BPO & CSBF Telemetry

2024 Laser Communications for Scientific Ballooning Workshop

Topic of Discussion

• Conventional (Line-of-Sight) Telemetry
• LOS Telemetry Transmitter (Also apply to LDB)
• Antenna Requirements
• Long Duration Balloon (LDB) Telemetry Options
• Iridium Telemetry Options
• TDRSS Telemetry Options
• Balloon Program TDRSS Utilization
• TDRSS Constellation Limitations
• Science to CSBF ROCC/OCC Interface
• Lower Antenna Requirements
• Upper Antenna Requirements
• Future of Telemetry via BPO
• Starlink & Commercial Options
• Optical Comms

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Slide 2

Conventional (LOS) Telemetry

LOS Telemetry Transmitter Options

• 15.6Mhz bandwidth digital transmitter (EVTM)
• 12Mbps UDP packet ethernet encoded data
• ≈ 1.3 A @ 28V
• CSBF can provide implementation documentation upon request
• 3 MHz bandwidth digital transmitter
• 1 Mbit bi-phase encoded data
• ≈ 1.1 A @ 28V
• 1 MHz bandwidth digital transmitter
• 330 Kbit bi-phase encoded data
• ≈ 0.5 A @ 28V
• CSBF can provide a 6 port RS232 converter with data rates up to 115,200 baud or a single port 115,200 baud RS232 converter
• Analog video transmitter
• NTSC
• ≈ 2A @28V

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• Science typically powers their own LOS transmitters
• On/Off control must be provided

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Slide 4

Antenna Requirements for Conventional Flights

• Lower
• LOS antenna hang below the gondola (minimum 1 ft)
• Standard CSBF configuration
• (2) Receiver antennas
• 1” wide X 27” long
• 24” separation (typical)
• (2) Transmitter antennas
• 5” diameter X 3” long
• 24” separation (typical)
• 36” separation from receive antennas
• (1) Air Traffic Control Transponder antenna
• 5” diameter X 3” long
• Standard Science configuration
• (1) transmit antenna for Sci TM

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• Upper
• Standard CSBF configuration
• (3) GPS antennas
• 4” diameter X 1” tall
• 24” separation from any transmitting antenna
• Mini-SIP Addition
• (1) GPS antennas
• 4” diameter X 1” tall
• 24” separation from any transmitting antenna
• (1) Iridium Cone Antenna

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Slide 5

LDB Telemetry Options

Iridium Telemetry Options for LDB Flights

• Iridium SBD (Email based)
• Always available
• Uplink commands
• Commands are checked 1/minute
• Downlink 255-byte science packet
• One packet every 1 to 15 minutes (selectable)
• Iridium Pilot – END OF LIFE
• IP based system
• Up to 134 Kbps throughput
• Typical throughput is ≈ 60 to 75Kbps (service is bursty)
• Connect to system from anywhere in the world
• Mission success cannot depend on Iridium Pilot link reliability
• 4 New SYSTEMS REMAINING

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Slide 7

TDRSS Telemetry Options for LDB Flights

• Omni Antenna (S-band)
• Science Interface: (High-Rate port)
• 6-10 kbps data
• High Gain Antenna (S-band)
• Science Interface: (High-Rate port)
• 75 kbps data
• Science Interface: (TDRSS Direct)
• 93 kbps data
• Science Interface: (EVTM via TDRSS)
• 150K (Continuous Availability)
• 150K – 1M (As Schedule Allows)
• Uplink commanding only available when requested by science
• CSBF requests 24-hour notice for TDRS commanding requirements

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• CSBF does not currently log Science TDRSS data, it will be the responsibility of the end user to log all data.

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Slide 8

Balloon Program TDRSS Utilization

• CSBF typically schedules satellite time within 24 hours of use
• This is because of the difficulty in predicting the trajectory (speed and direction) of the balloon
• Multiple Access Return (MAR)
• Primary method for Balloon Program data returns
• MA Returns through a single satellite allows for multiple satellite users to downlink data through the MA antenna array
• S-band frequencies only
• DAS version of MAR allows for the 150K continuous coverage
• Single Access Return (SAR)
• Each satellite has two steerable dish antennas, to support two Single Access Returns at one time.
• Allows for much higher data rates
• S-band, Ku-band, and Ka-band frequencies
• SAR events are typically scheduled by other projects weeks in advance, typically leaving only a couple of hours available to the balloon program per day

