Search found 1125 matches
- Wed Apr 23, 2008 5:19 pm
- Forum: BioSemi Hardware
- Topic: Shielding in EEG
- Replies: 8
- Views: 21841
We have successfully performed interference-free EEG recordings with the BioSemi ActiveTwo system near MRI rooms (a distance of 10-20 meters from the shielded room). However, given the large variation in technical details of MRI in setups, I can only recommend to do some actual tests with an ActiveT...
- Fri Apr 11, 2008 1:39 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: Datafeed with or without gaps?
- Replies: 4
- Views: 22835
The 2D output arrays from Downtsample-5th.vi have a constant number of rows (number of channels, dependent on the speedmode), and a variable number of columns (successive samples, amount of samples in an array depends on the value of the "display block size", which is constantly adjusted according t...
- Fri Apr 04, 2008 1:14 pm
- Forum: BioSemi Hardware
- Topic: additional sensors
- Replies: 1
- Views: 4785
The unit and scaling for each channel is listed in the BDF file header, see http://www.biosemi.com/faq/file_format.htm. Not all review programs may read and display this information properly (and may plot everything as uV instead of Siemens, degree Celsius, etc). Operation of the temperature sensor ...
- Fri Apr 04, 2008 12:35 pm
- Forum: BioSemi all other topics
- Topic: BDF Byte Reading c#
- Replies: 8
- Views: 15554
- Fri Mar 07, 2008 6:57 pm
- Forum: BioSemi Hardware
- Topic: Dry electrodes
- Replies: 1
- Views: 5318
- Tue Mar 04, 2008 4:38 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: ActiView Lite
- Replies: 1
- Views: 5479
Please read http://www.biosemi.nl/forum/viewtopic.php?t=65 ActiView Light only contains the basic acquisition code, the output is a 2D array of ADC values (rows are channels, columns are successive samples). You can use this array as input for your own signal processing code. Standard ActiView has t...
- Thu Feb 28, 2008 4:30 pm
- Forum: BioSemi Hardware
- Topic: Signal Quality Changing over Time: CM rejection problem?
- Replies: 1
- Views: 5353
I would initially suspect the DRL needle (stainless steel can be a problematic electrode material). I would recommend to use a normal surface electrode for the DRL (preferable Ag-AgCl). By the way, the DRL does not have to be located on the right leg, a location near the CMS is fine (but keep the di...
- Tue Jan 22, 2008 5:09 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: using an old version of Actiview
- Replies: 1
- Views: 5737
The new system is a Mk2, whereas the old system was probably a Mk1 (also http://www.biosemi.nl/forum/viewtopic.php?t=270). The difference between Mk1 and Mk2 is the number of channels in each speedmode, see http://www.biosemi.com/faq/adjust_samplerate.htm and http://www.biosemi.com/faq/make_own_acqu...
- Tue Jan 22, 2008 12:50 pm
- Forum: BioSemi all other topics
- Topic: BDF Byte Reading c#
- Replies: 8
- Views: 15554
- Mon Jan 21, 2008 4:18 pm
- Forum: BioSemi all other topics
- Topic: BDF Byte Reading c#
- Replies: 8
- Views: 15554
The answers is found in the LabVIEW code of the BDF reader. Add an extra least significant (zero) byte to generate an I32. In your example you will then have 00000000 00101000 10111110 11111111, with a value -8580096. Divide this by 8192 (256*32) to convert to uV. So, the first value is -1047.375 uV...
- Wed Jan 16, 2008 1:03 pm
- Forum: BioSemi Hardware
- Topic: Elec. ref. for one biosemi system multiple participants
- Replies: 1
- Views: 5723
It is not possible to measure two subjects simultaneously with only one AD-box. However, the ActiveTwo system offers the unique option to measure up to four subjects simultaneously with daisy-changed AD-boxes (each subject has its own AD-box). Information is found on http://www.biosemi.com/new.htm, ...
- Fri Jan 11, 2008 7:31 pm
- Forum: BioSemi Hardware
- Topic: GSR electrodes and signals
- Replies: 7
- Views: 16993
For the (old) 512 Hz version, the unit is Ohm, and the value in the BDF file is scaled as LSB = 0.03125 Ohm For the (new) 16 Hz version, the unit is nanoSiemens (0.001 uS), and the value in the BDF file is scaled as LSB = 0.03125 nanoSiemens ActiView cannot generate negative values (either Ohm or na...
- Fri Jan 11, 2008 7:03 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: Datafeed with or without gaps?
- Replies: 4
- Views: 22835
The AD-box always sends all samples to the PC, and the PC processes all samples. If for some reason, ActiView cannot keep up with the incoming data-stream, an error is detected and the program stops with a popup message. So, the data in the BDF file always contains ALL samples, you can be 100% sure ...
- Fri Dec 14, 2007 12:55 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: How is averaging computed?
