Search found 1124 matches

by Coen
Mon Feb 06, 2006 12:26 pm
Forum: BioSemi all other topics
Topic: How to report EMG parameters for BioSemi?
Replies: 3
Views: 9979

You are right: signals to file are unfiltered (besides the anti-aliasing filter depending on the sample rate) and unreferenced. Only the controls in the right sidebar affect the BDF file. Controls in the left sidebar only affect the display, they do not affect the BDF file. Best regards, Coen (BioSe...
by Coen
Thu Feb 02, 2006 2:51 pm
Forum: BioSemi Hardware
Topic: EMG design concept
Replies: 4
Views: 10789

by Coen
Wed Jan 25, 2006 5:20 pm
Forum: BioSemi Hardware
Topic: Skin electrodes
Replies: 2
Views: 18345

The two extra electrodes are for the GSR (Galvanic Skin Response) measurement. The response is displayed on the "Auxiliary Sensors" tabpage. For more information, see http://www.biosemi.nl/forum/viewtopic.php?t=79 and http://www.biosemi.nl/forum/viewtopic.php?t=30 Following the discussion on our use...
by Coen
Wed Jan 04, 2006 12:59 pm
Forum: BioSemi all other topics
Topic: hello, I'm walrus.
Replies: 1
Views: 8550

It is just a scaling issue. The 24-bit analog-to-digital converters have an output range from -8388608 (-2^23) to + 8388607 (2^23-1). The signal range of the electrode inputs is - 262144 uV to +262144 uV. The formula above converts the ADC output words in the BDF file into values in microVolt. It is...
by Coen
Thu Dec 08, 2005 12:49 pm
Forum: BioSemi Hardware
Topic: GSR captors
Replies: 1
Views: 8166

The hard- and software is set up for measuring two independent GSR signal, from 2 pairs of electrodes. Most customers only have a single GSR module installed (GSR1, one pair of electrodes). The green lights indicate when each GSR electrode makes proper contact with the subject's skin. Best regards, ...
by Coen
Mon Nov 21, 2005 5:38 pm
Forum: BioSemi all other topics
Topic: Other Programming Environment
Replies: 3
Views: 11300

Please read http://www.biosemi.com/faq/trigger_signals.htm

Best regards, Coen (BioSemi)
by Coen
Tue Nov 15, 2005 7:50 pm
Forum: BioSemi all other topics
Topic: Other platforms
Replies: 23
Views: 93823

The Labview_DLL.dll does not contain LabVIEW VI's. The dll contains function calls for the initialization and readout of a ringbuffer. The ringbuffer is then filled with data from the USB receiver, see http://www.biosemi.com/faq/make_own_acquisition_software.htm. These functions and the USB driver o...
by Coen
Tue Nov 15, 2005 11:40 am
Forum: BioSemi all other topics
Topic: Other platforms
Replies: 23
Views: 93823

BioSemi only provides drivers for Windows XP, drivers for use under Linux are not available. The ActiveTwo system can be used under Mac by using a National Instruments PCI-DIO32HS interface card (with NI drivers) with old style BioSemi receiver, instead of the current USB interface (use ActiView 4.0...
by Coen
Tue Nov 15, 2005 12:03 am
Forum: BioSemi Software (ActiView executable)
Topic: ActiveView Compilation Issues
Replies: 1
Views: 6123

I ran into this problem too during upgrading of the code to LabVIEW 8. It appeared that the ringbuffer is not always read in the proper place. The strange thing is that the problem does occur erratically: sometimes the program would behave OK, whereas in about half of the starts only zeros were read...
by Coen
Mon Nov 07, 2005 2:39 pm
Forum: BioSemi Software (ActiView executable)
Topic: Using the Labview_DLL.dll to access the USB datastream
Replies: 9
Views: 22133

