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Iridium: low power satellite communications for autonomous instruments. David Meldrum Scottish Association for Marine Science. General considerations Iridium overview SAMS experience with Iridium Future plans. General considerations. Bandwidth Timeliness Availability Polar coverage
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Iridium: low power satellite communications for autonomous instruments David Meldrum Scottish Association for Marine Science SOT Geneva 2007
General considerations • Iridium overview • SAMS experience with Iridium • Future plans SOT Geneva 2007
General considerations • Bandwidth • Timeliness • Availability • Polar coverage • Temperature spec • Cost • Energy • Cash • Physical size • Reliability • Future • Technical support SOT Geneva 2007
A common misbelief when things don’t work as they should… • ‘The system operators know about it and are doing something to fix it’ • WRONG on both counts! • The system wasn’t designed with your application in mind • You are a very minor user • You are a pain in the neck SOT Geneva 2007
Satcom systems available globally to platform operators SOT Geneva 2007
Low Earth Orbit and Geostationary Earth OrbitField of View for LEO (Iridium) and GEO (Inmarsat) SOT Geneva 2007
Typical LEO polar orbit SOT Geneva 2007
Satcom systems available globally to platform operators SOT Geneva 2007
Satcom systems available to POLAR platform operators • Argos: 6 sats, 400 bits/s (will increase) • Iridium: 66 sats, 2400 bits/s (will increase) SOT Geneva 2007
Iridium overview • Designed as a phone system: 2-way, real-time • 24/7 availability, true global coverage • 66 satellites • Inter-satellite links pass traffic to ground station • Basic data rate 2.4kbps • Various modes of access • Dial-up (better for larger file sizes) • Short Burst Data, SBD (up to 2 kbyte per message) • Future ‘near broadband’ service , ~100kbps • Platform location • GPS • Km-scale accuracy Iridium location in SBD SOT Geneva 2007
Iridium constellation SOT Geneva 2007
Iridium overview SOT Geneva 2007
Dial-up: on-line session with mobile SOT Geneva 2007
Transfer times for 37kbyte file Mode -> 3100 bps >4000 messages SOT Geneva 2007
Short Burst Data Pathways MODEM IRIDIUM NETWORK +SBDWB TX Buffer SENSOR +SBDI RX Buffer +SBDRB INTERNET Data@SBD.Iridium.com USER Iridium@sams.ac.uk • Simple AT commands SOT Geneva 2007
Example e-mail received by user (MO message) From: <Iridium SBD Service (Tempe, AZ)> Sent: Tue, 23 Sep 2003 22:02:24 Subject: SBD Msg From Unit: 300090807080903 MOMSN:152 MTMSN:0 Session Status: TRANSFER OK Message Size (bytes): 1960 Unit Location: Lat = 56.457321 Long = -5.458788 CEPradius = 2 Message is attached. SOT Geneva 2007
SBD Delivery Latency seconds SOT Geneva 2007
Iridium traffic SOT Geneva 2007
Current constellation SOT Geneva 2007
Replenishment plans ... Calendar Year 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Requirements and Supplier Selection Satellite R&D Satellite Qualification Satellite PDR Deploy & Launch Satellites ... 1st Launch 2 Satellites SOT Geneva 2007
Iridium ballpark costs • Dial-up + SBD modem: $1000 • SBD-only modem: $400 • Monthly fee: $14 - $30 • Call costs: ~$1 per minute • $0.1 per kbyte for files > few kbyte • Data costs: ~$1.50 per kbyte SOT Geneva 2007
dalriada.nsm.ac.uk/php SOT Geneva 2007
Temperature record SOT Geneva 2007
New suitcase buoys: GPS only SOT Geneva 2007
9601 (‘Taladega’) SBD modem SOT Geneva 2007
SAMS future plans:Solar powered Iridium drifters • Transparent hulls from Technocean • Solar panel equatorial plane • SVPB sensor fit • Li-ion batteries • Iridium 9601 + GPS • Extensive diagnostics • Participation in DBCP Iridium pilot programme…. SOT Geneva 2007
DBCP future plans • Iridium Pilot Project (Iridium-PP) • Practical evaluation in realistic conditions • Small platforms • Wide partnership • Support (cash and in-kind) by Iridium, manufacturers and DBCP • Open membership SOT Geneva 2007
Iridium-PP mailing list SOT Geneva 2007