Search found 899 matches

by Coen
Thu Jun 07, 2018 4:57 pm
Forum: BioSemi all other topics
Topic: Unwanted triggers during ABR measurement
Replies: 7
Views: 368

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: 252

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: 252

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: 256

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: 256

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: 368

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: 12137

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: 12137

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: 12137

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: 368

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: 363

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: 363

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: 510

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...
by Coen
Tue Mar 06, 2018 4:50 pm
Forum: BioSemi Software (ActiView executable)
Topic: Issue with trigger coding
Replies: 7
Views: 5742

Re: Issue with trigger coding

Trigger lines are High (colored) when the trigger generator (stimulus computer) sends a High, or when the particular input is unconnected (each input has a 10 kOhm pull-up resistor). Connect an unused line (input pin) to Pin 37 (Ground) to pull the line Low. Use positive trigger logic: Low = Idle, H...
by Coen
Fri Mar 02, 2018 3:15 pm
Forum: BioSemi Hardware
Topic: separate CMS/DRL lead or in bundle with other electrodes
Replies: 1
Views: 520

Re: separate CMS/DRL lead or in bundle with other electrodes

Whether the cms/drl is separate or not is absolutely unrelated to gel bridges.

Best regards, Coen (BioSemi)
by Coen
Thu Mar 01, 2018 8:09 pm
Forum: BioSemi all other topics
Topic: Exporting GSR signals for analysis
Replies: 10
Views: 1100

Re: Exporting GSR signals for analysis

Test with 2 buckets filled with salt water. Put CMS, DRL and one GSR electrode in one bucket, put the other GSR electrode in the other bucket. Connect the two buckets with a 100 kOhm resistor (solder pieces of wire to the resistor, put the bare wire ends in the water). ActiView will show a conductan...
by Coen
Wed Feb 28, 2018 5:23 pm
Forum: BioSemi all other topics
Topic: Exporting GSR signals for analysis
Replies: 10
Views: 1100

Re: Exporting GSR signals for analysis

Just a further remark about the range or the GSR measurement: As said above, the maximum conductance that can be measured is approx. 262 microSiemens (3.8 kOhm) ActiView has a lower conductive limit of approx. 0.6 microSiemens (1.7 MOhm). At conductances lower than 0.6 microSiemens the green "GSR in...
by Coen
Tue Feb 27, 2018 5:22 pm
Forum: BioSemi all other topics
Topic: Exporting GSR signals for analysis
Replies: 10
Views: 1100

Re: Exporting GSR signals for analysis

1 microSiemens conductance is 1 MOhm impedance (two electrodes in series). 500 kOhm per electrode sounds about right on the dry skin at 16 Hz.

Using electrode gel (but no skin scrubbing) should lower the resistance to something like 100 kOhm (10 microSiemens).

Best regards, Coen (BioSemi)
by Coen
Tue Feb 27, 2018 4:04 pm
Forum: BioSemi all other topics
Topic: Exporting GSR signals for analysis
Replies: 10
Views: 1100

Re: Exporting GSR signals for analysis

GSR has an LSB value of 0.03125 nanoSiemens. To convert to microSiemens, devide the value in the BDF file by 32,000 (sorry for introducing confusion with my mistake above). For example: Z=100 kOhm, ActiView displays 10,000 nanoSiemens, the BDF file has a value of 320,000 (= 10 uS) Z=10 kOhm, ActiVie...
by Coen
Mon Feb 26, 2018 5:17 pm
Forum: BioSemi all other topics
Topic: Exporting GSR signals for analysis
Replies: 10
Views: 1100

Re: Exporting GSR signals for analysis

The above formula is correct. As an extra check, compare the values calculated from the BDF file with the numerical values indicated in ActiView during recording (top of left sidebar).

Best regards, Coen (BioSemi)
by Coen
Tue Jan 30, 2018 7:19 pm
Forum: BioSemi Software (ActiView executable)
Topic: Y-axis labeling problems
Replies: 1
Views: 683

Re: Y-axis labeling problems

Load a CFG that shows the proper labels, adjust all ActiView controls to the settings required for a particular experiment, save the CFG under a new name.