Just an update on the information given on http://www.biosemi.com/faq/make_own_acquisition_software.htm: Most of the currently shipped ActiveTwo systems are of the Mk2 version. This recent version has the option for 24 extra channels, and consequently a higher data throughput is used. Please refer t...
by Coen
Wed Oct 26, 2005 12:35 pm
Forum: BioSemi all other topics
Topic: Other Programming Environment
Replies: 3
Views: 11300

by Coen
Tue Oct 25, 2005 1:28 pm
Forum: BioSemi Software (ActiView executable)
Topic: No reference or average reference?
Replies: 3
Views: 13857

1) It is important to realize that the choice of reference in ActiView only affect the displayed signals; the signals saved to file are always unreferenced. Display of unreferenced signals can be useful to spot problem electrodes. However, the unreferenced generally still show significant 50Hz inter...
by Coen
Thu Sep 22, 2005 2:38 pm
Forum: BioSemi Software (ActiView executable)
Topic: Recording sampling rate
Replies: 2
Views: 7899

With a hardware sample-rate of 2048 Hz (speedmodes 0, 4 and 8 ), ActiView supports sample-rates of the data to file of 2048, 1024, 512, and 256 Hz. At 256 Hz sample-rate, the bandwitdh is 67 Hz. Further bandwidth reduction can be achieved by apllying a low-pass filter off-line. Best regards, Coen (B...
by Coen
Thu Sep 01, 2005 3:07 pm
Forum: BioSemi Hardware
Topic: CMS/DRL:basic question
Replies: 2
Views: 8036

It does not matter in which order the electrodes connectors are plugged into the AD-box. However, valid EEG signals can only be measured with the CMS and DRL electrodes properly connected to the subject (blue light continuously on, see http://www.biosemi.nl/forum/viewtopic.php?t=42) Best regards, Co...
by Coen
Mon Aug 29, 2005 3:01 pm
Forum: BioSemi Hardware
Topic: GSR electrodes and units display
Replies: 7
Views: 20490

The ActiveTwo system uses an AC excitation current of 512 Hz, see http://www.biosemi.nl/forum/viewtopic.php?t=18 . The reason for using this relatively high frequency is that we want to remain well outside the EEG bandwidth (to prevent interference from the GSR excitation to be visible in the EEG si...
by Coen
Fri Aug 26, 2005 11:18 am
Forum: BioSemi Software (ActiView executable)
Topic: TCP/IP save to file
Replies: 4
Views: 10510

The BDF buffer is initialized with a length of exactly 2 seconds (e.g. 4096 columns when working on a sample rate of 2048 Hz). ActiView fills this buffer with data, in variable blocks (see http://www.biosemi.nl/forum/viewtopic.php?t=29), while the index variable is used to keep track on where the mo...
by Coen
Thu Aug 18, 2005 10:38 am
Forum: BioSemi Software (ActiView executable)
Topic: TCP/IP save to file
Replies: 4
Views: 10510

If you want to work with the BDF format (http://www.biosemi.com/faq/file_format.htm), it is best to use the 2D array. You will have to collect blocks of 1 second of data, and stream these to file. I recommend to copy the double buffered method used in ActiView (copy and paste the relevant sections o...
by Coen
Thu Aug 04, 2005 12:19 pm
Forum: BioSemi Software (ActiView executable)
Topic: Actiview components
Replies: 3
Views: 12200

ActiView is based on a state machine (case structure inside while-loop) with six (orange) states: State 0: Wait for START, and read/write CFG files State 1: Start acquisition, determine speedmode and AD-box version, set panel controls accordingly, stop acquisition State 2: Reset panel indicators Sta...
by Coen
Wed Aug 03, 2005 9:54 pm
Forum: BioSemi Hardware
Topic: Trigger Port Timing
Replies: 3
Views: 11174

The trigger lines are latched synchronous with the AD-box sampling, also see http://www.biosemi.nl/forum/viewtopic.php?t=53 It is possible that the latching moment coincides with a level change. This may lead to false codes if you change multiple lines at the same moment. If this presents a problem ...
by Coen
Wed Aug 03, 2005 9:35 pm
Forum: BioSemi Software (ActiView executable)
Topic: Labview DLL
Replies: 2
Views: 8121

