Programmer Guide/SPU Reference/ZEROCROSS: Difference between revisions
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{{DISPLAYTITLE:{{SUBPAGENAME}}}} | |||
Compute zero crossing rate. | |||
==<code>[SPU ZEROCROSS <var>X SR XMIN TYPE</var> OUT <var>Y</var>]</code>== | |||
{|class="einrahmen" | |||
!input !!description !!data type !!value type!!default value | |||
|- | |||
|<var>X</var>||signal vector||vector ||variable || | |||
|- | |||
|<var>SR</var>||sampling rate in Hz||number||constant||<code>1<code> | |||
|- | |||
|<var>XMIN</var>||signal amplitude threshold||number||constant ||<code>0</code> | |||
|- | |||
|<var>TYPE</var>||type of output value<BR>(<code>DENSITY, FREQUENCY, PERIODE, COUNT</code>)||number (int.), string||<code>0</code> (= <code>DENSITY</code>) | |||
|- | |||
!output !!description !!data type !!value type!!comment | |||
|- | |||
|<var>Y</var>||zero crossing rate converted to the selected value||number||variable | |||
|} | |||
;Description: | |||
{|class="einrahmen" | |||
!output !!<var>NORM</var>=<code>0</code> !!<var>NORM</var>=<code>1</code> !!description | |||
|- | |||
|<var>M1</var> | |||
|<math>\mu\!</math> | |||
|<math>\mu\!</math> | |||
|mean: <math>\mu = \frac{\sum_{i=0}^{N-1} x_i px_i}{\sum_{i=0}^{N-1} px_i}</math> | |||
|- | |||
|<var>M2</var> | |||
|<math>V\!</math> | |||
|<math>\frac{V}{\mu}</math> | |||
|variance: <math>\sigma^2 = V = \frac{\sum_{i=0}^{N-1}(x_i-\mu)^2px_i}{\sum_{i=0}^{N-1} px_i}</math> | |||
|- | |||
|<var>M3</var> | |||
|<math>S\!</math> | |||
|<math>\frac{S}{\sqrt{V^3}}</math> | |||
|skewness: <math>S = \frac{\sum_{i=0}^{N-1}(x_i-\mu)^3px_i}{\sum_{i=0}^{N-1} px_i}</math> | |||
|- | |||
|<var>M4</var> | |||
|<math>K\!</math> | |||
|<math>\frac{K}{V^2}</math> | |||
|kurtosis: <math>K = \frac{\sum_{i=0}^{N-1}(x_i-\mu)^4px_i}{\sum_{i=0}^{N-1} px_i}</math> | |||
|} | |||
;See also: | |||
<[[../#Signal Processing Atoms|SP-atoms]]> | |||
<!-- AN, 2.5.2011 --> | |||
{{DISPLAYTITLE:{{SUBPAGENAME}}}} | {{DISPLAYTITLE:{{SUBPAGENAME}}}} | ||
====ZEROCROSS - zerocrossing rate==== | ====ZEROCROSS - zerocrossing rate==== | ||
Revision as of 12:05, 9 May 2011
Compute zero crossing rate.
Contents
[SPU ZEROCROSS X SR XMIN TYPE OUT Y]
| input | description | data type | value type | default value |
|---|---|---|---|---|
| X | signal vector | vector | variable | |
| SR | sampling rate in Hz | number | constant | 1 |
| XMIN | signal amplitude threshold | number | constant | 0
|
| TYPE | type of output value ( DENSITY, FREQUENCY, PERIODE, COUNT) |
number (int.), string | 0 (= DENSITY)
| |
| output | description | data type | value type | comment |
| Y | zero crossing rate converted to the selected value | number | variable |
- Description
| output | NORM=0 |
NORM=1 |
description |
|---|---|---|---|
| M1 | μ | μ | mean: μ=∑i=0N−1xipxi∑i=0N−1pxi |
| M2 | V | Vμ | variance: σ2=V=∑i=0N−1(xi−μ)2pxi∑i=0N−1pxi |
| M3 | S | SV3 | skewness: S=∑i=0N−1(xi−μ)3pxi∑i=0N−1pxi |
| M4 | K | KV2 | kurtosis: K=∑i=0N−1(xi−μ)4pxi∑i=0N−1pxi |
- See also
<SP-atoms>
ZEROCROSS - zerocrossing rate
Usage:
ZEROCROSS x sr xmin type
Inputs:
| x | signal | |
| sr | sampling rate in Hz | |
| xmin | threshold | 0 (default) |
| type | Frequency | Period)
|
Outputs:
| y | number of zero crossings |
Function:
In this atom the zero crossings per second are counted, i.e. the points where between the last counted point and the current point, there exists a value xprev >= xmin and the current value xcurr<= 0 or xprev <= xmin and the current value is xcurr >= 0.
So if xmin = 0 all zero crossings, i.e. changes of signs, are counted. If xmin > 0 the signal has to exceed a certain absolute value if another point is to be counted.
