ITU-R HDBK HFB-1999 Handbook HF Broadcasting System Design《HF广播系统设计手册》.pdf

1、COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services STD*ITU-R HDBK HFB-ENGL 1999 S 4855232 0540553 b9T .II The role of the Radiocommunication Sector is to ensure the rational equitable. efficient and economical use of the radio-frequency

2、spectrum by all radiocornrnunication services, including satellite services and carry out studies without limit of frequency range on the basis of which Recomniendations are adopted The regulatory and policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunic

3、ation Conferences and Radiocommunication Assemblies supported by Study Groups Contact address for inquiries about radiocommunication matters: ITU Radiocommunication Bureau Place des Nations CH-I211 Geneva20 Switzerland Telephone t41 227305800 Fax +41 227305785 Internet brmailitu.int X 400 S=brmail;

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5、elegram ITU GENEVE Internet sales itu.int X .400 S=sales; P=itu; A=400net; C=ch O ITU 1999 All rights reserved No part of this publication may be reproduced or utilised in any form or by any mean electronic or mechanical including photocopying and microfilm. without written permission from the ITI C

6、OPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesINTERNATIONAL TELECOMMUNICATION UNION HANDBOOK HF broadcasting system design I999 Radiocommunication Bureau COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed

7、 by Information Handling Services STDeITU-R HDBK HFB-ENGL 1999 4855232 0540555 4b2 . . 111 . TABLE OF CONTENTS CHAPTER 1 . INTRODUCTION 1.1 HOW TO USE THIS HANDBOOK CHAPTER 2 . DEFINITION OF SERVICE REQUIRED . 2.1 2.1.1 2.1.2 2.1.3 2.2 GEOGRAPHIC AREA INTENDED TO BE SERVED . Area of primary interest

8、 Minimum area which could be considered . Method of defining the area HOURS AND DAYS OF OPERATION . 2.3 PERMANENT OR SHORT-TERM REQUIREMENT . 2.4 REQUIRED QUALITY . CHAPTER 3 - RECEPTION CONDITIONS . 3.1 3.1.1 3.1.2 3.2 3.2.1 3.2.2 3.2.3 3.3 3.3.1 3.3.2 3.4 3.4.1 3.4.2 3.4.3 RECEPTION ENVIRONMENT Im

9、pact of topography on reception . Noise considerations . FIELD STRENGTH RELATED VALUES . Signal-to-noise ratio . Minimum usable field strength . Tuning aspects Intrinsic receiver noise and noise limited sensitivity CHARACTERISTICS OF RECEIVERS . Technical charactenstics . RADIO FREQUENCY PROTECTION

10、RATIOS . RF-protection ratios for DSB . Relative RF-protection ratios for SSB Signal to interference ratio Page 1 2 5 5 5 5 5 6 6 6 9 9 9 9 13 13 16 17 18 19 19 21 22 23 24 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R HDBK

11、 HFB-ENGL 1999 = 4855232 054055b . iv . 3.5 RECEIVING ANTENNA CONSIDERATIONS . 3.5.1 Antenna types . 3.5.2 Receiving antennas for broadcast listeners . CHAPTER 4 . TRANSMISSION FACILITIES . 4.1 4.1.1 4.1.2 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.3 4.3.1 4.3.2 4.3.3 4.3.4 4.3.5 4.3.6 4.3.7 4.3.8 GE

12、NERAL, Available facilities New facilities TRANSMITTERS Transmitter technology . Amplitude-modulation double sideband (AM-DSB) operation . Single sideband (SSB) operation Frequency tolerance and stability . Spurious radiation level Overall transmitter efficiency . TRANSMITTING ANTENNAS Introduction

13、Radiation patterns . Types of transmitting antennas for HF broadcasting Selection of optimum antenna Designation of types of antenna. . Calculation of antenna pattern Measurement of antenna pattern . Comparison of measured and calculated pattern CHAPTER 5 . PROPAGATION 5.1 PROPAGATION PREDICTION . 5

14、.1.1 Recommendation ITU-R PIS33 method 5.1.2 Other methods . 5.2 FADING . 5.2.1 Short-term fading 5.2.2 Long-term fading 5.2.3 Combination of short- and long-term fading Page 24 24 24 25 25 25 25 26 26 26 29 31 32 32 33 33 35 37 46 46 46 48 48 51 51 51 51 51 51 52 52 IV COPYRIGHT International Telec

15、ommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTDJTU-R HDBK HFB-ENGL m 4i155212 ow0557 235 m -v- 6.1 6.2 6.2.1 6.2.2 6.2.3 6.3 6.4 6.5 6.6 6.7 CHAPTER 6 . SELECTION OF TRANSMISSION PARAMETERS . CWTER 7 . TROPICAL ZONE BROADCASTING . BASIC CONSIDERATIONS . SELECT

16、ION OF FREQUENCY BAND . Consideration of synchronization . Need for multiple frequency bands . Synchronization and multiple frequency use per programme USE OF EXISTING FACILITIES . SELECTION OF ANTENNA TYPE . SELECTION OF TRANSMITTER POWER . SPECIAL CONSIDEUTIONS FOR BROADCAST IN THE TROPICAL ZONE .

