5 ms·

The part of the satellite being "software-defined" is probably the phased-array antennas of the transponder/payload. I think it is unlikely that all the GHz RF

by okl 8y ago

The part of the satellite being "software-defined" is probably the phased-array antennas of the transponder/payload. I think it is unlikely that all the GHz RF processing is realized as SDR. Maybe someone can dig up more information?

IshKebab 8y ago
Why not? There are already plenty of SDRs that can operate in the GHz range. Obviously they don't output the raw RF signal directly but no SDR does that.
- stagger87 8y ago
  What is your definition of "raw RF"? To me that sounds like you mean upconverted baseband/IF, and in that case most SDRs output "raw RF".
  - IshKebab 8y ago
    No I mean the actual RF signal. As you said, no SDRs directly calculate the 2.4 GHz wave.
okl 8y ago
> Eutelsat Quantum is fitted with a suite of powerful operational software, which ensures that the payload resources are used as efficiently as possible. The software tool predicts, operates and manages the on-board configuration and reconfiguration of the satellite. [0] That makes it sounds like any other telco-satellite with beamforming. Edit: More information from [1] > Guilleux said the first Quantum satellite will have eight downlink beams that can range from a minimum diameter of 600 kilometers to a maximum of one-third of the Earth’s surface (the larger the beam, the more dispersed the signal power), and eight independent uplink beams. Customers can split any of those eight beams into smaller sub-beams and follow assets such as ships and planes, he said. O’Connor said the satellite will have a total of 3.5 GHz of capacity, from which any individual downlink beam could support up to 1 GHz. The first Eutelsat Quantum will function just in Ku-band, but Guilleux said future iterations could support other frequencies, including both military and civilian Ka-band. [0] - https://www.esa.int/Our_Activities/Telecommunications_Integrated_Applications/Quantum https://www.esa.int/Our_Activities/Telecommunications_Integr... [1] - https://spacenews.com/eutelsat-adding-two-more-quantum-satellites-to-fleet/ https://spacenews.com/eutelsat-adding-two-more-quantum-satel...
- shaklee3 8y ago
  What's the maximum number of beams? 8 beams at 3.5GHz is a very low capacity satellite, especially given that they likely cannot use all 3.5GHz everywhere.
  - portillo 8y ago
    Seems that those 8 beams can be further subdivided in different spot beams (not sure how many subdivisions are possible though). Also, a previous article [1] mentions that they are actually limited to a maximum of 1 GHz/beam (I understand each of the 8 beams is limited to 1 GHz). My impression is that this is more of a tech demonstration satellite (to test the new payload, resource management software, etc) rather than an actual commercial satellite, as the total throughput seems to be much lower than state-of-the-art spacecraft from other companies. [1] https://spacenews.com/eutelsat-adding-two-more-quantum-satellites-to-fleet/ https://spacenews.com/eutelsat-adding-two-more-quantum-satel...
    - shaklee3 8y ago
      I just responded to your other comment, so thanks for the SN article. I didn't realize the capacity was almost two orders of magnitude off what current and upcoming satellites are doing. I wonder who their customers are, since GEO satellites have been fighting to get the $(satellite cost)/Gbps down for years. I think this was answered by your link: "Quantum was made possible by the British government, which is funding 90 percent of ESA’s commitment of 71 million euros in the Quantum program" It's the government wasting a tremendous amount of money.
FPGAhacker 8y ago
It’s possible it’s the GHz RF. Even for hardware processing, you have to downconvert to something reasonable like a couple hundred MHz before it’s feasible to digitally signal process. If your software/processor/bus can’t keep up with that data rate, you can always go lower in hardware and still leave enough headroom for software to tune and process. I haven’t looked into SDR much though it’s in my “someday” list, so I don’t know how much is typically expected to be handled in software. I suppose it varies depending on the spectrum of interest. My last project, the GHz spectrum was downcoverted in analog to the hundreds of MHz range, and digitally downconverted further with low pass filters and frequency shifting and then piping out over pcie to a ring buffer for software to do the interesting signal processing. Xilinx has an RF Zynq FPGA in the works, or maybe available now, that has the analog front end conversion capabilities paired with an fpga with an embedded arm[1]. (No affiliation) 1. https://www.xilinx.com/products/technology/rfsampling.html https://www.xilinx.com/products/technology/rfsampling.html
- okl 8y ago
  It's definitely possible. I'm guessing based on cost/benefit. Here's an SDR R&D board from 2018 for "low bandwidth applications" using Spartan-6 FPGAS, (https://artes.esa.int/projects/spyrus https://artes.esa.int/projects/spyrus). Unfortunately they don't provide any results from the radiation test campaign (wonder why?)
- shaklee3 8y ago
  They can definitely do on-board signal processing once down converted. This will have a substantial hit on total capacity though, which is what matters most. See my other comments. Btw, you cannot use standard fpgas in space. They are a special kind hardened for radiation and redundancy.
  - Rebelgecko 8y ago
    Standard FPGAs can be usable in space depending on where they are. Consumer stuff can do OK in LEO, especially if you have some sort of watchdog or voting system.

