Search found 1124 matches
- Mon Feb 02, 2009 1:47 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Flexible downsampling?
- Replies: 1
- Views: 5279
The utility is written in open-source LabVIEW version 8.2. The code is available form our website, and can quite easily be modified by yourself (for labVIEW, see http://www.ni.com/labviewse/select.htm). The utility processes blocks of one second, or 1024 samples in you case. Delete 24 approximately ...
- Mon Jan 26, 2009 6:34 pm
- Forum: BioSemi Hardware
- Topic: optic fiber cable
- Replies: 3
- Views: 7497
- Thu Jan 22, 2009 5:51 pm
- Forum: BioSemi Hardware
- Topic: Error 5002
- Replies: 9
- Views: 17369
If a working system suddenly stops working, then the optical connection is the prime suspect. Start by replacing the optical fiber. No need to reflash the receiver, don't do it at this stage (won't void the warranty though) Service pack 3 works fine with the ActiveTwo, but it won't solve the Error 5...
- Thu Jan 22, 2009 1:15 pm
- Forum: BioSemi Hardware
- Topic: Biosemi ActiveTwo with NI Hardware
- Replies: 1
- Views: 5275
It is not necessary to use NI hardware for the interfacing of the BioSemi ActiveTwo system. Our USB-receiver ( http://www.biosemi.com/receiver.htm ) is used as an improved alternative for (previously used) NI cards. There would not be any advantage in interfacing via NI hardware, and therefore we do...
- Tue Jan 20, 2009 4:42 pm
- Forum: EEG data analysis
- Topic: Recording EOG's
- Replies: 6
- Views: 20879
- Fri Dec 19, 2008 11:39 am
- Forum: EEG data analysis
- Topic: drifts in channels & import into vision analyzer
- Replies: 2
- Views: 7295
- Fri Dec 12, 2008 3:50 pm
- Forum: BioSemi Hardware
- Topic: MRI compatibility
- Replies: 1
- Views: 5184
The ActiveTwo system (AD-box and active electrodes) will not be damaged by the magnetic and RF fields. However, there is certainly an issue with respect to subject safety. The RF fields during the scan may induce large currents in electrode wires inside the scanner (certain lengths of wire may act a...
- Wed Dec 03, 2008 7:25 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: 2 questions about reference
- Replies: 1
- Views: 5688
You are not doing anything wrong. The purple box is just a warning to let users know that no reference is selected for the displayed signals. You are fully correct that the reference selection does not influences the signals saved to file (indeed, signals on file are always unreferenced). The channe...
- Thu Nov 13, 2008 12:06 am
- Forum: BioSemi Hardware
- Topic: USB Driver (RECEIVER01) will not install on Windows Vista
- Replies: 3
- Views: 7471
In case of AHAAS (who started this thread), the problem was tracked down to an incompatible operating system: he was trying to install on a PC with Vista 64-bit. The current version of our drivers, and the current version of ActiView (compiled with LabVIEW 8.2), are not compatible with Vista 64-bit;...
- Wed Nov 05, 2008 4:37 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: TTL Pulse width recognition
- Replies: 3
- Views: 8672
The trigger length should be at least the duration of a (hardware) sample (e.g: > 0.5 millisecond on speedmode 4, > 61 microsecond on speedmode 7). Decimation to a lower sample rate in software works by applying an OR function on successive groups of trigger samples (e.g. if any of the samples in a ...
- Tue Nov 04, 2008 2:39 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: Computing electrode offset?
- Replies: 5
- Views: 20110
n your example, you will see a DC voltage of -10 mV on the offset page , and an AC signal in the range of 100 uV in the monopolar display. The ActiveTwo is a DC system, it will store the AC signal superimposed on the DC electrode offset in the same data sample. So, in your example, you will find a s...
- Thu Oct 30, 2008 5:08 pm
- Forum: EEG data analysis
- Topic: merging BDFs?
- Replies: 10
- Views: 35612
Formally, you are right. However, in practice it has been allowed to record several segments in a single BDF file since the introduction of the BDF format in 2001. The start of each segment is indicated by a High "epoch" bit in the status/trigger channel (bit 16 in last channel, see http://www.biose...
- Wed Oct 29, 2008 9:57 am
- Forum: BioSemi Hardware
- Topic: USB Driver (RECEIVER01) will not install on Windows Vista
- Replies: 3
- Views: 7471
Please try the latest version of the driver, available from http://www.biosemi.com/download/USB%20drivers%20XPVista/USB%20drivers%20XPVista.zip In case of further problems, please contact www.cortechsolutions.com (local BioSemi representative), they will help you quickly. Best regards, Coen (BioSemi)
- Fri Oct 24, 2008 4:47 pm
- Forum: BioSemi Software (ActiView executable)
- Topic: big voltage value
- Replies: 1
- Views: 5947
The ActiveTwo is a DC system, the EEG is superimposed on electrode offset voltages, see http://www.biosemi.com/faq/24bitsystem.htm . DC values of +13 mV and -25 mV as in the above examples are very normal.
