Balloon Communications

1
Balloon Communications

• Kevin Shoemaker
• Shoemaker Labs, Inc.
• Shoemakerlabs_at_gmail.com
• LCANS09

2
Communication Options

• VHF/UHF Line of Sight
• Shortwave Digital Modes
• Meteor Scatter
• Satellite Orbcomm, Inmarsat, Hamsat, GEO
• APRS
• Store and Forward

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Radio Horizon
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Path Loss
PathLoss?dB?C??20log?FR?-G1-G2? where, F
Frequency in MHz R Range in units defined by C
G1 Gain in dB of antenna 1 G2 Gain in dB of
antenna 2 C 32.45 for Kilometers 37.80 for
Nautical Miles 36.58 for Statute Miles -27.55
for Meters -37.87 for Feet
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Bandwidth Requirements

• Noise Energy kTB
• Telemetry (Khz)
• Video (MHz)
• Compression helps
• Conversion Gain

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Short Wave Propagation

• Diurnal Changes
• Frequency Selection Important
• Digital Modes mitigate fading
• Worldwide coverage

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Meteor Scatter

• 30 to 50 MHz operation
• Best 4-9 A.M.
• Low Power
• .5 Second windows max
• Medium Data Rate Packets

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Inmarsat

• 82 to -82 Degrees Latitude Coverage
• L Band
• 2.4 to 64 KBit Data Rates

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Inmarsat Equipment

• L Band Operation
• 82 to -82 Global Coverage
• Voice and Data
• Reasonably Priced

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Iridium

• 66 LEO Satellites
• Significant Military Usage
• Initially financed by Motorola
• TCP/IP Supported

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Iridium Equipment

• L Band operation (1610-1626 MHz, 1530-1559 MHz)
• Global Coverage
• Voice and Data
• Internet and e-mail capable

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Automatic Packet Reporting System

• Global Coverage
• Low Data Rates
• Low Cost
• ISS Installation
• Multiple AMSAT Operation

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APRS Balloons
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APRS 3D views for Balloon tracking
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APRS in Space

• 2001 PCSAT-1 Prototype Comms.
• 2006 PCSAT2 on ISS
• 2007 ANDE
• 2008 RAFT

• APRS space frequency is published as 145.825

See live downlink on http//pcsat.aprs.org
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Antenna Requirements

• VHF/UHF/Orbcomm Monopoles, Omni patterns
• Inmarsat Azimuth Tracking
• Iridium - Omni
• GEO Alt/Az Tracking
• APRS Omni
• Shortwave - Omni

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Cost vs. Bandwidth

• Generally speaking, the higher the bandwidth, the
  higher the cost and complexity.
• Video rates generally require motion control for
  long distances
• Lower data rates simpler and lend themselves to
  efficient coding schemes, cheaper as a result
• Lower data rates propagate further