1. Marcus Vilaça Manager, Systems Engineering Advanced Systems Division
USING THE NEW L BAND MSS ALLOCATIONS - Study Group 8 Seminar on Tomorrow’s Technological Innovations Geneva, 9 September 2004
Marcus Vilaça
Manager, Systems Engineering
Advanced Systems Division

2. Inmarsat Background
Established in 1979 as an international co-operative
Privatised in April 1999
Owns and operates 9 satellites : 4 x Inmarsat 2
5 x Inmarsat 3
Contract for 3 x Inmarsat 4 satellites signed in May 2000
Firmly established in maritime, aeronautical and land markets
Customer base of over 320,000 users
Current services include messaging, voice and data
Global presence & network of suppliers of services and equipment
GMDSS

3. Inmarsat 1st Generation Space Segment
Marecs Marisat
33 dBW EIRP dBW EIRP
2 x 5 MHz bandwidth x 5 MHz bandwidth
580 kg dry mass kg dry mass
13.5 m solar array m (w) x 3.8 m (h)
Launch : A – 20/12/81 (22/08/96) Launch : 1 – 19/02/76
B – 09/09/82 (F) – 10/06/76
B2 – 10/11/84 (23/01/02) – 14/10/76

4. Inmarsat 2 39 dBW EIRP 2 x 20 MHz Processed Bandwidth 700kg Dry Mass
14.5 m Solar Array Span
Launch: F1 – 30/10/90
F2 – 08/03/91
F3 – 16/12/91
F4 – 15/04/92

5. Inmarsat 3 49 dBW EIRP 2 x 60 MHz Processed Bandwidth 1000kg Dry Mass
20.5 m Solar Array Span
Launch: F1 – 03/04/96
F2 – 06/09/96
F3 – 18/12/96
F4 – 03/06/97
F5 – 04/02/98

6. Inmarsat 4 67 dBW EIRP 10 dB/K G/T 2 x 126 MHz Processed Bandwidth
9 m deployable reflector
3000 kg Dry Mass
6000 kg Launch Mass
12 kW spacecraft power
10 kW payload power
48 m Solar Array Span
Astrium’s Eurostar 3000 bus
Major Subcontractors
TRW Astro
EMS
Alcatel
Boeing
Launch : F1 – February 2005
F2 – July 2005

7. Inmarsat 4 Characteristics
Frequency Bands
Mobile L Band and Feeder C band
Transponders
Transparent bent-pipe, C/L, L/C, L/L, C/C & Navigational
Digital Channeliser/Beamformer
630 x 200 kHz channels, dynamically allocated to beams
256 beams
Mobile Link (RHCP, digital beam former)
228 narrow spot beams for BGAN service (1.1 degree grid)
19 wide spot beams for E&E service (4.05 degree grid)
1 global beam
Feeder Link (RHCP & LHCP)
1 global beam, dual polarisation

8. Inmarsat 4 Coverage

9. The MSS L Band Extension

10. Amethyst Programme Part of the ESA’s Artes 3 Line 4 study programme
Feasibility study focused on the changes required to the I4 payload design, to enable utilisation of the L band extension
Study lead by Astrium, supported by Inmarsat
Scenario 1 : Modification of I4 flight model 3 (“FM3”)
1A - Minimum Changes
1B - New DSP
Scenario 2 : Procurement a fourth spacecraft (“FM4”)
2A - New DSP
2B - Enhanced SSPA’s
Main Outputs: Design Solutions, ROM Cost & Development Plan

11. I4 Payload Block Diagram

12. I4 Frequency Plan

13. Baseline I4 L Band Pre-processor & DSP

14. Scenario 1 - L Band Pre-processor & DSP Changes

15. Scenario 1 – Other Equipment Changes
L Band Feed
New diplexers
Feed element retuning
ONet’s
New output filters

16. Scenario 2 - L Band Pre-processor & DSP Changes

17. Scenario 2 – Other Equipment Changes
L Band Feed
New diplexers
Feed element retuning
ONet’s
New output filters
New SSPA’s
Increased output power

18. Summary of Spectrum Issues

19. Planned Spectrum Activities
Studies into the use of the new bands and related sharing studies
Participation in the work being carried out by WP8D.
Regulatory study of the new bands
Assess the use of the new bands by existing terrestrial services, and the possibility of utilization of those bands for the provision of MSS in various countries, concentrating in Region 1 and Region 3.
Satellite antenna discrimination
Analyse the impact of PFD limits on the service coverage area by taking into account satellite antenna discrimination performance.

20. Conclusion
The MSS L Band extensions offer a great opportunity to significantly increase the capacity of MSS satellites.
The modifications required to the baseline Inmarsat 4 satellites to allow service provision in the new bands are significant, but can be kept within limits that allow reduced risk and lower cost and schedule impact.
A comprehensive study on the utilisation of the extended L band by existing services will be carried out, to provide an accurate picture of the current situation and of any possible constraints.