空接点脉冲信号，如1PPS，1PPM, 1PPH,在选用合适的控制电缆传输信号时，其实际传输距离< ( )m。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='29469' and id < 2398826 and id<>'2398826' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29469' and id > 2398826 and id<>'2398826' order by id asc limit 5