User note: FFT averaging - Revision history

Lmagimel at 09:10, 26 November 2024

2024-11-26T09:10:45Z

← Older revision		Revision as of 11:10, 26 November 2024
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			[[category:WikiOros]]
	NVGate provides many settings for averaging results. This document aims to describe these functions and parameters for averaging data results. This document focuses on averaging available at FFT modules. These are quite similar settings for SOA modules.		NVGate provides many settings for averaging results. This document aims to describe these functions and parameters for averaging data results. This document focuses on averaging available at FFT modules. These are quite similar settings for SOA modules.

Lmagimel at 07:40, 4 April 2022

2022-04-04T07:40:10Z

← Older revision		Revision as of 09:40, 4 April 2022
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	This technique is used for some modal tests with a shaker excitation to reject non-linear phenomena. In this case, the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.<br>		This technique is used for some modal tests with a shaker excitation to reject non-linear phenomena. In this case, the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.<br>

	We advice to read [[~~NVGate_FFT_Analyzer~~#Average\|ref peak hold averaging]] on FFT page for more info.		We advice to read [[NVGate_FFT#Average\|ref peak hold averaging]] on FFT page for more info.

Lmagimel: /* Ref. Peak Hold average */

2020-06-19T08:53:01Z

Ref. Peak Hold average

← Older revision		Revision as of 10:53, 19 June 2020
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	It is basically the same feature as the Peak Hold average. The main difference is that it collects and holds the data of the spectrum according to a new peak on the reference channel.		It is basically the same feature as the Peak Hold average. The main difference is that it collects and holds the data of the spectrum according to a new peak on the reference channel.

	This technique is used for some modal tests with a shaker excitation to reject non-linear phenomena. In this case, the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.		This technique is used for some modal tests with a shaker excitation to reject non-linear phenomena. In this case, the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.<br>

			We advice to read [[NVGate_FFT_Analyzer#Average\|ref peak hold averaging]] on FFT page for more info.

LDesmet: English edits

2020-06-18T21:19:01Z

English edits

Lmagimel: /* Ref. Peak Hold average */

2020-06-18T13:44:44Z

Ref. Peak Hold average

← Older revision		Revision as of 15:44, 18 June 2020
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	This technique is used for some modal test with a shaker excitation to reject non linear phenomena. In this case the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.		This technique is used for some modal test with a shaker excitation to reject non linear phenomena. In this case the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.

	~~[[category:Averaging]]~~

Lmagimel: /* Ref. Peak Hold average= */

2020-04-29T13:32:43Z

Ref. Peak Hold average=

← Older revision		Revision as of 15:32, 29 April 2020
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	[[Image:Averaging_07.png\|framed\|none]]		[[Image:Averaging_07.png\|framed\|none]]

	===Ref. Peak Hold average====		====Ref. Peak Hold average====

	In the same way the '''Ref. Peak Hold average''' is no more a mathematical average.		In the same way the '''Ref. Peak Hold average''' is no more a mathematical average.

Lmagimel: /* Peak Hold average */

2020-04-29T13:32:24Z

Peak Hold average

← Older revision		Revision as of 15:32, 29 April 2020
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	[[Image:Averaging_07.png\|framed\|none]]		[[Image:Averaging_07.png\|framed\|none]]
	~~Be careful phase of FRF in peak hold is not accurate (the channel reference for phase can change...). Use the ref. peak hold. (see below)~~


	===Ref. Peak Hold average====		===Ref. Peak Hold average====

Lmagimel at 13:31, 29 April 2020

2020-04-29T13:31:52Z

← Older revision		Revision as of 15:31, 29 April 2020
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	~~==Averaging==~~

	NVGate provides many settings for averaging result. This document aim at describing these functions and parameters for averaging data result. This document focuses on averaging available at FFT modules. These are quite similar setting for SOA modules.		NVGate provides many settings for averaging result. This document aim at describing these functions and parameters for averaging data result. This document focuses on averaging available at FFT modules. These are quite similar setting for SOA modules.

