1、STD-CEPT ERC REPORT 42-ENGL l99b W 232b4L4 00l55bb Tlb W ERC REPORT 42 European Radiocommunications Committee (ERC) within the European Conference of Postal and Telecommunications Administrations (CEPT) C - . . . ,. x. k HANDBOOK ON RADIO EQUIPMENT AND SYSTEMS RADIO MICROPHONES AND SIMPLE WIDE BAND
2、AUDIO LINKS Rome, October 1996 STD.CEPT ERC REPORT 42-ENGL 1996 W 2326434 0015567 952 m Copyright 1996 the European Conference of Postal and Telecommunications Administrations (CEPT) sTD.CEPT ERC REPORT 42-ENGL 1796 232b4l14 0015568 8qq 9 ERC REPORT 42 Pnge 1 CONTENTS Foreword 2 1. 2. 3. 4. 5. 6. 7.
3、 8. 9. 10. Introduction . . . . . . . . . 3 Definitions. , , , , , , , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Type Testing Standards and Current Frequency Allocations 4 Typical Applications . . . . . . .6 Radiated power polar patterns for bo
4、dy worn and handheld transmitters . 12 Radio Microphone Technical Parameters . . . ._ . . . 14 Radio Microphone System Calculations . . . . . Radio Microphone Development . . . . . . . . 20 Digital Possibilities . . 20 9.1. Spread Spectnun 23 9.2. 24 Simple Audio Links 24 Conclusion. . , . . . . . .
5、 . . . . . . . . . . . . . . Appendix A Current Frequency Allocations . . . . . . . 25 Appendix B Free Field Losses 27 Appendix C Multichannel Spectrum Plots showing Intermodulation Products and Interleaving . 29 Appendix D Intermodulation 35 Appendix E Grid Spacing ,. . 37 Appendix F RF Protection
6、Ratio . . 39 Typical Contribution Quality Radio Microphone _ . ., .,. . ._. ,. 4 1 . 43 Appendix I Typical High Power Non Contribution Quality Audio Link . 45 Appendix J Typical Contribution Quality High Power Audio Link with Narrow Band Cue Receiver 47 Acknowledgements . . . . . . . ._ . . ._ _ 49
7、. . . . , , . . . . , , . . . . . , , . . . . . . . . . . . . . . . . . . . . . . . . . . Appendix G Appendix H Typical Contribution Quality High Power Audio Link STDaCEPT ERC REPORT 42-ENGL 1996 9 232b414 00155b9 725 9 ERC REPORT 42 Page 2 FOREWORD This document is one in a series of three handbook
8、s, which contain relevant information on the operation and specifications of radio equipment used by broadcasters and independent programme makers for SAB /SAP work. The other parts in the series are: - - Talkback (in production) Video Links for ENG/OB use (ERC Report 38) STDSCEPT ERC REPORT 42-ENGL
9、 1996 2326434 0035570 447 = ERC REPORT 42 Page 3 1. INTRODUCTION The term SAB covers the use of radio by established terrestrial broadcasters in the making of their programmes. The term SAP has been introduced to cover the radio use of independent progamme makers and other commercial non broadcast u
10、se of radio as follows: Services Ancillary to Programme making (SAP) support the activities carried out in the making of ?programmes?. Programmes include film making, advertisements, corporate videos, sporting events, concerts, theatre and similar activities not initially meant for broadcasting to t
11、he general public. The terms ENG and OB in this handbook have the current agreed definitions (CCIR report 803-2, Annex to Vol. X and XI, parts 3) which refer to video and not audio. To clarify the terms for audio extra information is provided. The radio microphones and audio links referred to in thi
12、s document are regarded as being for professional use. They will be licensed and operate within regulated spectrum. 2. DEFINITIONS Radio microphones Radio microphones (also referred to as wireless microphones or cordless microphones) are small, low power (e50 mW) transmitters designed to be worn on
13、the body or handheld, for the transmission of close, personal sound. The receivers are more tailored to specific uses and may range from small and portable to nck mounted modules, as part of a multichannel system. Simple wideband audio links Simple wideband audio links are larger, higher power (50 m
14、W) transmitters, de- signed to be carried over the shoulder or operated from a fixed position to a distant receiver. The link can carry programme material in either mono or stereo, but a simple audio link will not normally be multiplexed. ENG OB Electronic News Gathering is the collection of televis
15、ion news stories without the use of film, using small handheld, electronic, colour cameras with microwave links to the news mom andlor portable video tape recorders. These cameras are now often combined with a built in recorder for sound and video, using a single operator, but may use an on board mi
16、crowave link for live events, or to a separate video recorder. Progamme sound from the radio microphone(s) may be fed direct to the camera or to a sound recordist and separate recorder. Outside Broadcast is the temporary provision of programme making facilities at the location of on-going news, spor
17、t or other events, lasting from a few hours to several weeks. Outside Broadcasts are generally planned in advance, but it is often necessary to accommodate short notice changes of venue or unforeseen requirements. Video links are required for mobile links, portable links and cordless cameras at the
