Search found 17 matches

by sandra2014
30 Jan 2015, 08:17
Forum: BCI Systems - Signal Processing
Topic: bci2000 for p300 classification
Replies: 8
Views: 3730

Re: bci2000 for p300 classification

Hi In fact , I am not exactly get your question ,But I guess the following example will help you ! For first question , let's assume that there are 10 word to type by BCI2000 . So there are 10*180 intensifications . It means each row/col intensify 15 times for one word (180 = 15*12 ; 12(row&col) = 6...
by sandra2014
28 Jan 2015, 07:27
Forum: BCI Systems - Signal Processing
Topic: Need help in SWLDA
Replies: 1
Views: 2730

Re: Need help in SWLDA

Hello , I don't know will you read this post but I hope will. In fact, I have a problem to ask you. That is what kind of SVM parameters you set ? I am using libsvm .There are some parameters to set , such as -s -t -c -g and so on. The feature extracted from P300 signal input SWLDA got adaptive perfo...
by sandra2014
28 Jan 2015, 07:22
Forum: BCI Systems - Signal Processing
Topic: Apply SVM in P300 Classification
Replies: 0
Views: 10090

Apply SVM in P300 Classification

Hi everyone, I have a problem about SVM in P300 Classification. I want to know what kind of kernel function mostly used in this field ? I have used SWLDA to classify P300 data which can gain adoptive result . While with the same feature vector , SVM get very poor performance . I use libsvm ,paramete...
by sandra2014
28 Jan 2015, 07:03
Forum: BCI Systems - Signal Processing
Topic: bci2000 for p300 classification
Replies: 8
Views: 3730

Re: bci2000 for p300 classification

I am sorry for too late to see it . If your mean the feature extraction in BCI2000 ,that is average the data between each stimulus start time and later 800ms according to each row/column ,in the selected channels. Then concatenate them in a vector ,i.e. feature vector . For example , if the number o...
by sandra2014
10 Oct 2014, 05:18
Forum: BCI Article Commentaries
Topic: t-CWT a method for P300 feature extraction
Replies: 0
Views: 10736

t-CWT a method for P300 feature extraction

Hi , everyone. I have read the article about feature extraction . "BCI Competition 2003—Data Sets Ib and IIb-Feature Extraction from ERP with the CWT and t-Value Scalogram" . And I want to realize the method provided in this article . But I have some problems . 1. In fact , I have met in many articl...
by sandra2014
05 Oct 2014, 23:39
Forum: Data Analysis
Topic: t-CWT for P300 feature extraction
Replies: 0
Views: 10451

t-CWT for P300 feature extraction

Hi, everyone . Is there anyone know t-CWT ,a kind of method for feature extraction from ERPs. Recently ,I am learning about it , but I met some problems. 1. How to do the data preprocessing for t-CWT ? 2. If there is 180 trials (fifteen 12-trial blocks), that is, 30 trials belong to target group ,15...
by sandra2014
27 Sep 2014, 07:55
Forum: Data Analysis
Topic: load_bcidat use in matlab
Replies: 1
Views: 2307

Re: load_bcidat use in matlab

I have solve this problem. Because matlab load the .dat file according the file path ,but the "load_bcidat.m " will can't find when the workpath re-set to the data path . By means of the following method will work. filename = strcat(pathname,filename); [signal, states, parameters] = load_bcidat(file...
by sandra2014
26 Sep 2014, 21:50
Forum: Data Analysis
Topic: load_bcidat use in matlab
Replies: 1
Views: 2307

load_bcidat use in matlab

Hi every! I have a question that is the "load_bcidat" can only load the .dat file which is in the same storage position with the "load_bcidat.m" and "load_bcidat.mexw32" ? I want to load some .dat files which are in another folder by means of "load_bcidat.m" in matlab, but some error occur. Anyone c...
by sandra2014
23 Sep 2014, 08:54
Forum: BCI Systems - Brain Signals
Topic: P300's .dat file
Replies: 9
Views: 4626

Re: P300's .dat file

Thanks, sincerely !

Sandra.
by sandra2014
17 Sep 2014, 23:14
Forum: BCI Systems - Signal Processing
Topic: applog file for p300Speller
Replies: 1
Views: 1537

Re: applog file for p300Speller

I have solved this problem ,if anyone met the same problem ,you can read this.
by sandra2014
17 Sep 2014, 23:13
Forum: BCI Systems - Signal Processing
Topic: bci2000 for p300 classification
Replies: 8
Views: 3730

Re: bci2000 for p300 classification

I have solved this problem ,if anyone met the same problem ,you can readthis .
by sandra2014
17 Sep 2014, 23:09
Forum: BCI Systems - Brain Signals
Topic: P300's .dat file
Replies: 9
Views: 4626

Re: P300's .dat file

Yes , I use the function load_bcidat . 1. [signal, states, parameters] = load_bcidat(filename, '-calibrated'); I tested this code with my matlab code ,and I can get same result when apply to my data acquired from NeuroScan .In fact the data which is loaded by '-calibrated' code is equal to the outpu...
by sandra2014
17 Sep 2014, 09:47
Forum: BCI Systems - Brain Signals
Topic: P300's .dat file
Replies: 9
Views: 4626

Re: P300's .dat file

Thanks for your help ,Chad ! In fact , I did the work what your suggestion a few days ago, I set the gains to 1 and offsets to 0, AlignChannels = 0;TransmitChList = 10 (the channel number) , the classifier is :1 1 1 1 (that is, just use one element of the TransmitChList channel as feature). The resu...
by sandra2014
16 Sep 2014, 05:15
Forum: BCI Systems - Brain Signals
Topic: P300's .dat file
Replies: 9
Views: 4626

Re: P300's .dat file

Hi Chad! Thanks for your reply! I had little confuse about how the dat file written . Now I understand what your reply about "the data are simultaneously written to a dat file and passed through the BCI2000 filter pipe" . 1.I have read the DataIOFilter's source code ,the SourceChOffset and SourceChG...
by sandra2014
15 Sep 2014, 08:55
Forum: BCI Systems - Brain Signals
Topic: P300's .dat file
Replies: 9
Views: 4626

P300's .dat file

Hi,everyone! I have some questions about the .dat file of P300Speller. 1.After the BCI2000 run,when the .dat file began to write? 2.Was the .dat file have pass through the DataIOFilter? If is not , where and when did the SourceChOffset and SourceChGain used ? 3.If I want to analog the SpatialFilter ...