en:wiki:funktionen:td-functions:phase_extraction
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- | + | ====== Phase Extraction ====== | |
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- | | + | |
- | //(remove this paragraph once the translation is finished)// | + | |
- | ====== Phase-Extraction ====== | + | |
{{: | {{: | ||
\\ | \\ | ||
- | **Beschreibung:** \\ | + | **Description:** \\ |
- | Am Anfang und am Ende der angegebenen Frequenz wird der Frequenzgang der geladenen Kurve begradigt. | + | Below the lower limit and above the upper limit specified frequency, the frequency response of the loaded curve is made flat. |
\\ | \\ | ||
- | **Optionen:** \\ | + | **Options: ** |
- | //Minimum phase:// \\ | + | |
- | //Linear phase:// \\ | + | |
- | //Excess phase:// \\ | + | |
- | //Advanced mixed phase:// | + | |
- | \\ | + | * //Minimum phase: //This option is used to calculate the unique impulse which has the specifed frequency response and is Minimum Phase. A minimum phase filter has the smallest possible group delay at any given frequency (consistent with producing the required overall frequency response), and hence the smallest signal latency, but the group delay may not be constant at all relevant frequencies. The minimum phase impulse has no pre-ringing but may have post-ringing. The location of the pulse peak is usually at or near the first sample of the filter. |
- | **Verwendung:** \\ | + | * //Linear phase: //This option is used to calculate a filter (impulse) which has the specified frequency response with a constant group delay at all frequencies. The price for a constant group delay is that the absolute group delay is large. The large constant delay may not matter if listening to audio, but needs to be taken into account if audio is live or needs to be synchronized with video. The impulse is symmetric, with the pulse peak located in the center of the filter. Accordingly, |
- | Soll nur ein Teil der Information aus einem Frequenzgang für eine Korrektur verwendet werden kann mit dieser Funktion der Rest ober- oder unterhalb des gewählten Spektrums verworfen, bzw. begradigt werden. Diese Funktion wird z.B. benötigt um mit den Informationen einer Nahfeldmessung [[: | + | * //Excess phase: //This option calculates a filter with constant 0 dB frequency response but which incorporates any group delay in the input curve in excess of that which the minimum phase component of that curve would produce. Because of the flat amplitude response, such a filter is often called an "All Pass" filter. A typical impulse response can be separated into the minimum phase component and the excess phase component. Convolving the two components reproduces the original pulse. |
+ | * //Advanced mixed phase: //With this option, while maintaining the frequency response, any phase curve between minimum phase (0), Linear Phase (1) and maximum phase (2) are calculated. The parameter can also be in between, for example, 0.159. Possible application: | ||
+ | \\ **Use:** \\ The choice of correction filter for a mixed-pulse response may be due principally due to the amount of acceptabe delay. For pure audio reproduction this usually does not matter. In the case of video or live music, a large delay may not be acceptable. Here the shortest lead time is achieved with a minimum phase correction filter. But no excess phase is corrected. | ||
- | \\ | + | A limited band of frequency response can be used for a correction with this function with the frequency response information discarded above or below the selected spectrum (that is, the frequency response output of this funtion is a horizontal straight line below the lower limit and above the higher limit). This function is required, for example to use a near-field recording of frequency response of a speaker driver |
- | **Beispiel: | + | |
- | In folgendem Beispiel soll ein Korrekturfilter erstellt werden, der nur den Bassbereich bis etwa 150Hz korrigiert. Dazu werden [[: | + | |
- | \\ | + | \\ **Example: |
- | \\ | + | |
- | {{:bilder_funktionen:funkt_bsp_phase-extraction_01.png? | + | |
- | Für den nächsten Schritt bestehen zwei Möglichkeiten: | + | \\ \\ {{: |
- | \\ | + | |
- | {{: | + | |
- | \\ | + | |
- | Sind dort keine Schnittpunkte zu finden kann man auch einen waagrechten Bereich suchen, und für beide Kurven eine etwas andere Trennfrequenz im nächsten Schritt eingeben. Wichtig ist dabei nur, dass die beiden Signalstärken am späteren Schnittpunkt identisch sind. (Sonst wäre der unkorrigierte Frequenzbereich einer Seite lauter) | + | |
- | \\ | + | In this case it is important that the uncorrected range of frequencies above approximately 150hz have the same gain applied by the filter, otherwise it will affect the balance of the channels. So for the next step there are two possibilities: |
- | {{: | + | |
- | \\ | + | |
- | In diesem Beispiel wurde in den Schnittpunkt bei etwa 150HZ gezoomt und der genaue Schnittpunkt mit der linken Maustaste angeklickt. Danach erhält man auf der rechten seite des Programmfensters die Frequenz, bei der die Markierung gesetzt wurde.\\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | \\ | + | |
- | {{: | + | |
- | Nun die Kurve 1 am Radiobutton aktivieren und TD Functions > Phase Extraction | + | Now activate the curve 1 on the radio button and select |
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- | \\ | + | |
- | \\ | + | |
- | {{: | + | |
- | \\ | + | |
- | Nach löschen der Original Inversen aus dem Kurvenfenster erhält man folgendes Bild. Die beiden neuen Dateien müssen noch mit dem Namen der alten Inversen | + | |
en/wiki/funktionen/td-functions/phase_extraction.txt · Last modified: 30/06/2016 18:22 by hamish