User FAQ - Revision history

Mellinger: /* Compiling, Building, and Debugging Issues */

2020-08-04T14:38:48Z

Compiling, Building, and Debugging Issues

← Older revision		Revision as of 14:38, 4 August 2020
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	*[[Programming FAQ\|Frequently Asked Questions]]		*[[Programming FAQ\|Frequently Asked Questions]]
	*[[Programming Howto:Quickstart Guide]]		*[[Programming Howto:Quickstart Guide]]
	*[[Programming Howto:Building BCI2000]]		*[[Programming Howto:Building and Customizing BCI2000]]
	*[[Programming Howto:SVN Client Setup]]		*[[Programming Howto:SVN Client Setup]]
	*[[Programming Howto:Using TortoiseSVN]]		*[[Programming Howto:Using TortoiseSVN]]

Mellinger at 14:36, 4 August 2020

2020-08-04T14:36:37Z

← Older revision		Revision as of 14:36, 4 August 2020
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	A: The current version of the BCI2000 gUSBamp source module will not work with the first generation of gUSBamps. Please contact [http://www.gtec.at/ gtec] for a firmware update, or amplifier replacement.		A: The current version of the BCI2000 gUSBamp source module will not work with the first generation of gUSBamps. Please contact [http://www.gtec.at/ gtec] for a firmware update, or amplifier replacement.

			<!--
	===Matlab Signal Processing shows an error at startup===		===Matlab Signal Processing shows an error at startup===
	Q: With Matlab R2009b installed, I cannot start up BCI2000 with the Matlab Signal Processing module. There is an error reported that the library "libeng" cannot be found.		Q: With Matlab R2009b installed, I cannot start up BCI2000 with the Matlab Signal Processing module. There is an error reported that the library "libeng" cannot be found.

	A: It appears that the Matlab R2009b installer does not add Matlab's bin/win32 directory to the system's PATH variable. After manually adding this directory to the PATH variable, the Matlab Signal Processing module is able to find the libeng library.		A: It appears that the Matlab R2009b installer does not add Matlab's bin/win32 directory to the system's PATH variable. After manually adding this directory to the PATH variable, the Matlab Signal Processing module is able to find the libeng library.
			-->
	==Configuration==		==Configuration==

Mellinger at 15:43, 17 January 2013

2013-01-17T15:43:56Z

← Older revision		Revision as of 15:43, 17 January 2013
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			==Compiling, Building, and Debugging Issues==
			For programming-related information, please see
			*[[Programming FAQ\|Frequently Asked Questions]]
			*[[Programming Howto:Quickstart Guide]]
			*[[Programming Howto:Building BCI2000]]
			*[[Programming Howto:SVN Client Setup]]
			*[[Programming Howto:Using TortoiseSVN]]

	==Troubleshooting==		==Troubleshooting==

Mellinger: /* Replaying Recorded Data */

2012-01-30T14:35:44Z

Replaying Recorded Data

← Older revision		Revision as of 14:35, 30 January 2012
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	Q: Rather than controlling BCI2000 from a brain signal, I would like to use a recorded data file as input. Is there a kind of "replay mode" in BCI2000?		Q: Rather than controlling BCI2000 from a brain signal, I would like to use a recorded data file as input. Is there a kind of "replay mode" in BCI2000?

	A: While ~~this could easily be done by, e.g., writing~~ a source module that reads from a file, we have not ~~done this~~, and that for at least two reasons:		A: While there exists a [[Contributions:FilePlayback\|contributed source module that reads from a file]], we have not included it into the BCI2000 core distribution, and that for at least two reasons:
	#If the version of BCI2000 that you are using is not the exact same as the one that was used to record the data, and/or you change some system parameters, then, depending on the experimental paradigm, results may be undefined. E.g., in a 2D cursor task, what should happen if you slow down the cursor such that the cursor has not yet reached a target when in the original data file it has (i.e., and the trial is over?).		#If the version of BCI2000 that you are using is not the exact same as the one that was used to record the data, and/or you change some system parameters, then, depending on the experimental paradigm, results may be undefined. E.g., in a 2D cursor task, what should happen if you slow down the cursor such that the cursor has not yet reached a target when in the original data file it has (i.e., and the trial is over?).
	#Scientifically, it is a bad idea to "simulate" online performance by loading a datafile, changing a few parameters, and seeing how it would have worked. If you are interested in evaluating the effect of different signal processing routines, you should write your own offline analysis routine that uses statistical analyses, together with a comprehensive body of data, or you need to run comprehensive online studies.		#Scientifically, it is a bad idea to "simulate" online performance by loading a datafile, changing a few parameters, and seeing how it would have worked. If you are interested in evaluating the effect of different signal processing routines, you should write your own offline analysis routine that uses statistical analyses, together with a comprehensive body of data, or you need to run comprehensive online studies.

