RRC Propagation Information Field strength prediction method

Regional Information Meeting and Workshop related to the Regional Information Meeting and Workshop related to the RRC-06 for the administrations of the African countriesRRC-06 for the administrations of the African countries

Dakar, Senegal, 25-29 April 2005Dakar, Senegal, 25-29 April 2005

RRC Propagation Information

Field strength prediction method

Pham Nhu HaiRadiocommunication Bureau

RRC information meeting and workshop

Dakar, Senegal 25-29 April 2005

OutlineOutline

Overview – propagation modelsRRC propagation curves/tablesRRC propagation zonesPropagation prediction methodPropagation for other services



Propagation modelsPropagation models

Path specific– Terrain data – Time consuming– Accurate but no agreed methods for

broadcasting Path general

– General terrain data required (effective heights)– Fast easy to use– ITU conference (ITU-R P 370, 529, 1146 and

1546)



One propagation model!One propagation model!

ITU-R P.1546 replaces– ITU-R P.370 (BC VHF/UHF)– ITU-R P.529 (LM VHF/UHF)– ITU-R P.1146 (LM & BC, 1-3 GHz)

Path general methods30 MHz – 3000 MHz1 km – 1000 km1% - 50% percentage of time



RRC propagation modelRRC propagation model

Set of propagation curves/tables of field strength (dBu) vs distance (km)– Heights of transmitting/base antenna– 100, 600 and 2000 MHz– 1%, 10% and 50%– Receiving antenna height of 10m in open area

Detailed inter/extrapolation procedures– Other percentage of time– Other frequencies– Other transmitting/base antenna heights



RRC propagation zonesRRC propagation zones



600 MHz, 50% Land temperate600 MHz, 50% Land temperate



600 MHz, 1% Land temperate600 MHz, 1% Land temperate



600 MHz, 1% warm seas600 MHz, 1% warm seas



Propagation prediction methodPropagation prediction method

Maximum field strength values Determine transmitting/base antenna

height Interpolation of field strength as a function

of– Transmitting/base height h1

– Distance– Frequency– Percentage of time



Propagation prediction method (2)Propagation prediction method (2)

Mixed pathsCorrection for receiving/mobile

antenna heightCorrection of terrain clearance angleLocation variability in land area-

coverage predictionFS prediction in 16 easy steps!!!!



Transmitting/base antenna height Transmitting/base antenna height hh11

Land paths >= 15 km– h1= heff (height over average terrain 3-15

km)Land paths < 15 km– h1= ha (height of the mast) for d<=3km– h1= ha + (heff-ha)(d-3)/12 for 3 <d<15 km

Sea paths– h1= heff for h1 >=1 m



Field strength for a height hField strength for a height h11

h1 <> 10, 20, 75,….., 1200 mh1 in the range 10 – 3000 m

E = Einf +

(Esup-Einf)log(h1/hinf)/log(hsup/hinf)– hinf = 600 if h1> 1200 – hsup = 1200 if h1> 1200

h1 in the range 0 – 10 mNegative h1 (terrain clearance angle)



Field strength = f (distance)Field strength = f (distance)

If d does not coincide with one of the tabulation distancesE = Einf +

(Esup-Einf)log(d/dinf)/log(dsup/dinf)



Field strength = f (frequency)Field strength = f (frequency)

If freq does not coincide with one of the nominal values (100, 600)E = Einf +

(Esup-Einf)log(f/finf)/log(fsup/finf)



Mixed path considerationMixed path consideration

ITU-R P.370– Based on

percentage of land and sea path

– Shows unrealistic “recovery effect”

– Sea curves show large variation wrt effective heights

RRC (P.1546)– Longest

contiguous path is important (breaking down ducting)

– Avoid “recovery effect”

– Consistent set of sea curves



FS prediction in 16 easy steps!!!FS prediction in 16 easy steps!!!



ConclusionsConclusions

One propagation modelBased on ITU-R P.1546Data available in curves and tablesBetter prediction for sea pathsStep-by-step FS prediction methodTGFC……………..

RRC Propagation Information Field strength prediction method

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