the receiver could expect to receive at the particular location, in the absence or presence of interference. Based on the calculated metric value or values, the system identifies the estimated location of the receiver.
摘要:
According to one aspect of the invention, sampled data that is received from a receiver is divided into segments of data of increasing length. A current value range for a delay value and a current value range for a modulation frequency value are calculated relative to each signal source from a set of signal sources that are overhead the signal receiver. An estimate for the delay value and an estimate for the modulation frequency value are calculated by iteratively updating the current value range for the delay value and for the modulation frequency value. The iterative update of the current value range for the delay value and for the modulation frequency value is performed overthe set of signal sources and over the segments of data of increasing length. According to another aspect of the technique, for each signal source, I and Q correlation integrals and their magnitude value are calculated corresponding to the estimate of the modulation frequency value and the estimate of the delay value. In addition, for each signal source, I and Q correlation integrals and thier magnitude values are calculated corresponding to a set of delay values that surround the estimate of the delay value. A shape of a magnitude-curve is interpolated using the magnitude values corresponding to the estimate of the delay value and corresponding to the set of delay values that surround the estimate of the delay value. The location of the receiver is calculated using the shape of the magnitude-curve to represent the I and Q correlation integrals for each signal source.
摘要:
Techniques are provided for synthesizing a long coherent I and Q correlation integral at a particular frequency by synthetically combining a sequence of shorter correlation integrals at the same or different frequency. Techniques are also provided for acquiring a carrier-modulated signal with an unknown shift of the carrier frequency, and possibly some additional unknown signal parameters. These techniques involve synthesizing coherent correlation sums at a fine frequency resolution, using coherent correlation sums that are calculated at a coarse frequency resolution. This approach allows for coherent processing of the received signal over an arbitrarily long time interval, while avoiding the excessive computational requirements of traditional methods.
摘要:
According to one aspect of the invention, sampled data that is received from a receiver is divided into segments of data of increasing length. A current value range for a delay value and a current value range for a modulation frequency value are calculated relative to each signal source from a set of signal sources that are overhead the signal receiver. An estimate for the delay value and an estimate for the modulation frequency value are calculated by iteratively updating the current value range for the delay value and for the modulation frequency value. The iterative update of the current value range for the delay value and for the modulation frequency value is performed overthe set of signal sources and over the segments of data of increasing length. According to another aspect of the technique, for each signal source, I and Q correlation integrals and their magnitude value are calculated corresponding to the estimate of the modulation frequency value and the estimate of the delay value. In addition, for each signal source, I and Q correlation integrals and thier magnitude values are calculated corresponding to a set of delay values that surround the estimate of the delay value. A shape of a magnitude-curve is interpolated using the magnitude values corresponding to the estimate of the delay value and corresponding to the set of delay values that surround the estimate of the delay value. The location of the receiver is calculated using the shape of the magnitude-curve to represent the I and Q correlation integrals for each signal source.