18、OB location. Additionally, video links may be required as part of a temporary point to point connection between the OB van and the studio. STD-CEPT ERC REPORT 42-ENGL 199b m 23Zb4L4 0015571 383 m ERC REPORT 42 Page 4 Programme sound is not normally recorded directly on a video carnerdrecorder. Both
19、radio microphones and audio links are required depending on the size of the location and degree of public access. Additional audio links may be required as part of a temporary connection to the OB van depending on site conditions. The definitions of ENG and OB are not mutually exclusive, certain ope
20、rations could be in either category, even with ENG operation being part of a larger OB. For this document the term ENG is used to refer to small lightweight radio microphone systems operating to the video camera or mobile sound recordist. OB is used to refer to more complex radio systems with multip
21、le radio microphones and where necessary, audio links. Companding Compander Contribution quality Diversity reception Multichannel set Interleaved set A composite word from compressing and expanding. An analogue technique for improving the signal to noise ratio of a transmission system. The audio dyn
22、amic range is compressed before transmission, by increasing the low level signals, usually using a 2: I logarithmic law (60 dB dynamic range reduced to 30 a). The complementary process of expansion is carried out on the demodulated signal in the receiver. The complementary circuitry in transmitter a
23、nd receiver to implement the companding. A full broadcast quality signal used in the creation of a programme, the first RF link prior to any processing taking place. The use of two or more antennas with switching or combining receiver circuitry. The antennas are positioned to provide complementary c
24、overage, dramatically reducing signal dropout due to multi-path cancellation. A number of frequencies which are selected to be intermodulation free for simultaneous use at one site. Other Multichannel sets within the same frequency band that can be used simultaneously when sufficient physical separa
25、tion is available e.g., in an adjoi- ning studio or theatre. 3. TYPE TESTING STANDARDS AND CURRENT FREQUENCY ALLOCATIONS The majority of European countries have had type approval standards appropriate to radio microphones. All were based on a bandwidth of approximately 200 kHz and frequency modulati
26、on. CEPT Recommen- dation T/R 20-06 (1977) “Transmitters and Receivers for low power Cordless Microphones” was the first pan-European proposal and became the basis for many national type approval standards. However higher power audio link equipment largely was not covered by existing standards. Duri
27、ng 1991, ETSI was requested to update T/R 20-06 and this work has resulted in three standards : 1. I-ETS 300 422 Radio Equipment and Systems (RES); Technical characteristics and test methods for radio microphones in the 25 MHz to 3 GHz frequency range 2. ETS 300 454 Radio Equipment and Systems (RES)
28、; Wide band audio links; Technical characteristics and test methods STD-CEPT ERC REPORT 42-ENGL L99b 2326414 0035572 ZIT ERC REPORT 42 Page 5 1. ETS 300 445 Radio Equipment and Systems (RES); Electro-Magnetic Compatibility (EMC) standard for radio microphones and similar Radio Frequency (RF) audio l
29、ink equipment Within the ETSI standards a radio microphone is a device of 50 mWatts e.r.p. or less and similar devices above this power limit are referred to as audio links. Radio microphones and audio links can both be considered as an alternative when the physical connection of a cable is impracti
30、cal or undesirable. In order to replace the cable, the radio system must be capable of providing a full audio bandwidth signal (20 Hz - 20 kHz), with high dynamic nnge and good signal to noise performance even under weak signal conditions. To achieve these operational criteria, to date, both radio m
31、icrophones and audio links have used wide band frequency modulation. As part of the updating of T/R 20-06, ETSI carried out a survey of frequency allocations for Radio Microphones within Europe. The results can be found in Appendix A. When examining the apparently large allocations in some countries
32、, it should be borne in mind that allocations are often on a geographically restricted basis dependent upon allocations to other users of the band. In many countries allocations are to be found in the 30 - 50 MHz range. Because of man made interferen- ce and length of aerial, the band is rarely used
33、 for high quality radio microphones. STDmCEPT ERC REPORT QZ-ENGL 1996 232h414 0015573 156 = Presenter with handheld radio rniuophone iransmiiter -/ - L-,-, Small mcelver mounted on camera I ERC REPORT 42 Page fi 4. TYPICAL APPLICATIONS With the advent of the lightweight combined video camerairecorde
