# US 2019/0379449 A1 · Broadband satellite communication system using optical feeder links

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- Number: US 2019/0379449 A1
- Document ID: US20190379449A1
- Status: Published application
- Kind: A1
- Application number: 16/547,081
- Filed: 2019-08-21
- Published: 2019-12-12
- Earliest claimed: 2015-12-31
- Assignees: Viasat, Inc. C/O Patent Department
- Applicants: Viasat, Inc. C/O Patent Department
- Inventors: AARON J. MENDELSOHN
- Web page: https://patentgrep.com/patent/US20190379449A1

## CPC

- H04B 7/2041: {Spot beam multiple access}
- H04B 7/18513: {Transmission in a satellite or space-based system}
- H04B 7/18515: {Transmission equipment in satellites or space-based relays}
- H04B 7/18517: {Transmission equipment in earth stations}
- H04B 10/118: specially adapted for satellite communication
- H01Q 1/288: {Satellite antennas}
- H01Q 25/00: Antennas or antenna systems providing at least two radiating patterns (arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00)
- H04B: TRANSMISSION
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)

## Abstract

Broadband satellite communications systems using optical feeder links are disclosed. Various optical modulation schemes are disclosed that can provide improved capacity for fixed spot beam, on board beamforming, and ground-based beamforming broadband satellite systems.

## Claims

### Claim 1

A method of transmitting information through a satellite of a satellite communications system, comprising:
receiving a plurality of binary data streams within a beamformer, the binary data streams for transmission to a plurality of user beam coverage areas;
generating a plurality of beam element signals, each beam element signal generated such that when transmitted from an antenna array in the satellite the beam element signals superpose with one another to form at least one user spot beam; and
transmitting the beam element signals from the beamformer to a SAN;
receiving beam element signals with the SAN;
modulating the received beam element signals onto an optical carrier;
transmitting the modulated optical carrier from the at least one SAN to the satellite;
receiving the modulated optical carrier within a satellite;
demultiplexing the modulated optical carrier and outputting a plurality of optical signals, each of the plurality of demultiplexed optical signals having a wavelength in a unique optical channel;
generating a plurality of analog electrical signals, each having an amplitude determined in response to the optical intensity of one of the demultiplexed optical signals;
applying the plurality of analog electrical signals to elements of an antenna array such that when the beam element signals are superposed with one another, they form at least one user spot beam.

### Claim 2 (depends on 1)

The method of claim 1, further including generating the plurality of beam element signals based on the quality of the optical links between the satellite and the SAN.

### Claim 3 (depends on 1)

The method of claim 1, further including:
generating at least one timing pilot signal within the beamformer;
transmitting the timing pilot signal together with the beam element signals to a first SAN and a second SAN;
receiving timing pilot signals within the first SAN and the second SAN;
modulating the received timing pilot signals onto a first and second optical carriers in the first and second SAN respectively;
transmitting the first and second optical carrier from the corresponding SANs;
receiving in the satellite the first and second optical carriers from the first and second SAN;
demodulating the first and second optical carrier to obtain a corresponding first and second timing pilot signal in the satellite;
determining a time difference between the first timing pilot signal and the second timing pilot signal, and generating a timing correction signals based on the time difference; and
transmitting the timing correction signal to the first and second SAN.

### Claim 4 (depends on 3)

The method of claim 3, further including delaying the transmission of the beam element signals from one or both of the SANs to reduce the time difference.

### Claim 5 (depends on 3)

The method of claim 3, wherein each of the first and the second SAN receives a subset of the plurality of beam element signals.

### Claim 6 (depends on 3)

The method of claim 3, further comprising positioning lenses within the satellite to receive optical signals from a subset of the SANs, wherein SANs are included in the subset based on the attenuation of optical signals transmitted over the optical link between each of the SANs and the satellite.

### Claim 7 (depends on 6)

The method of claim 6, wherein the positioning lenses further comprises redirecting a lens away from the first SAN and pointing the lens at the second SAN if the optical link between the satellite and the second SAN has less attenuation than the optical link between the satellite and the first SAN.