RF Terminology » Satellite Communication » Iridium vs Globalstar vs ICO Satellite Constellations: A Comparison
Iridium vs Globalstar vs ICO Satellite Constellations: A Comparison
satellite communication
iridium
globalstar
ico
satellite system
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This article outlines the differences between Iridium, Globalstar, and ICO satellite constellations.
Comparison Table
| Specification | Iridium | Globalstar | ICO |
|---|---|---|---|
| Number of Satellites | 72 | 52 | 12 |
| Altitude (km) | 780 | 1,414 | 10,390 |
| Elevation (min.) | 8 degrees | 20 degrees | 20 degrees |
| Uplink Frequency (GHz) | 29.2 | 6.9 | 7 |
| Downlink Frequency (GHz) | 19.5 | 5.1 | 5.2 |
| Inter-satellite Frequency (GHz) | 23.3 | - | - |
| Mobile Station Frequency (GHz) | 1.6 | 2.5 | 2 |
| Bit Rate (Kbps) | 2.4 | 9.6 | 4.8 |
| Coverage | Global | +/-70° Latitude | Global |
| Access Technique | FDMA/TDMA | CDMA | FDMA/TDMA |
| Number of Channels | 4000 | 2700 | 4500 |
| Lifetime (Years) | 5.8 | 7.5 | 12 |
Key Differences Explained
The table highlights several key differences between these satellite systems.
- Number of Satellites: Iridium uses a larger constellation (72 satellites) than Globalstar (52) or ICO (12). This impacts coverage and redundancy.
- Altitude: Iridium operates at a lower altitude (780 km) compared to Globalstar (1,414 km) and ICO (10,390 km). Lower altitude generally means lower latency but requires more satellites for global coverage.
- Coverage: While Iridium and ICO offer global coverage, Globalstar’s coverage is limited to +/-70 degrees latitude.
- Frequency Bands: Each system uses different frequency bands for uplink, downlink, and mobile station communication. Iridium uniquely employs inter-satellite links.
- Access Technique: Iridium and ICO use FDMA/TDMA, while Globalstar uses CDMA.
- Bit Rate: Globalstar provides a higher bit rate (9.6 Kbps) compared to Iridium (2.4 Kbps) and ICO (4.8 Kbps).
- Lifetime: The expected lifespan of the satellites differs significantly between the systems.
