Search found 1039 matches

by Coen
Tue Jan 11, 2022 4:47 pm
Forum: BioSemi Hardware
Topic: Connecting Audio output to BioSemi AD-BOX
Replies: 5
Views: 232

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: 5
Views: 232

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: 5
Views: 232

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: 19170

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: 533

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: 515

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: 515

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: 661

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: 661

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: 505

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: 2093

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: 899

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: 854

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)
by Coen
Mon Oct 18, 2021 2:43 pm
Forum: BioSemi Software (ActiView executable)
Topic: ActiView responding to keyboard commands even when it does not have focus
Replies: 2
Views: 994

Re: ActiView responding to keyboard commands even when it does not have focus

In the latest 9.00 Windows version of ActiView (put on our website today), I have deleted the arrow Left/Right/Up/Down and Pgup/Pgdn keyboard shortcuts. In LabVIEW 2021, the "key focus" property node does not work for the Menu Ring controls, and therefore I could not get the shortcuts to work fully ...
by Coen
Thu Sep 30, 2021 12:49 pm
Forum: BioSemi Software (LabVIEW programming)
Topic: Correct way to index AUX channels?
Replies: 1
Views: 1029

Re: Correct way to index AUX channels?

The senso signals are sent from the AD-box in a block of 16 channels. Installed sensors generate data on dedicated channels in the block, uninstalled sensors generate flatliners. ActiView processes the 16 channels into 7 sensor channels (displayed and saved to BDF file). Inspect the LabVIEW source c...
by Coen
Fri Sep 24, 2021 11:44 am
Forum: BioSemi Hardware
Topic: CM out of range with more than 64 electrodes
Replies: 3
Views: 1349

Re: CM out of range with more than 64 electrodes

We do not offer a daisy chain option for two 64 channel systems on the same subject.

Best regards, Coen (BioSemi)
by Coen
Wed Sep 22, 2021 9:00 pm
Forum: BioSemi Hardware
Topic: CM out of range with more than 64 electrodes
Replies: 3
Views: 1349

Re: CM out of range with more than 64 electrodes

You can only use the channels that are actually installed in the AD-box. To check: inspect the offsets with no electrodes connected to the AD-box, installed channels are maximally negative, uninstalled channels are zero. You will probably find that only channels 1-64 are installed. In order to use m...
by Coen
Wed Sep 22, 2021 8:58 pm
Forum: BioSemi Hardware
Topic: Combing 10-20 and ABCD electrodes for recording 128 electrodes
Replies: 2
Views: 1180

Re: Combing 10-20 and ABCD electrodes for recording 128 electrodes

You can only use the channels that are actually installed in the AD-box. To check: inspect the offsets with no electrodes connected to the AD-box, installed channels are maximally negative, uninstalled channels are zero. You will probably find that only channels 1-64 are installed. In order to use m...
by Coen
Mon Sep 20, 2021 1:02 pm
Forum: BioSemi Software (ActiView executable)
Topic: the unit of EMG data
Replies: 1
Views: 1044

Re: the unit of EMG data

The scaling of each channel is found in the BDF header, see https://www.biosemi.com/faq/file_format.htm (physical and digital min/max values). The electrode channels are LSB = 31.25 nV (1/32 uV). The scaling in ActiView does not affect the BDF file. All settings in the left sidebar only affect the d...
by Coen
Mon Sep 13, 2021 2:17 pm
Forum: BioSemi Hardware
Topic: Weird noise
Replies: 4
Views: 1510

Re: Weird noise

Determine the frequency of the interference (zoom in, make spectrum), it looks like 50 Hz from the mains supply. Test with electrodes in water. Increase/decrease the area of the included loop between cables of CMS/DRL and other electrodes to determine whether an electric or magnetic field causes the...
by Coen
Sun Sep 12, 2021 9:42 pm
Forum: BioSemi Hardware
Topic: Weird noise
Replies: 4
Views: 1510

Re: Weird noise

Gel bridge between CMS and DRL, see viewtopic.php?f=7&t=810&p=3048

Best regards, Coen (BioSemi)
by Coen
Fri Aug 27, 2021 12:08 pm
Forum: EEG data analysis
Topic: Biosemi data format/Reading .bdf into Matlab
Replies: 9
Views: 20513

Re: Biosemi data format/Reading .bdf into Matlab

Use the digital and physical min/max values in the file header to scale the data, see https://www.biosemi.com/faq/file_format.htm . From the file header, you can conclude that the scaling for the EEG channels is LSB = 31.25 nV (1/32th uV) Using the BDF --> EDF converter to rescale the data is possib...
by Coen
Thu Aug 19, 2021 12:38 pm
Forum: BioSemi Hardware
Topic: Battery Life
Replies: 1
Views: 1401

Re: Battery Life

A 64 channel system should work more than 12 hours on a new battery, and still more than 6 hours on a battery that is a few years old. 2.5 hours is certainly too short, you should replace the internal cells of the battery.

Best regards, Coen (BioSemi)
by Coen
Mon Aug 16, 2021 1:26 pm
Forum: BioSemi Software (ActiView executable)
Topic: Defining in code the number of channels
Replies: 2
Views: 1401

Re: Defining in code the number of channels

The above is in principle possible by modifying the (open source LabVIEW) code of ActiView.

Note that you can save the settings (including TCP/IP selections) in the CFG file.

Best regards, Coen (BioSemi)
by Coen
Mon Jul 26, 2021 2:02 pm
Forum: BioSemi Software (ActiView executable)
Topic: ActiView example client raw data transformation
Replies: 2
Views: 1529

Re: ActiView example client raw data transformation

Each sample is a 24-bit word from the Analog-to Digital converter. Each 24-bit sample is sent as 3 bytes.

TCP blocksize is in samples
Buffersize is in bytes

Best regards, Coen (BioSemi)
by Coen
Thu Jun 24, 2021 1:26 pm
Forum: BioSemi all other topics
Topic: Synchronizing EEG signal with EMG and speech
Replies: 5
Views: 2093

Re: Synchronizing EEG signal with EMG and speech

The ActiveTwo system can measure EEG, EMG (with flat electrodes and headbox, see https://www.biosemi.com/accessoires.htm) and microphone (via ERGO input), all simultaneous, synchronized and up to 16 kHz sample rate. Trying to use other devices for EMG and sound acquisition seems a needless complicat...
by Coen
Wed Jun 16, 2021 5:29 pm
Forum: EEG data analysis
Topic: 1Hz Unexpected Frequency in Signal
Replies: 1
Views: 1660

Re: 1Hz Unexpected Frequency in Signal

"Is it possible that something in the hardware is causing this?"

No, the BioSemi system does not generate any signal of exactly 1 Hz.

Best regards, Coen (BioSemi)
by Coen
Thu Jun 10, 2021 3:27 pm
Forum: BioSemi all other topics
Topic: Strange activity on a single electrode
Replies: 14
Views: 19170

Re: Strange activity on a single electrode

You should indeed first remove the flat/bad channels, and then reference to one or more of the remaining valid channels.

Best regards, Coen (BioSemi)
by Coen
Fri May 07, 2021 11:54 am
Forum: BioSemi Hardware
Topic: Is this the problem of battery?
Replies: 3
Views: 2389

Re: Is this the problem of battery?

You probably left the batteries too long (several months) is a discharged state. Always charge the batteries before storing and recharge them every few months. The cells can sometimes be recovered with a few charge/discharge cycles. If not, then contact your local BioSemi representative for replacem...