The paper introduces the principle of frequency measure based on double-counter and multi-periods pulse synchronization method, and the designing with microprocessor is offered.

介绍了双计数器多周期同步法频率测量原理，给出了用单片机实现的具体实现方案。

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I often try to double-check a counter the first time I add it to a report.

我经常尝试仔细检查我第一次添加到报告的计数器。

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Data selector alternately to realize the functions of double edge trigger addition counter output the odd and even data in two counters.

数据选择器则将两个计数器中处于保持状态的奇偶数据交替输出，实现双边沿触发加法计数器的功能。

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As United held firm, with an ever-present menace on the counter-attack, Ancelotti made a double change with 20 minutes left, replacing Yuri Zhirkov and Drogba with Florent Malouda and Nicolas Anelka.

BBC: Chelsea 0-1 Man Utd

These love to pretend that they live in one of the world's toughest urban jungles, beset by warring gangs and malevolent Nature, when, in reality, the biggest danger they face is that the person behind the counter at Starbucks might mis-hear their order for a double tall, decaf, non-fat latte with a vanilla shot and make their coffee with full-fat milk by mistake.

ECONOMIST: California life: City of frauds | The

When it said recently it expected the UK economy to shrink slightly in the first quarter of 2012, I did wonder whether the downbeat prediction would turn out to be a counter-indicator - a sign that we had definitely avoided a double dip.

BBC: Britain's zig-zag economy