CHAPTER 1

Definitions

The following definitions supplement those contained in the International Telecommunication Convention and in the Radio Regulations.

1.1 Coverage area

The area within which the field strength of the wanted transmitter is equal to or greater than the usable field strength.

In this area the protection against interference is provided for 99% of time.

Note - The field strength of the wanted transmitter is derived from the propagation curve relating to 50% of locations and for 50% of time.

1.2 Service area

The part of the coverage area in which the administration has the right to demand that the agreed protection conditions be provided.

1.3 Usable field strength (Eu)

Minimum value of the field strength necessary to permit a desired reception quality, under specified receiving conditions, in the presence of natural and man-made noise and interference, either in an existing situation or as determined by agreements or frequency plans.

Note 1 - The desired quality is determined in particular by the protection ratio against noise and interference and, in the case of fluctuating noise or interference, by the percentage of time during which the required quality must be ensured.

Note 2 - The receiving conditions include, amongst others:

- the type of transmission and frequency band used;

- the receiving equipment characteristics (antenna gain, receiver characteristics, siting);

- receiver operating conditions, particularly the geographical zone, the time and the season, or if the receiver is mobile, the local variations of the field strength due to propagation effects.

Note 3 - The usable field strength can be calculated by the simplified multiplication method

1) See Chapter 4.

, or the power sum method

2) See CCIR Recommendation 499-2.

. For the application of the Article 4 procedure, the simplified multiplication method is used.

1.4 Nuisance field

The field strength of the interfering transmitter (at its pertinent e.r.p.) modified by the relevant protection ratio.

CHAPTER 2

Propagation

2.1 Propagation data for the VHF broadcasting service

2.1.1 General

The propagation data given in this chapter were used for the planning of the broadcasting service. They relate field strength to path length and the effective transmitting antenna height. They represent the field strength exceeded at 50% of locations for 50% and 1 % of the time and apply to both horizontal and vertical polarization.

The data are given for various types of areas and climates, namely, land, cold sea, warm sea and areas subject to extreme super-refractivity. The definition of these categories has to be based on statistical data; it is thus to a certain extent arbitrary, but experience indicates that the following distinctions are appropriate for the application of the data set out in this chapter.

Cold sea

Seas, oceans and other substantial bodies of water at latitudes greater than 23.5° North or South, but excluding the Mediterranean, the Black Sea, the Red Sea and the area extending from the Shatt-al-Arab to and including the Gulf of Oman.

Warm sea

Seas, oceans and other substantial bodies of water at latitudes less than 23.5° North or South, including the Mediterranean and the Black Sea.

Area of extreme super-refractivity

Seas, oceans and other substantial bodies of water in the area extending from the Shatt-al-Arab to and including the Gulf of Oman.

Note - In bilateral and multilateral negotiations during the Conference, some administrations in the Eastern Mediterranean area (East of 30° E) used the criteria described in section 2.3, for the application of the 1 % time curves, the sea area was assumed to include also a coastal strip extending up to 50 km inland and for the Nile delta region (from 30° East to 32° East) a coastal strip extending up to 200 km inland.

2.1.2 Area of extreme super-refractivity

2.1.2.1 Oversea paths

For oversea path calculations for 50% of the time, Figure 2.2 was used. For the application of the 1 % time curves, the sea area includes also a coastal strip extending up to 50 km inland.

For oversea paths in the area from the Shatt-al-Arab up to and including the Gulf of Oman, calculations for propagation occurring for 1 % of the time were based on the following formulae:

E = 106.9 - 20 log d for 10 ≤ d ≤ 400

E= 78.9- 0.06 d for d > 400

where

d = path length in km,

E = field strength in dB (μV/m).

2.1.2.2 Overland paths

For overland path calculations for 50% of the time, Figure 2.1 was used. For overland path calculations for 1 % of the time, Figure 2.3 was used, but any coastal strip as defined in section 2.1.2.1 was treated as sea.

2.1.2.3 Mixed paths

For both 1% and 50% of the time, mixed paths were evaluated according to the procedure set out in section 2.1.3.5.

2.1.3 Application of the curves

2.1.3.1 Time variability

The field-strength values given in Figures 2.1 to 2.5, are those exceeded for 50% and 1 % of the time. They are expressed in decibels relative to 1 μV/m and correspond to an effective radiated power of 1 kW.

The 50% time curves were used for the determination of coverage areas. The 50% and 1% time curves were used for interference calculations for steady and tropospheric interference respectively.

2.1.3.2 Effective transmitter antenna height

The effective height of the transmitting antenna, h1, is defined as its height over the average ground level between distances of 3 km and 15 km from the transmitter in the direction of the receiver. The height of the receiving antenna, h2, was assumed to be 10 m above ground level.

The curves given in Figures 2.1 to 2.5 correspond to effective transmitter antenna heights, h1, from 37.5 to 1200 metres.

For effective antenna heights, h1, of 20 m and 10 m, additional curves can be derived from the 37.5 m curve by applying correction factors of - 5dB and - 11 dB for distances up to 25 km, and 0 dB in both cases for distances in excess of 250 km, with linear interpolation for intermediate distances. For effective transmitter antenna heights, h1, of less than 10 m, the values derived for 10 m are used.

2.1.3.3 Location variability

The curves given are representative of 50% of locations, the percentage which was used for planning purposes.

2.1.3.4 Terrain irregularity correction

The curves for propagation overland refer to the kind of irregular rolling terrain found in many parts of Region 1. No terrain irregularity correction was taken into account in drawing up the Plan.

Note - In bilateral or multilateral coordinations during the Conference, some administrations took account of actual path profiles. This method may also be used for coordination after the Conference.

2.1.3.5 Mixed land/sea path calculations

When the propagation path is partially over land and partially over sea, the following method is used for interpolation between the appropriate land and sea curves.

EL,t: field strength for land path equal in length to the mixed path for t% of the time,

ES,t: field strength for sea path equal in length to the mixed path for t% of the time,

EM,t: field strength for mixed path for t% of the time,

ds : length of sea path,

dT : length of total path.

The field strength for the mixed path(EM,t) is then determined by using the formula:

In the calculations of mixed paths, a computerized approximation of the coastline was employed. It should be borne in mind that in some cases this may give rise to certain inaccuracies when compared to calculations based on the actual coastline.

2.2 Propagation data for the aeronautical radionavigation service

The compatibility calculations are based on free space propagation conditions. In drawing up the Plan the calculations were limited to the test points of the aeronautical radionavigation station in line of sight from the broadcasting station, it being assumed that the effective Earth's radius is 4/3 of the actual radius.

2.3 Additional propagation data for the Eastern Mediterranean