	~~Of course there is nothing in the code that would prohibit you from writing your own such module, but you should note the two caveats above.~~

	For off-line analyses, you might also check out the [[User Reference:Command Line Processing\|Command Line Processing Environment]] which allows you to feed existing data files into arbitrary BCI2000 filter chains.		For off-line analyses, you might also check out the [[User Reference:Command Line Processing\|Command Line Processing Environment]] which allows you to feed existing data files into arbitrary BCI2000 filter chains.

Jhill: /* Offline Filtering */

2012-01-28T02:37:25Z

Offline Filtering

← Older revision		Revision as of 02:37, 28 January 2012
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	Q: I would like to see what would have happened if I had set my online processing parameters differently.		Q: I would like to see what would have happened if I had set my online processing parameters differently.

	A: You can perform an offline analysis by recreating a BCI2000 filter chain either [[User_Reference:Command_Line_Processing\|from the system command-line]] or [[User_Reference:Matlab_Tools\|from within Matlab]]. In either case, it is possible to substitute different parameter values into the processing chain. Naturally, however, if the original experiment included any kind of feedback that was dependent on the processed signal, you will not see the effects of this since you are working with a "frozen" data set that reflects the activity of a brain that was experiencing the results of the original parameters only. Also, you should be aware that finding the "best" set of parameters for a given data-set is not the same thing as finding the parameter set that will work best next time. If you optimize parameters on a fixed data set, and do not hold out some data on which to perform (once only) a final evaluation, then you will almost certainly be looking at an unrealistically inflated level of performance.		A: You can perform an offline analysis by recreating a BCI2000 filter chain either [[User_Reference:Command_Line_Processing\|from the system command-line]] or [[User_Reference:Matlab_Tools\|from within Matlab]]. In either case, it is possible to substitute different parameter values into the processing chain. Naturally, however, if the original experiment included any kind of feedback that was dependent on the processed signal, you will not see the effects of this since you are working with a "frozen" data set that reflects the activity of a brain that was experiencing the results of the original parameters only. Also, you should be aware that finding the "best" set of parameters for a given data-set is not the same thing as finding the parameter set that will work best next time. If you optimize parameters on a fixed data set, and do not hold out some data on which to perform (once only) a final evaluation, then you will almost certainly be looking at an unrealistically inflated level of performance, and may end up with parameters that will generalize <i>less</i> well to new data.

	==See also==		==See also==

Jhill: /* Offline Filtering */

2012-01-28T02:36:12Z

Offline Filtering

← Older revision		Revision as of 02:36, 28 January 2012
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	Q: I would like to apply a filter to recorded data, and then use the BCI2000 OfflineAnalysis and P300Classifier tools for data analysis.		Q: I would like to apply a filter to recorded data, and then use the BCI2000 OfflineAnalysis and P300Classifier tools for data analysis.

	A: You may achieve this using Matlab. First, use the [[User Reference:Matlab MEX Files#load_bcidat\|load_bcidat]] mex file to load data into Matlab. Then, apply the desired filtering to the "signal" output variable. Finally, save the resulting filtered data using the [[User Reference:Matlab MEX Files#save_bcidat\|save_bcidat]] mex file.		A: You may achieve this using Matlab. First, use the [[User Reference:Matlab MEX Files#load_bcidat\|load_bcidat]] mex file to load data into Matlab. Then, apply the desired filtering to the "signal" output variable. Finally, save the resulting filtered data using the [[User Reference:Matlab MEX Files#save_bcidat\|save_bcidat]] mex file. For elementary filtering operations, this procedure has been wrapped up in a simple Matlab GUI. See [[Contributions:FilterGUI]] for a description of this program.

	~~For elementary filtering operations, this procedure has been wrapped up in~~ a ~~simple Matlab GUI. See~~ [[~~Contributions~~:~~FilterGUI~~]] for a ~~description~~ of ~~this program~~.		Q: I would like to see what would have happened if I had set my online processing parameters differently.

