Search found 915 matches

by Coen
Mon Oct 22, 2018 11:44 am
Forum: BioSemi Software (ActiView executable)
Topic: Sending Frequency of data from TCP/IP
Replies: 4
Views: 67

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: 4
Views: 67

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: 5
Views: 157

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: 5
Views: 157

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: 5
Views: 157

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: 6410

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: 6410

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: 452

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: 363

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: 387

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: 411

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: 481

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: 784

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: 784

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: 613

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: 784

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: 1214

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...
by Coen
Mon May 07, 2018 5:20 pm
Forum: BioSemi Hardware
Topic: Error 5000
Replies: 4
Views: 898

Re: Error 5000

There are no meaningful tests with the old firmware in combination with Windows 10, a firmware upgrade to version 4.0 is required.
by Coen
Mon May 07, 2018 12:20 pm
Forum: BioSemi Hardware
Topic: Error 5000
Replies: 4
Views: 898

Re: Error 5000

Your USB-receiver does not have the 4.0 firmware, and does not work with Windows 10. Sent your USB-receiver to your local dealer (Starlab) for a firmware update. Because you have connected an USB-receiver with old firmware to the Windows 10 computer, you must run the registry cleaning tool before co...
by Coen
Wed May 02, 2018 1:52 pm
Forum: ECG/EMG data analysis
Topic: GSR extraction from bdf file
Replies: 4
Views: 1054

Re: GSR extraction from bdf file

BDF is not BDF+, EDF browser reads both, ActiView generates BDF files.

Use one of the standard solutions (https://www.biosemi.com/download.htm), or make your own file reader based on BDF specs (https://www.biosemi.com/faq/file_format.htm).

Best regards, Coen (BioSemi)
by Coen
Wed May 02, 2018 11:26 am
Forum: ECG/EMG data analysis
Topic: GSR extraction from bdf file
Replies: 4
Views: 1054

Re: GSR extraction from bdf file

Use EDF browser (https://www.teuniz.net/edfbrowser/), for scaling see viewtopic.php?f=7&t=1013

Best regards, Coen (BioSemi)
by Coen
Wed Apr 25, 2018 3:14 pm
Forum: BioSemi all other topics
Topic: Unwanted triggers during ABR measurement
Replies: 7
Views: 1214

Re: Unwanted triggers during ABR measurement

Use all 16 trigger lines or use D flip-flops to latch the triggers and sent them to the USB-receiver on the same moment (also see viewtopic.php?f=1&t=53&p=144 , sample clock is available on pin 32 of the trigger port)

Best regards, Coen (BioSemi)
by Coen
Mon Apr 23, 2018 3:29 pm
Forum: ECG/EMG data analysis
Topic: offline heart rate extraction from ECG signal
Replies: 10
Views: 12846

Re: offline heart rate extraction from ECG signal

You should indeed record both E7 and E8 (use the "add 8 EX electrodes" in the TCP/IP tabpage) . The noise that you see in the raw E7 and E8 signals is mainly Common Mode (same noise for both channels). When you calculate E7-E8, then the Common Mode noise is canceled out, and the ECG remains (this is...
by Coen
Thu Apr 19, 2018 1:57 pm
Forum: ECG/EMG data analysis
Topic: offline heart rate extraction from ECG signal
Replies: 10
Views: 12846

Re: offline heart rate extraction from ECG signal

CMS on the center of the chest may give better CMRR, DRL can be anywhere on the body.

Divide the 24-bit results by 32 to scale the values to microVolt.

You are using active electrodes (preamp integrated with electrode), ignore the remark about passive electrodes.

Best regards, Coen (BioSemi)
by Coen
Tue Apr 17, 2018 2:25 pm
Forum: ECG/EMG data analysis
Topic: offline heart rate extraction from ECG signal
Replies: 10
Views: 12846

Re: offline heart rate extraction from ECG signal

ECG/EEG/EMG is measured BETWEEN two (or more) electrodes. The signal of a single electrodes with respect to CMS (raw, unreferenced) is not a valid signal, see https://www.biosemi.com/faq/cms&drl.htm http://www.biosemi.nl/forum/viewtopic.php?f=1&t=33&p=86 http://www.biosemi.nl/forum/viewtopic.php?f=1...
by Coen
Fri Apr 13, 2018 5:01 pm
Forum: BioSemi all other topics
Topic: Unwanted triggers during ABR measurement
Replies: 7
Views: 1214

Re: Unwanted triggers during ABR measurement

The problem may be that your trigger generator does not switch the separate lines (bits) within one sample period (62 microsecond). Try using trigger values that switch only one line, e.i. 1,2,4,8,16,32,64 and 128. High (unconnected) lines 9-16 do not cause false triggers. Best regards, Coen (BioSemi)
by Coen
Fri Apr 06, 2018 9:11 pm
Forum: BioSemi Hardware
Topic: Problem with 32 channel headbox / EKG
Replies: 3
Views: 948

Re: Problem with 32 channel headbox / EKG

Run the system with no electrodes connected: channels with offset at minimum (-262 mV) are installed, channels with offset at zero are not installed. Purchase 8-channel modules (EUR 1600) for the additional channels you want to use and install them in the proper slots in the motherboard. Best regard...
by Coen
Fri Apr 06, 2018 2:06 pm
Forum: BioSemi Hardware
Topic: Problem with 32 channel headbox / EKG
Replies: 3
Views: 948

Re: Problem with 32 channel headbox / EKG

Check whether there are actually Amp/ADC modules installed on the B channels (inspect offsets with nothing connected to the AD-box).

Best regards, Coen
by Coen
Tue Mar 20, 2018 9:33 pm
Forum: BioSemi Hardware
Topic: Necessary Equipment for Assembling a New EEG Lab
Replies: 1
Views: 1083

Re: Necessary Equipment for Assembling a New EEG Lab

The first 7 items are bundled as "Base System" (EUR 11,000), see https://www.biosemi.com/faq/prices.htm Missing from the list are the "Amplifier/ADC" modules (EUR 1600 per 8-channel module). For 32 channels, you will need 4 modules. Most users add one more module for flat-type electrodes for EOG/EMG...