en:wiki:funktionen:td-functions:phase_extraction
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en:wiki:funktionen:td-functions:phase_extraction [28/06/2016 22:02] – hamish | en:wiki:funktionen:td-functions:phase_extraction [30/06/2016 18:22] (current) – hamish | ||
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- | **Options: ** \\ | + | **Options: ** |
- | //Minimum phase: // \\ | + | |
- | //Linear phase: // \\ | + | |
- | //Excess phase: // \\ | + | |
- | //Advanced mixed phase:// | + | |
- | [Can Uli or another | + | * //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 |
+ | * //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, | ||
+ | * //Excess phase: //This option calculates | ||
+ | * //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 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. | ||
- | \\ | ||
- | **Use:** \\ | ||
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 [[: | 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 [[: | ||
- | \\ | + | \\ **Example: |
- | **Example: | + | |
- | In the following example, a correction filter is desired which corrects only the bass up to about 150Hz. For this purpose [[: | + | |
- | \\ | + | \\ \\ {{: |
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- | {{: | + | |
- | 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 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: |
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- | {{: | + | |
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- | {{: | + | |
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- | In this example, we have zoomed into the intersection at about 150HZ and clicked the exact point of intersection with the left mouse button. Then you get on the right side of the program window, the frequency at which the mark has been set.\\ | + | |
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- | {{: | + | |
- | Now activate the curve 1 on the radio button and select TD Functions> | + | Now activate the curve 1 on the radio button and select TD Functions> |
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- | {{: | + | |
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- | After deleting the original curves you get the following picture. The two new files still must be saved with the name of the old inverse (or Pulse48Linv.dbl Pulse48Rinv.dbl). After that you can create a filter with Room Macro 4. | + | |
en/wiki/funktionen/td-functions/phase_extraction.1467151367.txt.gz · Last modified: 28/06/2016 22:02 by hamish