Phase multi-path mitigation

A device that mitigates the effect of a multi-path-induced error in a global navigation satellite system (GNSS), comprising:

• a receiver that receives a composite signal, including a band-limited direct-path signal and at least one band-limited multi-path signal, wherein the direct-path signal and the multi-path signal are modulated with periodic phase reversals;
• a measurement mechanism that samples the composite signal as a function of time during a time interval having at least one of the periodic phase reversals;
• a processor;
• a memory including at least one program module that is executed by the processor, the at least one program module containing instructions for determining a phase error φε between the composite signal and the direct-path signal due to the multi-path signal in accordance with the measured composite signal as a function of time and a pre-determined filter characteristic of one or more filters in the GNSS that are used to band limit the direct-path signal and the multi-path signal;
• wherein the determining is responsive to phase errors corresponding to time delays of the multi-path signal relative to the direct-path signal that are shorter than a filter step response time of the one or more filters used to band limit the direct-path signal and the multi-path signal;
• and
• wherein the device is configured to correct for the phase error φε.

A device that mitigates the effect of a multi-path-induced error in a global navigation satellite system (GNSS), comprising:

• a receiving means that receives a composite signal, including a band-limited direct-path signal and at least one band-limited multi-path signal, wherein the direct-path signal and the multi-path signal are modulated with periodic phase reversals;
• a measurement means that samples the in-phase I and quadrature Q components of the composite signal as a function of time during a time interval having at least one of the periodic phase reversals;
• a processor means;
• a memory means including at least one program module that is executed by the processor, the at least one program module containing instructions for:
• determining an amplitude of the direct-path signal;
• determining an amplitude of the multi-path signal;
• determining a phase difference φm between the direct-path signal and the multi-path signal;
• determining a time delay δ of the multi-path signal relative to the direct-path signal;
• and
• determining the phase error φε between the composite signal and the direct-path signal due to the multi-path signal,
• wherein the determining operations are in accordance with a pre-determined filter step response of one or more filters in the GNSS used to band limit the direct-path signal and the multi-path signal, a measured amplitude of the composite signal and the measured in-phase I and quadrature Q components of the composite signal as a function of time, wherein the determining is responsive to phase errors corresponding to time delays of the multi-path signal relative to the direct-path signal that are shorter than the filter step response time of the one or more filters, and wherein the device is configured to correct for the phase error φε.

A method of mitigating the effect of a multi-path-induced error in a global navigation satellite system (GNSS), comprising:

• receiving a composite signal, including a band-limited direct-path signal and at least one band-limited multi-path signal, wherein the direct-path signal and the multi-path signal are modulated with periodic phase reversals;
• measuring the composite signal as a function of time during a time interval having at least one of the periodic phase reversals;
• determining a time error Δt, the time error Δt corresponding to a difference between an actual phase reversal time including the effect of the multi-path signal and a phase reversal time without the effect of the multi-path signal, in accordance with the measured composite signal as a function of time and a pre-determined filter characteristic of one or more filters in the GNSS used to band limit the direct-path signal and the multi-path signal;
• wherein the determining is responsive to phase errors corresponding to time delays of the multi-path signal relative to the direct-path signal that are shorter than a filter step response time of the one or more filters used to band limit the direct-path signal and the multi-path signal;
• and
• correcting for an error in a pseudo-range corresponding to the time error Δt.

A device that mitigates the effect of a multi-path-induced error in a global navigation satellite system (GNSS), comprising:

• a receiver that receives a composite signal, including a band-limited direct-path signal and at least one band-limited multi-path signal, wherein the direct-path signal and the multi-path signal are modulated with periodic phase reversals;
• a measurement mechanism that samples the composite signal as a function of time during a time interval having at least one of the periodic phase reversals;
• a processor;
• memory including at least one program module that is executed by the processor, the at least one program module containing instructions for determining a time error Δt, the time error Δt corresponding to a difference between an actual phase reversal time including the effect of the multi-path signal and a phase reversal time without the effect of the multi-path signal, in accordance with the measured composite signal as a function of time and a pre-determined filter characteristic of one or more filters in the GNSS used to band limit the direct-path signal and the multi-path signal;
• wherein the determining is responsive to phase errors corresponding to time delays of the multi-path signal relative to the direct-path signal that are
• shorter than a filter step response time of the one or more filters used to band limit the direct-path signal and the multi-path signal;
• and
• wherein the device is configured to correct for in an error corresponding to the time error Δt in a pseudo-range.

A device that mitigates the effect of a multi-path-induced error in a global navigation satellite system (GNSS), comprising:

• a receiving means that receives a composite signal, including a band-limited direct-path signal and at least one band-limited multi-path signal, wherein the direct-path signal and the multi-path signal are modulated with periodic phase reversals;
• a measurement means that samples the in-phase I and quadrature Q components of the composite signal as a function of time during a time interval having at least one of the periodic phase reversals;
• a processor means;
• a memory means including at least one program module that is executed by the processor, the at least one program module containing instructions for:
• determining a time error Δt, the time error Δt corresponding to a difference between an actual phase reversal time including the effect of the multi-path signal and a phase reversal time without the effect of the multi-path signal;
• wherein the determining operation is in accordance with a pre-determined filter step response corresponding to one or more filters in the GNSS that are used to band limit the direct-path signal and the multi-path signal, a measured amplitude of the composite signal and the measured in-phase I and quadrature Q components of the composite signal as a function of time, wherein the determining is responsive to phase errors corresponding to time delays of the multi-path signal relative to the direct-path signal that are shorter than the filter step response time of the one or more filters, and wherein the device is configured to correct for an error corresponding to the time error Δt in a pseudo-range.