High throughput satellite system with RF service uplink beams and optical feeder downlink beams
Described herein are space based subsystems of a satellite, and related methods, for use in producing an optical feeder downlink beam in dependence on RF service uplink beams received from service terminals within a specified RF frequency range. Beneficially certain embodiments eliminate the need for any type of frequency conversion equipment in the spaced based subsystem that is used to produce the optical feeder downlink beam. Also described herein are ground based subsystems, and related methods, for use in transmitting an optical feeder uplink beam to a satellite configured to receive the optical feeder uplink beam and in dependence thereon produce and transmit a plurality of RF service downlink beams within a specified RF frequency range to service terminals. Also described herein is are space based subsystems of a satellite, and related methods, for use in transmitting a plurality of RF service downlink beams to service terminals.
1. A space based subsystem of a satellite for use in producing an optical feeder downlink beam in dependence on RF service uplink beams received from service terminals within a specified RF frequency range, the space based subsystem comprising:
a plurality of lasers, each of the lasers operable to emit an optical signal having a different peak wavelength within a specified optical wavelength range;
a plurality of electro-optical modulators (EOMs), each of the EOMs configured to receive an optical signal from a respective one of the plurality of lasers, receive a different data modulated RF carrier signal that has been modulated to carry return link data corresponding to a plurality of RF service uplink beams received from a plurality of service terminals, and output an optical data signal carrying return link data corresponding to the plurality of RF service uplink beams and having an RF frequency within the same specified RF frequency range within which the satellite is configured to receive RF service uplink beams from service terminals;
a wavelength-division multiplexing (WDM) multiplexer configured to receive the optical data signals output by the plurality of EOMs, and combine the plurality of optical data signals into a wavelength division multiplexed optical signal;
an optical amplifier configured to amplify the wavelength division multiplexed optical signal to thereby produce an optically amplified wavelength division multiplexed optical signal; and
transmitter optics configured to receive the optically amplified wavelength division multiplexed optical signal and transmit an optical feeder downlink beam to a ground based subsystem in dependence thereon;
wherein because RF frequencies of the optical data signals output by the plurality of EOMs are within the same specified RF frequency range within which the satellite is configured to receive RF service uplink beams from service terminals, there is an elimination of any need for the satellite to perform any frequency conversions when producing the optical feeder downlink beam in dependence on RF service uplink beams.
2. The subsystem of claim 1 , further comprising:
antennas and RF components configured to receive RF service uplink beams from service terminals and produce the data modulated RF carrier signals that are provided to the EOMs and used by the EOMs to produce the optical data signals that are provided by the EOMs to the WDM multiplexer.
3. The system of claim 2 , wherein the antennas include a plurality of feed horns and one or more reflectors.
4. The system of claim 3 , wherein the RF components include orthomode junctions, one or more types of filters, low noise amplifiers and combiners.
5. The subsystem of claim 1 , wherein the specified RF frequency range within which the satellite is configured to receive the plurality of RF service uplink beams comprises an uplink portion of the Ka band.
6. The subsystem of claim 5 , wherein the uplink portion of the Ka band is from 29.5 to 30 GHz, and thus, has a bandwidth of 0.5 GHz.
7. The subsystem of claim 1 , wherein the specified optical wavelength range is a contiguous optical wavelength range within an infrared (IR) spectrum.
8. The subsystem of claim 1 , wherein the specified optical wavelength range is a non-contiguous optical wavelength range within an infrared (IR) spectrum.
9. A method for enabling a space based subsystem of a satellite to produce and transmit an optical feeder downlink beam in dependence on RF service uplink beams received from service terminals within a specified RF frequency range, the method comprising:
emitting a plurality of optical signals each having a different peak wavelength that is within a specified optical wavelength range;
electro-optically modulating each of the optical signals with one of a plurality of different data modulated RF carrier signals, each of which has been modulated to carry return link data for at least one of a plurality of RF service uplink beams, to thereby produce a plurality of optical data signals, each of which carries return link data for at least one of the plurality of RF service uplink beams and has an RF frequency within the same specified RF frequency range within which the satellite is configured to receive RF service uplink beams from service terminals;
multiplexing the plurality of optical data signals to thereby produce a wavelength division multiplexed optical signal that includes return link data corresponding to the RF service uplink beams;
producing an optical feeder downlink beam, in dependence on the wavelength division multiplexed optical signal; and
transmitting the optical feeder downlink beam through free-space from the satellite to a ground based gateway;
wherein because RF frequencies of the optical data signals produced during the electro-optically modulating are within the same specified RF frequency range within which the satellite is configured to receive RF service uplink beams from service terminals, there is an elimination of any need for the satellite to perform any frequency conversions when producing the optical feeder downlink beam in dependence on the RF service uplink beams.
10. The method of claim 9 , further comprising:
receiving the plurality of RF service uplink beams; and
producing the plurality of data modulated RF carrier signals that have been modulated to carry the return link data corresponding to the RF service uplink beams received from the service terminals.
11. The method of claim 9 , wherein the specified RF frequency range within which the satellite is configured to receive the plurality of RF service uplink beams comprises an uplink portion of the Ka band.
12. The method of claim 11 , wherein the uplink portion of the Ka band is from 29.5 to 30 GHz, and thus, has a bandwidth of 0.5 GHz.
13. The subsystem of claim 9 , wherein the specified optical wavelength range is a contiguous optical wavelength range within an infrared (IR) spectrum.
14. The method of claim 9 , wherein the specified optical wavelength range is a non-contiguous optical wavelength range within an infrared (IR) spectrum.
15. The method of claim 9 , wherein the emitting is performed using a plurality of lasers.
16. The method of claim 9 , wherein the electro-optically modulating is performed using a plurality of electro-optical modulators (EOMs).
17. The method of claim 9 , wherein the multiplexing is performed using a wavelength-division multiplexing (WDM) multiplexer.
18. The method of claim 9 , further comprising optically amplifying the plurality of optical data signals before providing the plurality of optical data signals to the WDM multiplexer.
19. A method for enabling a space based subsystem of a satellite to produce and transmit an optical feeder downlink beam in dependence on RF service uplink beams received from service terminals within a specified RF frequency range, the method comprising:
modulating each of a plurality of optical signals with one of a plurality of different data modulated RF carrier signals to thereby produce a plurality of optical data signals, wherein each of the optical signals has a different peak wavelength, and wherein each of the data modulated RF carrier signals has an RF frequency within the same specified RF frequency range within which the satellite is configured to receive RF service uplink beams from service terminals;
multiplexing the plurality of optical data signals to thereby produce a wavelength division multiplexed optical signal;
producing an optical feeder downlink beam, in dependence on the wavelength division multiplexed optical signal; and
transmitting the optical feeder downlink beam through free-space from the satellite to a ground based gateway;
wherein because RF frequencies of the optical data signals produced during the modulating are within the same specified RF frequency range within which the satellite is configured to receive RF service uplink beams from service terminals, there is an elimination of any need for the satellite to perform any frequency conversions when producing the optical feeder downlink beam in dependence on the RF service uplink beams.
20. The method of claim 19 , wherein the specified RF frequency range within which the satellite is configured to receive the plurality of RF service uplink beams comprises an uplink portion of the Ka band.