# US 2017/0289939 A1 · Synchronization for satellite system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0289939 A1 - Document ID: US20170289939A1 - Status: Published application - Kind: A1 - Application number: 15/172,859 - Filed: 2016-06-03 - Published: 2017-10-05 - Earliest claimed: 2016-03-29 - Assignees: Space Systems/Loral, Inc. - Applicants: Space Systems/Loral, LLC - Inventors: William Hreha; Anne Elizabeth Wharton; David Linford Foulke; Richard Wallace Voreck; Shervin Shambayati - Web page: https://patentgrep.com/patent/US20170289939A1 ## CPC - H01Q 21/24: Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction {(circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001)} - H01Q 3/2682: {Time delay steered arrays} - H04B 7/043: {using best eigenmode, e.g. beam forming or beam steering} - H04B 7/18515: {Transmission equipment in satellites or space-based relays} - H04B 7/18519: {Operations control, administration or maintenance} - H04B 7/18523: {Satellite systems for providing broadcast service to terrestrial stations, i.e. broadcast satellite service (arrangements specially adapted for satellite broadcast receiving H04H40/90; picture transmission via satellite H04N1/00103; television transmission via satellite H04N7/20)} - H04B 7/18534: {for enhancing link reliablility, e.g. satellites diversity} - H04B 7/18541: {for handover of resources} - H04B 7/18578: {Satellite systems for providing broadband data service to individual earth stations (for selecting H04W; provisions for broadband connection, H04Q11/0478)} - H04B 7/18584: {Arrangements for data networking, i.e. for data packet routing, for congestion control (data switching networks H04L12/00)} - H04W 16/28: using beam steering - H04W 56/0015: {one node acting as a reference for the others} - H04W 72/0446: Resources in time domain, e.g. slots or frames - H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA - H04W 72/21: in the uplink direction of a wireless link, i.e. towards the network - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - H04B 7/18513: {Transmission in a satellite or space-based system} - H04B 7/18521: {Systems of inter linked satellites, i.e. inter satellite service (for optical links between satellites H04B10/118)} - H04B 7/18547: {for geolocalisation of a station (position fixing by direction or distance determination G01S5/00)} - H04B 7/18595: {Arrangements for adapting broadband applications to satellite systems} - H04B 7/19: Earth-synchronous stations - H04W 72/046: {the resource being in the space domain, e.g. beams} - H04W 84/18: Self-organising networks, e.g. ad-hoc networks or sensor networks - H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72) - H04B: TRANSMISSION - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Synchronization technology is implemented for a satellite communication system. Master clock information is accessed at a terrestrial location. A timing message based on the master clock information is transmitted from the terrestrial location to a satellite as the satellite is in orbit. The satellite is synchronized to the master clock based on the timing message. A beacon signal is transmitted from the satellite toward Earth. The beacon signal includes timing information. The beacon signal is received at a ground based gateway. The gateway is synchronized to the satellite based on the beacon signal. Communication is sent from the gateway to a terminal via the satellite. The communication includes timing data. The terminal is synchronized to the gateway based on the timing data. ## Claims ### Claim 1 A method of operating a satellite communications system, comprising: accessing master clock information at a terrestrial location; transmitting a timing message based on the master clock information from the terrestrial location to a satellite as the satellite is in orbit; synchronizing the satellite to the master clock based on the timing message; transmitting a beacon signal from the satellite, the beacon signal includes timing information; receiving the beacon signal at a ground based gateway; synchronizing the gateway to the satellite based on the beacon signal; sending communication from the gateway to a terminal via the satellite, the communication includes timing data; and synchronizing the terminal to the gateway based on the timing data. ### Claim 2 (depends on 1) The method of claim 1, wherein: the timing message includes a command to set a clock on the satellite. ### Claim 3 (depends on 1) The method of claim 1, wherein: the beacon signal indicates timing of an epoch for time domain beam hopping and indicates a quantity of epochs from a time reference. ### Claim 4 (depends on 1) The method of claim 1, wherein: the satellite receives the timing message as the satellites travels in orbit closest to the terrestrial location. ### Claim 5 (depends on 1) The method of claim 1, wherein: the satellite is a non-geostationary satellite. ### Claim 6 (depends on 1) The method of claim 1, wherein: the terminal synchronizes to the gateway while communicating user data with the gateway. ### Claim 7 (depends on 1) The method of claim 1, further comprising: establishing communication between the gateway and the satellite to implement connections between the gateway and a plurality of terminals via the satellite, the synchronizing the gateway to the satellite based on the beacon signal is performed before the establishing communication for a current orbit. ### Claim 8 (depends on 1) The method of claim 1, wherein: the sending communication from the gateway to the terminal includes sending a frame, the timing data is in the frame. ### Claim 9 (depends on 1) The method of claim 1, wherein: the synchronizing the gateway to the satellite based on the beacon signal comprises using a location of the satellite and a location of the gateway to determine a transmission delay of the beacon signal and adjusting timing on the gateway based