© irt r. grosskopf br info meeting on rrc-04/05 2003 rainer grosskopf institut für rundfunktechnik...

© IRT R. Grosskopf BR Info Meeting on RRC-04/05 2003

Rainer Grosskopf

Institut für Rundfunktechnik GmbH

Propagation ConsiderationsOverview of the activities within Task Group 6/8

BR Information Meeting on RRC-04/05

© IRT R. Grosskopf Propagation considerations BR Info Meeting on RRC-04/05 18.9.2003 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


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


History

• The 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. 14 (Jan 2002)


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)


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


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)


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



• 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 :



dN values for 1 % of time



• 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


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



• 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



Geographical division of the planning area

into propagation zones

GE89



6-8/142-A42-10

90

80

70

60

50

40

30

20

10

0

–10

–20

–30

–40

–5010 100 1 000

h1 = 1 200 mh1 = 600 mh1 = 300 m

FIGURE A.4.2-10

Propagation curves for the broadcasting service in Zone 4Field strength (dB(V/m)) for 1 kW e.r.p.

Frequency: 100 MHz; maritime regions and low-altitude coastal land50% of the time; 50% of the locations; h2 = 10 m

Distance (km)

Fiel

d st

reng

th (

dB V

/m)

Finals Acts GE 89


h1 = 150 mh1 = 75 mh1 = 37.5 m

6-8/142-A42-20

90

80

70

60

50

40

30

20

10

0

–10

–20

–30

–40

–5010 100 1 000

h1 = 1 200 mh1 = 600 mh1 = 300 m

FIGURE A.4.2-20

Propagation curves for the broadcasting service in Zone CField strength (dB(V/m)) for 1 kW e.r.p.

Frequency: 100 MHz10% of time; 50% of the locations; h2 = 10 m

Distance (km)

Fie

ld s

tren

gth

(dB V

/m)

Finals Acts GE 89


h1 = 150 mh1 = 75 mh1 = 37.5 m



• 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


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


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


• 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)

Receiving antenna height loss correction


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


Conclusions

Rec.1546• However, Rec.1546 has still some anomalies

• 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


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


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


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

© irt r. grosskopf br info meeting on rrc-04/05 2003 rainer grosskopf institut für rundfunktechnik...

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