Background Report 1394b:Optoelectronic Data Communications

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Background Report1394bOptoelectronic Data
Communications

• ECE 4006C
• Tiffany Lovett
• Tornya Moore
• Mareisha Winters
• January 31, 2002

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Key features of 1394?

• It is a hardware and software standard for
  transporting data at 100, 200, or 400 Mbps
• It is a digital interface - no need to convert
  digital data into analog
• It is physically small and can replace larger,
  more expensive interfaces
• It is easy to use

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Key features of 1394?

• It is hot pluggable - users can add or remove
  1394 devices while the bus is active
• It is inexpensive
• It is a scaleable architecture - can mix 100,
  200, and 400 Mbps devices on a bus
• It has a flexible topology
• It is non-proprietary - there is no licensing
  problem to use for products.

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1394 Cable

• Is a small, thin serial cable
• Contains six wires two of the wires carry power
  the remaining four wires are grouped into two
  twisted signal pairs

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How 1394 Works

• Supports both asynchronous and isochronous data
  transfers
• 1394 device requests control of the physical
  layer
• Asynchronous The address if the sender
  receiver is transmitted by the packet data. Once
  the receiver accepts the packet, an
  acknowledgement is returned to the original
  sender
• Isochronous The sender requests an isochronous
  channel with a specific bandwidth. Isochronous
  channel IDs are transmitted followed by the
  packet data. The receiver monitors the incoming
  datas channel ID

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Why 1394b?

• 1394b is a revision of the initial 1394 standard
• 1394b is twice the speed, and allows for longer
  distances
• It provides new connection options such as
  Plastic Optical Fiber, Glass Optical Fiber and
  UTP-S. Previously 1394 could only be connected
  via copper cabling
• 1394b is a prime choice for connecting personal
  computers with digital devices (i.e. cameras, DVD
  players, and camcorders)

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Photodetectors

• Optoelectronic device that senses and measures
  the output of a typical light source
• There are three steps in the photodetection
  process
• (1) absorption of optical energy and
  generation of carriers
• (2) transportation of the photogenerated
  carriers across the
• absorption region
• (3) carrier collection and generation of a
  photocurrent
• The three main types are photoconductors, PIN
  photodiode, and Avalanche photodiodes
• For high-speed applications the PIN photodiode is
  the best choice because it has no internal gain
  and can attain very large bandwidths.

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Emitters

• Three types are LEDs, Edge emitting lasers, and
  VSCELs
• LEDs produce light by a process known as
  spontaneous emission, resulting in incoherent
  light
• Lasers produce light by stimulated emission,
  which results in coherent light
• For high-speed applications VCSELs are superior
  to LEDs and Edge emitting lasers because they
  achieve high data rates easier and they are less
  expensive

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Project Goals

• Investigate and purchase of PIN photodiodes and
  VSCELs available that meet the 1394b
  specifications
• Implement optoelectronic portion of the 1394b
  test bed with evaluation boards
• Verify functionality of PIN photodiodes and
  VSCELs as receivers and transmitters for 1394b
• Implement own version of 1394b test bed and
  verify functionality