Search found 1056 matches

by Coen
Fri May 20, 2022 12:55 pm
Forum: BioSemi Hardware
Topic: CMS/DRL out of range and box shutdown
Replies: 1
Views: 48

Re: CMS/DRL out of range and box shutdown

Blue LED blinking: DRL runs into 50 uA current limit, usually caused by defect channel (broken wire of active electrode) AD box shuts down and battery remains on (green LED): short circuit detected, usually caused by connectors polluted with electrode gel AD-box and battery shut down (red LED): empt...
by Coen
Thu May 12, 2022 2:16 pm
Forum: BioSemi Hardware
Topic: Connecting Audio output to BioSemi AD-BOX
Replies: 7
Views: 1659

Re: Connecting Audio output to BioSemi AD-BOX

We can replace the CMS/DRL input with an ERGO, and you can then use A sets with integrated CMS/DRL.

Interfacing the audio with an AIB is also possible, but then the sample rate is limited to 2 kHz (optical ERGO works up to 16 kHz).

Best regards, Coen (BioSemi)
by Coen
Fri May 06, 2022 3:32 pm
Forum: ECG/EMG data analysis
Topic: Biosemi for recording motor-evoked potentials
Replies: 5
Views: 17394

Re: Biosemi for recording motor-evoked potentials

TMS may cause electrical currents through the electrodes. The skin-gel-electrode interface behaves like a battery or electrolytic capacitor and may become charged (polarized) due to these currents. This results in high, slowly decaying, offset voltages.

Best regards, Coen (BioSemi)
by Coen
Thu Apr 28, 2022 1:22 pm
Forum: EEG data analysis
Topic: Error in electrodes number during recording
Replies: 1
Views: 232

Re: Error in electrodes number during recording

Use just the Reducer. Do not use the Converter (converts 24-bit BDF to 16-bit EDF).

Best regards, Coen (BioSemi)
by Coen
Fri Apr 22, 2022 1:31 pm
Forum: BioSemi Software (ActiView executable)
Topic: Incorrect trigger numbers
Replies: 1
Views: 300

Re: Incorrect trigger numbers

EEGLAB should be modified to show two 8-bit trigger codes (instead of one 16-bit)

OR

Connect trigger lines 9-16 (pin 9-16) to ground (pin 37)

Bets regards, Coen (BioSemi)
by Coen
Fri Apr 08, 2022 12:47 pm
Forum: BioSemi Software (ActiView executable)
Topic: Saving an experiment as mulitple BDF files
Replies: 1
Views: 463

Re: Saving an experiment as mulitple BDF files

Ample buffering ensures that the files join seamlessly, not a single sample is lost. In case of an hickup, ActiView will always stop with an error message. By the way, you can join and split BDF files afterwards with ActiTools ( https://www.biosemi.com/download/ToolsForRuntimeEngine2021/ActiTools901...
by Coen
Tue Mar 15, 2022 10:04 pm
Forum: BioSemi Hardware
Topic: Battery
Replies: 2
Views: 788

Re: Battery

The AD-box is on speedmode 0, instead of 4-7. Or are you doing hyperscanning (2 subjects with daisy chained AD-boxes) ?

It is not a battery problem.

Best regards, Coen (BioSemi)
by Coen
Thu Mar 10, 2022 1:57 pm
Forum: BioSemi Hardware
Topic: 64 channels with 16KHz sampling rate?
Replies: 2
Views: 737

Re: 64 channels with 16KHz sampling rate?

AD-boxes can indeed be reprogrammed with HighSpeed firmware to allow 128+8+sensors channels at 16 kHz sample rate. Production date of the AD-box needs to be 2010 or later (serial ADC16-XX-XXXX or higher), the upgrade is free of charge. Older AD-boxes (ADC12-XX-XXXX or lower) need a new motherboard a...
by Coen
Wed Feb 16, 2022 2:01 pm
Forum: BioSemi Hardware
Topic: ERGO 16 Hz oscillation: bug or feature?
Replies: 2
Views: 950

Re: ERGO 16 Hz oscillation: bug or feature?

When nothing is connected to the ERGO, then the floating inputs may pick up interference (50 Hz form the mains, or 16 Hz from the GSR circuit). This is normal. However, when a signal source is properly connected to the ERGO, then there should not be 16 Hz interference. Please check the microphone co...
by Coen
Wed Feb 16, 2022 1:49 pm
Forum: EEG data analysis
Topic: From 32 A,B,C,D,E,F,G and H to 32 channels
Replies: 1
Views: 923

Re: From 32 A,B,C,D,E,F,G and H to 32 channels

Use ActiTools 901: https://www.biosemi.com/download.htm

Use the REDUCER to select channels A1-A32 and maybe EX1-EX8.

