# US 2014/0152498 A1 · Systems and methods for monitoring broadband radio frequency interference > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152498 A1 - Document ID: US20140152498A1 - Status: Published application - Kind: A1 - Application number: 13/690,231 - Filed: 2012-11-30 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Honeywell International Inc. - Applicants: Honeywell International Inc. - Inventors: Joseph E. Scheitlin; Mats Anders Brenner; John M. Howard; Kim Class - Web page: https://patentgrep.com/patent/US20140152498A1 ## CPC - G01S 19/21: Interference related issues {; Issues related to cross-correlation, spoofing or other methods of denial of service} - G01S 19/15: Aircraft landing systems - G01S 19/215: {issues related to spoofing} - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## 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. ## Claims ### Claim 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; 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; compare the instantaneous carrier to noise value to the exclusion threshold value; and alter how the measurements are used to provide global positioning data based on the comparison. ### Claim 2 (depends on 1) 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. ### Claim 3 (depends on 1) The system of claim 1, wherein the first time period is 200 seconds. ### Claim 4 (depends on 1) 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. ### Claim 5 (depends on 1) 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. ### Claim 6 (depends on 5) 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. ### Claim 7 (depends on 1) 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. ### Claim 8 (depends on 7) 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. ### Claim 9 (depends on 1) The system of claim 1, wherein the global positioning data include pseudorange corrections. ### Claim 10 (depends on 1) 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. ### Claim 11 The system of claim, wherein at least one global navigation satellite system receiver contains the processing unit and the memory unit ### Claim 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; 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; 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. ### Claim 13 (depends on 12) 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. ### Claim 14 (depends on 12) 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. ### Claim 15 (depends on 14) 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. ### Claim 16 (depends on 12) The method of claim 12, further comprising verifying that the signals associated with the at least one satellite are consistent for a single receiver. ### Claim 17 (depends on 12) 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. ### Claim 18 (depends on 12) 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. ### Claim 19 A program product for monitoring broadband radio frequency interference, the program product comprising a plurality of instructions tangibly stored on a non-transitory storage medium, the instructions operable when executed, to cause a processing unit to: calculate a set of statistics based on at least one received signal associated with at least one receiver and at least one satellite, wherein the set of statistics include a smoothed carrier to noise value and an instantaneous carrier to noise value for the at least one received signal; detect broadband radio frequency interference by comparing the smoothed carrier to noise value to the present carrier to noise value, and computing a jammer power to noise power value based on an average difference between the smoothed carrier to noise value and a present carrier to noise value, and then computing an instantaneous carrier to noise value from the smoothed carrier to noise value and a jammer power to noise power value, wherein the at least one received signal is excluded from calculation of global positioning data based on the comparison of the instantaneous carrier to noise value to an exclusion threshold; and when the at least one received signal is excluded, monitor the at least one received signal for readmittance to the calculation of global positioning data. ### Claim 20 (depends on 19) The program product of claim 19, wherein the the plurality of instructions cause a processing unit to: calculate the exclusion threshold based on the variance of carrier to noise values; and compare the instantaneous carrier to noise value against the exclusion threshold.