	~~{\|cellspacing~~=~~"0" cellpadding~~ = ~~"10" style~~=~~"border-style:solid; border-color:black; border-width:1px;" width~~=~~"100%"~~		===Why averaging?===
	~~\|<font color~~=~~"#4F81BD"><font size~~ = ~~"4">''' 1/ Why averaging?'''</font></font>~~

	\|}

	There are many reasons that lead to average measurement to get accurate results.		There are many reasons that lead to average measurement to get accurate results.
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	Averaging parameters should be setup according analysis and tracked phenomena.		Averaging parameters should be setup according analysis and tracked phenomena.
			===Averaging Domain===

	~~{\|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;" width="100%"~~
	~~\|<font color="#4F81BD"><font size = "4">'''2/ Averaging Domain'''</font></font>~~

	\|}

	Averaging could be done in either '''Frequency''' or '''Time Domain'''.		Averaging could be done in either '''Frequency''' or '''Time Domain'''.

	* '''Frequency Average~~'''~~		====Frequency Average====

	Each signal block generates an FFT, the average result is the average of the spectrum :		Each signal block generates an FFT, the average result is the average of the spectrum :
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	Data result is available for magnitude only. There is no information about the phase.		Data result is available for magnitude only. There is no information about the phase.

	* '''Time Domain~~'''~~		====Time Domain====

	The average is performed in time domain, the FFT is computed on the average time signal data		The average is performed in time domain, the FFT is computed on the average time signal data
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	This allows to focus on a specific phenomena even if there is no trigger available to perform Time domain analysis.		This allows to focus on a specific phenomena even if there is no trigger available to perform Time domain analysis.

	~~{\|cellspacing~~=~~"0" cellpadding~~ = ~~"10" style~~=~~"border-style:solid; border-color:black; border-width:1px;" width~~=~~"100%"~~		===Average Type===
	~~\|<font color~~=~~"#4F81BD"><font size~~ = ~~"4">'''3/ Average Type'''</font></font>~~

	\|}

	~~1) '''~~linear average~~'''~~
			====linear average====

	For the '''linear average''', each "n" spectrum get the same weight for the averaging. It usually set for long time averaging result. The result is according the global level of energy for each narrow band during the duration of measurement.		For the '''linear average''', each "n" spectrum get the same weight for the averaging. It usually set for long time averaging result. The result is according the global level of energy for each narrow band during the duration of measurement.
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	[[Image:Averaging_05.png\|framed\|none]]		[[Image:Averaging_05.png\|framed\|none]]

	~~2) '''~~Exponential Average~~'''~~		====Exponential Average====

	The '''Exponential Average''' is computed with a linear average for the last "n" spectrums whereas older spectrum has a lower weight. Exponential average provides an infinite sliding result. This is commonly use with a low value of average. As it kept the student variation in memory for a short time, this is a good setting for monitoring or tracking non temporary phenomena.		The '''Exponential Average''' is computed with a linear average for the last "n" spectrums whereas older spectrum has a lower weight. Exponential average provides an infinite sliding result. This is commonly use with a low value of average. As it kept the student variation in memory for a short time, this is a good setting for monitoring or tracking non temporary phenomena.
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	[[Image:Averaging_06.png\|framed\|none]]		[[Image:Averaging_06.png\|framed\|none]]

	~~3) '''~~Peak Hold average~~'''~~		====Peak Hold average====

	The '''Peak Hold average''' is not any mathematical average. The peak hold provides a result that correspond, at each band, for the maximal value of each the "n" spectrum. It is useful to get the maximal values as a worst case of measurement:		The '''Peak Hold average''' is not any mathematical average. The peak hold provides a result that correspond, at each band, for the maximal value of each the "n" spectrum. It is useful to get the maximal values as a worst case of measurement:

	[[Image:Averaging_07.png\|framed\|none]]		[[Image:Averaging_07.png\|framed\|none]]
			Be careful phase of FRF in peak hold is not accurate (the channel reference for phase can change...). Use the ref. peak hold. (see below)


	~~4) '''~~Ref. Peak Hold average~~'''~~		===Ref. Peak Hold average====

	In the same way the '''Ref. Peak Hold average''' is no more a mathematical average.		In the same way the '''Ref. Peak Hold average''' is no more a mathematical average.

Lmagimel: Created page with "==Averaging== NVGate provides many settings for averaging result. This document aim at describing these functions and parameters for averaging data result. This document focu..."

2020-04-29T13:28:07Z

Created page with "==Averaging== NVGate provides many settings for averaging result. This document aim at describing these functions and parameters for averaging data result. This document focu..."

New page

==Averaging==

NVGate provides many settings for averaging result. This document aim at describing these functions and parameters for averaging data result. This document focuses on averaging available at FFT modules. These are quite similar setting for SOA modules.

