A Global Satellite Communications Network with GNURadio
Dan CaJacob
SpaceQuest, Ltd.
2014 GNURadio Conference September 17, 2014 Outline
1. Introduction 2. AIS Overview 3. Spacecraft 4. Ground Stations 5. Operations 6. Demonstration 7. Conclusion
2 About SpaceQuest
● Founded in 1994
● Building small spacecraft for commercial, government, international and university customers
● Fixed-price modified COTS and custom spacecraft components
● 10 employees – We're Hiring!
● Located in Fairfax, VA 3 Recent Notable Projects
● 2005 – 2007: Bigelow Aerospace Inflatable Space Station Demonstrators – Built 3 spacecraft – Launched 2 ● AIS microsat constellation – Launched 8 satellites since 2009 – About 2 satellites every 2 years – Primary focus of this talk
4 AIS Overview
● “Automatic Identification System”
● Internationally mandated system
● Class A – All ships >= 300 GT ● Class B – Personal watercraft AIS GPS – Not mandatory Transceiver Receiver ● VHF: 161.975 / 162.025 MHz
● Self Organizing Time Division Multiplex Access (SOTDMA)
● Intended for line-of-sight Chart communications Plotter ● Low power – up to 12 W 5 AIS Overview
AIS Base Station
6 AIS Mission
1 1. Receive AIS packets from orbit 2. Download the packets 2 3. Distribute the data to interested parties 4. Derive analytical insights
Customer 3
Customer SQ
7 Customer AIS History
Early Experiments Commercial Constellation 2007 2009 – SQ launches microsat with AIS Bent Pipe – Launch 2 AIS microsats (AS3 & AS4) and On Board Processing (OBP) capability 2011 – SQ demonstrates decoding of AIS – And another 2... (AS5 & AS6) spectrum collected from the microsat 2013 ● Previously thought to be impossible – And 2 more... (AS7 & AS8) due to packet collisions 2008 2014 – First introduction to GNURadio & Ettus by – You get the picture (AS9 & AS10) AMRAD, Maitland Bottoms and Ed – 6 months after the 2013 launch! Criscuolo. Thanks!
8 System Overview
● Network – Satellites – Ground Stations
9 System: Ground Stations
● TT&C ● Payload Data – Directional – S-Band RX Only ● VHF / UHF Full Duplex – VHF / S-Band Full ● UHF / UHF Half Duplex Duplex – Omni-directional
10 System: Spacecraft
● Size – Approximately 10 x 10 x 10 in – 15 kg / 33 lbs – Designed to be hand-carried on commercial aircraft ● Orbit – Sun-synchronous Low Earth Orbit ● Full Earth coverage 2x per day ● Commonly used by imaging satellites ● Launch – Dnepr / SS-18 – Converted Soviet Intercontinental Ballistic Missile (ICBM) ● Largest in the world
12 System: Spacecraft
● Size – Approximately 10 x 10 x 10 in – 15 kg / 33 lbs – Designed to be hand-carried on commercial aircraft ● Orbit – Sun-synchronous Low Earth Orbit ● Full Earth coverage 2x per day ● Commonly used by imaging satellites ● Launch – Dnepr / SS-18 – Converted Soviet Intercontinental Ballistic Missile (ICBM) ● Largest in the world
14 System: Spacecraft
● Power
● Thermal
● C&DH
● Communications
● Attitude Control
● Payload
16 System: Spacecraft: Communications
● Communications – VHF TT&C RX (primary) ● 9600 baud – Dual Redundant TT&C UHF RX (Secondary) ● 9600 baud – Dual Redundant UHF TT&C TRXs ● 9.6 – 56.6 kbps – Dual Redundant S-Band TXs ● Up to 1 Mbps – S-Band RX ● 9.6 – 115.2 kbps – Experimental SDR ● Multi-waveform ● Multi-baud 20 Communications
