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Group RDS : 4 version A
The group 4A is used to transmit the hour and the date.
If this group is used, hours and date have to correspond exactly at the hour " Universal Time Coordinate " UTC + local offset. Otherwise the data must be positioned in 0.
When this group is used, it must be transmitted every minutes. The Clock time group is inserted so that the minute edge will occur within ± 0.1 seconds of the end of the Clock time group.
Hours and date are transmitted by using 34 bits, Assemble available data sets (part1,2 and 3) to form a block of 37 bits, 3 spare bits are used to complet the part 3.
Modified Julian Date : The date of day is coded on 17 bits to form a number from 0 to 99999 allowing to determine the day, the month and the year, as well as the daytime of the week, the number of the week and the number of the year since 1900. (See secondary G of file rbds1998.pdf for details of conversion funtions).