Use the EDITOR to change the ABC labels to 1020 labels according to https://www.biosemi.com/pics/cap_32_layout_medium.jpg

Best regards, Coen (BioSemi)
by Coen
Fri Feb 11, 2022 1:14 pm
Forum: BioSemi Hardware
Topic: what is going on with the raw trigger data?
Replies: 2
Views: 958

Re: what is going on with the raw trigger data?

The samples are 24-bit words. The 16 least significant bits are the 16 trigger lines. The 8 most significant bits are used for system status, see https://www.biosemi.com/faq/trigger_signals.htm .

Best regards, Coen (BioSemi)
by Coen
Wed Feb 02, 2022 2:21 pm
Forum: BioSemi Hardware
Topic: ActiveTwo flashing lights, bettary solid green
Replies: 1
Views: 1014

Re: ActiveTwo flashing lights, bettary solid green

2 or 3 flashing lights on the AD-box indicate that a short circuit is detected. If this happens only with the electrodes connected, then inspect your electrode sets (short circuit between cable shields and electrode wires, electrode gel in the connectors) If this happens without any electrodes conne...
by Coen
Tue Feb 01, 2022 11:14 pm
Forum: BioSemi Hardware
Topic: ABR Noise
Replies: 5
Views: 1369

Re: ABR Noise

Do not shield the cables (a suitable drive signal for the shields is not readily available), reduce the length to a few inches.

The spikes look like a contact problem (a short circuit would make the blue light blink).

Best regards, Coen (Biosemi)
by Coen
Tue Feb 01, 2022 1:48 pm
Forum: BioSemi Software (ActiView executable)
Topic: Trace randomly fell completely flat
Replies: 3
Views: 1143

Re: Trace randomly fell completely flat

Version 9.00 (latest) has the following keyboard shortcuts: - ENTER = Start - HOME = Reset baselines (display only) - F1-F8 = Triggers 9-16 All other keyboard shortcuts (Up/Down, Left/Right, PgUp/PgDn) that were available in older versions of ActiView have been deleted in version 9.00. Best regards,...
by Coen
Mon Jan 31, 2022 6:35 pm
Forum: BioSemi Hardware
Topic: ABR Noise
Replies: 5
Views: 1369

Re: ABR Noise

I assume that EX1 and EX2 are active electrodes, and therefore they do not generate interference with unshielded cables. The (unshielded) length of cable between the tiptrode and active electrode circuit should not be more than a few inches.

Best regards, Coen (BioSemi)
by Coen
Sun Jan 30, 2022 2:05 pm
Forum: BioSemi Hardware
Topic: ABR Noise
Replies: 5
Views: 1369

Re: ABR Noise

There is high 50/60 Hz mains interference on the tiptrode channels. How did you connect the tiptrode to the EX input ? If you used a long (more than a few cm) unshielded wire, then that explains the high interference level. Higher offsets for the tiptrodes are normal (gold vs AgAgCl electrode materi...
by Coen
Sun Jan 30, 2022 2:00 pm
Forum: BioSemi Software (ActiView executable)
Topic: Trace randomly fell completely flat
Replies: 3
Views: 1143

Re: Trace randomly fell completely flat

Did you press the keyboard shortcut PgUp or PgDn with an earlier version of ActiView than 9.00 ? If yes, then the display switched to a different (empty) group of channels. BDF file is not affected.

Best regards, Coen (BioSemi)
by Coen
Tue Jan 11, 2022 4:47 pm
Forum: BioSemi Hardware
Topic: Connecting Audio output to BioSemi AD-BOX
Replies: 7
Views: 1659

Re: Connecting Audio output to BioSemi AD-BOX

Yes, Erg1 channel on the "Sensors" tabpage.

Best regards, Coen (BioSemi)
by Coen
Tue Jan 11, 2022 3:10 pm
Forum: BioSemi Hardware
Topic: Connecting Audio output to BioSemi AD-BOX
Replies: 7
Views: 1659

Re: Connecting Audio output to BioSemi AD-BOX

Installation takes 1-2 days. We supply a 3.5 mm audio plug to OPTICAL-ERGO wire with the OPTICAL-ERGO (which has a standard 8-pole ERGO input, see viewtopic.php?f=1&t=931&p=2854 ).