) + s p b M Payload V Telemetry, Tracking 1 H – U H F s ) T Operations p s F T & Command b p T & k b T C 4 k & 6 V C U (TT&C) ( .2 H p k 5 F D l n 1 ) o in li 1 s H w k n p a n ( – b lf l 9 w 6 0 -D in 6 o . 0 u k 0 D (9 6 p ( 0 d 9 l 9 b a k ( e .6 p in k x s lo l n T – ) y p li T a U p & 2 P 8 d U C .8 d n d L k n a a i b a B o n p B - l k s - S y (9 ) S a 6 P 0 F 0 H b p V s )
21 System: Spacecraft
VHF TT&C & AIS Antennas
22 System: Spacecraft
UHF TT&C 23 Antennas System: Spacecraft
GPS Antenna
24 System: Spacecraft
S-Band 25 Antennas System: Spacecraft: Payload
● AIS Payloads – On-Board Processing (OBP) – Bent Pipe – Linear Transponder – Record and Playback ● SDR
27 Spacecraft: OBP Payloads
Continuous Collection
AIS Data VHF Custom Payload LNA Mass RXs ASICs Computer Storage
Payload Downlink
Payload S-Band Mass Filter Amp Storage Computer TX
28 Spacecraft: Bent Pipe Payload
● Bent Pipe
IF VHF Down S-Band LNA Filter Amp RXs Converter TX
29 Spacecraft: Linear Transponder Payload
● Linear Transponder – Multiple RX Channels – Multiple TX Channels
Linear LNA Transponder VHF S-Band
30 Spacecraft: Record and Playback
● Record and Playback are performed separately
IF Audio VHF Down LNA RXs Converter
Begin End Playback Record ADC Mass ADC Storage
S-Band Filter Amp TX 31 System: Ground Stations
● TT&C ● Payload Data – Directional – S-Band RX Only ● VHF / UHF Full Duplex – VHF / S-Band Full ● UHF / UHF Half Duplex Duplex – Omni-directional
32 TT&C Ground Stations: Locations
● Fairfax VA (2)
● Concord, CA
● Cambridge, ON
● North Pole, AK (2)
● Hawaii
● Maine
● Svalbard *
● More coming online
33 * SQ Modem provided for customer Payload Ground Stations: Locations
● Own – North Pole AK ● Operate – Hawaii – Maine – Las Vegas, NV ● SQ-Provided modems in use – Svalbard – Troll Station, Antarctica – Tromso, Norway – Dubai – Saudi Arabia – Singapore – Adelaide, Australia – Cork, Ireland – Cambridge, ON 34 Ground Station Design: TT&C
● Classic (Old) – Modified ICom radios – Custom UHF Radio – PacComm or custom TNCs – Expensive, but simple glue hardware
● Common – Yaesu / AlfaSpid rotators and controller – M2 Yagis – Amateur Low Noise Amplifier (LNA)
● New – 2U, Rack-Mount Enclosure – Ettus USRP SDR – Quad-core Mini-ATX computer (Ubuntu) – GNURadio & UHD – RF Interface Board – High Power Amplifier (HPA) – Combo LNA and Band-Pass Filter (BPF) – I/O: Power, Ethernet, RF 36 Ground Station Design: TT&C
● Classic (Old) – Modified ICom radios – Custom UHF Radio – PacComm or custom TNCs – Expensive, but simple glue hardware
● Common – Yaesu / AlfaSpid rotators and controller – M2 Yagis – Amateur Low Noise Amplifier (LNA)
● New – 2U, Rack-Mount Enclosure – Ettus USRP SDR – Quad-core Mini-ATX computer (Ubuntu) – GNURadio & UHD – RF Interface Board – High Power Amplifier (HPA) – Combo LNA and Band-Pass Filter (BPF) – I/O: Power, Ethernet, RF 37 Ground Station Design: TT&C: Software
● MAC – SSGS Server SSGS – SSGS Client Server SOAP – Communications Station (new) Web-Services ● Software Modem – Implemented in GR SSL VPN – GFSK TCP/IP – Bursty – Runs on the TT&C Nodes TNC Node – Connects to SSGS via Comm- ● TCP/IP Station – Sockets Server IPC – Web-services – SSGS Message Queues FG ● POSIX (old) Client ● RabbitMQ ● ZeroMQ (future) 39 Ground Station Design: TT&C Modem
● Software Modem design Socket RX Section