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Slide 9

TDRSS Constellation Limitations

Satellites available to the balloon program are clustered in three regions

• Atlantic Ocean Region
• F6 (1^st gen sat)
• MAR: 150kbps
• SAR: 1Mbps
• F12 (3^rd gen sat)
• No MAR available
• SAR: 1Mbps
• Pacific Ocean Region
• F10, F11 (2^nd, 3^rd gen sat)
• MAR: 1Mbps
• SAR: 1Mbps
• Indian Ocean Region
• F7 (1^st gen sat)
• MAR: 150kbps
• SAR: 1Mbps

Only one payload can transmit to one satellite at data rates above 150kbps

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F-7

F-10

F-11

F-6

F-12

Slide 10

Science to CSBF ROCC/OCC Interface for LDB Flights

• Two Science ports each to the LDB OCC and ROCC computers are required.
• data port at 115,200 baud (configurable)
• commanding port at 2400 baud
• Third port required for TDRSS HGA (TDRSS Direct Data – 93kbps) at OCC
• data port at 115,200
• EVTM LOS at ROCC
• Standard Ethernet port to connect to the CSBF Launch Site Mission Network
• Mission Network has internet access as well
• EVTM via TDRSS at OCC
• Standard Ethernet port to connect to the CSBF OCC Mission Network
• Mission Network has internet access as well
• Dedicated LOS transmitter (other than EVTM) will require additional interfaces at the ROCC

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Slide 11

Lower Antenna Requirements for LDB Flights

• LOS antenna hang below the gondola (minimum 1 ft)
• Standard CSBF configuration
• (2) Receiver antennas
• 1” wide X 27” long
• 24” separation (typical)
• (2) Transmitter antennas
• 5” diameter X 3” long
• 24” separation (typical)
• 36” separation from receive antennas
• (1) Air Traffic Control Transponder antenna
• 5” diameter X 3” long
• Standard Science configuration
• (1) Transmit antenna for Sci TM

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Slide 12

Upper Antenna Requirements for LDB Flights

Upper antennas need an unobstructed view of the sky; they should be the highest objects on the gondola

• Standard LDB configuration
• (3) GPS antennas
• 4” diameter X 1” tall
• (1) GPS antennas for air traffic control transponder
• 4” diameter X 1” tall
• Not used in Antarctica
• (3) Iridium antennas
• 3” diameter X 7” tall
• 2 feet separation between radiating antennas
• (1) TDRSS Omni
• 7” diameter X 12” tall (mid-latitude only)
• 7” diameter X 27” tall (Antarctic only)
• 2 feet separation between transmitting antennas
• Optional Antennas
• (1) TDRSS HGA
• 24” diameter X 16” tall
• 25 lbs
• Requires two additional GPS antennas with a minimum separation of 8’
• (1) Iridium Pilot
• 23” diameter X 8” tall
• 28 lbs
• 3 feet separation to any other antenna

Slide 13

Future of Telemetry

Commercial Providers

• Engaged with the NASA Commercial Services Project (CSP)
• “The Communication Services Project (CSP) is pioneering the future of NASA’s near-Earth space communications, evaluating commercial SATCOM networks’ feasibility to reliably support future NASA missions.”
• “Private sector innovation in near-Earth space is accelerating quickly and dramatically. Tapping those advances will ensure NASA missions have the reliable, secure and continual space communications on which their long-term operations depend. That is needed as the legacy NASA owned and operated Tracking and Data Relay Satellite (TDRS) system is decommissioned in coming years.”

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• We are also communicating with vendors and evaluating market options to supplement and replace current services that are end of life or soon to be.

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CSP: https://www1.grc.nasa.gov/space/scan/communications-services-program/

Slide 15

SpaceX Starlink

• Flown on SN08-SuperBIT
• Flown on SN09-EUSO II
• Flying on GUSTO
• Implementation will require additional configuration by CSBF to allow ease of use by science
• Requires nominal 75-90W during flight
• At startup and during firmware updates power demand can increase to 200W
• POE injector with higher power capability is required
• Speeds seen by SN08-SuperBIT
• 4Mbps – 30Mbps to ground
• Lower speeds at remote regions of ocean
• Higher speeds near larger land mass

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NASA/Bill Rodman

Slide 16

Free Space Optical Communications

• Renewed interest in optical communications and advancements in optics have brought this technology within our grasp
• The BPO is committed to demonstrating this technology from our platform in the next 2 years
• Working with NASA, other government agencies, and commercial partners

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Slide 17