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？

风吹摇摆

zgq800712 发表于 2013-6-24 22:58
骚年，google会用不？

8 M- ~& g" k* ?不要用古狗，用百度！

木头脑瓜

风吹摇摆 发表于 2013-6-25 08:37
不要用古狗，用百度！

6 j( D+ F, l6 ]' ]6 t狗主的地盘敢不用古狗^_^

超級狗

: u! y- W( }6 G' d7 m用途很廣，我找到的並非全部，大家參考一下好了。

零交越計數器（Zero Crossing Counter）

解釋︰
* I8 z( ?4 L" _2 `) B- f5 o以零做為基準點的計數器，當訊號跨越零點時才計數。
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優點︰

• 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。
  

0 U3 j6 _2 d$ W* O) T4 L2 M應用︰
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• 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）。
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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！
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{:soso_e163:}
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xiongbindhu

超級狗 发表于 2013-6-25 09:07
, A: S' k$ C+ n% |  Z用途很廣，我找到的並非全部，大家參考一下好了。
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8 u1 y5 E) V  R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。
# i7 F3 O  u6 L4 h3q，gogo

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).

2 H: t$ I# d/ d( d; f+ MHow 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)
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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

: ~6 Y7 F) D* N6 k, i0 OOne 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.