术语解释“zero crossing counter”
骚年，google会用不?
不要用古狗，用百度！
狗主的地盘敢不用古狗^_^
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︰
以零做為基準點的計數器，當訊號跨越零點時才計數。
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。
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！
我看的资料这边，那应该是用来测量信号频率的。
3q，gogo
Zero Crossing Counter
In some DSP applications, it can be very helpful to know how many times your signal has crossed the zero-line (amplitude origin).
How 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
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.