Software defined radios are key to satellite direct to future smartphone communication

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Nextbigfuture was able to ask Rob Hoyt of Tethers Unlimited how he will be able to use 27 large high low-earth orbit satellites to provide high-speed internet directly to smartphones.

The GlobalFi approach will be to put all of the antenna gain required on the space side, so it can close high-throughput links to ordinary smartphones without requiring the user to buy a hotspot antenna, satphone sleeve, or other dongle/device. This does require very large antennas on the satellite, but will enable the system to address a market of billions of smartphone users.

The GlobalFi satellites will be in high LEO, not GEO (the DARPA Constructable Platform contract is focused on GEO platforms, but GlobalFi platforms would be in LEO).

Each antenna will have multiple steered beams. The primary reflector is fed by an array of our SWIFT radios acting (sort of) as a phased array. The SWIFT radios are software defined radios, and they have the ability to vary their frequencies to account for doppler effects.

There is a lot of work from DARPA and other companies on SWIFT radios.

Tether Unlimited already as SWIFT software defined radio in cubesats

The SWIFT radios are a family of software-defined radios designed to provide high-performance communications for CubeSats and other small spacecraft. SWIFT radios are built on a modular platform, using a common baseband board combined with one or more RF frontends optimized for each application. This modular design enables frequency and bandwidth flexibility. SWIFT modules are compatible with Type-1 encryption modules such as the KI-55 and GNOME, and can support AES-256 encryption natively. Their form factor is compatible with common CubeSat bus platforms. SWIFT radios have successfully passed exhaustive compatibility testing with multiple ground stations.

The SWIFT SDR family includes transmitter and receiver solutions covering a wide range of frequencies, including:

SWIFT-SLX: S-band SGLS/USB/ISM Transmitter
SWIFT-XTS: 100 Mbps X-Band Downlink + SGLS/USB/ISM Transceiver
SWIFT-KTX: K-Band transmitter
SWIFT-UTX: UHF SATCOM and Wideband TT&C

All SWIFT software defined radios share a common link-layer software architecture called SWIFT-LINK. SWIFT-LINK provides abstracted and frequency-agnostic multi-network, multi-channel, full-duplex communications support.

The SWIFT™ platform combines commercial components with intelligent design and fabrication processes to provide CubeSat and small satellite builders with high performance, reliable radio solutions. A high-density FPGA, significant onboard memory, precise clock synthesis, and high bandwidth analog converters enable SWIFT radios to be compatible with nearly any RF communications waveform.

This high-performance modular hardware and software architecture has the following key features:
• Small form factor ranging from 0.25U to 1U depending upon product
• Designed for over 1 year LEO orbital lifetimes
* Versatile Structural Radiation Shielding (VSRS™) provides radiation protection for operations in GEO and beyond Earth’s orbit
• Application and frequency-band specific RF frontends are optimized for sensitivity, power consumption, and throughput
* Current designs support up to 100 MHz instantaneous transmit and receive bandwidth

TUI is developing a wide-band receiver to enable CubeSats to receive signals across a very wide range of frequencies. First generation SWIFT-WRX units will receive signals across the range of 50 MHz – 7 GHz. TUI intends in the future to expand this range to 50 MHz-19 GHz.

Availability: EM’s delivered, for FM please call

Tethers Unlimited work is one of four projects out of 150+ NASA Innovative Advanced Concept projects that were highlighted in a NASA technology review.

Rob Hoyt of Tethers Unlimited presented “In-Space Recycling and Manufacturing” at the Future In-Space Operations (FISO) Working Group Presentations. The FISO (Future In-Space Operations) Telecon Series hosts the presentations. As of August 2015, Dan Dumbacher, former Deputy AA of HEOMD at NASA HQ and Director of the Engineering Directorate at MSFC, as well as a leader in major NASA programs, now on the faculty of Purdue University, has joined as a FISO telecon co-chair. This is not a NASA telecon.

They are working on a platform of several satellites in geosynchronous and other orbits. They would all share electricity, data and other services. This would improve the profitability of the satellites.

Large Satellite construction

They are also working on the construction of large antennas in orbit. The would be able to provide 12 gigabit per second internet from geosynchronous orbit. There is a 2017 patent for the Orbweaver system for building large antennas in orbit.

June 2017, Firmamentum, a division of Tethers Unlimited got a contract from DARPA to develop a system that would use in-space manufacturing and robotic assembly to construct on orbit a small satellite able to provide high-bandwidth satellite communications (SATCOM) services to mobile receivers on the ground. Under the OrbWeaver Direct-to-Phase-II Small Business Innovation Research (SBIR) effort, Firmamentum aims to combine its technologies for in-space recycling, in-space manufacturing, and robotic assembly to create a system that could launch as a secondary payload on an Evolved Expendable Launch Vehicle (EELV).

This system would recycle a structural element of that rocket, known as an EELV Secondary Payload Adapter (ESPA) ring, by converting the ring’s aluminum material into a very large, high-precision antenna reflector. The OrbWeaver™ payload would then attach this large antenna to an array of TUI’s SWIFT® software defined radios launched with the OrbWeaver payload to create a small satellite capable of delivering up to 12 gigabits per second of data to K-band very small aperture terminals (VSAT) on the ground.

They are creating an open interface standard for satellites to be plugged into a common platform.

If the platforms were plugged in with multiple large antenna satellites, they could provide internet to large areas of the earth. 27 of them would be able to provide internet everywhere over the earth to smartphones.

All of the technological innovations could be proven within seven years so that funding could be raised to build the direct internet satellite to smartphone global communication grid.