RANET: Understanding the scheduling system, directory structure, and data formats of the WorldSpace

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RANET Understanding the scheduling system,
directory structure, and data formats of the
WorldSpace ModuleBMG and RANET Training
Course on Tsunami Dissemination SystemsThe BMG
5-in-1 Client and RANET WorldSpace
ModuleJakarta, IndonesiaMarch 20-22, 2007
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Quick Review

• WorldSpace satellites are a wide area broadcast
  covering continental scale areas.
• The satellites can broadcast both audio and data
  channels, but RANET currently only utilizes the
  data capacity on ALC DATA and FVI DATA.
• The signal is digital what does that mean?
  What formats capable of being carried on the
  broadcast?

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Basic Broadcast Format

• In essence RANET (as do other content providers
  on First Voice Intl data channel) broadcasts a
  website that is stored on the users hard drive.
  
• The broadcast is downloaded to the following
  directory on the computer
• file///C/Program Files/WorldSpace/TSDAB/Content/

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Where do the warnings arrive?

• Root download directory
• file///C/Program Files/WorldSpace/TSDAB/Content/
  
• Warning file directory
• /warning/
• Therefore full path is
• file///C/Program Files/WorldSpace/TSDAB/Content/
  warning/

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BMG 5-in-1 trigger?

• BMG 5-in-1 monitors the warning directory for new
  files
• file///C/Program Files/WorldSpace/TSDAB/Content/
  warning/
• New files are copied to the BMG 5-in-1 directory
  structure, which then trigger other monitoring
  scripts and processes.

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How much data and how fast?

• ALC DATA and FVI DATA are 64kbps channels.
• 64 kbps 64 kilobits per second
• 8 kb 1 KB (kilobyte)
• So 64 kbps / 8 kb 8 KBps
• 8 KBps x 60 seconds 480 KB per minute
• 480 KB per minute x 60 28.8 MB per hour
• What is the implication of sending a file that is
  large?
• What is the effect of sending a 300KB image file
  with a tsunami warning?

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FVI DATA Channel Scheduler and the Warning
Interrupt

• The FVI data channels (64KBps) operate on a 15
  minutes schedule. XX00 XX15XX15
  XX30XX30 XX45XX45 XX00
• The scheduler sends files for uplink at the
  beginning of each quarter. The actual schedule
  of files to be broadcast is sent 5 minutes before
  each broadcast quarter.
• If FVI DATA operates on a 15 minute schedule,
  then how does a tsunami warning receive priority?

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FVI DATA Channel Scheduler and the Warning
Interrupt

• Content in a broadcast quarter (e.g. XX00
  XX15) files are broadcast in ABC order (for the
  most part) and queued.
• So if you are receiving file A, then file B Z
  are queued for broadcast.
• The warning system deletes files B Z, and then
  inserts the warnings in the queue.
• So the broadcast order becomes A, Warn1, Warn2,
  Warn3, Warn 4, Warn 5. (Note Warning messages
  repeated 5 times.)
• Note A file that is actively broadcasting
  cannot be deleted from the queue, so most of the
  delay in receiving a message is waiting for the
  current file to finish broadcasting. RANET,
  working with FVI, has changed the system, such
  that files sizes are kept to an absolute minimum
  about of time. (Bandwidth time for the
  broadcast.)