# US 10,502,835 B2 · Methods and systems for inherent fast time to first position fix (TTFF) and high sensitivity > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,835 B2 - Document ID: US10502835B2 - Status: Granted - Kind: B2 - Application number: 15/472,180 - Filed: 2017-03-28 - Published: 2017-09-28 - Granted: 2019-12-10 - Earliest claimed: 2016-03-28 - Applicants: UTI Limited Partnership - Inventors: Yang Gao; Wentao Zhang - Web page: https://patentgrep.com/patent/US10502835B2 ## CPC - G01S 19/08: providing integrity information, e.g. health of satellites or quality of ephemeris data - G01S 19/02: Details of the space or ground control segments - G01S 19/07: providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections - 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 inherent fast Time To First position Fix (TTFF) and high sensitivity are described. An embodiment of a method may include interpolating a satellite position in response to a navigation message having initial conditions for satellite ephemeris data converted into Keplerian format, wherein signal fixation is maintained in response to receiving the navigation signal at least once per day. ## Claims ### Claim 1 A method for inherent fast Time To First position Fix (TTFF) and high sensitivity, comprising: obtaining an ephemeris data set at a control segment system; converting the ephemeris data set between Cartesian initial conditions and Keplerian initial conditions using a processing component of the control segment system; interpolating a satellite position in response to a navigation message having initial conditions for satellite ephemeris data converted into Keplerian format using the processing component of the control segment system; wherein signal fixation is maintained in response to receiving the navigation signal at least once per day. ### Claim 2 (depends on 1) The method of claim 1, further comprising: determining the ephemeris data set in response to received global observations of a satellite vehicle at a control segment at the control segment system; converting the ephemeris data set from Cartesian initial conditions to Keplerian initial conditions using the processing component of the control segment system; encoding the Keplerian initial conditions into a navigation message using the processing component of the control segment system; and uploading the navigation message to a satellite segment. ### Claim 3 (depends on 2) The method of claim 2, wherein determining the ephemeris data set further comprises performing a Precise Orbital Determination (POD) process on the received global observations using the processing component of the ground segment system. ### Claim 4 (depends on 3) The method of claim 3, further comprising preprocessing the received global observations before performing the POD process using the processing component of the ground segment system. ### Claim 5 (depends on 1) The method of claim 1, further comprising: receiving the navigation message comprising the ephemeris data set converted from Cartesian initial conditions to Keplerian initial conditions at a satellite segment system; storing the navigation message using a processing component and a data storage component of the satellite segment system; determining whether a reference time period has elapsed using the processing component of the satellite segment system; retrieving the navigation message in response to a determination that the reference time period has elapsed; and broadcasting the navigation message using a data communication component of the satellite segment system. ### Claim 6 (depends on 1) The method of claim 1, further comprising: receiving the navigation message comprising the ephemeris data set converted from Cartesian initial conditions to Keplerian initial conditions at an endpoint segment; converting the Keplerian initial conditions back to Cartesian initial conditions using a processing component of the endpoint segment; numerically integrating the Cartesian initial conditions using the processing component of the endpoint segment; and interpolating a position for a satellite vehicle for a specified time in response to the numerically integrated the Cartesian initial conditions using the processing component of the endpoint segment. ### Claim 7 (depends on 6) The method of claim 6, further comprising decoding the navigation message. ### Claim 8 (depends on 6) The method of claim 6 further comprising transforming the numerical integration data from Earth Center Inertial (ECI) to Earth Center and Earth Fixed (ECEF) format. ### Claim 9 (depends on 6) The methods of claim 6, wherein the navigation message comprises satellite clock data. ### Claim 10 (depends on 6) The methods of claim 6, wherein the navigation message comprises six Keplerian elements. ### Claim 11 (depends on 6) The methods of claim 6, wherein the navigation message comprises a Solar radiation parameter. ### Claim 12 (depends on 6) The methods of claim 6, wherein the navigation message comprises ionosphere information. ### Claim 13 (depends on 6) The methods of claim 6, wherein the navigation message comprises system time parameters. ### Claim 14 (depends on 6) The methods of claim 6, wherein the navigation message comprises Earth orientation parameters. ### Claim 15 (depends on 6) The methods of claim 6, wherein the navigation message comprises Almanac data. ### Claim 16 A system for inherent fast Time To First position Fix (TTFF) and high sensitivity, comprising: a control segment configured to: obtain an ephemeris data set; convert the ephemeris data set between Cartesian initial conditions and Keplerian initial conditions; and an endpoint segment configured to interpolate a satellite position in response to a navigation message having initial conditions for satellite ephemeris data converted into Keplerian format; wherein signal fixation is maintained in response to receiving the navigation signal at least once per day. ### Claim 17 (depends on 16) The system of claim 16, wherein the control segment is further configured to: determine the ephemeris data set in response to received global observations of a satellite vehicle; convert the ephemeris data set from Cartesian initial conditions to Keplerian initial conditions; encode the Keplerian initial conditions into a navigation message; and upload the navigation message to a satellite segment. ### Claim 18 (depends on 16) The system of claim 16, wherein the space segment is further configured to: receive the navigation message comprising the ephemeris data set converted from Cartesian initial conditions to Keplerian initial conditions; store the navigation message; determine whether a reference time period has elapsed; retrieve the navigation message in response to a determination that the reference time period has elapsed; and broadcast the navigation message. ### Claim 19 (depends on 16) The system of claim 16, wherein the endpoint segment is further configured to: receive the navigation message comprising the ephemeris data set converted from Cartesian initial conditions to Keplerian initial conditions; convert the Keplerian initial conditions back to Cartesian initial conditions; numerically integrate the Cartesian initial conditions; and interpolate a position for a satellite vehicle for a specified time in response to the numerically integrated the Cartesian initial conditions.