PURPOSE: To utilize effectively the processing time for call detection even in case an idle circuit number is produced by supplying the count output of a counter circuit as an address and providing a circuit number memory to a call detecting part to deliver the selected circuit number.
CONSTITUTION: A count output (x) which advances every time region (t) is supplied to a circuit number memory 10 as an address from a counter circuit 6. Then the circuit numbers N stored in the address corresponding to the memory 10 are successively read out and sent to a circuit selecting circuit 7 and a call detection control memory 8. The circuit 7, as shown in a figure 3, selects successively the circuit corresponding parts 2 of six circuits packaged within a unit of unit number U=1 to the 1st∼6th time regions (t) to check the presence or absence a call signal. Then the circuit 7 starts immediately selection of the part 2 packaged in a unit of number U=2 at and after the 7th time region (t). Thus the part 2 never allots any region (t) to the circuit number N consisting of the unpackaged unit number U=1 and intra-unit numbers L=7 and L=8.
MASUJIMA HIKARI
TAKANO RIYOUJI
MISE KIYOBUMI
