1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 2 G0BISTELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(94%,%2!0(G0G042!.3-)33)/.-!).4%.!.#%G0G0-%!352%-%.43/(b) that certain Administrations consider it desirable to have available apparatus for making simplemeasurements automatically and periodicall
2、y, giving an indication of the performance rating and transmitting an alarmwhen this rating exceeds the limits permitted for automatic switched channels,unanimously declares the view(1) that it is desirable to make character error rate measurements after commissioning the transmission systemand for
3、maintenance purposes on the international sections of international telegraph circuits made up of at least twochannels;(2) that these measurements should be made at the nominal modulation rate of the circuit under test preferablywith the stardardized text specified in Recommendation R.51 bis;(3) tha
4、t it is desirable to define the effective net margin as follows:a) for regenerative equipment use the appropriate Recommendation,b) non-regenerative equipment, error rate tests should use a margin of no less than 40% and should be madein conjunction with distortion measurements.Note Recommendation R.54 gives an allowable character error rate of 3 per 100 000 for the complete circuit.The proportion of this character error rate allowable on the international section only is for further study.
