Search found 928 matches

by Coen
Mon Jan 14, 2019 3:09 pm
Forum: BioSemi Software (ActiView executable)
Topic: Trigger code oddities
Replies: 1
Views: 34

Re: Trigger code oddities

Instead of 0 --> 255 -->0 , your code probably generates 0 --->255 ---> 254 ---> 0 0 = 00000000 254 = 11111110 255 = 11111111 The 8 bits do not return to 0 simultaneously. Solution: toggle only one bit per trigger event, see http://www.biosemi.nl/forum/viewtopic.php?f=7&t=1022 In general: always use...
by Coen
Thu Jan 10, 2019 1:09 pm
Forum: BioSemi Hardware
Topic: Error 5000
Replies: 1
Views: 44

Re: Error 5000

Common causes of intermittent 5000 errors are (ordered from most to least likely): - bad optical fiber - bad USB cable - bad optical transmitter - bad optical receiver Replace fiber and USB cable. If the problem persists, then sent the AD-box and USB receiver to BioSemi for testing and repair. Best ...
by Coen
Fri Jan 04, 2019 1:04 pm
Forum: BioSemi Hardware
Topic: Error 5000
Replies: 1
Views: 134

Re: Error 5000

Use the registry cleaning tool to remove the manually installed driver, see https://www.biosemi.com/faq/install_USB.htm

Do not install the driver manually under W10, just plug in the USB-Receiver and the driver will install automatically.

Best regards, Coen (BioSemi)
by Coen
Tue Dec 18, 2018 2:46 pm
Forum: BioSemi all other topics
Topic: Calculating CMS & DRL Values
Replies: 2
Views: 190

Re: Calculating CMS & DRL Values

The data stream consists of measured voltages. A voltage is a difference in potential. In case of the ActiveTwo, the electrode potentials are measured with respect to the potential of a point between the CMS and DRL electrodes, see http://www.biosemi.nl/forum/viewtopic.php?f=1&t=177&p=391 . You are ...
by Coen
Wed Dec 12, 2018 1:36 pm
Forum: BioSemi Hardware
Topic: Odd ~17Hz noise in all channels
Replies: 2
Views: 230

Re: Odd ~17Hz noise in all channels

Is GSR used and connected to the subject ?

Is the interference seen in the bucket test (without GSR electrodes) ?

Best regards, Coen (BioSemi)
by Coen
Wed Nov 28, 2018 12:42 pm
Forum: BioSemi all other topics
Topic: Trigger error in low sample rate
Replies: 1
Views: 281

Re: Trigger error in low sample rate

Use positive trigger logic (down-sampling uses OR function to calculate trigger of multiple samples)
Use "analog" trigger display to investigate the problem.

see viewtopic.php?f=7&t=1022

Best regards, Coen (BioSemi)
by Coen
Tue Nov 27, 2018 5:13 pm
Forum: BioSemi Hardware
Topic: Custom electrodes for EXG channel
Replies: 1
Views: 338

Re: Custom electrodes for EXG channel

BioSemi treats the schematics as proprietary information, they are not shared with anyone outside the company.

Best regards, Coen (BioSemi)
by Coen
Mon Nov 05, 2018 3:13 pm
Forum: EEG data analysis
Topic: Impact of reference electrode for import on data ?
Replies: 3
Views: 537

Re: Impact of reference electrode for import on data ?

It does not matter. A reference far away generates high Common Mode voltages, a reference close to the area of interest generates small signal amplitudes. Re-referencing cancels these effects.

Best regards, Coen (BioSemi)
by Coen
Fri Nov 02, 2018 12:49 pm
Forum: EEG data analysis
Topic: Impact of reference electrode for import on data ?
Replies: 3
Views: 537

Re: Impact of reference electrode for import on data ?

A voltage is a difference in potential. So, the choice of reference does of course affect the eventual EEG voltages. The choice during import does not affect later alternative choices of the reference.