Best regards, Coen (BioSemi)
by Coen
Tue Jan 11, 2022 12:54 pm
Forum: BioSemi Hardware
Topic: Connecting Audio output to BioSemi AD-BOX
Replies: 7
Views: 1659

Re: Connecting Audio output to BioSemi AD-BOX

You need to purchase an ERGO input and an OPTICAL-ERGO, see https://www.biosemi.com/accessoires.htm (EUR 400 + EUR 1000). The AD-box needs to be sent to BioSemi for installation of the ERGO input on AUX2. The OPTICAL-ERGO is essential to maintain galvanic isolation between the (mains powered) sound ...
by Coen
Thu Dec 23, 2021 1:59 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 14
Views: 21712

Re: Strange activity on a single electrode

You can use an average reference (from 2 electrodes to all electrodes), as long as you make sure that the average only contains good/valid channels.

Best regards, Coen (BioSemi)
by Coen
Fri Dec 17, 2021 1:51 pm
Forum: BioSemi Hardware
Topic: correct way to wire a GSR sensor test?
Replies: 4
Views: 1847

Re: correct way to wire a GSR sensor test?

Connect the GSR and DRL electrodes to one of the GSR electrodes (no resistor needed). Connect your rheostat between the GSR electrodes. ActiView displays the conductance in nanoSiemens in the left sidebar (for example: 100 kOhm displays as 10,000 nanoSiemens)

Best regards, Coen (BioSemi)
by Coen
Fri Dec 17, 2021 1:28 pm
Forum: EEG data analysis
Topic: Gain and offset for physical values
Replies: 4
Views: 1736

Re: Gain and offset for physical values

The BDF file header defines the gain of each channel with the physical and digital minimum and maximum values. The file format does in principle support minimum and maximum values that are not symmetrical around zero. I am not familiar with the EEGlab routines, but I suspect that the "offset" parame...
by Coen
Thu Dec 16, 2021 2:12 pm
Forum: EEG data analysis
Topic: Gain and offset for physical values
Replies: 4
Views: 1736

Re: Gain and offset for physical values

It is a DC amplifier, data is not high-pass filtered. Offset is simply the low-passed value of the data (cut-off frequency < 1 Hz) ABR (speedmode 9) saves 5 channels in ActiView 813 and 900: 3 DC monopolar (unreferenced) low-frequency channels and 2 AC bipolar (referenced) high-frequency channels. O...
by Coen
Mon Dec 06, 2021 3:29 pm
Forum: BioSemi Software (ActiView executable)
Topic: Problem with ActiView receiving triggers
Replies: 4
Views: 1920

Re: Problem with ActiView receiving triggers

Test with the parallel adapter connected to the USB-receiver, but with the USB-microUSB cable disconnected from the MacBook. All 16 trigger lines should now be Low in ActiView (your screenshot shows lines 1-8 high and 9-16 low). If not, the adapter is not functioning properly and should be replaced....
by Coen
Mon Dec 06, 2021 2:26 pm
Forum: BioSemi Software (ActiView executable)
Topic: Problem with ActiView receiving triggers
Replies: 4
Views: 1920

Re: Problem with ActiView receiving triggers

What are you using to interface the Macbook with the parallel trigger port on the USB-receiver ?

Best regards, Coen (BioSemi)
by Coen
Fri Dec 03, 2021 3:07 pm
Forum: BioSemi Hardware
Topic: Finding GSR input
Replies: 1
Views: 1487

Re: Finding GSR input

If there is no GSR label, then there is no GSR input. Aux3 (unlabeled) is currently not connected. BioSemi can install a GSR input on Aux3.

Best regards, Coen (BioSemi)
by Coen
Tue Nov 16, 2021 6:50 pm
Forum: BioSemi all other topics
Topic: Synchronizing EEG signal with EMG and speech
Replies: 5
Views: 3432

Re: Synchronizing EEG signal with EMG and speech

ActiRead (https://www.biosemi.com/download.htm) is made available complete with LabVIEW source code especially for researchers who want to add special features. You can add a sound output by programming in LabVIEW, as well as changing the ERGO amplitude. Up to 128 EEG channels on 16 kHz are possible...
by Coen
Mon Oct 25, 2021 3:32 pm
Forum: BioSemi Hardware
Topic: Spikes when using response box
Replies: 1
Views: 1899

Re: Spikes when using response box

The voltage switching in the response button boxes may cause very small Common Mode spikes in the EEG signal. Averaging over a lot of sweeps makes the spikes visible (all the small spikes add up, the EEG noise cancels out). Since the spikes are Common Mode, referencing reduces them with a factor of ...
by Coen
Wed Oct 20, 2021 6:56 pm
Forum: EEG data analysis
Topic: 'Common' reference after biosig import of GSR, Resp and Plet
Replies: 1
Views: 1819

Re: 'Common' reference after biosig import of GSR, Resp and Plet

You are correct: referencing should only be applied to the EEG channels, the sensor channels should remain unreferenced (or else the EEG reference is subtracted from the sensor channels).

Best regards, Coen (BioSemi)