ITU-R P 581-2-1990 THE CONCEPT OF WORST MONTH 《概念》.pdf

1、CCIR VOLUMEMV 90 W 4855212 0500350 T 46 Rec. 581-2 , RECOMMENDATION 581-2 THE CONCEPT OF “WORST MONTH” (Question 2/5) (1982-1986- 1990) . The CCIR, CONSIDERING (a) reference; (b) to the period of reference of the performance criteria; (c) that performance criteria for radiocommunication systems ofte

2、n refer to “any month” as the period of that for the design of such systems it is necessary to have statistics of propagation effects that are relevant that consequently there is a need for an unambiguous definition for the period of reference, - UNANIMOUSLY RECOMMENDS 1. that the fraction of time d

3、uring which a preselected threshold is exceeded in the worst month of a year is referred to as “the annual worst-month time fraction of excess”; 2. the annual worst-month time fraction of excess; that the statistic relevant for the performance criteria referring to “any month” is the long-term avera

4、ge of 3. that the worst month of a year for a preselected threshold for any performance degrading mechanism, be that month in a period of twelve consecutive calendar months, during which the threshold is exceeded for the longest time. The worst month is not necessarily the same month for all thresho

5、ld levels. Note - Report 723 presents a model for the conversion of the average annual time fraction of excess to the average annual worst-month time fraction of excess. Global values of the parameters of this model are given, as well as more detailed values for several regions of the world. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services