The Comm Uplink

by Web FishJan 1, 2013 @ 02:01pm

The only link between PilotFish and the rest of the (civilized) world. Provides a one-way channel for reporting position, status and other select telemetry.  

  • Current selection: Iridium 9602-I & SBD service
  • Status: Finalized

  • Criteria: Reliable coverage across the passage area, overall cost, standard I/O, manage-able power footprint, easy programmability/debugging, small physical footprint 
  • Finalists: Iridium 9602, Iridium 9603, SPOT Satellite Personal Tracker
  • Main decision factors: Universal coverage, cost (compared with the other Iridium terminals)

 (click image for larger view) 

Spec summary:

  • Frequency Range 1616 MHz to 1626.5 MHz
  • Multiplexing Method TDMA/FDMA
  • Idle current (peak) 195mA
  • Transmit Current (peak) 1.5A
  • Receive Current (peak) 195mA
  • SBD message transfer – average current 190mA
  • SBD message transfer – average power 1.0W

 

Caveats:

  • Iridium service cost is magnitudes higher than all systems based on the Low Earth Orbit satellite constellation. Unfortunately, LEO solutions do not have sufficient coverage over the North Pacific. On the flip-side, using a full-featured data modem allows us to customize the contents of the data message and provide additional telemetry to mission control;
  • Power draw upon transmission can be in the 2A+ - need to ensure navionics power pack can provide sufficient surge power (with or without solar boost)
  • Still need to determine the right antenna and antenna positioning

 

Comments (2) -

Brian Dunning
Brian DunningUnited States
1/1/2013 2:54:40 PM #

I can help you narrow down one option: I took our SPOT to Hawaii for fun and we never got a message from it. Their coverage only gets you a bit more than halfway from CA to HI.

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Chris D
Chris DUnited States
1/4/2013 10:54:13 AM #

Yes, I believe SPOT uses the Globalstar LEO constellation. There is a low-res coverage map here: http://www.globalstar.com/en/index.php?cid=106. We've chosen the wrong ocean... Smile

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