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Do LightSquared and the FCC Threaten GPS

Presumed transcript of a radio conversation between a US naval ship and Canadian authorities (CND) off the coast of Newfoundland. US Ship: Please divert your course 0.5 degrees to the south to avoid a collision. CND reply: Recommend you divert your course 15 degrees to the South to avoid a collisi

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Do LightSquared and the FCC Threaten GPS

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Presentation Transcript

    1. Do LightSquared and the FCC Threaten GPS? Tom Stansell Stansell Consulting Tom@Stansell.com

    2. The Lighthouse Story

    7. How Can ATC Signals Affect GPS? LightSquared plans 40,000 high power transmitters Desensitization by overdriving RF amplifiers Gain compression of RF/IF amplifiers with strong signals Depends somewhat on number of signal sampling levels AGC performance also can be adversely affected Creating third order intermodulation products In nonlinear GPS RF/IF due to strong input signals Major threat to StarFire and OmniSTAR Correction messages from Inmarsat in the MSS Band

    8. LTE Signal Characteristics Base station requires a linear amplifier Uses 4.5 MHz out of any 5 MHz band Carrier spacing is 15 kHz, which is the data rate Orthogonal Frequency Division Multiplexing (OFDM) In a 10 MHz band, 600 subcarriers Filling 600 x 0.015 = 9 MHz

    9. NTIA Frequency Allocation Chart

    10. MSS and GNSS Allocations

    11. FCC Table of Allocations

    12. Page 31 of FCC Table of Allocations

    13. LightSquared Signal Characteristics

    14. Transmitter Bandpass Filters

    15. Free Space Propagation Loss

    16. Potential 3rd Order Intermod Products

    18. The LightSquared Dilemma

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