PURPOSE: To attain accurate charging even when a charging-pulse period is varied during a call, by calculating periodical data before and after the variation in charging-pulse period.
CONSTITUTION: Charging pulse period assignment part 11 displays a charging pulse period on control part 13 and arithmetic part 14 under the control of timer part 12. Every second, control part 13 reads out remaining time A-a from memory 15 and inputs it to arithmetic unit 16, where it is subtracted by data "1"; when the result is not "0", it is written to memory 15 and when "0", one charging pulse is generated by pulse generating part 17 and a second numeral equivalent to the charging pulse period. At point T in time when the period from assignment part 11 is changed from A to B, time A-a read out from memory 15 is written to arithmetic part 14, where the remaining time is multiplied by period rate B/A to obtain time (b), so that it will be stored in memory 15. Afterward, a pulse is generated at period B
OKI FUMIO
NAKAGAWA TOORU
NIPPON TELEGRAPH & TELEPHONE