shortwave broadcasting: a primer on coordination … · wbu primer on coordination of shortwave...

WBU Primer on Coordination of Shortwave Schedules of 8

DRAFT

SHORTWAVE BROADCASTING: A PRIMER ON COORDINATION OF SEASONAL SCHEDULES∗∗∗∗

Introduction Several frequency bands have been allocated for shortwave radio broadcasting (HFBC) by the International Telecommunication Union (ITU). Because of the long distance propagation characteristics of shortwave signals, frequency re-use results in interference, often of a severe nature. The shortwave bands are crowded with radio transmissions, very frequently transforming each other’s services into just squeaking noises. This situation persists, created by some ten thousand odd shortwave transmissions everyday all over the world in a rather limited number of channels, each lasting from 15 minutes to several hours. Several mechanisms have been tried for effective reduction of harmful interference in shortwave services and for orderly use of the allocated spectrum. In a pioneering move several years ago, a regional group of broadcasters was set up to carry out mutual adjustments in their seasonal shortwave schedules. This novel approach of coordinated use of shortwave bands proved to be effective in significantly reducing mutual interference among shortwave services. The activity has now extended to several regions of the world. Since January 1999, the coordination method became a part of the ITU regulations governing the use of the shortwave bands. As the coordination activity progresses, the extent of interference seems to decline gradually. Shortwave Radio Bands The following frequency bands are in use for shortwave broadcasting : 3900-4000 KHz, 5950-6200 KHz, 7100-7300 KHz, 9500-9900 KHz, 11650-12050 KHz, 13600-13800 KHz, 15100-15600 KHz, 17550-17900 KHz, 21450-21850 KHz, 25670-26100 KHz. The following bands, though not allocated, are nevertheless being used by most broadcasters (also called out-of-band transmission): 5900-5950 KHz, 7300-7350 KHz, 9400-9500 KHz, 11600-11650 KHz, 12050-12100 KHz, 13570-13600 KHz and 13800-13870 KHz The following ‘tropical bands’ are also being used for national coverage in the Tropical Zones: 2300-2495 KHz, 3200-3400 KHz, 4750-4995 KHz and 5005-5060 KHz Shortwave Propagation Shortwave radio signals travel by ionospheric propagation. The characteristics of ionosphere are well understood and its impact on shortwave propagation can be predicted with a fair amount of accuracy in the long term. This includes prediction of propagation path, coverage area and field strength of the signal in the target area. However, the ionosphere undergoes dynamic changes in the short term and its disposition in that time frame brings in an element of uncertainty.

∗ Prepared by the WBU-TC Task Group on Coordination Procedures for HF Broadcasting.


Shortwave signals travel far. Given the right parameters, it is quite possible for shortwave signals to reach multiple coverage areas far away from each other. This happens because of the process of successive refraction in the ionosphere and reflection from the surface of the earth. Seasonal Schedules The behaviour of the ionosphere is governed by the 11 year solar cycle. In addition, there are seasonal variations.. However, for the purpose of scheduling, the year long period has been divided into two periods (seasons), going by the characteristics of the ionosphere. Season A spans form end-March to end-October and season B from end-October to end- March of the next year. A set of frequencies used for transmissions, along with their time lines, is known as a shortwave schedule for that season. Generally, a different set of shortwave frequencies has to be used in each season. In some cases, significant continuity is maintained in the use of the channels from one season to another. Use of Channels Generally the use of frequency spectrum for communication services outside of national boundaries has to be made only after assignment by the ITU or, in certain cases, after registration with this agency. In the case of shortwave broadcasting, no permanent frequency channel assignments are made to any country. The frequencies, once registered, are only ‘loaned’ to individual countries for a fixed duration. All countries formally seek use of the frequencies for their transmissions every season. Each such transmission is known as a “requirement”. However, there is no guarantee to safeguard this usage. Spectrum Congestion Currently shortwave radio bands are highly congested which adversely impacts reliability and service quality. The number of transmissions greatly exceeds the capacity of the available spectrum. Most often, more than one shortwave broadcast is made on the same frequency at the same time, directed to the same coverage area. This causes interference in shortwave services, making the content inaudible. At the best of times, shortwave broadcasting has always left much to be desired in terms of reception quality and continuity. Resolution of Congestion Several mechanisms have been tried for reducing harmful interference in shortwave services. For one, former Article 17 of the ITU Radio Regulations was employed as such a mechanism. However, this attempt failed primarily because the combined projected channel requirements at that time by far exceeded the total capacity of the frequency spectrum. Since January, 1999, a new ITU mechanism for orderly use of the shortwave bands came into force. Its provisions, contained in Article S12, were adopted at the 1997 World Radiocommunication Conference. Article S12 and Coordination The operating mechanism under Article S12 follows a fresh approach in resolution of the problem. Simply put, the mechanism operates, on a seasonal basis, as under: • Seasonal schedules are provided to the Radiocommunication Bureau (BR) of the ITU by countries

intending to use shortwave frequencies for broadcasting. • The BR consolidates all the schedules received by it into a “combined schedule” for that particular

season. • The BR carries out an in-depth technical analysis on the combined schedule using the approved

ITU software. The results indicate performance parameters for each transmission contained in the seasonal schedules. Interference among the requirements is quantitatively calculated and reflected in the results.