Best regards, Coen (BioSemi)
by Coen
Thu Nov 01, 2018 7:15 pm
Forum: BioSemi Software (ActiView executable)
Topic: modify STRIDE value for use with Matlab API
Replies: 1
Views: 460

Re: modify STRIDE value for use with Matlab API

The default Stride is set at approx. 60 milliseconds. If your ("huge") delays are much larger than this value, then the bottle-neck lies elsewhere (ActiView, TCP/IP transfer, PC processing speeds, etc.). Stride can be adjusted by calling functions in the Labview_DLL.dll: OPEN_DRIVER_ASYNC --> BSIF_S...
by Coen
Wed Oct 31, 2018 4:24 pm
Forum: BioSemi Software (ActiView executable)
Topic: Sending Frequency of data from TCP/IP
Replies: 7
Views: 685

Re: Sending Frequency of data from TCP/IP

Your approach will work, providing that the value generated by ActiView divided by the value you select manually is an integer. For example: if ActiView generates a value of 16 samples/chan, the you can manually set 1, 2, 4 or 8 samples/chan.

Best regards, Coen (BioSemi)
by Coen
Fri Oct 26, 2018 12:59 pm
Forum: BioSemi Hardware
Topic: Random '20202020...' triggers
Replies: 1
Views: 494

Re: Random '20202020...' triggers

viewtopic.php?f=7&t=977&p=2985

Best regards, Coen (BioSemi)
by Coen
Wed Oct 24, 2018 12:19 pm
Forum: EEG data analysis
Topic: Inconsistencies with channel locations
Replies: 6
Views: 818

Re: Inconsistencies with channel locations

Geographic coordinates (EEGLab) have now been added to the position file, see https://www.biosemi.com/download/Cap_coords_all.xls

Best regards, Coen (BioSemi)
by Coen
Mon Oct 22, 2018 11:44 am
Forum: BioSemi Software (ActiView executable)
Topic: Sending Frequency of data from TCP/IP
Replies: 7
Views: 685

Re: Sending Frequency of data from TCP/IP

The TCP_samples/channel is generated in ActiView and linked to the packet size that is used to read the ringbuffer and the minimum step size for scrolling the data on screen. You can change only the value by editing the (open-source) LabVIEW code of ActiView (LabVIEW programming environment required...
by Coen
Mon Oct 15, 2018 1:55 pm
Forum: BioSemi Software (ActiView executable)
Topic: Sending Frequency of data from TCP/IP
Replies: 7
Views: 685

Re: Sending Frequency of data from TCP/IP

The data is buffered (in the ringbuffer and in ActiView and in the TCP/IP protocol) so the sending rate over TCP/IP fluctuates.

Collect 4096 samples in your receive program, and you have exact 2 seconds of data.

Best regards, Coen (BioSemi)
by Coen
Thu Oct 04, 2018 4:16 pm
Forum: EEG data analysis
Topic: Inconsistencies with channel locations
Replies: 6
Views: 818

Re: Inconsistencies with channel locations

Basically, we use the ISO spherical system (https://en.wikipedia.org/wiki/Spherical_coordinate_system) whereas EEGLAB uses coordinates based on the geograpic system (https://en.wikipedia.org/wiki/Geographic_coordinate_system). The relation between the two systems is a bijection (one-to-one correspon...
by Coen
Thu Oct 04, 2018 1:56 am
Forum: EEG data analysis
Topic: Inconsistencies with channel locations
Replies: 6
Views: 818

Re: Inconsistencies with channel locations

for positive values of inclination:

sph_phi = 90 - inclination
sph_theta = -90 + azimuth

for negative values of inclination:

sph_phi = 90 + inclination
sph_theta = 90 + azimuth

Best regards, Coen (BioSemi)
by Coen
Mon Oct 01, 2018 11:09 pm
Forum: EEG data analysis
Topic: Inconsistencies with channel locations
Replies: 6
Views: 818

Re: Inconsistencies with channel locations

Quote: you give the inclination and azimuth of Fp1 as -92 and -72, but in the .ced file, sph_theta and sph_phi are 18 and -2. C3 has an inclination and azimuth of -46 and 0 in the excel file and sph_theta and sph_phi are 90 and 44 in the corresponding .ced file for the same cap. Comment: I am not fa...
by Coen
Wed Sep 19, 2018 5:07 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 9
Views: 7292

Re: Strange activity on a single electrode

Certainly, if you subtract a reference from a flat channel than the result is the (inverted) reference with respect to CMS.

Best regards, Coen (BioSemi)
by Coen
Sat Sep 08, 2018 10:10 am
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 9
Views: 7292

Re: Strange activity on a single electrode

No, they are bad.

