术语解释“zero crossing counter”

xiongbindhu

术语解释“zero crossing counter”,干啥用的？

skatecom

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zgq800712

骚年，google会用不？
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风吹摇摆

zgq800712 发表于 2013-6-24 22:58
" g0 \- _1 E  _1 z! ^骚年，google会用不？

不要用古狗，用百度！
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木头脑瓜

风吹摇摆 发表于 2013-6-25 08:37
( y: W$ r+ m/ I0 }; c$ g不要用古狗，用百度！

1 Z" g4 f. v1 p6 F. i9 [9 d狗主的地盘敢不用古狗^_^

超級狗

用途很廣，我找到的並非全部，大家參考一下好了。
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零交越計數器（Zero Crossing Counter）

解釋︰
以零做為基準點的計數器，當訊號跨越零點時才計數。

優點︰
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• 對於不斷變換的訊號有較精準的頻率量測值。
• 有些控制希望在零點時做變化調整，才不會有副作用。
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應用︰

• 影像處理
• 語音辮識
• 光學分析
• 都普勒（Doppler）雷達
• 電源供應器功率因子調整（PFC）。
  

......

我以前的工作經驗，交換機（PBX）有用到。振鈴產生器（Ring Generator）會在零交越（Zero Crossing）時才將振鈴繼電器（Ring Relay）切換回正常的位置，避免電話端殘存的高電平回灌交換機（PBX），將振鈴產生器（Ring Generator）打死！

{:soso_e163:}

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xiongbindhu

超級狗 发表于 2013-6-25 09:07
用途很廣，我找到的並非全部，大家參考一下好了。
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零交越計數器（Zero Crossing Counter）

{:soso_e163:}
我看的资料这边，那应该是用来测量信号频率的。
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zgq800712

Zero Crossing Counter
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In some DSP applications, it can be very helpful to know how many times your signal has crossed the zero-line (amplitude origin).

4 ~7 x' K; H0 ZHow is this helpful?  Well, zero-crossings can tell you very quickly if your signal is composed of high frequency content or not.  Let's say your sample rate is 50kHz and over a small window of 1,000 samples there are 500 zero-crossings.  That would mean that every two samples crosses the zero-line (i.e. 12.5kHz)

In speech processing, the zero-crossing counts can help distinguish between voiced and un-voiced speech.  Un-voiced sounds are very noise-like ('Shh' and 'Sss' for example).  In addition, zero-crossings could also be used to determine if your signal has a DC offset.  If you signal is 'muted' and you are not seeing alot of zero-crossings might mean that your signal is offset from the zero-line

4 O# c( A% \$ [" q# I9 h, QOne nice thing about the matlab code below is that it is implemented in a very DSP-friendly way.  It ports very easily into C-Code and does minimizes the amount of conditional statements for faster processing time.