- Replies: 1
- Views: 19130
- Mon Dec 10, 2007 1:52 pm
- Forum: BioSemi Hardware
- Topic: Actiview USB drops least significant bit of trigger
- Replies: 8
- Views: 13286
- Fri Dec 07, 2007 1:21 pm
- Forum: BioSemi Hardware
- Topic: Actiview USB drops least significant bit of trigger
- Replies: 8
- Views: 13286
- Tue Dec 04, 2007 1:28 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: Data timestamping & Running two VIs concurrently
- Replies: 5
- Views: 25353
Thanks for the feedback. Just one further remark: I forgot to extra emphasize to use global variables, and not local variables, to communicate between the parallel while loops. A pair of local variables is basically the same as a connection wire in the diagram. So, when write data to a local variabl...
- Fri Nov 30, 2007 7:40 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: change left sidebar
- Replies: 1
- Views: 18762
The left sidebar (which is actually a tab control with the tabs not visible), is coupled to the main tab control at two places in the diagram: - Orange state 0, find the relevant code by right-clicking on the left sidebar outline, and select Find --> Local Variables (controls the left sidebar during...
- Thu Nov 29, 2007 6:24 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: Data timestamping & Running two VIs concurrently
- Replies: 5
- Views: 25353
Right-click problem: the VI should be stopped (CTRL+.) and in Edit Mode (CTRL+M) First, make sure that the ActiView VI is not running by pressing the red square on the About tabpage (or the "Edit" button in the Light version), or use CTRL+. (Control plus Dot). The toolbar should show up on top of th...
- Thu Nov 29, 2007 5:26 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Actiview display settings
- Replies: 1
- Views: 5865
The plot color cannot be changed in the current executable versions, you will have to make the changes in LabVIEW (right-click on the chart --> show legend --> right-click on trace icon --> select color, or better use a property node with "active plot" and "plot color" and change the color by connec...
- Wed Nov 28, 2007 7:37 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: Data timestamping & Running two VIs concurrently
- Replies: 5
- Views: 25353
Because Windows is not a real-time operating system, it is not possible to accurately time stamp the data within ActiView. Proper time stamping can only be archived in hardware, for example by using the trigger port on the USB receiver. LabVIEW allows multi-threading. You can run your additional VIs...
- Mon Nov 26, 2007 1:04 pm
- Forum: BioSemi Hardware
- Topic: Actiview USB drops least significant bit of trigger
- Replies: 8
- Views: 13286
- Fri Nov 23, 2007 2:55 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Actiview configuration
- Replies: 1
- Views: 6350
The hardware sampling rate can be adjusted with the speedmode switch (rotary switch on the front-panel of the AD-box). Use the settings 4.5,6 or 7, see http://www.biosemi.com/faq/adjust_samplerate.htm). The sample rate can then be further reduced in software by using the "decimation" selector in the...
- Fri Nov 02, 2007 3:36 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Labview_DLL
- Replies: 6
- Views: 11581
I didn't mean to say that your question was inappropriate. I just wanted to express my view on your plan to develop a Matlab alternative for our LabVIEW solution. There may well be others here on the forum who don't agree with me. In other words, I tried to stir up the discussion a bit, and I am eag...
- Fri Nov 02, 2007 1:19 pm
- Forum: BioSemi Software (LabVIEW programming)
- Topic: Adding additional features
- Replies: 2
- Views: 20930
Please read viewtopic.php?t=65&highlight=labview
Start with inspecting the "Light" version, the code shows the basic setup quite clearly. Please don't hesitate to post or email specific questions.
Best regards, Coen (BioSemi)
Start with inspecting the "Light" version, the code shows the basic setup quite clearly. Please don't hesitate to post or email specific questions.
Best regards, Coen (BioSemi)
- Fri Nov 02, 2007 12:03 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Labview_DLL
- Replies: 6
- Views: 11581
BioSemi only supports programming in LabVIEW, because we are convinced that LabVIEW currently the is the best and most versatile programming environment for the acquisition and analysis of electro-physiological data. BioSemi has adopted an open-source policy, and encourages customers to developed La...
- Wed Oct 17, 2007 2:32 pm
- Forum: BioSemi Hardware
- Topic: How can I make my own acquisition software ? details
- Replies: 3
- Views: 7833
The above is valid for our Mk1 systems (delivered until August 2005), the current Mk2 systems do indeed have extra channels. Meanwhile, the FAQ has been updated, and the figures for both Mk1 and Mk2 are listed, see http://www.biosemi.com/faq/make_own_acquisition_software.htm). To check whether your ...
- Fri Oct 05, 2007 5:23 pm
- Forum: BioSemi all other topics
- Topic: TCP/IP processing
- Replies: 2
- Views: 8981
- Tue Oct 02, 2007 7:31 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Ring buffer - how to increase the number of samples
- Replies: 1
- Views: 6781
Both approaches are possible. - Example of defining a new buffer can be found in the full standard version of ActiView. A (double) buffer is used to store the 1 second blocks saved to the BDF file, and another buffer is used to calculate the online average (ERP). - Instead of reading small blocks of...
- Mon Oct 01, 2007 3:33 pm
- Forum: EEG data analysis
- Topic: Mark I or Mark II?
- Replies: 1
- Views: 7185
If the Serial Number starts with ADC4 to ADC11, then it's a Mark 1. If the Serial Number starts with ADC12, then it's a Mark 2. Alternatively, you can check the indicator on the "About ActiView" tabpage in ActiView. With the system running (it is not necessary to connect electrodes), the software sh...