• The combined schedule along with the technical analysis and its results are forwarded to all participating countries on a CD-ROM.

• The task of finding interference free channels is left to the concerned administrations. The role of the broadcasters in the coordination activity has been highlighted in the Article., making it the first time ever that such a role has been formally accorded to them by the ITU. Guided by results of the


BR analysis, broadcasters in the affected countries - in some cases frequency management organisations – take steps to eliminate potential interference in their services. This is attempted in two ways, either individually or in groups. (See below)

• The coordination activity generally results in changes to the individual seasonal schedules. The schedules, so updated, are forwarded to the BR.

• The BR combines all the schedules once again and carries out a fresh technical analysis. This combined schedule, known as the Seasonal Schedule, is forwarded to all administrations on CD-ROM for implementation.

Clearly, the coordination activity is the crucial element in reducing interference. The process is described in the following. Individual Coordination Individual broadcasters get in touch with their counterparts in those organisations from where the interfering transmissions originate. Such a process is known as coordination. The objective is to make changes in the schedules or in technical parameters of their respective transmissions so that mutual interference can either be eliminated or substantially reduced. Often this requires one or more meetings. Group Coordination Individual coordination is time and resource consuming. A more efficient method is that of group coordination. All interested broadcasters get together in groups. A series of individual coordination meetings, each comprising representatives of two organisations, are arranged among the participants. In these bilateral meetings, ways and means are found out to eliminate mutual interference. The basic idea is to ensure that transmissions, operating either co-channel or adjacent channel, do not target the same coverage area at the same time. This requires modification of either the technical parameters of transmissions or their scheduling or a combination of the two. Some of the steps that are taken to eliminate interference are:

• Modification of transmission parameters

This modification can be attempted in one or both transmissions to remove the overlap between them. Among these measures are:

- Changing transmission frequency - Changing antenna azimuth angle (direction of emission) - Changing antenna radiation characteristics - Reducing transmitter power - Changing target area - Changing service operation time • Modification of schedules

One of the two parties may volunteer to delete an interfering transmission from their schedule. This step is taken as a part of a package deal involving several transmissions of the two parties.

• No solution reached

In many cases no solution is reached and the matter is left for further consideration. Active Coordination Groups The coordination process evolved over the years after a group of broadcasters in Europe and North America took the first pioneering steps. This group, now known as the International Broadcasters’ High Frequency Coordination Committee - HFCC for short – innovated several procedures and software packages to facilitate coordination, achieving significant interference reduction in their services. The HFCC (website: www.hfcc.org) meets twice a year for this purpose. More recently another group, known as the ASBU group, has emerged in North Africa under the auspices of the Arab States Broadcasting Union. A similar group was created several years ago in the Asia-Pacific under the auspices of the Asia-Pacific Broadcasting Union (ABU, website: www.abu.org.my). Known as the ABU-HFC, the group has participation from several broadcasters in Europe, Africa and North America in addition to those in the Asia-Pacific.


The three established coordination groups are in close touch with each other. In August 1998, they formally established a joint Group of Experts to provide interaction between them and carry out developmental work on issues of common interest. Additionally, all the coordination groups are in close contact with the BR and have provided valuable assistance to the latter in implementing Article S12. Mechanism of Coordination All the three shortwave schedule coordination groups use a uniform coordination mechanism, outlined in the following: • Prior to the coordination meeting, schedules provided by the participating broadcasters are

assembled into a Combined Schedule. For this purpose, the HFCC software is employed. • The combined schedule provides details of all the transmissions (power, antenna type, transmitting

station, target area, timing etc) at a glance. More importantly, it highlights co-channel and adjacent channel interference (collisions) among these transmissions in a graphical manner. Among other databases provided are individual collision lists and individual schedules.

• At the outset, the meeting divides itself into a number of bilateral meetings or consultations. These meetings are not structured, nor do these follow any rigid scheduling. The initiative is left to the interested parties desirous of coordinating their shortwave frequencies with others. The bilateral meetings work on a platform of cooperation and give and take. Generally, at the end of each meeting, resolution of most mutual problems is arrived at. The atmosphere is totally informal, there are no written agreements and verbal agreements are confirmed by a mere handshake. This aspect of informality and honouring verbal commitments forms the bedrock of the coordination process and leads to its success.

• At the end of each day, all parties provide their updated schedules (arrived at as a result of coordination through the day) to the meeting Secretariat. A fresh combined schedule is prepared and provided to the participants. The coordination on the next day is based on the new combined schedule.

• The process goes on till the final day when, after several iterations, the final combined and individual schedules are produced and provided to all the participants.