			A: You can perform an offline analysis by recreating a BCI2000 filter chain either [[User_Reference:Command_Line_Processing\|from the system command-line]] or [[User_Reference:Matlab_Tools\|from within Matlab]]. In either case, it is possible to substitute different parameter values into the processing chain. Naturally, however, if the original experiment included any kind of feedback that was dependent on the processed signal, you will not see the effects of this since you are working with a "frozen" data set that reflects the activity of a brain that was experiencing the results of the original parameters only. Also, you should be aware that finding the "best" set of parameters for a given data-set is not the same thing as finding the parameter set that will work best next time. If you optimize parameters on a fixed data set, and do not hold out some data on which to perform (once only) a final evaluation, then you will almost certainly be looking at an unrealistically inflated level of performance.

	==See also==		==See also==

Mellinger: /* Joystick Control */

2010-05-19T13:48:52Z

Joystick Control

← Older revision		Revision as of 13:48, 19 May 2010
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	JoystickYpos		JoystickYpos
	By modifying the simple expression shown above, it would also be easy to use a combination of classified brain signals and states to drive an output such as the Cursor Task.		By modifying the simple expression shown above, it would also be easy to use a combination of classified brain signals and states to drive an output such as the Cursor Task.

			==Data Analysis==
			===Offline Filtering===
			Q: I would like to apply a filter to recorded data, and then use the BCI2000 OfflineAnalysis and P300Classifier tools for data analysis.

			A: You may achieve this using Matlab. First, use the [[User Reference:Matlab MEX Files#load_bcidat\|load_bcidat]] mex file to load data into Matlab. Then, apply the desired filtering to the "signal" output variable. Finally, save the resulting filtered data using the [[User Reference:Matlab MEX Files#save_bcidat\|save_bcidat]] mex file.

			For elementary filtering operations, this procedure has been wrapped up in a simple Matlab GUI. See [[Contributions:FilterGUI]] for a description of this program.

	==See also==		==See also==

Mellinger: /* Timing Issues */

2010-02-02T13:39:52Z

Timing Issues

← Older revision		Revision as of 13:39, 2 February 2010
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	When this is the case, the jumping cursor is merely a cosmetic problem.		When this is the case, the jumping cursor is merely a cosmetic problem.
	Otherwise, try the following:		Otherwise, try the following:
	*Increase the "~~Source decimation~~" parameter on the "Visualize" tab to reduce the processor load associated with the source signal display.		*Increase the "VisualizeSourceDecimation" parameter on the "Visualize" tab to reduce the processor load associated with the source signal display.
	*Increase the "SampleBlockSize" parameter to reduce the system update rate.		*Increase the "SampleBlockSize" parameter to reduce the system update rate.

Mellinger: /* gUSBamp not recognized */

2010-01-19T17:30:49Z

gUSBamp not recognized

← Older revision		Revision as of 17:30, 19 January 2010
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	A: The current version of the BCI2000 gUSBamp source module will not work with the first generation of gUSBamps. Please contact [http://www.gtec.at/ gtec] for a firmware update, or amplifier replacement.		A: The current version of the BCI2000 gUSBamp source module will not work with the first generation of gUSBamps. Please contact [http://www.gtec.at/ gtec] for a firmware update, or amplifier replacement.

			===Matlab Signal Processing shows an error at startup===
			Q: With Matlab R2009b installed, I cannot start up BCI2000 with the Matlab Signal Processing module. There is an error reported that the library "libeng" cannot be found.

			A: It appears that the Matlab R2009b installer does not add Matlab's bin/win32 directory to the system's PATH variable. After manually adding this directory to the PATH variable, the Matlab Signal Processing module is able to find the libeng library.

	==Configuration==		==Configuration==

Mellinger: /* Feedback */

2009-11-18T14:30:10Z

Feedback

← Older revision		Revision as of 14:30, 18 November 2009
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	===Feedback===		===Feedback===
	Q: The first time a subject is run using the cursor feedback protocol, during the first trial of the first run only, the cursor moves to the top of the screen and does not respond to ~~use~~ input. BCI2000 outputs increasingly large negative numbers during this run.		Q: The first time a subject is run using the cursor feedback protocol, during the first trial of the first run only, the cursor moves to the top of the screen and does not respond to user input. BCI2000 outputs increasingly large negative numbers during this run.

	A: This is not so much a bug as a side effect of the way the adaptation mechanism works. Since the adaptation mechanism hasn't been trained, all it has are the initial values for offset and gain. For each subject, it will take a few trials to adapt BCI2000 to this subject's signals.		A: This is not so much a bug as a side effect of the way the adaptation mechanism works. Since the adaptation mechanism hasn't been trained, all it has are the initial values for offset and gain. For each subject, it will take a few trials to adapt BCI2000 to this subject's signals.