17、 NEED FOR NEW TRANSMITIER OR ANTENNA . 7.1 7.2 7.2.1 7.2.2 7.3 7.4 7.5 7.5.1 7.5.2 7.5.3 7.5.4 7.6 7.7 7.7.1 7.7.2 7.7.3 7.7.4 INTRODUCTION PROPAGATION PREDICTION . Prediction of MUF Prediction of sky-wave field strength ATMOSPHERIC RADIO NOISE AND SIGNAL-TO-NOISE RATIO MINIMUM FIELD TO BE PROTECTED

18、 . TRANSMITTING ANTENNAS Dipoles Horizontal arrays of horizontal dipoles H- 112 Array fed out-of-phase . High incidence array . INTERFERENCE DUE TO SHARING OF BANDS FADING . Fading due to sporadic-E Fading due to F-region irregularities Surge fading Fading allowance for the planning of HF broadcast

19、services in the tropical bands . Page 53 53 53 53 55 56 57 57 57 58 58 61 61 62 62 63 63 64 65 65 66 67 69 69 73 73 73 74 74 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R HDBK HFB-ENGL 3999 H 4855232 0540558 371 111 . vi .

20、CHAPTER 8 . OPTIMIZATION OF SETS OF ANTENNAE AND SETS OF TRANSMITTERS 8.1 ANTENNA SET OPTIMIZATION . 8.1.1 Types of rotatable antennas 8.1.2 Electrical characteristics . 8.1.3 Mechanical characteristics 8.1.4 HF feeding of a rotatable antenna . 8.1.5 Usages of rotatable antennas 8.2 SELECTION OF TRA

21、NSMITTERS . CHAPTER 9 - ESTABLISHING AN HI?-BROADCASTING PLANT 9.1 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.2 9.2.1 9.2.2 9.2.3 9.3 9.3.1 9.3.2 9.3.3 9.3.4 9.3.5 9.3.6 9.3.7 9.3.8 9.3.9 SITING CONS IDERATIONS Preliminary site requirements determination Environmental considerations Site requirements Utility a

22、vailability . Cost considerations . TRANSMITTING PLANT INFRASTRUCTURE Site planning . Site development Building requirements TRANSMITTING STATION SUBSYSTEMS General Program feeds . RF power generating subsystem . RF switchbay Baluns . Dummy loads Transmission lines Pow er supply Safety and protectio

23、n Page 77 77 80 80 83 84 84 85 87 87 87 87 88 89 89 90 90 90 91 94 94 94 97 99 100 101 101 103 106 VI COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD.ITU-R HDBK HFB-ENGL 1999 4855232 0540559 O08 . vii . 9.4 MINIMEATION OF THE NUMBE

24、RS OF TRANSMITERS AND ANTENNAS 9.4.1 Number of transmitters and their power ratings . 9.4.2 Number of antennas required to support a given transmission schedule 9.4.3 Selection of transmitter . CHAPTER 10 . STATION START-UP . 10.1 ORGANIZATION OF OPERATION 10.2 TECHNICAL RESOURCES REQUIRED FOR OPERA

25、TIONAL CONDITIONS OF WORK 10.3 DOCUMENTATION . 10.4 TRAINING . CHAPTER 11 - FREQUENCY MANAGEMENT AND COORDINATION 1 1.1 GENERAL CONSIDERATIONS 1 1.2 SELECTION OF FREQUENCY 11.3 ASSESSMENT OF THE INTERFERENCE SITUATION . 11.4 COORDINATION OF FREQUENCY USAGE 11.4.1 Summary of existing planning methods

26、 and identification of relevant ITU-R ITU-R Recommendations and Resolutions 1 1.5 I-IF BANDS ALLOCATED TO THE BROADCASTING SERVICE . 11.5.1 Decisions of WRC-95 . 1 1 S.2 Decisions of WRC-97 . 11.6 11.7 NOTIFICATION TO THE APPROPFUATEBODIES/ORGANISATIONS . IMMEDIATE EVALUATION OF THE SUCCESS OF THE T

27、RANSMISSION 1 1.8 PRACTICAL ASPECTS OF FREQUENCY PLANNING CHAPTER 12 . VERIFICATION OF OVERALL SYSTEM PERFORMANCE AND SERVICE ACHIEVED 12.1 OBJECTIVE METHOD . 12.2 SUBJECTIVE METHOD . CHAPTER 13 . PREVENTIVE MAINTENANCE 13.1 MAINTENANCE OF TRANSMITTER 13.1.1 Introduction 13.1.2 Physical maintenance

28、Page 108 109 109 111 113 113 113 113 114 115 115 115 115 115 115 116 117 117 118 118 118 121 121 121 123 123 123 123 VI1 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R HDBK HFB-ENGL L999 D 4855232 0540560 82T 9 . viii . 13.1

29、.3 13.1.4 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 13.2.7 Operability Safety MAINTENANCE OF ANTENNA SYSTEM General. . Maintenance of antenna Maintenance of antenna field Maintenance of tower systems Maintenance of transmission lines . Maintenance of wooden poles Safety CHAPTER 14 . CONCLUSION CHAPTER

