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Rainer Grosskopf Institut für Rundfunktechnik GmbH

Propagation Considerations Overview of the activities within Task Group 6/8 BR Information Meeting on RRC-04/05. Rainer Grosskopf Institut für Rundfunktechnik GmbH. Propagation Considerations. History Recommendation ITU-R P.1546 Propagation curves for non-European areas

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Rainer Grosskopf Institut für Rundfunktechnik GmbH

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  1. Propagation ConsiderationsOverview of the activities within Task Group 6/8BR Information Meeting on RRC-04/05 Rainer Grosskopf Institut für Rundfunktechnik GmbH

  2. Propagation Considerations • History • Recommendation ITU-R P.1546 • Propagation curves for non-European areas • Requirements for terrain data • Receiving antenna height loss correction • Miscellaneous • Conclusions

  3. Introduction • It seemed to be a simple task to provide propagation information for the planning to be undertaken by the RRC 04/05 • There is just one ITU-R-Recommendation dealing with propagation for terrestrial point-to-area services in the frequency range 30 MHz to 3GHz • Recommendation ITU-R P.1546 (replacing former Recs. 370, 529, 1146) • Unfortunately the Task Group 6/8 did not fully support that idea

  4. History • The recommended point-to-area prediction method for the planning to be undertaken by the RRCis Recommendation ITU-R P.1546 - Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz • Task Group 6/8 is of the opinion that this will be a satisfactory basis for developing a plan by the Conference Chairman’s Report, Doc. 14 (Jan 2002)

  5. History • The currently recommended point-to-area prediction method for the planning to be undertaken by the RRC is Recommendation ITU-R P.1546 - Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz • Task Group 6/8 is of the opinion that this will be a satisfactory basis for developing a plan by the Conference Chairman’s Report, Doc. 142 (July 2003)

  6. History • Some countries and/or delegates wished to use • the former Rec. 370 • the GE89 curves for their regions (Africa) • curves based on former Rec. 370 for T-DAB planning in Band III (CEPT) • Rec. 1546 only in Band V • path specific methods with terrain profile data But life was not as easy as it looks like

  7. History • WP 3K is aware of the problem and works to solve it • The main problem is the mixed land-sea path approach • WP 3K tried to avoid the mixed land-sea path anomaly (unphysical recovery effect) in former Rec. 370 • But new anomalies were built in by the new approach • Unfortunately there are still some anomalies in Rec. 1546 (also in former Rec. 370 - but nobody cares)

  8. Recommendation ITU-R P.1546 • Extended range of applicability : • All frequencies between 30 to 3000 MHz • Distances between 1 to 1000 km • All time percentages between 1% and 50% • New curves for 10 m and 20 m transmitting antenna height h1 • Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 3 000 MHz

  9. Recommendation ITU-R P.1546 • Curves are considered applicable in temperate climates • Variation of field strength with distance is to a large extent controlled by the vertical refractivity gradient • Rec. 453 contains global database of the vertical refractivity gradients dN in N-units/km in the lowest 65 m of the atmosphere (in electronic form) Applicable for all climatic regions of the world :

  10. Recommendation ITU-R P.453 dN values for 1 % of time

  11. Recommendation ITU-R P.1546 • The field strength curves of Rec. 1546 are considered to represent temperate climate with a reference value of gradient dN0 , e.g. • dN0= - 43.3/ -141.9/ -301.3 N-units/km for 50/ 10/ 1 % of time • For a different radio-climatic region of the world, calculate the difference in gradient  = dN0 – dN •  is used to adjust curves for other climatic regions

  12. Curves for non-European areas • Propagation curves are needed for regions prone to extreme super-refractivity and ducting • To get a consistent set of propagation curves for various climatic regions it is advisable to use only one method • Rec.1546 provides a procedure to extend the applicability of the field strength curves for various regions of the world • This procedure was used to derive propagation curves for the geographical zones defined in Geneva 89

  13. Curves for non-European areas • dN-values were chosen in a way to fit the curves based on Rec.1546 as good as possible to the original curves of GE89 • Parameters used to derive the new curves based on Rec.1546 for various climatic zones are • Description of the geographical zones in GE89 • Path type • Refractivity gradient • Effective transmitting antenna height

  14. Curves for non-European areas Geographical division of the planning area into propagation zones GE89

  15. Curves for non-European areas

  16. Curves for non-European areas • GE89 curves can be reproduced, largely, using the procedures for modifying the temperate zone curves found in Rec.1546 • Necessary to adopt somewhat extreme values of dN (Rec.453) • However, recent measurements in the Gulf area indicate: • dN  –2000 for 1 % of time (-1780 lowest value in Rec. 453) • The values of dN can be widely variable in any climatic zone • RRC may find it advisable to recommend appropriate refractive index lapse rates as parameters in Rec.1546 for each Zone

  17. Requirements for terrain data • Rec.1546 can be used with or without terrain height data • Worldwide terrain data (~1 km) are available: GLOBE • Due to the increase in computation time it is not practical to use terrain data in the context of RRC calculations • Detailed prediction methods can be used on a bilateral or multilateral agreement or for coverage area calculations • Higher resolution of terrain data (~100 m) necessary

  18. Requirements for terrain data • Not intended to use TCA-correction in RRC calculations • heff values should be provided by administrations • Terrain data could be used to provide heff values • Ground cover data (urban, open) not necessarily needed • Type of propagation path, such as land, sea or mixed land-sea paths can be derived from digital maps, such as IDWM • Information on cold sea/warm sea divisions and geographic data for other propagation areas are needed

  19. Receiving antenna height loss correction • For planning purposes the ground cover at rx is not known • Receiving antenna at 10 m in open area is assumed • Height loss correction for a receiving height of 1.5 m a.g.l. • Height loss from 10 m to 1.5 m is approximately: 13 dB at VHF and 16 dB at UHF (Rec. 1546, former 370) • For planning purposes, other values may be used • In bilateral negotiations when the ground cover type is known, the height loss correction formula may be used (Rec.1546)

  20. Miscellaneous Several subsections did not cause much discussion • Mixed paths over Zones of different propagation characteristics • Prediction of wanted and unwanted signal levels • Location statistics • Propagation information for shared services

  21. Conclusions • Most discussions were on choice of prediction method • Final decision will be made at first session of RRC in 2004 • Factors influencing the choice of a prediction method • Impact on existing plans • Usage of various methods may be confusing • Desirable to have one single method for the whole planning area and for all frequency bands •  Rec.1546 • However, Rec.1546 has still some anomalies

  22. Conclusions Alternative methods in the Report to RRC are: • Recommendation ITU-R P.1546 • Curves based on Rec.1546 for various climatic zones • Former Recommendation ITU-R P.370 (used for ST61) • GE89 curves based on former Rec.370 (derived and used for the planning in the African Broadcasting Area) • VHF curves based on former Rec.370 (derived and used for T-DAB allotment planning in Wiesbaden 95

  23. Conclusions Further alternative: • There is still a lack of propagation data in some parts of the planning area affected by ducting phenomena (e.g. the Gulf, the Red Sea and the East Mediterranean area) • If any new reliable data for those areas show anomalies with the prediction methods used by the Conference • Propagation predictions for requirements affected are to be re-calculated and the matter dealt with as the RRC decides

  24. Acknowledgement • I would like to thank all participants of TG 6/8 and WP 3K for their contributions and fruitful discussions • Good luck to WP 3K in November • Good luck to all those who will participate in the first session of the RRC in 2004 - and make wise decisions

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