1、BRITISH STANDARD BS 6513-1: 1984 Wideband cabled distribution systems Part 1: Glossary of terms UDC 621.396.44:654.195.2+621.397.132.122:654.197.2:001.4BS6513-1:1984 This British Standard, having been prepared under the directionof the Electronic Equipment Standards Committee,was published underthe
2、authority of the BoardofBSI and comes into effect on 31 July 1984 BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference EEL/25 Draft for comment 83/23534 DC ISBN 0 580 13903 4 Committees responsible for this British Standard The preparation of this British
3、 Standard was entrusted by the Electronic Equipment Standards Committee (EEL/-) to Technical Committee EEL/25 upon which the following bodies were represented: British Broadcasting Corporation British Radio and Electronic Equipment Manufacturers Association British Telecommunications Department of T
4、rade and Industry, Directorate of Radio Technology Institution of Electronic and Radio Engineers Radio, Electrical and Television Retailers Association The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Kinematograph, Sound and Telev
5、ision Society Cable Television Association of Great Britain Consumer Standards Advisory Committee of BSI Consumers Association Electric Cable Makers Confederation Electronic Components Industry Federation Electronic Engineering Association Independent Broadcasting Authority Institution of Electrical
6、 Engineers Society of Cable Television Engineers Telecommunication Engineering and Manufacturing Association Amendments issued since publication Amd. No. Date of issue CommentsBS 6513-1:1984 BSI 07-1999 i Contents Page Committees responsible Inside front cover Foreword ii 0 Scope 1 Section 1. System
7、 structures and practices 1 Section 2. Active equipment stations 1 Section 3. Feeders 2 Section 4. Distribution system equipment 2 Section 5. Subscriber-related equipment 3 Section 6. Characteristics of the signal 4 Section 7. Performance characteristics 4 Section 8. Miscellaneous 5 Index 7 Figure 1
8、 Illustrative diagram showing application of some terms defined 6 Publications referred to Inside back coverBS6513-1:1984 ii BSI 07-1999 Foreword This Part of BS6513 has been prepared under the direction of the Electronic Equipment Standards Committee. It is based on a draft provided by the Departme
9、nt of Trade and Industry. It forms Part1of a multipart standard for wide-band cabled distribution systems; the other Parts to date are as follows: Part 2: Methods of measurement; Part 3: Specification for performance requirements, including system safety, for downstream television and f.m. sound rad
10、io signals; Part 4: Specification for performance requirements, including system safety, for upstream television. Defined terms used in other definitions are shown in italics. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are re
11、sponsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. This standard has
12、 been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6513-1:1984 BSI 07-1999 1 0 Scope This Part of BS6513 gives terms and definitions which are applicable to wideband cabled distribution systems. The a
13、pplication of these terms is illustrated inFigure 1. NOTE 1Terms that are not defined in this glossary but are used in other Parts of the standard are defined in BS4727-3:Group04or in the appropriate International Radio Consultative Committee (CCIR) document. However, this standard uses the term “ca
14、bled distribution system” instead of “wired distribution system” as defined in BS4727-3:Group04. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. Section 1. System structures and practices No. Term Definition 1 01 tree structured network tree net
15、work A cabled distribution system in which subscribers feeders are connected to spur feeders via subscribers taps. 1 02 star structured network star network A cabled distribution system in which subscribers feeders are connected directly to star points. 1 03 switched star structured network s witche
16、d star network A cabled distribution system in which subscribers feeders are connected directly to switching points. 1 04 bidirectional system two-way system A cabled distribution system incorporating both forward and reverse paths. 1 05 forward path downstream The transmission path followed by sign
17、als travelling away from a head end towards a subscribers premises. 1 06 reverse path upstream The transmission path followed by signals travelling away from a subscribers premises towards a head end. 1 07 status monitoring A process whereby specific conditions throughout a cabled distribution syste
18、m are centrally monitored. 1 08 encryption scrambling A process by which a signal is deliberately modified so that it will not yield a picture (or sound) of acceptable quality unless it is first subjected to a complementary process to restore it substantially to its original form. 1 09 decryption de
