标准摘要
[中文适用范围]： IEC 60728 的这一部分定义了地面广播和卫星接收系统头端中使用的设备的特性（没有卫星室外单元，并且头端中没有 IEC 60728-3 中所述的宽带放大器）。用于 FSS 的卫星室外机在 ETSI ETS 300 158 中进行了描述，对于 BSS 在 ETSI ETS 300 249 中进行了描述。ETSI ETS 300 457 中规定了两种类型（FSS 和 BSS）卫星室外机的测试方法。该标准 • 涵盖了频率范围 5 MHz 至 3 000 MHz， • 确定某些参数的性能要求， • 规定某些参数的数据发布要求， • 规定测量方法； • 引入了定义质量等级（Q 等级）的最低要求。该标准定义了外部源/接收器（例如天线、电缆调制解调器终端系统等）与电缆网络的系统接口之间的上行/下行信号的总体特性。在模块化头端系统的情况下，还描述了调制器、转换器等单一设备。本标准中未描述电缆调制解调器终端系统、加密器、解密器等。如果此类设备用于前端，则应满足射频、视频、音频和数据接口的相关参数。根据3.1 中的定义，头端分为以下三个质量等级： • 1 级：中央头端； • 2 级：集线器头端或集线器站点； • 3 级：MATV 头端/个人接收头端。 [外文原描述]： It defines the characteristics of equipment used in the headends of terrestrial broadcast and satellite receiving systems (without satellite outdoor units and without those broadband amplifiers in the headend as described in IEC 60728-3). The satellite outdoor units for FSS are described in ETSI ETS 300 158, for BSS in ETSI ETS 300 249. Test methods for both types (FSS and BSS) of satellite outdoor units are laid down in ETSI ETS 300 457. This edition includes the following significant technical changes with respect to the previous edition: Revised title and scope Clause 3, several new terms and definitions Subclause 4.1, Methods of measurement for digitally modulated signals Subclause 4.6.2, RF signal-to-noise ratio (SD,RF/N) for digitally modulated signals Subclause 4.8.2, Procedure for the measurement of group delay variation on DVB channel converters Subclause 4.9, Phase noise of an RF carrier Subclause 4.15, Decoding margin (Teletext). Annex D, Special national conditions. Annex E, Correction factors for noise. Annex F, Digital signal level and bandwidth. Annex G, Minimum frequency distance of converted satellite signals in the IF range. Annex H, Measurement errors which occur due to mismatched equipment. .Annex I, Correction factor for spectrum analyser
英文名称Cable networks for television signals, sound signals and interactive services - Part 5: Headend equipment