{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;" width="100%"
|''' 1/ Why averaging?'''

|}

There are many reasons that lead to average measurement to get accurate results.

FFT analysis is performed on an extract of time signal which is called "trigger block"

Averaging enable to get compliance with the basics FFT hypothesis.

* Get a analysis on a stationary signal data
* Reduce input noise, averaging increase the signal/noise ratio
* By definition FFT estimator provides 100% standard deviation

[[Image:Averaging_01.png|framed|none]]

[[Image:Averaging_02.png|framed|none]]

Averaging parameters should be setup according analysis and tracked phenomena.

{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;" width="100%"
|'''2/ Averaging Domain'''

|}

Averaging could be done in either '''Frequency''' or '''Time Domain'''.

* '''Frequency Average'''

Each signal block generates an FFT, the average result is the average of the spectrum :

[[Image:Averaging_03.png|framed|none]]

Data result is available for magnitude only. There is no information about the phase.

* '''Time Domain'''

The average is performed in time domain, the FFT is computed on the average time signal data

[[Image:Averaging_04.png|framed|none]]

It results complex data that can be displayed in Magnitude and Phase (or Real Imaginary).

Time domain averaging makes sense for synchronous time block, it must be use with a trigger for block synchronization, else the average make no sense.

This average is useful to avoid getting result from external sources. For example in a noisy factory, setting a trigger linked to a specific machine will prevent from getting noise from other machine.

There is an additional average type named '''Frequency Synchronous '''or '''FDSA.''' This is based on Frequency domain average but it act as Time domain average. It uses one frequency line (specifies by user) as a phase reference, each FFT is recomputed so that the phase of this reference frequency is set to "0".

This allows to focus on a specific phenomena even if there is no trigger available to perform Time domain analysis.

{|cellspacing="0" cellpadding = "10" style="border-style:solid; border-color:black; border-width:1px;" width="100%"
|'''3/ Average Type'''

|}

1) '''linear average'''

For the '''linear average''', each "n" spectrum get the same weight for the averaging. It usually set for long time averaging result. The result is according the global level of energy for each narrow band during the duration of measurement.

[[Image:Averaging_05.png|framed|none]]

2) '''Exponential Average'''

The '''Exponential Average''' is computed with a linear average for the last "n" spectrums whereas older spectrum has a lower weight. Exponential average provides an infinite sliding result. This is commonly use with a low value of average. As it kept the student variation in memory for a short time, this is a good setting for monitoring or tracking non temporary phenomena.

[[Image:Averaging_06.png|framed|none]]

3) '''Peak Hold average'''

The '''Peak Hold average''' is not any mathematical average. The peak hold provides a result that correspond, at each band, for the maximal value of each the "n" spectrum. It is useful to get the maximal values as a worst case of measurement:

[[Image:Averaging_07.png|framed|none]]

4) '''Ref. Peak Hold average'''

In the same way the '''Ref. Peak Hold average''' is no more a mathematical average.

It is basically same feature as the Peak Hold average. The main difference that it collects and holds the data of the spectrum according to a new peak on the reference channel.

This technique is used for some modal test with a shaker excitation to reject non linear phenomena. In this case the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.

[[category:Averaging]]

← Older revision		Revision as of 23:19, 18 June 2020
Line 1:		Line 1:

	NVGate provides many settings for averaging ~~result~~. This document ~~aim at describing~~ these functions and parameters for averaging data ~~result~~. This document focuses on averaging available at FFT modules. These are quite similar ~~setting~~ for SOA modules.		NVGate provides many settings for averaging results. This document aims to describe these functions and parameters for averaging data results. This document focuses on averaging available at FFT modules. These are quite similar settings for SOA modules.

	===Why averaging?===		===Why averaging?===
Line 6:		Line 6:


	There are many reasons that lead to average measurement to ~~get~~ accurate results.		There are many reasons that lead to average measurement to provide accurate results.

	FFT analysis is performed on an extract of time signal which is called "trigger block"		FFT analysis is performed on an extract of time signal which is called "trigger block"

	Averaging ~~enable to get~~ compliance with the basics FFT hypothesis.		Averaging enables compliance with the basics FFT hypothesis.

	* Get a analysis on a stationary signal data		* Get a analysis on a stationary signal data.
	* Reduce input noise, averaging increase the signal/noise ratio		* Reduce input noise, averaging increase the signal/noise ratio.
	* By definition FFT estimator provides 100% standard deviation		* By definition FFT estimator provides 100% standard deviation.