19、scrambling The process of removing the modification of a signal introduced by encryption. 1 10 switching The selection of a desired signal from a number of available signals. Section 2. Active equipment stations 2 01 head end Equipment that is connected between receiving antennas or other signal sou
20、rces and the remainder of the cabled distribution system to process the signals to be distributed. NOTEThe head end may, for example, comprise antenna amplifiers, frequency converters, combiners, separators and generators. 2 02 local head end hub head end A subsidiary head end often located at the c
21、entre of its service area with inputs from a supertrunk feeder (or microwave link) and possibly other sources. 2 03 distribution point A point where signals are taken from the trunk feeder to energize branch and/or spur feeders. NOTEIn some cases a distribution point may be directly connected to the
22、 head end. 2 04 conversion point A distribution point at which frequency conversion of one or more of the input signals is effected. 2 05 data concentration point A distribution point to which several switching points are connected, where data signals to and from those switching points are handled.B
23、S6513-1:1984 2 BSI 07-1999 No. Term Definition 2 06 star point A point in a cabled distribution system where signals are taken from a branch feeder to energize a number of subscribers feeders. 2 07 switching point switched star point A star point at which one or more of the signals applied to, or re
24、ceived from, the subscribers feeders are switched, usually by remote control. Section 3. Feeders 3 01 feeder A transmission path forming part of a cabled distribution system. Such a path may consist of a metallic cable, optical fibre, waveguide, or any combination of them. NOTEThis term is also appl
25、ied to paths containing one or more radio links. 3 02 supertrunk feeder A feeder that connects only between head ends. 3 03 trunk feeder A feeder used for connection between: a) a head end and a distribution point; b) two or more distribution points. 3 04 branch feeder sub-trunk feeder A feeder used
26、 for connecting a distribution point to: a) spur feeders; or b) one or more star points 3 05 spur feeder A feeder to which subscribers taps or looped system outlets are connected. 3 06 subscribers feeder A feeder connecting a star point or a subscribers tap to a system outlet. Section 4. Distributio
27、n system equipment 4 01 antenna amplifier An amplifier (often a low noise type) associated with a receiving antenna. 4 02 trunk amplifier An amplifier to compensate for attenuation in a trunk feeder. 4 03 bridger amplifier 1) An amplifier for connection in a trunk feeder to provide a distribution po
28、int. 2) An amplifier for connection in a branch feeder, to energize one or more branch or spur feeders. 4 04 trunk bridger amplifier An amplifier to compensate for attenuation in a trunk feeder and also to provide a distribution point. 4 05 distribution amplifier An amplifier designed to feed one or
29、 more branch or spur feeders. 4 06 branch amplifier A distribution amplifier to compensate for attenuation in a branch feeder. 4 07 spur amplifier line extender A distribution amplifier to compensate for attenuation in a spur feeder. 4 08 automatic level controlled amplifier An amplifier that includ
30、es means to control automatically the level of the signal(s) at its output. NOTEThis may be achieved using variation of gain or slope or both, by means of: a) one or more pilot carriers; b) a temperature-sensing device; c) remote control. .BS6513-1:1984 BSI 07-1999 3 No. Term Definition 4 09 automat
31、ic gain controlled amplifier An amplifier with the means to maintain constant the level of the signal at its output, using the signal to be controlled as the control stimulus. 4 10 frequency converter A device for changing the carrier frequency of one or more signals prior to transmission on a feede
32、r. 4 11 encrypter scrambler An equipment for encryption of a signal. 4 12 decrypter descrambler An equipment for decryption of an encrypted signal. NOTEIn cabled distribution systems this will often be located in the subscribers premises. 4 13 combiner A device in which the signals arriving at two o
33、r more input ports are fed to a single output port. NOTESome forms of this device may be used in the reverse direction as a splitter. 4 14 separator A device in which the signal energy at one (input) port which covers a frequency band is divided between two or more (output) ports each of which cover
34、s a part of that frequency band. NOTE 1For example, a diplexer is a two-output separator. NOTE 2Some forms of this device may be used in the reverse direction for combining. 4 15 splitter spur unit A device in which the signal energy at the input port is divided equally or unequally between two or m