Software Tools Several software programme packages are employed for processing of the schedule data which can contain up to 200,000 entries. The BR uses the newly developed HFBC software package, which includes a package for schedule generation of seasonal schedules. This is freely available to all ITU member countries (see ITU website www.itu.int/brsoft/terrestrial/hf-propagation/index.html). The coordination groups use a software programme for generation of seasonal schedules (RT060100). This is compatible with the corresponding programme of the ITU and is available to all participants of these groups. For combining the seasonal schedules, the coordination groups use the HFCCSOFT package. Though there is considerable difference in software used by the BR and the coordination groups, efforts are on to make them compatible with each other. E-mail Coordination The process followed is the same as in the case of group coordination. However, no face- to-face meetings take place. Coordination between participants is carried out via e-mail. Though this is not a substitute for the regular coordination meeting, nevertheless, recent experience has shown that this method is quite useful. At least one coordination group employs this method to coordinate one of the two seasonal schedules. Guidelines Governing the Coordination Process The success of the coordination process is based on the spirit of informality, flexibility in approach and cooperation among its members. Nevertheless, it is pertinent to adopt some guidelines to ensure a smooth process. A sample set of guidelines, employed by an operating coordination group, is provided as Annex 1.


Results and Cost Benefits of Coordination Results obtained at the coordination meetings are amazingly good. It is not unusual to obtain reduction in the number of transmissions facing potential interference by 25 to 40%. Sometimes even better results are obtained. It is pertinent here to get an idea of the number of hours of transmission involved in coordination within a group. As an example, in one of the three coordination groups, for the B-1999 season there were about 5500 daily transmissions totaling 12600 hours everyday. As a result of coordination, potential interference was eliminated from transmissions spanning over 710 hours every day. The reduction in interference among transmissions has a significant operational cost saving advantage. The estimated cost of these transmissions was of the order of US$ 50 million. The administrative cost involved in the process, in comparison, was miniscule. Field Results In the long term, shortwave coordination activity is expected to help reduce interference in shortwave transmissions significantly. Indeed, several participants of one of the coordination groups have indicated improved reception of their shortwave services in the last couple of years, based on reports from their listeners. In addition, the number of requirements projected by shortwave broadcasters is in decline, as their schedules get gradually stabilised. Both are welcome developments and can be attributed to the efforts made by all shortwave broadcasters in coordinating their schedules.

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Annex 1

GUIDELINES GOVERNING THE COORDINATION PROCESS

1. Introduction The success of the HFBC coordination process is predicated on simplicity of procedures and flexibility in approach. In following these guidelines for the coordination process, these cardinal requirements should be observed.

2. Region of Operation • For the purpose of definition, the ‘region’ of operation should be the [XXX] region but

this should not be a restricting factor. • As the coordination process develops, the ‘region’ of operation should be expanded as

necessary. 3. Participation in the Coordination Process

• All participants must abide by the guidelines. • Participating delegations may include representatives from their respective ‘ITU

regulatory administrations’. • All participants must have authorisation from their respective organisations to make

appropriate changes in their seasonal schedules during the coordination process. • The following are eligible for participation: ! All members of [YYY] organisation ! All Affiliates of [YYY] organisation ! Members of sister Broadcasting Unions ! Non-members broadcasting from the country of an [YYY] member if:

- represented by the concerned member , or - if specifically permitted by the member to handle its own channel requirements.

! Non-members broadcasting into the ‘region’ from outside of it. ! For other categories, participation will be decided by the [YYY] Steering

Committee∗ if potential benefits are seen to accrue through such participation.

4. New Admissions New requests for admissions [after ZZZ date] will be considered by the [YYY] Steering Committee in accordance with item 3 above. Admission will be effective after the Steering Committee approval is obtained.

5. Submission of Seasonal Requirements • Seasonal schedule requirements should be the minimum deemed necessary to operate

scheduled services and realistic in terms of number of channels and transmission time. • All submitted requirements should be taken into account.

∗ The seven member Steering Committee is appointed by the [YYY] participants for a two year term.


• Prior to submission, all requirements should be technically verified as appropriate for the intended use, taking into account accurate values of propagation factors such as sun-spot numbers.

• Any channel requirements not intended for use during the season should be eliminated from the seasonal schedule before submission.

• The Internet electronic mail facility should be used to the maximum possible extent.

6. Interaction with ITU-BR • Procedures should be according to Article S12 of the Radio Regulations, as applicable. • Interaction should be carried on with BR on a continuing basis.

7. Interaction with other Coordination Groups • Close contact with other coordination groups, including the ABU-HFC, HFCC and ASBU

groups, should be maintained. • Combined schedule data should be exchanged with such coordination groups.

8. Financial Aspects • The coordination process will, in principle, operate on users-pay basis.

9. Near Future Arrangements • In the next few years, once a degree of stability is achieved, the [YYY] process may operate

as an autonomous body. A firm decision on this matter will be taken at an appropriate juncture.

• A monitoring group should be created within [YYY] to evaluate efficiency of frequency usage from season to season. This method should be employed to identify frequencies projected as requirements for a particular season but not put to use (wooden frequencies). This measure is intended to deter participants from projecting unrealistic frequency requirements.

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shortwave broadcasting: a primer on coordination … · wbu primer on coordination of shortwave...

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