ITU-R REPORT BO.633-3 PDF

Introduction

The provision of broadcasting-satellite services to countries within a Region entails careful planning of frequency allotment and satellite location to reduce interference to an acceptable level. This Report deals with the problems of planning, mainly for the 12 GHz band, and outlines the parameters involved in preparing plans, together with methods of assessing the likely success of a plan and its efficiency.

The following features of planning are mentioned initially as they are of a general nature, applying to services in all relevant bands:

— It is assumed that all broadcasting-satellite services of the same kind, to the same service area, would generally be provided from the same geostationary orbital position to permit the use of a fixed receiving antennas. Some important exceptions are: services designed for different audiences (e.g., programmes for individual reception and programmes for community reception), exceptionally large service area requirements satisfied by using more than one satellite per service area, and services provided to areas of intentional overlap between service areas within the territory of an administration (e.g., to allow the territory to be served by fewer than the authorized number of satellites during the initial phases of implementation of the Plan);

— for the purpose of calculating the wanted-to-interfering signal ratio in the case of several interfering signals, the total interfering signal may be calculated on the basis of adding the component interfering signal powers received by the antenna;

— whenever possible, the coverage area should be the minimum necessary to provide the required coverage;

— if a plan is agreed on that is based on certain technical parameters (e.g., channel bandwidth and channel spacing), an administration may nevertheless implement systems with parameters different from those adopted, provided that it does not cause more interference than it would cause, nor demand greater protection from interference than it could demand, if it adhered to the adopted parameters;

— if it is proposed initially to operate a broadcasting-satellite service for community reception, and at a later date to operate broadcasting-satellite services for individual reception in the same frequency band, both services should employ the same modulation system to facilitate compatibility. Under such circumstances, it would also be necessary to assume sharing criteria that would allow for the broadcasting services ultimately required. However, if a system is designed for community reception on a permanent basis with no plans for later use of the same frequency band for individual reception, the assumption of sharing criteria more stringent than those required for the planned system could be wasteful;

— all the signals transmitted from the same orbital position and meant for the same audience should generally be of the same polarization, however, exceptionally large service requirements may make it necessary to use both polarizations (in interleaved channels as discussed in § 2.1.2) from the same orbital position and meant for the same audience.

Sections 2 to 8 deal with planning of the 12 GHz band in general terms. Sections 9 and 10 discuss the results of 12 GHz planning in Regions 1 and 3, and Region 2 respectively. Section 11 considers the planning of broadcasting satellites in other bands, and § 12 deals with spacecraft service functions.