34、r, an ENG crew can comprise only a reporter and a camera operator. To enable reports to be recorded in difficult locations, a radio microphone is used between the reporter and the camera. ERC REPORT 42 Page 7 When news interviews have to be made quickly a handheld radio microphone transmitter is use
35、d, with the interviewer wearing a body worn transmitter and a small lapel microphone. Sound recordist with 2 small receivers for interviewer and interviewee. I I I I Interviewer wiai body worn transmitter for personal mic. + handheld for interview Figure 2: Interviewer + interviewee to sound recordi
36、st (1 handheld, 1 body worn transmitter, 2 small receivers) STD-CEPT ERC REPORT Y2-ENGL 199b m Z32b41Y 0015575 T27 m ERC REPORT 42 Page 8 For documentary type productions a sound operator will mix the sound from a number of radio microphones, either for recording as separate audio, or to be recorded
37、 on the video recorder. It is common practice to use a radio microphone as a link from the mixer to the recorder to ease freedom of movement. Small receiver mounted on camera % Interviewer with body worn radio microphone transmitter L e- c c L z 5- c Interviewee with body worn c radio microphone tra
38、nsmitter / e c c c z 0 e c Sound remrdist with 2 small recebe and body worn transmitier as a low power link to camera Figure 3: Interviewer + interviewee to sound recordist, link between sound recordist and camera. (3 body pack transmitters, 3 small receivers) STDmCEPT ERC REPORT 42-ENGL 1996 = 2326
39、434 00L557b 9b5 = ERC REPORT 42 Page 9 For outside broadcast applications the division between radio microphones (e50 mW) and audio links (50 mW) is largely academic. For instance, at an outside broadcast event such as a golf tournament, the audio may need to be transmitted over a distance of 1 - 2
40、Km in order to get the signals from the playing area back to the outside broadcast vehicle. In this situation the device would need to be between 1 and 5 watts, depending on local factors. If the transmitter is a conventional 10 mW handheld radio microphone, held by an interviewer, it may feed into
41、an adjacent audio link system worn by an assistant which then relays the signal to the outside broadcast unit. I CarnerawiihVkion IinkTramrnMw mistant with small radb microphone receiver and bacK pack Audio Unk transmitter Intefviewer wlth Hanu heid Radio rnkmphorm lransrnhier tor intewiew Figure 4:
42、 Interviewer to assistant, link to OB van (1 handheld transmitter, 1 small receiver, 1 link transmitter) Alternatively it could be a conventional body worn radio microphone worn by the interviewer with an attached booster amplifier giving a higher final output power direct without the use of an addi
43、tional audio link. However, power will be limited by sizehattery considerations and not normally be above 500 mW. STD.CEPT ERC REPORT 42-ENGL L99b - 232b4L4 0025577 8T1 ERC REPORT 42 Page 10 unk io OB van A I I ;.I I Asslstani Wh boom micmphone connecied directly into back pad50 m 3m 8m 50 m 50 m 5m
44、 15 m Note: 1. The worst case intermodulation scenario, 2 above, with close handheld interferers would be unworkable. 2. Case 4 above, not recommended. STD-CEPT ERC REPORT 42-ENGL 397b m 2326434 0035587 740 W ERC REPORT 42 Page 20 8. RADIO MICROPHONE DEVELOPMENT Radio Microphones have been in use si
45、nce the early 1940s mainly in the film and broadcast industries. In the 1970s they started to appear in a broader area of the entertainment industry, especially within the theatres and concert halls. Since the 1980s the popularity of stage musicals has meant an explosion in the use of multichannel s
46、ystems within theatres throughout Europe. The development of these large multi- channel systems has been reflected in both outside broadcast and studio use as programme makers either cover existing productions or produce their own. The indoor use of large multichannel sets of radio microphones now f
47、alls mainly into two categories: 1. The large single studiohtage multichannel set (can be AO channels). This requires a high level of intermodulation interference protection between the chosen radio microphone frequencies in the set as the transmitters will be operating in close proximity to each ot
48、her. 2. This The use of large numbers of radio microphones in adjacent halls or studios within a complex but usually with each hall or stage operating less channels than 1 above. situation requires a high level of intermodulation interference protection between the radio microphones within each set,
49、 but can have lower intermodulation protection between frequencies in other sets. This is where the interleaving of frequency sets will give considerable improvements in spectrum use (Appendix C). In the London theatre an average of 26 radio microphone channels are in use with peaks to 40 and an expected rise up to 50 channels when some of the newer American musical productions arrive. Similar numbers of channels are also required for events where performers use an extensive radio infrastructure, including
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