Best regards, Coen (BioSemi)
by Coen
Wed Aug 22, 2018 11:14 am
Forum: EEG data analysis
Topic: TCP/IP EEG data transform
Replies: 1
Views: 992

Re: TCP/IP EEG data transform

24-bit integer, EEG channels: LSB = 31.25 nV (1/32th microVolt), so signal range is -262 mV to 262 mV.

Best regards, Coen (BioSemi)
by Coen
Wed Aug 08, 2018 2:07 pm
Forum: BioSemi all other topics
Topic: infant research
Replies: 1
Views: 792

Re: infant research

Everything is the same as with adults, just purchase the appropriate small sized headcaps, see https://www.biosemi.com/headcap.htm Since the electrodes are closer to together, there is more change on gel bridges. So, be careful to not use too much electrode gel (just enough to fill the holder). Best...
by Coen
Tue Aug 07, 2018 12:00 pm
Forum: BioSemi Software (ActiView executable)
Topic: ActiView doesn't recognize 64 channels after upgrade
Replies: 2
Views: 874

Re: ActiView doesn't recognize 64 channels after upgrade

Your AD-box is on speedmode 7. Switch to speedmode 4, 5 or 6, see https://www.biosemi.com/faq/adjust_samplerate.htm . Check that you have actually 64 channels installed: run AD-box without any electrodes connected and check the offsets, enabled channels have maximally negative offset, disabled chann...
by Coen
Wed Aug 01, 2018 8:35 pm
Forum: BioSemi Software (ActiView executable)
Topic: Trigger Data from TCP/IP
Replies: 2
Views: 901

Re: Trigger Data from TCP/IP

The trigger are bit 8-23 of the 32 bit integer, see https://www.biosemi.com/faq/trigger_signals.htm (ignore bit 0-7, bit 24-31 are status bits)

Best regards, Coen (BioSemi)
by Coen
Tue Jul 17, 2018 12:00 pm
Forum: BioSemi Software (ActiView executable)
Topic: Start File using triggers?
Replies: 2
Views: 944

Re: Start File using triggers?

The above option is not included in standard ActiView. However, since ActiView is fully open-source LabVIEW, it can be quite easily added by the user.

Best regards, Coen (BioSemi)
by Coen
Tue Jul 17, 2018 11:58 am
Forum: BioSemi all other topics
Topic: Trigger Problem
Replies: 5
Views: 1330

Re: Trigger Problem

I don't see how "nothing connected to the trigger port" can mean anything else than the situation where no connector is inserted in the 37-pole trigger port. Each line can be pulled Low by connecting the respective pin (1-16) to pin 37. However, with the CFG set to "1", lines 9 and 10 will only reac...
by Coen
Mon Jul 09, 2018 7:12 pm
Forum: BioSemi all other topics
Topic: Trigger Problem
Replies: 5
Views: 1330

Re: Trigger Problem

Check that lines 9 (lower brown) and 10 (lower red) are gray when nothing is connected to the trigger port (all other lines should be colored). Check the operation of the switches (a brown or red dot/line should appear on respectively line 9 and 10 when the switch is pressed. Best regards, Coen (Bio...
by Coen
Wed Jun 27, 2018 2:26 pm
Forum: BioSemi Hardware
Topic: Installing in a Faraday Cage
Replies: 1
Views: 1063

Re: Installing in a Faraday Cage

Only the optical fiber goes through the cage wall. You can use an optional fiber coupler (search for st-st coupler)

The triggers go to the USB receiver (near computer) outside the cage.

Best regards, Coen (BioSemi)
by Coen
Wed Jun 20, 2018 2:40 pm
Forum: BioSemi all other topics
Topic: Trigger Problem
Replies: 5
Views: 1330

Re: Trigger Problem

Trigger line 10 (pin 10) is unconnected and therefore always High (internal pull-up). Check with "analog" trigger display (colored bars). OR If you use response switches (with CFG set to "1", see http://www.biosemi.nl/forum/viewtopic.php?f=7&t=977&p=2985) then your switch number 2 may be disconnecte...
by Coen
Thu Jun 07, 2018 4:57 pm
Forum: BioSemi all other topics
Topic: Unwanted triggers during ABR measurement
Replies: 7
Views: 1922

Re: Unwanted triggers during ABR measurement

ERGO's have floating CMOS (high impedance) inputs. When nothing is connected, the smallest charge pickup can cause random drift and switching, see traces in the "Auxiliary Sensors" tabpage. You describe normal behavior. With the "0" setting in the CFG, the ERGO's are disconnect from the trigger line...