1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 . TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0G0/ location; country.The sound programme signal should be controlled by the sending broadcaster so that the amplitudes of thepeaks only rarely exceed the peak amplitude of the permitted maximum
2、(sine-wave test) signal._1)Based on CCIR Recommendation 661 2.2 Fascicle IV.3 Rec. N.13A.1.2 Test signal and level definitionsA.1.2.1 alignment signal (AS)Sine-wave signal at 1020 Hz at a level of 0 dBm0s, which is used to align the international sound-programmeconnection.A.1.2.2 measurement signal
3、(MS)Sine-wave signal at 1020 Hz at a level 12 dB below the alignment signal level, which should be used for long-term measurements and measurements at all frequencies.A.1.2.3 permitted maximum signal (PMS)Sine-wave signal at 1020 Hz, 9 dB above the alignment signal level, equivalent to the permitted
4、 maximumprogramme-signal level.A.2 Test signal formatA.2.1 A three-level sinusoidal test signal at a reference frequency of 1 kHz should be used to check the alignment ofinternational sound programme connection. These three levels should be combined with the source identification and berepeated cycl
5、ically as specified in the format shown in Figure A-1/N.13 for monophonic and stereophonic connections.FIGURE 1/N.13.D01d01-scFascicle IV.3 Rec. N.13 3A.2.2 Provisionally, the portion of the test signal designated at +9 dBm0s in Figure A-1/N.13 will be replaced by asignal at 0 dBm0s. The resulting t
6、wo-level test signal is required until all transmission systems are capable of carryingsinusoidal signals at +9 dBm0s without producing excessive channel loading or crosstalk into other channels.A.2.3 Some organizations may not have automatically generated test levels as defined in A.2.1 and A.2.2.
7、In thesecases, the alignment level of 0 dBm0s at 1020 Hz should be used for the alignment of international sound programmeconnections.A.3 Measurement methodsThe fundamental concept of the test signals is to provide organizations with accurate and well defined levels.These levels are intended to prov
8、ide rapid identification of level errors as well as to allow operational personnelsufficient time to make the necessary level adjustments at the appropriate points in the international sound programmeconnection. Alignment of the connection is made by adjusting the alignment signal to the appropriate
9、 point on theprogramme level meter. Identification of left and right channels is provided as shown in Figure A-1/N.13.References1 CCITT Recommendation Automatic equipment for rapidly measuring stereophonic pairs and monophonicsound-programme circuits, links and connections, Vol. IV, Rec. O.33.2 CCIR Recommendation Signals for the alignment of international sound-programme connections, Vol. XII,Rec. 661, ITU, Geneva, 1986.
