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标题: 术语解释“zero crossing counter” [打印本页]
作者: xiongbindhu    时间: 2013-6-24 17:17
标题: 术语解释“zero crossing counter”
术语解释“zero crossing counter”,干啥用的？
作者: skatecom    时间: 2013-6-24 19:29
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作者: zgq800712    时间: 2013-6-24 22:58
骚年，google会用不？
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作者: 风吹摇摆    时间: 2013-6-25 08:37
zgq800712 发表于 2013-6-24 22:58
& x* L& V2 q1 j2 ^  A2 m; h- n骚年，google会用不？

" j/ @; y7 N8 @& s0 ]不要用古狗，用百度！
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作者: 木头脑瓜    时间: 2013-6-25 08:57
风吹摇摆 发表于 2013-6-25 08:37 8 G2 W1 Y  k" s1 v# Q
不要用古狗，用百度！

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作者: 超級狗    时间: 2013-6-25 09:07
本帖最后由 超級狗 于 2013-6-25 15:24 编辑
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用途很廣，我找到的並非全部，大家參考一下好了。8 u5 @- ^: Q# V, K, o
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零交越計數器（Zero Crossing Counter）
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解釋︰: f7 ^, x5 U$ B7 c# ?) ?+ ], [' U: V
以零做為基準點的計數器，當訊號跨越零點時才計數。. l' h4 V  r# Q6 c$ E

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應用︰
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; M1 I+ z: w( o; l9 B) |7 q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！# J/ J( `5 N, A) w! ?; B/ M
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{:soso_e163:}
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作者: xiongbindhu    时间: 2013-6-25 12:37
超級狗 发表于 2013-6-25 09:07
9 e8 E3 F5 V' A9 D* n$ s/ Y用途很廣，我找到的並非全部，大家參考一下好了。8 D8 _% Q- Y9 ]% g3 t7 u
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零交越計數器（Zero Crossing Counter）
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{:soso_e163:} ' b  w! f5 I2 }" O$ S1 Q  p! _% w2 R
我看的资料这边，那应该是用来测量信号频率的。
# C8 R, D& a# g1 w8 O% N/ e3q，gogo
作者: zgq800712    时间: 2013-6-25 15:00
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). ) P3 q- Q1 `4 x; H

3 G) a: J9 A% ^; Q3 Y2 JHow 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); W/ h% G9 |) P

' i: Q+ P; `0 IIn 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" L1 v( ~! f0 {* Z
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One 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.



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