Peak

The title of this article is ambiguous. Further meanings are listed under Peak (disambiguation) .

The term peak comes from English and means 'summit, peak, peak value'. In measurement technology and stochastics , a peak is used to denote a significant peak value .

If you plot measured values ​​in a diagram in a vertical direction (ordinate, y-axis) against time, location or another variable (e.g. wavelength ) as the horizontal axis (abscissa, x-axis), increased measured values ​​appear as They are also called peaks. For them, on the one hand the x-value of the maximum is interesting, but also mostly either the height of the apex or the area under the peak. In practice, the measured values ​​to the left and right of the peak are usually not zero, but the peak is a clear rise and fall again (deflection) of the measuring signal above the background noise .

Three peak symmetries ( chromatography )

Examples:

• Chromatography ( gas chromatography , high-performance liquid chromatography ): each peak in the chromatogram corresponds to a detected substance
• every “photopeak” in a gamma spectrum corresponds to a proven gamma spectral line
• in economic statistics , for example, Peak Oil , the point in time when global oil production peaks
• In acoustics and audio technology, the peaks are called the level and are measured with the level meter (peak meter), which shows the maximum peak over a measuring period

The measures for the intensity of the peak are generally the factors that are also used as a basis for normal distribution , in particular values ​​that are used to evaluate the time of the peak:

• the crest factor, a measure of the ratio of peak level to mean value ( effective value in electrical measurement technology)

${\displaystyle k_{s}={\frac {x_{\mathrm {max} }}{x_{\mathrm {med} }}}}$or for negative peaks with only positive scales, otherwise ${\displaystyle k_{s}={\frac {x_{\mathrm {med} }}{x_{\mathrm {min} }}}}$ ${\displaystyle k_{s}={\frac {|x_{\mathrm {max/min} }-x_{\mathrm {med} }|}{x_{\mathrm {med} }}}}$

• the tailing factor (' sidecut ' of the tip, width of the peak), at around 5% or 10% of the peak height, which is also a measure of the symmetry of the peak

${\displaystyle k_{t}={\frac {y_{\mathrm {a} }}{y_{\mathrm {b} }}}}$or with y _a , y _b as the distance of the underlying percentage from peak value ${\displaystyle k_{t}={\frac {y_{\mathrm {a} }+y_{\mathrm {b} }}{2y_{\mathrm {a} }}}}$

See also

• Transients
• Glitch (electronics)
• Prime time
• Peakfinder