Systems and methods for monitoring broadband radio frequency interference

Patent metadata

Field	Value
Publication number	US-9297904-B2
Application number	US-201213690231-A
Country	US
Kind code	B2
Filing date	Nov 30, 2012
Priority date	Nov 30, 2012
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

Systems and methods for monitoring broadband radio frequency interference are provided. In certain embodiments, a method comprises calculating a smoothed carrier to noise value for a received signal on a processing unit, wherein the received signal is associated with a receiver and at least one satellite; calculating an average jammer power to noise power value for the receiver; calculating an instantaneous carrier to noise value for the received signal based on the average jammer power to noise power value and the smoothed carrier to noise value; comparing the instantaneous carrier to noise value to an exclusion threshold, and determining whether to exclude the received signal from calculations of global positioning data based on the comparison of the instantaneous carrier to noise value to the exclusion threshold; and when the received signal is excluded, monitoring the received signal for readmittance to the calculation of global positioning data.

First claim

What is claimed is:

1. A system for monitoring broadband radio frequency interference, the system comprising:
at least one global navigation satellite system receiver configured to receive signals from at least one satellite and provide measurements from the at least one satellite, wherein the measurements are used to calculate global positioning data;
at least one memory unit configured to store instructions and data; and
a processing unit coupled to the at least one global navigation satellite system receiver and the at least one memory unit, where the instructions direct the processing unit to:
measure a carrier to noise value for the at least one satellite through the at least one global navigation satellite system receiver;
calculate a smoothed carrier to noise value, wherein the smoothed carrier to noise value is calculated based on measurements from the at least one global navigation satellite system receiver during a first time period;
calculate a jammer power to noise power value, wherein the jammer power to noise power value comprises the average drop in the carrier to noise value for valid satellite measurements, where the drop comprises a difference between the smoothed carrier to noise values and a present carrier to noise value;
calculate an average jammer power to noise power value, based on the jammer power to noise power value;
calculate an instantaneous carrier to noise value based on the average jammer power to noise power value and the smoothed carrier to noise value;
calculate an exclusion threshold value based on the variance of the carrier to noise values from the at least one global navigation satellite system receiver;
compare the instantaneous carrier to noise value to the exclusion threshold value; and
when the instantaneous carrier to noise value is below the exclusion threshold value, exclude the measurements from the calculation of global positioning data.

2. The system of claim 1 , wherein the at least one global navigation satellite system receiver is a reference receiver in a ground based augmentation system and the measurements are used to provide pseudorange corrections and flight path approach guidance to aircraft.

3. The system of claim 1 , wherein the first time period is 200 seconds.

4. The system of claim 1 , wherein the processing unit determines that the carrier to noise value has converged before the processing unit calculates the smoothed carrier to noise value.

5. The system of claim 1 , wherein the processing unit determines that drops in carrier to noise values are consistent for the signals received by the at least one global navigation satellite system receiver.

6. The system of claim 5 , wherein the drops in carrier to noise value for the signals received which are not consistent for the signals received by the at least one global navigation satellite system receiver are not used in the calculation of the jammer power to noise power value or the average power to noise power value.

7. The system of claim 1 , wherein the processing unit alters how the measurements are used by excluding measurements from the at least one satellite from being used in calculations to provide global positioning data.

8. The system of claim 7 , wherein the processing unit further monitors measurements from the at least one satellite for readmittance into calculations to provide global positioning data when the measurements from the at least one satellite are excluded.

9. The system of claim 1 , wherein the global positioning data include pseudorange corrections.

10. The system of claim 1 , wherein the processing unit is further configured to:
compare the jammer power to noise power value against a jammer mask; and
alter the calculation of the global positioning data based on the comparison of the jammer power to noise power value and the jammer mask, wherein the jammer power mask is a power spectral density level that defines regulatory and performance limits for radio frequency interference.

11. The system of claim 1 , wherein at least one global navigation satellite system receiver contains the processing unit and the memory unit.

12. A method for monitoring broadband radio frequency interference, the method comprising:
measuring a carrier to noise value for at least one satellite through at least one global navigation satellite system receiver;
calculating a smoothed carrier to noise value, wherein the smoothed carrier to noise value is calculated based on measurements from the at least one global navigation satellite system receiver during a first time period;
calculating a jammer power to noise power value, wherein the jammer power to noise power value comprises the average drop in the carrier to noise value for valid satellite measurements, where the drop comprises a difference between the smoothed carrier to noise values and a present carrier to noise value;
calculating an average jammer power to noise power value, based on the jammer power to noise power value;
calculating an instantaneous carrier to noise value based on the average jammer power to noise power value and the smoothed carrier to noise value;
determining whether to exclude signals received from the at least one satellite from calculations of global positioning data based on a comparison of the instantaneous carrier to noise value to an exclusion threshold based on the variance of the carrier to noise values from the at least one global navigation satellite system receiver; and
when the signals received from the at least one satellite are excluded, monitoring the signals received from the at least one satellite for readmittance to the calculation of global positioning data.

13. The method of claim 12 , wherein determining whether to exclude the signals comprises:
calculating the exclusion threshold based on the variance of carrier to noise values; and
comparing the instantaneous carrier to noise value against the exclusion threshold.

14. The method of claim 12 , wherein monitoring the signals for readmittance comprises:
calculating a readmittance threshold based on the variance of carrier to noise values;
comparing the instantaneous carrier to noise value against the readmittance threshold;
determining whether readmitting the signals improves the calculation of global positioning data; and
readmitting the signals if the instantaneous carrier to noise value exceeds the readmittance threshold and the received signal improves the performance of global positioning data.

15. The method of claim 14 , wherein determining that readmitting the signals improves the calculation of global positioning data comprises determining whether an error in a pseudorange decreases when the signals are readmitted.

16. The method of claim 12 , further comprising verifying that the signals associated with the at least one satellite are consistent for a single receiver.

17. The method of claim 12 , wherein calculating a smoothed carrier to noise value comprises waiting for carrier to noise values from the at least one receiver to converge before using the smoothed carrier to noise value.

18. The method of claim 12 , further comprising determining whether to alter the calculations of global positioning data based on the comparison of the average jammer power to noise power value and a pre-defined jammer power mask, wherein the jammer power mask is a power spectral density level that defines regulatory and performance limits for radio frequency interference.

19. A program product for monitoring broadband radio frequency interference, the pro

Assignees

• Honeywell Int Inc

Inventors

• Scheitlin Joseph E
• Brenner Mats Anders
• Howard John M
• Class Kim

Classifications

• G01S19/215

  issues related to spoofing · CPC title

• G01S19/21 Primary

  Interference related issues {; Issues related to cross-correlation, spoofing or other methods of denial of service} · CPC title

• G01S19/15

  Aircraft landing systems · CPC title