Doppler FM Clock Channel Frame USRP IPC Correction Demod Recovery Decode Decode
TUN Socket TX Section
HPA Channel FM Doppler IPC Tagging USRP Control Coding Mod Correction
TUN 40 Routine filtering and re-sampling not shown for clarity Ground Station Design: Custom Blocks
● Custom Blocks – Execution Time Limit – Sinks / Sources – Packet / Frame Tagging THE FREE & OPEN SOFTWA RE RA DIO ECOSYSTEM – HPA Control – Framing
41 Ground Station Design: Custom Blocks
● Custom Blocks – Execution Time Limit – Sinks / Sources – Packet / Frame Tagging – HPA Control – Framing
42 Ground Station Design: Custom Blocks
● Custom Blocks – Execution Time Limit – Sinks / Sources – Packet / Frame Tagging – HPA Control – Framing
43 Ground Station Design: Custom Blocks
● Custom Blocks – Execution Time Limit – Sinks / Sources – Packet / Frame Tagging – HPA Control – Framing
44 Ground Station Design: Custom Blocks
● Custom Blocks – Execution Time Limit – Sinks / Sources – Packet / Frame Tagging More on this later – HPA Control – Framing
45 Ground Station Design: Custom Blocks
● Custom Blocks – Execution Time Limit – Sinks / Sources – Packet / Frame Tagging – HPA Control – Framing
46 Ground Station Design: UHF LNA + BPF
● Power – 12V on Center Conductor ● 1 dB Noise Figure
● 20 MHz Bandwidth
● Hermetically Sealed
47 Ground Station Design: TT&C: RF Interface Board
● T/R Switching control via GPIO from USRP – > 50 dB isolation
● Driver amplifier
● HPA control
● LNA power and control – Fed via center-conductor – Short-Circuit Protection
● RF filtering – RX & TX ● Diagnostics – Forward and Reflected Power – Driver amp and HPA current – LNA voltage detection – LNA and T/R Switch override ● USRP Power Control – Solid State Relay 48 Ground Station Design: TT&C: HPA
● VHF & UHF Models – Other bands possible ● Power – 25 W – Adjustable ● Unconditionally Stable
49 Ground Station Design: Payload
● 2U, Rack-Mount Enclosure
● Ettus USRP SDR
● Quad-core Mini-ATX computer – Ubuntu LTS – GNURadio – UHD ● I/O – Power – Ethernet – RF ● Typically S-Band RX Only
● Optional – RF Interface Board – High Power Amplifier (HPA)
50 Ground Station Design: Payload: Software
● S-Band RX Only – Streaming – GFSK – FEC – Speed ● Up to 1 Mbps ● Normally – 200 – 400 kbps 51 Ground Station Design: Payload
● Software modem design
USRP Linear Transponder Section (Post-Process)
Doppler File File PFB File Correction Sink Source Resampler Sink
Bent Pipe Section
FM PFB File Demod Resampler Sink
OBP Decode Section IPC FM Clock Channel Frame Demod Recovery Decode Decode TUN
52 Routine filtering and re-sampling not shown for clarity Configuration Management
● Old: Hand-managed via SSH – Manageable for a few nodes – Nightmare beyond that ● New: Ansible – Python-based – YAML recipe structure – Jinja templates – Layered definition ● Base GR + UHD configuration VPN ● Application specific recipes – TT&C (SQTNCs) – Payload (SQANTs) ● Node-specific customization Node Node Node – Like sudo apt-get install ground-station – Can deploy multiple nodes at once or even as a group 53 Operations
● TT&C – Manual ● Autonomous – TT&C and Payload ● Payload
● Advanced – rsync – SSH ● Ground testing 54 Manual Operations
● SSGS Client – accessible anywhere with an internet connection ● Java JNLP application – Commands – File Operations ● Upload ● Download ● Script Deploy
