术语解释“zero crossing counter”

xiongbindhu

术语解释“zero crossing counter”,干啥用的？

skatecom

zgq800712

骚年，google会用不？
8 i7 \" {  ]/ Y

风吹摇摆

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

0 R: P- p7 E' q( m0 b6 I不要用古狗，用百度！
9 z% n2 M7 u  n* e% R5 V

木头脑瓜

风吹摇摆 发表于 2013-6-25 08:37
不要用古狗，用百度！

7 k, z+ x# x' q0 `8 A$ ?狗主的地盘敢不用古狗^_^

超級狗

' g8 K" w4 j* t7 S7 z8 H' X0 F) E4 P7 [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）

7 Y2 s7 x! u0 K' v, B解釋︰
6 _: o# l" h/ r以零做為基準點的計數器，當訊號跨越零點時才計數。

優點︰
% b1 c9 E; j7 C/ H4 ?% o

• 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。
  5 G' S  Y. X, q

) l2 E$ B9 ^( j9 a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）。
  

7 E! n  ~, u# x......
" G- h1 G" F$ X$ l1 [5 B
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:}

xiongbindhu

超級狗 发表于 2013-6-25 09:07
, \/ [5 _) s, S. j0 e' ?, _0 x* x用途很廣，我找到的並非全部，大家參考一下好了。

# t7 o: F' n$ I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。
3q，gogo

zgq800712

Zero Crossing Counter
  t0 U  M" ^+ @; \5 X( ^
8 w- x, E8 q' y  B  y( j  o
& g7 U; n3 u( ^# n8 A" w; {; ]
In some DSP applications, it can be very helpful to know how many times your signal has crossed the zero-line (amplitude origin).
9 y" q2 k! @3 u. n
' N" ^! F( |0 g. {* ^* OHow 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)
3 {. [' e9 Z. a& }9 e* z: \0 a
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

! Q5 E* n. _9 q+ lOne 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.