| 摘要 |
<p>PURPOSE:To remove noises and signals which are not required and to make it possible to detect a required scanning signal by storing the arriving histories of the scanning signals having a specified arriving interval into a RAM, and detecting the scanning signals only when the the number of the histories exceed a reference value. CONSTITUTION:The arriving interval of scanning signals is preset in a RAM control circuit 3 with control data (b). The access timing of the RAM 4 for storing the history of the arriving signal is set. The contents of the RAM 4 are sequentially written into a shift register SR 5. The presence or absence of the arriving signal (a) is updated and stored in the SR 5 at this timing. The updated contents of the histories are written into the RAM 4 again. When the SR 5 is shifted and the contents are updated, the number of the histories is counted in a counter 6. The counted value is compared with a reference value of control data (c) in a comparator 7. When the counted value is larger than the reference value and the signal (a) is in the present state, the signal (a) is not a noise and the like. A scan-arriving signal (d) for indicating the fact that the signal is the scanning signal having the specified arriving interval is outputted to an electronic computer. Thus the processing load of the electronic computer can be alleviated.</p> |