Best regards, Coen (BioSemi)
by Coen
Mon Jan 29, 2018 4:35 pm
Forum: BioSemi all other topics
Topic: Trigger from a Presentation logfile to BDF file
Replies: 2
Views: 671

Re: Trigger from a Presentation logfile to BDF file

The triggers from presentation must be acquired through the trigger port on the USB-receiver. All Triggers offered to the trigger port are always saved in the BDF file with proper timing. If triggers are missing from the BDF file, then there is a hardware or Presentation error. Triggers cannot be ad...
by Coen
Tue Jan 09, 2018 1:39 pm
Forum: BioSemi Hardware
Topic: Pairs of channels showing the same EEG activity
Replies: 1
Views: 853

Re: Pairs of channels showing the same EEG activity

The listed electrodes are close to the CMS. In the unreferenced signals, there will be very little EEG activity, just electrode noise and 50/60 Hz interference (because of the reduced CMRR in unreferenced form). The noise and interference probably "fools" the ICA. It is essential to always reference...
by Coen
Fri Dec 08, 2017 2:23 pm
Forum: BioSemi Hardware
Topic: Seeing Delayed Components
Replies: 1
Views: 937

Re: Seeing Delayed Components

Check the timing between the visual stimuli and the triggers with the additional Photo Sensor (and ERGO input) connected to the AD-box. Also see https://www.biosemi.com/accessoires.htm and https://www.biosemi.com/faq/review_trigger_timing.htm. If you find a timing difference between the Photo Sensor...
by Coen
Wed Nov 29, 2017 1:27 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 4
Views: 5510

Re: Strange activity on a single electrode

Only the electrode(s) shorted to the DRL are affected. Refer to the schematic in https://www.biosemi.com/pics/zero_ref1_big.gif . A gel bridge between an electrode and the DRL can be represented in the schematic as a short between the electrode and the DRL opamp output. The DRL will still drive the ...
by Coen
Mon Nov 20, 2017 4:49 pm
Forum: EEG data analysis
Topic: Extracting Status Information (Electrode Offset, CMS in range)
Replies: 1
Views: 1032

Re: Extracting Status Information (Electrode Offset, CMS in range)

Status information is coded in the Most Significant Byte (8 Most Significant Bits) of the trigger/status channel (always the last channel), see https://www.biosemi.com/faq/trigger_signals.htm Offsets are the DC values of the channels, see http://www.biosemi.nl/forum/viewtopic.php?t=56 Best regards, ...
by Coen
Tue Oct 24, 2017 12:01 pm
Forum: EEG data analysis
Topic: slow drifting on EEG
Replies: 3
Views: 1659

Re: slow drifting on EEG

The above is fully correct.

Best regards, Coen (BioSemi)
by Coen
Mon Oct 23, 2017 2:25 pm
Forum: EEG data analysis
Topic: slow drifting on EEG
Replies: 3
Views: 1659

Re: slow drifting on EEG

Always reference the data before further processing, see https://www.biosemi.com/faq/cms&drl.htm Raw data (with respect to CMS) is NOT valid data, do not regard or use CMS or DRL as reference. With proper referencing, location of CMS and DRL does not affect the data (but may affect interference leve...
by Coen
Tue Oct 17, 2017 3:25 pm
Forum: BioSemi all other topics
Topic: Sending triggers via National Instruments Digital I/O PCIe-6509
Replies: 2
Views: 1248

Re: Sending triggers via National Instruments Digital I/O PCIe-6509

Connect up to 16 lines, depending on the number of codes you need. Connecting only the first 8 lines is fine (9-16 will be always high). Pause On/Off is controlled by trigger lines 1-8. Set the preferred codes in the CFG file, see http://www.biosemi.nl/forum/viewtopic.php?f=2&t=711&p=2174 Best regar...