35、ore output ports. NOTESome forms of this device may be used in the reverse direction as a combiner. 4 16 directional coupler A splitter in which the attenuation between any two output ports exceeds the sum of the attenuations between the input port and each of those output ports. 4 17 equalizer A de
36、vice designed to compensate over a certain frequency range the amplitude/frequency distortion or the phase/frequency distortion introduced by feeders or equipment. NOTEThis device is used for the compensation of linear distortion only. 4 18 subscribers tap A device for connecting a subscribers feede
37、r to a spur feeder. Section 5. Subscriber-related equipment 5 01 channel selector A device incorporated in the system for selecting the desired channel; often at the subscribers premises. 5 02 remote channel selector A channel selector located at the switching point and operated by remote control. 5
38、 03 system outlet A device for interconnecting a subscribers feeder and a receiver lead. 5 04 looped system outlet A device through which the spur feeder passes and to which is connected a receiver lead, without the use of a subscribers feeder. 5 05 receiver lead A lead that connects the system outl
39、et to the subscribers apparatus. NOTEIt may include filters and balun transformers in addition to the cable.BS6513-1:1984 4 BSI 07-1999 No. Term Definition 5 06 signal adaptor A device which, in a cabled distribution system distributing television signals not conforming in r.f. structure to any CCIR
40、 system, modifies the signal to achieve conformity with the appropriate CCIR system, without changing the baseband characteristics. 5 07 cabled system receiver A television or sound receiver specifically designed to operate from a cabled distribution system. 5 08 set-top converter A device connected
41、 in a receiver lead, to change the system carrier frequencies to those for which the receiver was designed. 5 09 remote addressable converter An equipment serving the purpose of a set-top converter which is situated outside the subscribers premises but is remotely operated by the subscriber, which i
42、s addressable from the distribution system. Section 6. Characteristics of the signal 6 01 standard reference power (P 0 ) The power dissipated in a757 resistor with a voltage drop of14V r.m.s. across it, which is equal to1/75pW. 6 02 level The decibel ratio of a power, P 1 , to the standard referenc
43、e power, P 0 , expressed in decibels, i.e.: This may be expressed in decibels relative to14V in757 or more simply as dB(4V) if there is no risk of ambiguity. NOTEBy “power” in relation to a vision-modulated carrier is meant power at the peak of the modulation envelope (i.e.the maximum r.m.s. voltage
44、 squared and divided by the resistance). 6 03 attenuation Of a system or part thereof. The ratio of the input power to the output power, expressed in decibels. 6 04 gain Of a system or part thereof. The ratio of the output power to the input power, expressed in decibels. 6 05 frequency response The
45、gain or attenuation of a system plotted against frequency. 6 06 slope Between any two points in a system. The difference in gain or attenuation at two specified frequencies. 6 07 signal tilt The difference in level deliberately established between specified signals or groups of signals at any point
46、in a system. 6 08 block tilt A particular case of signal tilt in which the difference in level is established between signals or groups of signals occupying specific frequency bands within the spectrum. Section 7. Performance characteristics 7 01 crossview video crosstalk The effect, in a multicircu
47、it system, on a wanted television signal of the undesired transfer of one or more television signal(s) from other circuit(s). 7 02 composite beat A spurious signal resulting from intermodulation, consisting of a group or groups of closely spaced products. 7 03 cross-modulation The undesired modulati
48、on of the carrier of a desired signal by the modulation of another signal as a result of system non-linearities. 10log 10 p 1 p 0 - dBBS6513-1:1984 BSI 07-1999 5 No. Term Definition 7 04 intermodulation The process whereby non-linearity in equipment in a system produces spurious output signals (call
49、ed intermodulation products) at frequencies which are linear combinations of those of the input. 7 05 mutual isolation The attenuation between one system outlet and another at any frequency within the range of the system under investigation. It is always specified, for any particular installation, as the minimum value obtained within specified frequency limits. 7 06 echo rating (E) The result of a system test with a 2T sine-squared pulse, employing the boundary line on a specified graticule within which all parts of the receiv
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