Please see http://www.biosemi.com/faq/make_own_acq ... ftware.htm

Best regards, Coen (BioSemi)
by Coen
Mon Jul 25, 2005 12:36 pm
Forum: BioSemi Software (ActiView executable)
Topic: TCP/IP Server
Replies: 3
Views: 12518

Download the Client application from http://www.biosemi.com/download.htm --> http://www.biosemi.com/download/ActiveTwoClient_4.zip The latest versions of ActiView stream the data of a selected number of channels on the network. The Client application reads in this data via TCP/IP, the data can then ...
by Coen
Mon Jun 06, 2005 1:12 pm
Forum: BioSemi Hardware
Topic: Error 5002
Replies: 9
Views: 17307

Install Service Pack 2, it repaires several USB related problems. If your USB receiver was delivered before before May 2004, then install the firmware upgrade from http://www.biosemi.com/download/USB%20drivers%20V1.0/USB_firmware_update_V1.1.zip. Receivers manufactured after May 2004 are already pro...
by Coen
Mon Jun 06, 2005 10:54 am
Forum: BioSemi Hardware
Topic: Error 5002
Replies: 9
Views: 17307

Make sure that your PC has an USB2.0 port, USB 1 won't work at all (too slow). Check in the device manager, the Universal Serial Bus controller should show "Enhanced Host Controller" Your PC has to be fast enough, minimum is a 1.5 GHz Pentium 4 Also, check the lights on the USB receiver: - optic lin...
by Coen
Tue May 17, 2005 2:19 pm
Forum: BioSemi Software (ActiView executable)
Topic: actiview v5.16 modification
Replies: 1
Views: 7571

The raw data stream is available as a 2-d array at the output of the downsample-xx.vi subvi. It is best to use this array for further processing with your own routines, also see http://www.biosemi.nl/forum/viewtopic.php?t=29 and http://www.biosemi.nl/forum/viewtopic.php?t=44. The signals to screen a...
by Coen
Wed Apr 06, 2005 10:44 am
Forum: BioSemi Hardware
Topic: Error 5002
Replies: 9
Views: 17307

It is most probably a problem in the USB port (or card) of your PC. Try another PC to locate the problem.

Best regards, Coen (BioSemi)
by Coen
Tue Mar 22, 2005 11:17 pm
Forum: BioSemi Hardware
Topic: CMS+DRL Placement in ABR Recordings
Replies: 1
Views: 6783

We have seen good result with CMS and DRL on the forehead (see http://www.biosemi.com/abr.htm). The loction of CMS and DRL is not critical, see viewtopic.php?t=40 and viewtopic.php?t=33.

Best regards, Coen (BioSemi)
by Coen
Tue Mar 22, 2005 8:10 pm
Forum: BioSemi Software (ActiView executable)
Topic: Computing electrode offset?
Replies: 5
Views: 20020

There is not really any computation involved, the offset values are basically the values (in uV) of each sample from each analog-to-digital converter. The ADC has an range of -262 mV to + 262mV, the LSB is 1/32th uV, these values define the scaling. The ADC values are easily available in the ActiVie...
by Coen
Thu Mar 10, 2005 4:27 pm
Forum: BioSemi Software (ActiView executable)
Topic: ActiView Modifications
Replies: 2
Views: 7997

The step in the signal is generated on purpose to "null" each trace at the start of the screen. This ensures that signals do not drift off screen even if they are displayed without any high-pass filtering (as pure DC signals). The signals are nulled at the start of the acquisition, every time a filt...
by Coen
Tue Mar 08, 2005 1:16 pm
Forum: BioSemi Hardware
Topic: timing reading trigger inputs
Replies: 1
Views: 6674

The data on the trigger lines is latched 1.4 microseconds before the falling edge of the clock (sample rate) signal (pin 32). The timing relative to the falling edge in the clock signal is the same for all sample rates (speedmodes).

Best regards, Coen (BioSemi)