1. Satellite Communications Chris Webster NSF Users Workshop 2007 NCAR - EOL

2. Reasons / Motivation Safety situational awareness Remote real-time instrument monitoring Remote real-time science Remote real-time instrument control Project coordination Troubleshooting

3. History 2002, Iridium first used on the P3 for IHOP –Small data feed including A/C track. 2003, BAMEX – P3 –Chat introduced 2005, RAINEX - P3 –Images sent to plane were requested. –We learned a lot. 2005, HIAPER – INMARSAT 2007, C-130 Upgraded to INMARSAT

4. Existing EOL Uses Driftsonde (Iridium) –Instrument Control & Data Retrieval ISFF (GOES Motosat) –Summary Data Retrieval ISS / GAUS (Motosat) –Instrument Control & Data Retrieval Aircraft (INMARSAT & Iridium) –Chat, Two-way data, Trouble Shooting

5. Driftsonde

6. Options GOESIridium –Capabilities / Limitations / Cost GlobalStar Motosat / Direcway - Consumer INMARSAT 3 –Capabilities / Limitations / Cost High Bandwidth Line of Site Options Exist Commercial KU Band / TDRSS S Band Commercial Remote Internet –Ground Dish (get photo from PASE).

7. Iridium Capabilities –True Global/Polar Coverage –2800 baud per modem. Pros –Compact –Multiple units can be ganged. NASA DC-8 gangs 8 Iridiums. Limitations –Low bandwidth –Thrashes and disconnects when too much traffic. Cost –$1,500 per unit/modem (not including installation). –7 cents per KB

8. INMARSAT 3 Capabilities –64Kbps (per modem), there are two on each aircraft. –Upcoming INMARSAT 4 4 times the bandwidth Fewer coverage holes Pros –Good bandwidth Limitations –Not Polar (~76 degrees Latitude). –Other “holes” exist in the globe. Cost –$300K per unit –5.7 cents per KB –GV, 1 second data is about $270 / hour using MPDS mode.

10. Problems Encountered Incomplete Global Coverage (some) Dropped connections and cycling connections Extraneous Traffic –Chat “away tracking” overhead –“Phone home” traffic –Microsoft automatic updates Short time-out before redialing Satellite Handoff Security (Firewall necessary)

11. Drop-outs are a fact of life Aircraft Shadow –GV tail wing shadows antenna on 10 degree bank turn (away from satellite). –C130 conformal antenna shadow flying to/from a satellite. Satellite Handoff –1 minute for INMARSAT to redial. Holes in Satellite Coverage (INMARSAT).

12. Applications Internet Relay Chat (IRC) Data Feed from aircraft –Into SQL database available to anyone for real-time ground processing/display. Generic file transfer Google Earth tracks with satellite overlays –onboard and on ground.

13. Your instrument can fly but you can’t. What do you need?

14. What do you want? Communication (chat) Current weather products up to aircraft Situational awareness (onboard and ground). Aircraft Guidance / Coordination Instrument monitoring Are there unsatisfied needs? –Instrument Control –Short transmission lag

15. Questions How can we connect with the other SATCOM communities (e.g. Marine, Polar Research, Earth Sciences, Oil, Security, Transportation, HAM)?

16. Priorities