ETSI ETR 132 TECHNICAL August 1994 REPORT Source: EBU/ETSI JTC Reference: DTR/JTC-00011 ICS: 33.060 Key words: Broadcasting, FM, radio, transmitter, VHF European Broadcasting Union Union Européenne de Radio-Télévision EBU UER Radio broadcasting systems; Code of practice for site engineering Very High Frequency (VHF), frequency modulated, sound broadcasting transmitters ETSI European Telecommunications Standards Institute ETSI Secretariat Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [email protected] Tel.: +33 92 94 42 00 - Fax: +33 93 65 47 16 Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. © European Telecommunications Standards Institute 1994. All rights reserved. New presentation - see History box © European Broadcasting Union 1994. All rights reserved. Page 2 ETR 132: August 1994 Whilst every care has been taken in the preparation and publication of this document, errors in content, typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to "ETSI Editing and Committee Support Dept." at the address shown on the title page. Page 3 ETR 132: August 1994 Contents Foreword .......................................................................................................................................................7 1 Scope ..................................................................................................................................................9 2 References..........................................................................................................................................9 3 Abbreviations.....................................................................................................................................10 4 Site selection .....................................................................................................................................10 4.1 Coverage and frequency planning .....................................................................................10 4.2 Propagation analysis..........................................................................................................11 4.3 Compatibility with aeronautical services ............................................................................11 4.4 Compatibility with reception of other broadcasts ...............................................................11 4.5 Compatibility with other radio site users ............................................................................12 4.6 Capacity of existing sites ...................................................................................................12 4.7 Environmental and planning considerations ......................................................................12 5 Combiners.........................................................................................................................................12 5.1 Introduction ........................................................................................................................12 5.2 Selection of parameters.....................................................................................................13 5.3 Frequency response ..........................................................................................................14 5.4 Matching ............................................................................................................................15 5.5 Filters .................................................................................................................................15 5.6 Directional couplers ...........................................................................................................16 5.7 Combiners .........................................................................................................................17 5.8 Starpoint combiners...........................................................................................................17 5.9 Directional filters ................................................................................................................18 5.10 Function of module ............................................................................................................18 5.11 Cascading of modules .......................................................................................................19 5.12 Multiplexers........................................................................................................................22 5.13 Stretchline combiners ........................................................................................................22 6 Antennas and feeders .......................................................................................................................24 6.1 Choice of transmitting antenna type ..................................................................................24 6.2 Transmitting antenna system specification........................................................................24 6.3 Receiving antenna systems...............................................................................................25 7 Interference generated on site ..........................................................................................................26 7.1 Modulation related effects (out of band emissions) ...........................................................26 7.1.1 Overdeviation ................................................................................................26 7.1.2 The effect of multiplex signal power..............................................................27 7.1.3 Broadband noise and spurious products.......................................................27 7.2 Spurious emissions............................................................................................................33 7.2.1 Intermodulation effects..................................................................................33 7.2.2 Other spurious emissions..............................................................................33 7.3 Protection of re-broadcast reception..................................................................................33 7.4 Natural and man-made noise ............................................................................................33 8 Audio processing limiter ....................................................................................................................33 8.1 Introduction ........................................................................................................................33 8.2 Major limiter types..............................................................................................................34 8.2.1 Principles of operation...................................................................................34 8.2.1.1 Feedback-controlled broadband limiter ...............................34 8.2.1.2 Forward-controlled broadband limiter..................................34 8.2.1.3 Multiband limiter...................................................................35 Page 4 ETR 132: August 1994 8.2.1.4 Advantages and disadvantages of the different types of limiters with regard to the limiting characteristics and its effect on the audio signal .................................................... 35 8.3 Static and dynamic response of limiters as a function of typical parameters.................... 36 8.4 Measurement methods to characterise audio-frequency limiter circuits........................... 39 8.5 Measurements and assessment with the help of programme signals .............................. 41 9 Earthing ............................................................................................................................................ 42 9.1 Electric shock .................................................................................................................... 42 9.2 Lightning............................................................................................................................ 42 9.2.1 Thermal effects............................................................................................. 42 9.2.2 Electrodynamic effects.................................................................................. 43 9.2.3 Electrochemical effects................................................................................. 43 9.2.4 Electromagnetic field effects......................................................................... 43 9.3 Feeder earthing................................................................................................................. 43 9.4 Recommended earthing arrangements for UHF and VHF transmitting aerial masts generally high and medium powered stations................................................................... 44 9.5 Recommended earthing arrangements for UHF and VHF transmitting aerial towers generally high and medium powered stations................................................................... 44 9.6 Recommended earthing arrangements for UHF, VHF and SHF transmitter towers generally low powered stations ........................................................................................