Reducing satellite signal interference in a global positioning system receiver

A method for reducing satellite signal cross-interference in a satellite positioning system receiver, said method comprising the steps of:

• receiving as an input waveform a first signal and a second signal from respective satellites of a plurality of satellite positioning system satellites, wherein said first signal is stronger than said second signal;
• estimating characteristics of said first signal to form estimated data;
• constructing an interference waveform using said estimated data;
• and
• subtracting said interference waveform from said first input waveform to produce an output waveform.

A method for reducing satellite signal cross-interference in a satellite positioning system receiver, said method comprising the steps of:

• receiving as an input waveform a first signal and a second signal from respective satellites of a plurality of satellite positioning system satellites, wherein said first signal is stronger than said second signal;
• estimating characteristics of said first signal to form estimated data;
• constructing an interference waveform using said estimated data and a hypothesized carrier frequency of said second signal and a first pseudorandom code corresponding to said first signal and a second pseudorandom code corresponding to said second signal;
• performing tests for times of arrival of said second signal to produce an output waveform;
• and
• discarding portions of said output waveform for which said interference waveform is above a predetermined threshold.

A method for reducing satellite signal cross-interference in a satellite positioning system receiver, said method comprising the steps of:

• receiving as an input waveform a first signal and a second signal from respective satellites of a plurality of satellite positioning system satellites, wherein said first signal is stronger than said second signal;
• estimating characteristics of said first signal to form estimated data;
• detecting the presence of an interference component in said input signal by processing said estimated data and a hypothesized carrier frequency of said second signal;
• determining the width of a peak of a signal produced by cross-correlations of said first signal and the PN code of said second signal if said interference component is detected;
• comparing said width of said peak with a predetermined threshold;
• performing tests for times of arrival of said second signal to produce an output waveform;
• and
• deleting said peak from said output waveform if said width of said peak exceeds said predetermined threshold.

A method for reducing satellite signal cross-interference in a satellite positioning system receiver, said method comprising the steps of:

• receiving as an input waveform a first signal and a second signal from respective satellites of a plurality of satellite positioning system satellites, wherein said first signal is stronger than said second signal;
• performing tests for times of arrival of said second signal to produce an output waveform;
• subtracting a mean noise level from said output waveform to produce a modified output waveform;
• establishing a detection threshold by multiplying a first constant by a root mean squared level of said modified output waveform;
• and
• modifying said detection threshold by multiplying said detection threshold by a first value to produce a modified detection threshold.

An apparatus comprising:

• an input circuit operable to receive satellite positioning system signals from a plurality of satellite positioning system satellites, and wherein a first received signal is stronger than a second received signal;
• a processor coupled to said input circuit, said processor operable to estimate characteristics of said first signal;
• construct an interference waveform based on the estimated characteristics;
• perform tests for times of arrival of said second signal to produce an output waveform;
• and
• subtract said interference waveform from said output waveform to remove interference effects of said first signal from said output waveform.

An apparatus comprising:

• an input circuit operable to receive satellite positioning system signals from a plurality of satellite positioning system satellites, and wherein a first received signal is stronger than a second received signal;
• a processor coupled to said input circuit, said processor operable to estimate characteristics of said first signal;
• construct an interference waveform based on the estimated characteristics;
• and
• subtract said interference waveform from the received satellite positioning system signals to remove interference effects of said first signal from said received signals.

An apparatus comprising:

• an input circuit operable to receive satellite positioning system signals from a plurality of satellite positioning system satellites, and wherein a first received signal is stronger than a second received signal;
• a processor coupled to said input circuit, said processor operable to estimate characteristics of said first signal;
• construct an interference waveform based on the estimated characteristics and a first locally generated code corresponding to said first signal and a second locally generated code corresponding to said second signal;
• perform tests for times of arrival of said second signal to produce an output waveform;
• and
• discard portions of said output waveform for which said interference waveform is above a predetermined threshold.

An apparatus comprising:

• an input circuit operable to receive satellite positioning system signals from a plurality of satellite positioning system satellites, and wherein a first received signal is stronger than a second received signal;
• a processor coupled to said input circuit, said processor operable to estimate characteristics of said first signal;
• determine the possibility of interference from said first signal with said second signal using the estimated characteristics and a characteristic of said second signal;
• perform tests for a time-of-arrival of said second signal to produce an output waveform;
• compare the width of a peak in said output waveform with a predetermined threshold;
• and
• discard said peak from further processing if said width exceeds said predetermined threshold, and the possibility of interference from said first signal with said second signal is affirmative.

An apparatus comprising:

• an input circuit operable to receive satellite positioning system signals from a plurality of satellite positioning system satellites, and wherein a first received signal is stronger than a second received signal;
• a processor coupled to said input circuit, said processor operable to perform tests for times of arrival of said second signal to produce an output waveform;
• subtract a mean noise level from said output waveform to form a modified output waveform;
• establish a detection threshold based on a root mean squared value of data in said output waveform;
• compare said modified output waveform with said detection threshold;
• and
• signal a detection if a portion of said modified output waveform exceeds said detection threshold.

A method for processing satellite positioning system (SPS) signals transmitted from a first satellite, said method comprising the steps of:

• receiving said SPS signals at a mobile SPS receiver;
• determining at least one signal-to-noise ratio for at least one of said SPS signals;
• and
• transmitting said at least one signal-to-noise ratio to a remote processing system.

A method for processing satellite positioning system (SPS) signals transmitted from a first satellite, said method comprising the steps of:

• receiving said SPS signals at a mobile SPS receiver;
• determining at least one peak width for at least one of said SPS signals;
• and
• transmitting said at least one peak width to a remote processing system.