on the timing information in the beacon signal and the transmission delay. ### Claim 10 (depends on 9) The method of claim 9, further comprising: determining the location of the satellite including: receiving GPS signals at a ground based gateway; receiving the beacon signal at the ground based gateway; determining time of receipt in GPS time of the beacon signal at the ground based gateway; and calculating location of the satellite using the time of receipt in GPS time of the beacon signal at the multiple ground based gateways. ### Claim 11 (depends on 9) The method of claim 9, further comprising determining the Doppler to the satellite including receiving the beacon signal at the ground based gateway, determining frequency offset over time of the beacon signal at the ground based gateway; and calculating Doppler to the satellite using the history of the beacon signal frequency offset. ### Claim 12 (depends on 9) The method of claim 9, further comprising determining the location of the satellite including: receiving GPS signals at multiple ground based gateways; identifying GPS time at the multiple gateways; receiving the beacon signal at the multiple ground based gateways; determining times of receipt in GPS time of the beacon signal at the multiple ground based gateways; and calculating location of the satellite using the times of receipt in GPS time of the beacon signal at the multiple ground based gateways. ### Claim 13 A satellite communication system, comprising: a satellite comprising an antenna system configured to receive command information from a ground location and transmit a beacon signal toward a ground based gateway, the command information includes a command to adjust a clock on the satellite to synchronize the satellite to a master clock, the beacon signal includes timing information to synchronize the gateway to the satellite. ### Claim 14 (depends on 13) The satellite communication system of claim 13, wherein: the satellite clock is adjusted during the reconfiguration time; and the beacon signal indicates timing of an epoch for time domain beam hopping and indicates a quantity of epochs from a time reference. ### Claim 15 (depends on 13) The satellite communication system of claim 13, wherein: the satellite is a non-geostationary satellite. ### Claim 16 (depends on 13) The satellite communication system of claim 13, wherein: the satellite is a non-geostationary satellite; and the clock on the satellite is adjusted by the terrestrial location in burst of small increments periodically while the satellite is in view. ### Claim 17 (depends on 13) The satellite communication system of claim 13, further comprising: the gateway, synchronizing the gateway to the satellite includes using a location of the satellite and a location of the gateway to determine a transmission delay of the beacon signal and adjusting timing on the gateway based on the timing information in the beacon signal and the transmission delay. ### Claim 18 (depends on 17) The satellite communication system of claim 17, wherein: the gateway is configured to determine the location of the satellite by working with other gateways to receive GPS signals at multiple ground based gateways, identify GPS time at the multiple gateways, receive the beacon signal at the multiple ground based gateways, determine times of receipt in GPS time of the beacon signal at the multiple ground based gateways and calculate location of the satellite using the times of receipt in GPS time of the beacon signal at the multiple ground based gateways. ### Claim 19 A satellite based communication system, comprising: a gateway configured to communicate with a terminal via the satellite, the gateway is configured to receive a beacon signal from the satellite and synchronize to the satellite based on the beacon signal, the gateway configured to send communication to the terminal via the satellite, the communication with the terminal includes timing data for the terminal to synchronize to the gateway. ### Claim 20 (depends on 19) The satellite communication system of claim 19, wherein: the beacon signal indicates timing of an epoch for time domain beam hopping and indicates a quantity of epochs from a time reference. ### Claim 21 (depends on 19) The satellite communication system of claim 19, wherein: the gateway is configured to establish communication between the gateway and the satellite to implement connections between the gateway and a plurality of terminals via the satellite, the gateway configured to synchronize to the satellite based on the beacon signal before the establishing communication for a current orbit. ### Claim 22 (depends on 19) The satellite communication system of claim 19, wherein: the gateway is configured to synchronize to the satellite based on the beacon signal by using a location of the satellite and a location of the gateway to determine a transmission delay of the beacon signal and adjusting timing on the gateway based on the timing information in the beacon signal and the transmission delay. ### Claim 23 (depends on 22) The satellite communication system of claim 22, wherein: the gateway is configured to determine the location of the satellite by working with other gateways to receive GPS signals at multiple ground based gateways, identify GPS time at the multiple gateways, receive the beacon signal at the multiple ground based gateways, determine times of receipt in GPS time of the beacon signal at the multiple ground based gateways and calculate location of the satellite using the times of receipt in GPS time of the beacon signal at the multiple ground based gateways. ### Claim 24 (depends on 19) The satellite communication system of claim 19, wherein: an additional gateway, the gateway and the additional gateway are connected to the terminal via the satellite, the gateway and the additional gateway are configured to establish independent timing with the terminal.