	[[Image:Averaging_01.png\|framed\|none]]		[[Image:Averaging_01.png\|framed\|none]]
Line 43:		Line 43:
	It results complex data that can be displayed in Magnitude and Phase (or Real Imaginary).		It results complex data that can be displayed in Magnitude and Phase (or Real Imaginary).

	Time domain averaging makes sense for synchronous time block, it must be use with a trigger for block synchronization, ~~else~~ the average make no sense.		Time domain averaging makes sense for synchronous time block, it must be use with a trigger for block synchronization, otherwise the average will not make sense.

	This average is useful to avoid getting ~~result~~ from external sources. For example in a noisy factory, setting a trigger linked to a specific machine will prevent from ~~getting~~ noise from other machine.		This average is useful to avoid getting results from external sources. For example, in a noisy factory, setting a trigger linked to a specific machine will prevent from receiving noise from other machine.

	There is an additional average type named '''Frequency Synchronous '''or '''FDSA.''' This is based on Frequency domain average but it ~~act~~ as Time domain average. It uses one frequency line (specifies by user) as a phase reference, each FFT is recomputed so that the phase of this reference frequency is set to "0".		There is an additional average type named '''Frequency Synchronous '''or '''FDSA.''' This is based on Frequency domain average but it acts as Time domain average. It uses one frequency line (specifies by user) as a phase reference, each FFT is recomputed so that the phase of this reference frequency is set to "0".

	This allows to focus on a specific phenomena even if there is no trigger available to perform Time domain analysis.		This allows to focus on a specific phenomena even if there is no trigger available to perform Time domain analysis.
Line 57:		Line 57:
	====linear average====		====linear average====

	For the '''linear average''', each "n" spectrum ~~get~~ the same weight for the averaging. It usually set for long time averaging result. The result is according the global level of energy for each narrow band during the duration of measurement.		For the '''linear average''', each "n" spectrum gets the same weight for the averaging. Its usually set for long time averaging result. The result is according the global level of energy for each narrow band during the duration of measurement.

	[[Image:Averaging_05.png\|framed\|none]]		[[Image:Averaging_05.png\|framed\|none]]
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	====Exponential Average====		====Exponential Average====

	The '''Exponential Average''' is computed with a linear average for the last "n" spectrums whereas older spectrum ~~has~~ a lower weight. Exponential ~~average~~ provides an infinite sliding result. This is commonly ~~use~~ with a low value of average. As it ~~kept~~ the student variation in memory for a short time, this is a good setting for monitoring or tracking non temporary phenomena.		The '''Exponential Average''' is computed with a linear average for the last "n" spectrums whereas older spectrum have a lower weight. Exponential averaging provides an infinite sliding result. This is commonly used with a low value of average. As it keeps the student variation in memory for a short time, this is a good setting for monitoring or tracking non-temporary phenomena.

	[[Image:Averaging_06.png\|framed\|none]]		[[Image:Averaging_06.png\|framed\|none]]
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	====Peak Hold average====		====Peak Hold average====

	The '''Peak Hold average''' is not ~~any~~ mathematical average. The peak hold provides a result that ~~correspond~~, at each band, for the maximal value of each the "n" spectrum. It is useful to get the maximal values as a worst case of measurement:		The '''Peak Hold average''' is not a mathematical average. The peak hold provides a result that corresponds, at each band, for the maximal value of each the "n" spectrum. It is useful to get the maximal values as a worst case of measurement:

	[[Image:Averaging_07.png\|framed\|none]]		[[Image:Averaging_07.png\|framed\|none]]
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	====Ref. Peak Hold average====		====Ref. Peak Hold average====

	In the same way the '''Ref. Peak Hold average''' is ~~no more~~ a mathematical average.		In the same way the '''Ref. Peak Hold average''' is not a mathematical average.

	It is basically same feature as the Peak Hold average. The main difference that it collects and holds the data of the spectrum according to a new peak on the reference channel.		It is basically the same feature as the Peak Hold average. The main difference is that it collects and holds the data of the spectrum according to a new peak on the reference channel.

	This technique is used for some modal ~~test~~ with a shaker excitation to reject non linear phenomena. In this case the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.		This technique is used for some modal tests with a shaker excitation to reject non-linear phenomena. In this case, the Ref. Peak Hold average is used as a tracking filter linked with excitation frequency.