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Use of L-Band frequencies for Direct Readout services

This article discusses the allocation and potential reallocation of L-band frequencies for direct readout services in satellite meteorology, highlighting the importance of real-time access to polar-orbiting satellites for weather applications and emergency support missions. It also addresses the impact of potential interference and the need for mitigation measures to ensure the usability of LEO satellite systems worldwide.

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Use of L-Band frequencies for Direct Readout services

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  1. Use of L-Band frequencies for Direct Readout services Jérôme Lafeuille WMO Space Programme Geneva

  2. International Telecommunications Union (ITU) allocated L-band to METAIDS and METSAT (Space to Earth) on a co-primary basis • WMO : UN authoritative voice on atmosphere, climate and related environmental issues • WMO has mission to lead cooperation on weather & climate observation networks, standardization, data exchange … NOAA 2011 Satellite Direct Readout Conference

  3. First APT reception from Tiros-8 in Lannion, France, 24 Dec 1963 NOAA 2011 Satellite Direct Readout Conference

  4. Direct Readout: a success story • Since 47 years, Direct Readout services have been the foundation of global cooperation in satellite meteorology • There is no affordable substitute to Direct Readout to access data from polar-orbiting satellites in real time • Real time access is essential for weather applications and other emergency support missions NOAA 2011 Satellite Direct Readout Conference

  5. Use of 1675-1710 MHz NOAA 2011 Satellite Direct Readout Conference

  6. 18 H 00 H N 12 H 06 H NOAA 2011 Satellite Direct Readout Conference

  7. CGMS baseline configuration DWSS 18 H FY-3B, 3D, 3F NOAA-18, 19, NPP, JPSS-1, -2 00 H 12 H FY-3A, 3C, 3E, 3G Metop-A, B, C 06 H NOAA 2011 Satellite Direct Readout Conference

  8. Potential reallocation of 1695-1710 MHz Impact on polar-orbiting Direct Readout services • All operational LEO systems (except NPP) use L-band and plan to use it throughout the decade • In addition to « NOAA administered » satellite series the CGMS baseline includes: • Metop series • FY-3 am series • FY-3 pm series • DWSS (TBC, proposed for inclusion) • All are important to provide the required measurements with the necessary robustness NOAA 2011 Satellite Direct Readout Conference

  9. Exclusion zones around 18 user sitesWhat about the other 150+ users ? NOAA 2011 Satellite Direct Readout Conference

  10. Potential reallocation of 1695-1710 MHz Discussion of mitigation measures • Assuming that the exclusion zones can guarantee reception at federal sites …… users, outside of exclusion zones, would be exposed to severe interference preventing operational use • Assuming retransmission of « NOAA administered» satellite data, would Metop, FY3 AM and PM data be included ? • Assuming that they are, such retransmission would anyway not provide real-time • Rebroadcast would entail the use of other part of the spectrum • Not subject to weather conditions, or to interference NOAA 2011 Satellite Direct Readout Conference

  11. Potential reallocation of 1695-1710 MHz Conclusions (1) at the national level • Threat for users of polar-orbit Direct Readout services over the USA • Proposed mitigation measures unlikely to solve the issue • Benefit to society ? NOAA 2011 Satellite Direct Readout Conference

  12. Potential reallocation of 1695-1710 MHz Conclusions (2) International perspective • Detrimental to global standardization effort • Risk of propagation to other countries • Would affect the usability of LEO satellite systems worldwide, and the ability of the global meteorological community to serve the society • Impact on radiosondes to be considered as well NOAA 2011 Satellite Direct Readout Conference

  13. Potential reallocation of 1695-1710 MHz Conclusions (3) International perspective • GEO Task: AR-06-11: Radio Frequency Protection • “Recognizing the fundamental importance of radio-frequencies necessary for all GEOSS components, in particular in-situ, ground- and space-based observations, as well as the increasing economical and political pressure on corresponding parts of the spectrum, undertake appropriate coordinated advocacy activities in association with Member countries, including representations to the International Telecommunication Union (ITU) and other bodies in charge of frequency management…” NOAA 2011 Satellite Direct Readout Conference

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