by okl 8y ago

IshKebab 8y ago

Why not? There are already plenty of SDRs that can operate in the GHz range. Obviously they don't output the raw RF signal directly but no SDR does that.

stagger87 8y ago
What is your definition of "raw RF"? To me that sounds like you mean upconverted baseband/IF, and in that case most SDRs output "raw RF".
- IshKebab 8y ago
  No I mean the actual RF signal. As you said, no SDRs directly calculate the 2.4 GHz wave.

okl 8y ago

> Eutelsat Quantum is fitted with a suite of powerful operational software, which ensures that the payload resources are used as efficiently as possible. The software tool predicts, operates and manages the on-board configuration and reconfiguration of the satellite. [0] That makes it sounds like any other telco-satellite with beamforming. Edit: More information from [1] > Guilleux said the first Quantum satellite will have eight downlink beams that can range from a minimum diameter of 600 kilometers to a maximum of one-third of the Earth’s surface (the larger the beam, the more dispersed the signal power), and eight independent uplink beams. Customers can split any of those eight beams into smaller sub-beams and follow assets such as ships and planes, he said. O’Connor said the satellite will have a total of 3.5 GHz of capacity, from which any individual downlink beam could support up to 1 GHz. The first Eutelsat Quantum will function just in Ku-band, but Guilleux said future iterations could support other frequencies, including both military and civilian Ka-band. [0] - https://www.esa.int/Our_Activities/Telecommunications_Integrated_Applications/Quantum https://www.esa.int/Our_Activities/Telecommunications_Integr... [1] - https://spacenews.com/eutelsat-adding-two-more-quantum-satellites-to-fleet/ https://spacenews.com/eutelsat-adding-two-more-quantum-satel...

shaklee3 8y ago
What's the maximum number of beams? 8 beams at 3.5GHz is a very low capacity satellite, especially given that they likely cannot use all 3.5GHz everywhere.
- portillo 8y ago
  Seems that those 8 beams can be further subdivided in different spot beams (not sure how many subdivisions are possible though). Also, a previous article [1] mentions that they are actually limited to a maximum of 1 GHz/beam (I understand each of the 8 beams is limited to 1 GHz). My impression is that this is more of a tech demonstration satellite (to test the new payload, resource management software, etc) rather than an actual commercial satellite, as the total throughput seems to be much lower than state-of-the-art spacecraft from other companies. [1] https://spacenews.com/eutelsat-adding-two-more-quantum-satellites-to-fleet/ https://spacenews.com/eutelsat-adding-two-more-quantum-satel...
  - shaklee3 8y ago
    I just responded to your other comment, so thanks for the SN article. I didn't realize the capacity was almost two orders of magnitude off what current and upcoming satellites are doing. I wonder who their customers are, since GEO satellites have been fighting to get the $(satellite cost)/Gbps down for years. I think this was answered by your link: "Quantum was made possible by the British government, which is funding 90 percent of ESA’s commitment of 71 million euros in the Quantum program" It's the government wasting a tremendous amount of money.

FPGAhacker 8y ago

It’s possible it’s the GHz RF. Even for hardware processing, you have to downconvert to something reasonable like a couple hundred MHz before it’s feasible to digitally signal process. If your software/processor/bus can’t keep up with that data rate, you can always go lower in hardware and still leave enough headroom for software to tune and process. I haven’t looked into SDR much though it’s in my “someday” list, so I don’t know how much is typically expected to be handled in software. I suppose it varies depending on the spectrum of interest. My last project, the GHz spectrum was downcoverted in analog to the hundreds of MHz range, and digitally downconverted further with low pass filters and frequency shifting and then piping out over pcie to a ring buffer for software to do the interesting signal processing. Xilinx has an RF Zynq FPGA in the works, or maybe available now, that has the analog front end conversion capabilities paired with an fpga with an embedded arm[1]. (No affiliation) 1. https://www.xilinx.com/products/technology/rfsampling.html https://www.xilinx.com/products/technology/rfsampling.html

okl 8y ago
It's definitely possible. I'm guessing based on cost/benefit. Here's an SDR R&D board from 2018 for "low bandwidth applications" using Spartan-6 FPGAS, (https://artes.esa.int/projects/spyrus https://artes.esa.int/projects/spyrus). Unfortunately they don't provide any results from the radiation test campaign (wonder why?)
shaklee3 8y ago
They can definitely do on-board signal processing once down converted. This will have a substantial hit on total capacity though, which is what matters most. See my other comments. Btw, you cannot use standard fpgas in space. They are a special kind hardened for radiation and redundancy.
- Rebelgecko 8y ago
  Standard FPGAs can be usable in space depending on where they are. Consumer stuff can do OK in LEO, especially if you have some sort of watchdog or voting system.