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

This article outlines the differences between Iridium, Globalstar, and ICO satellite constellations.

Comparison Table

SpecificationIridiumGlobalstarICO
Number of Satellites725212
Altitude (km)7801,41410,390
Elevation (min.)8 degrees20 degrees20 degrees
Uplink Frequency (GHz)29.26.97
Downlink Frequency (GHz)19.55.15.2
Inter-satellite Frequency (GHz)23.3--
Mobile Station Frequency (GHz)1.62.52
Bit Rate (Kbps)2.49.64.8
CoverageGlobal+/-70° LatitudeGlobal
Access TechniqueFDMA/TDMACDMAFDMA/TDMA
Number of Channels400027004500
Lifetime (Years)5.87.512

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.