30、 15 . ANNEX . Page 124 124 125 125 125 129 130 131 132 132 135 137 VI11 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTDmITU-R HDBK HFB-ENGL 1999 4855232 0540563 7bb H -1- CHAPTER 1 INTRODUCTION 1 Introduction Short-wave broadcastin

31、g, also known as “HF broadcasting”, has been in existence for many years and has been subject to considerable changes. The HF transmission medium has provided a means of disseminating information on a very wide variety of topics to audiences of the order of hundreds of millions of people, throughout

32、 the world. Valuable scientific, engineering and practical experience has been accumulated over decades in the complex aspects of HF broadcasting station planning and design as well as in the number of particular components needed to be properly considered if a Handbook is to provide a comprehensive

33、 overview and guidance of paramount importance. Specific attention is also to be focused on the management aspects of HF Broadcasting station planning and design as well as its operation and maintenance. The objective of the Handbook is to provide practical and illustrative guidance even to radio en

34、gineers not having been previously exposed to the particular task of HF broadcasting station planning. Considerable effort has been made to meet the expectations of HF broadcasting station planners from the developing world where, generally, such experience is very limited, if it exists at all. Base

35、d on proposals and comments made particularly by the Telecommunication Development Bureau (BDT), the Special Rapporteurs Group 10A-5 of the Radiocommunication Bureau has kindly accepted to carry out fundamental changes to the Handbook structure in order to incorporate this “development” perspective.

36、 In accordance with the wish expressed by the BDT, this Handbook has been prepared in a concise and practical manner and does not attempt to cover the theory and design of HF broadcasting antennae. The use of mathematical formulae has been avoided as far as possible and graphs and tables have been u

37、sed instead. It must be recognized that the choice of frequency, type and the ultimate design and construction of directional antennae, feeder and switching systems for a given HF broadcasting service requires expert knowledge and practical experience and perhaps the soundest and most useful advice

38、that can be given to the developing countries is that they should endeavour to obtain the necessary supplementary expert assistance and consultation. It is well known that HF propagation is variable: - with time of day; - from day to day; - from month to month; - from year to year, COPYRIGHT Interna

39、tional Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R HDBK HFB-ENGL 1997 m 4855212 0540562 bT2 -2- these variations being governed by the impact of solar activity on the earths ionosphere. Such variations create reception difficulties for listeners

40、. Broadcasters must therefore choose their transmitting equipment, their transmitting sites, their frequencies and even their hours of transmission to minimize, as far as possible, any difficulties which could prevent listeners from receiving the intended messages. With the Tropical Zone there are s

41、pecial problems to be faced. Natural noise levels are high because of the large number of thunderstorms and this creates special reception problems. There is an extra usage of the HF bands because of noise problems at medium-wave frequencies (MF) and, regrettably, the relative lack of development of

42、 VHF/FM broadcasting services in a number of countries. Some of these problems may be resolved at a later date by increasing use of Digital Audio Broadcasting (DAB) satellite transmissions but, in the meantime, the HF bands must continue to be used. In addition to the natural problems just described

43、, there is also the fact that most of the HF spectrum available for broadcasting is congested, that is, there are too many transmissions to permit good reception quality to be achieved in all reception areas at all times. Faced with these problems, it is essential that broadcasters have available th

44、e best guidance possible, not only for the selection of a suitable combination of transmitting antenna and frequency, but also for maintaining and operating their station equipment and infrastructure under optimum conditions. 1.1 As a guidance through this handbook the flowchart in Figure 1.1 is int

45、ended to help the reader to: 1) 2) How to use this handbook provide a guideline to the order of relevant items to be covered serve as a quick index to lead to the appropriate chapter COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTDm

46、ITU-R HDBK HFB-ENGL 1799 YB55212 0540563 539 -3- Normal operation and maintenance Chapter 13 Start Chapter 1 $. New service requirement Chapter 1 M .d Fr: = noise figure of the receiver (dB). The equivalent field strength of intrinsic receiver noise which corresponds to Fa is obtained by the (Equati

47、on 3-5). A small value of Fr (less than 3 dE3 for example) is easily obtained in the current model of the receiver. When an antenna of suitable length combined with a short length feeder and an associated matching circuit is used the value of La is not prominent (less than 5 dB for example), therefo

48、re, a small value of F, (less than 8 dB for example) can be easily obtained. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R HDBK HFB-ENGL 1999 4855222 054057b 297 - 17- The noise-limited sensitivity of a receiver is defined

49、in Recommendation ITU-R BS.703 and is summarized for the HF bands as follows: - for planning purposes, “sensitivity” is understood to mean “noise-limited sensitivity”, given in terms of field strength, required to achieve a specified signal-to-noise ratio at the audio output ; for the HF bands, telescopic rod antennas are frequently used. Therefore, receivers using these types of antennas should be used as a reference, even though a variety of external antennas may occasionally be used to improve reception; for the HF bands, 40 dB(pV/m) is suggested for the minimum sensitivity of an