1、 Rec. ITU-R BT.266-1 1 RECOMMENDATION ITU-R BT.266-1*Phase pre-correction of television transmitters (1959-1992) The ITU Radiocommunication Assembly, considering a) that most current television receivers use quasi-synchronous detection; b) that a linear overall phase response is essential for data b
2、roadcasting services, for example, Teletext; c) that different transmitter phase pre-corrections are used in different countries; d) that current receivers are designed to operate with the existing phase characteristics of the transmitters to ensure an overall phase linearity; e) that modern receive
3、r filter technology does not necessarily require a transmitter phase pre-correction; f) that considerable benefits are obtained if the phase pre-correction of transmitters were removed and receivers with a linear phase characteristic were used, recommends 1 that administrations which are changing th
4、eir transmitters to operate with no phase pre-correction, so that receivers with a linear phase characteristic may be used, should allow a sufficiently long transition period and should agree with receiver manufacturers to ensure that the dates for pre-correction and receiver change are aligned; 2 t
5、hat any intermediate pre-correction changes during the transition period should be sufficiently small so that there is no noticeable impairment of the reception quality; 3 that administrations within a given broadcasting area should arrange to have similar transition periods and similar intermediate pre-correction changes. _ *Radiocommunication Study Group 6 made editorial amendments to this Recommendation in 2002 in accordance with Resolution ITU-R 44.