55 Normal Payload Operations
● Download the latest AIS payload data
● S-Band
● UDP – Simplex downlink – HDLC framing – GFSK – Adjustable speed ● 200 – 400 kbps commonly – Adjustable FEC 56 Advanced Payload Operations
● TCP/IP – Modified Payload Software Modem ● Includes TX Section – TUN provides RAW socket access – “Tuned” for ● Lossy connection ● Asymmetric link – 9600 baud uplink – Up to 1 Mbps downlink – SSH ● Direct access to P/L computer – rsync ● Real time-acknowledged down/uploads 57 Autonomous Operations
● TT&C and Payload operations scheduled with custom software – SSGS “Skycraper” performs auto. commands, uploads and downloads during scheduled TT&C passes – Spacecraft and payload ground stations perform tasks according to payload schedules
58 Autonomous Operations: Scheduling
Scheduler Server
XML Request SSL Scheduler DB
Explicit Pass Requests Config Implicit Pass Requests
Payload Passes TT&C Passes VPN
Payload Payload Payload SSGS Node Node Node Server 59 Ground Testing Operations
● Flatsat – Flight-spare software development platform ● One GS per flatsat – Otherwise always “stepping” on each other – Flatsat GS: ● Mac mini ● 3 x Ettus B100 USRPs – WBX: TT&C – SBX: S-Band (Payload) – WBX: AIS simulator ● Isolated communications – Custom attenuator provides space-like channel and protects sensitive RXs from powerful Txs – All connections cabled ● Automated testing – Same as for flight spacecraft – AIS recordings from space played back on a loop with USRP 60 Ground Testing Operations
● Flatsat – Flight-spare software development platform ● One GS per flatsat – Otherwise always “stepping” on each other – Flatsat GS: ● Mac mini ● 3 x Ettus B100 USRPs – WBX: TT&C – SBX: Sband -50 dB – WBX: AIS simulator ● Isolated communications – Custom attenuator provides space-like channel and protects sensitive RXs from powerful Txs – All connections cabled ● Automated testing Spacecraft GSE – Same as for flight spacecraft – AIS recordings from space played back on a loop with USRP -75 dB 61 Ground Testing Operations
● Flatsat – Flight-spare software development platform ● One GS per flatsat – Otherwise always “stepping” on each other – Flatsat GS: Spacecraft GSE ● Mac mini ● 3 x Ettus B100 USRPs – WBX: TT&C – SBX: Sband – WBX: AIS simulator ● Isolated communications – Custom attenuator provides space-like channel and protects sensitive RXs from powerful Txs – All connections cabled ● Automated testing – Same as for flight spacecraft – AIS recordings from space played back on a loop with USRP 62 Ground Testing Operations
● Flatsat – Flight-spare software development platform ● One GS per flatsat – Otherwise always “stepping” on each other – Flatsat GS: Spacecraft GSE ● Mac mini ● 3 x Ettus B100 USRPs – WBX: TT&C – SBX: Sband – WBX: AIS simulator ● Isolated communications – Custom attenuator provides space-like channel and protects sensitive RXs from powerful Txs – All connections cabled ● Automated testing – Same as for flight spacecraft – AIS recordings from space played back on a loop with USRP 63 Demonstration
The infamous, ill-advised live demonstration.
64 Conclusion
GNURadio makes everything better
65 SpaceQuest Loves Open Source
THE FREE & OPEN SOFTWARE RADIO ECOSY STEM
66 Apologies to any projects we forgot Questions?
www.spacequest.com