L20 标准查询与下载

ITU-R P.844-1-1994 在VHF和UHF频段内(30MHz-3GHz)影响频率共享的电离层因素

Radio propagation at VHF is mainly controlled by physical objects, such as terrain and ground cover (clutter), and tropospheric factors, principally refraction. However, at VHF, ionospheric propagation over long distances can take place with relatively s

Ionospheric Factors Affecting Frequency Sharing in the VHF and UHF Bands (30 MHz-3 GHz)

ITU-T SERIES G SUPP 31-1993 为局域网确定阻抗策略的原则

This Supplement gives the background and guidance required to support a consistent approach to impedance planning in the local network. It is clear that impedance issues are having an increasingly important influence on end-to-end performance as they can

Principles of Determining an Impedance Strategy for the Local Network - Transmission Systems and Media General Characteristics of National Systems Forming Part of International Connections Study Group XII; 11 pp

ITU-R BR.649-1-1992 模拟语音磁带记录的测量方法.第10/11F部分.记录声音程序交换

that the international exchang of monophonic z d st reophonic re orded i alogue sound programmes between broadcasting organizations may be made by means of magnetic recordings on tape, as stipulated in Recommendation 407

Measuring Methods for Analogue Audio Tape Recordings - Section 10/11F - Exchange of Recorded Sound Programmes

ITU-R BT.711-1-1992 合成数字演播的同步参考信号

This Annex describes an analogue reference signal for the synchronization of component digital video equipment

Synchronizing reference signals for the component digital studio

ITU-R BT.807-1992 数据广播的参考模型

The study and development of systems and services of data broadcasting are active in various areas such as the television and sound channels in terrestrial and satellite broadcasting.

Reference Model for Data Broadcasting

ITU-T S.17-1989 应答模拟器

Bearer services provide for information transfer between ISDN access points. They are characterized by a set of low layer attributes including information transfer and access attributes depicting the bearer capability associated with each bearer service,

Answer-Back Unit Simulators - Telegraph Services Terminal Equipment (Study Group IX) 1 pp

ITU-T S.7-1989 电传机马达的控制

that if a complex installation connected to the telex network incorporates both outgoing-only terminals and terminals which may be called, then the call number of the group of terminals which may be called, or of one of them, should appear in the answerba

Control of Teleprinter Motors - Telegraph Services Terminal Equipment (Study Group IX) 2 pp

ITU-T S.11-1989 供凿孔纸带转发用的起止复凿设备的使用

that when a station is equipped with receiving reperforating equipment, it is often necessary to clear the perforated tape of the perforator to ensure transmission of the last characters of a message received during the perforation of the first character

Use of Start-Stop Reperforating Equipment for Perforated Tape Retransmission - Telegraph Services Terminal Equipment (Study Group IX) 1 pp

ITU-T SERIES D SUPP 1-1988 成本和资费研究方法

Cost and tariff study method

Cost and tariff study method

ITU-T SERIES E.800 SUPP 1-1988 厄兰公式表

Supplement 1 was approved in Melbourne (1988) and originally published in Blue Book, Fascicle II.3.

Table of the Erlang formula