Best regards, Coen
Best regards, Coen
- Wed Oct 22, 2008 6:11 pm
- Forum: BioSemi Hardware
- Topic: pin connections of the connectors on the AD-box
- Replies: 1
- Views: 4530
- Tue Oct 21, 2008 9:52 am
- Forum: BioSemi Hardware
- Topic: Interference, noise and the like
- Replies: 11
- Views: 19860
The active electrodes eliminate interference by capacitive coupling of the electrode cables with interference sources. In most practical situations, this interference pickup by the electrode wires is the main cause for 50 Hz interference. Therefore, the advantage of active electrodes is appreciated ...
- Mon Oct 20, 2008 10:54 pm
- Forum: BioSemi Hardware
- Topic: Interference, noise and the like
- Replies: 11
- Views: 19860
With the ActiveTwo system, it is not possible to pickup 50 Hz interference inside a properly shielded mu-metal room (provided the electrodes, AD-box and battery are inside the room, and the USB-receiver with PC are outside the room). Whether the electrodes are active or passive plays no role in this...
- Mon Oct 20, 2008 5:53 pm
- Forum: BioSemi Hardware
- Topic: Interference, noise and the like
- Replies: 11
- Views: 19860
Active electrodes, nor any shieding of electrode cables or the experimentation room guards against the effects alternating magnetic fields. As explained, only the bundling of electrode cables has effect (as with any other system). The unique setup of the ActiveTwo (active electrodes, battery power s...
- Mon Oct 20, 2008 5:37 pm
- Forum: BioSemi Hardware
- Topic: Interference, noise and the like
- Replies: 11
- Views: 19860
A Faraday cage shields against electric fields. However, unless metal with a high magnetic permeability is used, the cage does not shield at all for magnetic fields. Therefore, only cages made of special a alloys (mu-metal made of iron and nickel) will effectively shield against magnetic interferenc...
- Mon Oct 13, 2008 5:35 am
- Forum: BioSemi Hardware
- Topic: Power supply
- Replies: 1
- Views: 4727
No, the ActiveTwo system is designed to only operate from a battery power supply. This is one of the reasons of the high level of performance, see http://www.biosemi.com/faq/battery_and_fiber.htm .
Best regards, Coen (Coen)
Best regards, Coen (Coen)
- Sun Oct 05, 2008 7:42 pm
- Forum: BioSemi Hardware
- Topic: New Hardware issues
- Replies: 1
- Views: 5078
All Mk2 systems are the same as far as the acquisition software is concerned. Please test the third system with the standard ActiView software; if there is a problem, it should also show up there. Check that there is no confusion with speedmodes. Check that there is no mix up of receivers (Mk1 recei...
- Tue Sep 23, 2008 10:18 am
- Forum: BioSemi Hardware
- Topic: battery charger
- Replies: 1
- Views: 6235
f the battery gets warm during charging, then the problem is probably that one of the internal cells is shorted. Please sent the battery-box to BioSemi for replacement of the internal cells. If the battery discharges too quickly when operating the the AD-box, then the battery is probably at the end ...
- Fri Sep 12, 2008 4:28 pm
- Forum: BioSemi Hardware
- Topic: EOG hangdowns
- Replies: 1
- Views: 5473
The flat-type electrodes with touchproof connectors are all identical. It does not matter which electrode is connected to which EX input, and they can be located anywhere on the body. The ActiView display of bipolar combinations is just a software choice (by modifying the LabVIEW code, any other com...
- Thu Sep 04, 2008 11:42 am
- Forum: BioSemi Hardware
- Topic: incredibly noisy signals
- Replies: 1
- Views: 5520
- Tue Sep 02, 2008 12:28 pm
- Forum: BioSemi Hardware
- Topic: Speed-mode setting on BioSemi AD box
- Replies: 4
- Views: 8805
Just one extra remark: keep in mind that the analog bandwidth is approx. 1/5th of the sample-rate (-3 dB point is indicated in the right sidebar). So, ensure that you select the sample-rate high enough to retain sufficient high frequency information in the data. For most EEG work, it is recommended ...
- Mon Sep 01, 2008 12:21 pm
- Forum: BioSemi Hardware
- Topic: Speed-mode setting on BioSemi AD box
- Replies: 4
- Views: 8805
You can use speedmodes 4, 5 or 6. Speedmode 6 will give you a maximum sample-rate of 8 kHz, and a minimum sample rate of 128 Hz (by using the "decimation" option in software). "Sensors" refers to the extra optional sensors connected to the Aux inputs (GSR, Plethysmograph, Respiration, ect, see http:...
- Thu Aug 28, 2008 11:46 am
- Forum: BioSemi all other topics
- Topic: Other platforms
- Replies: 23
- Views: 94093
Our policy is actually a bit more subtle than stated in my previous message. We are prepared to share the source code of the Windows driver (and have done so in the past), under the following conditions: - you will have to convince us that you actually have the knowledge to do anything useful with i...
- Fri Aug 22, 2008 3:13 pm
- Forum: BioSemi Hardware
- Topic: Triggering
- Replies: 1
- Views: 4638
- Mon Aug 11, 2008 6:23 pm
- Forum: ECG/EMG data analysis
- Topic: offline heart rate extraction from ECG signal
- Replies: 13
- Views: 34631
A VI to calculate the heartrate from 2 EX channels is available for download from http://www.biosemi.com/download/Heartrate.vi , I have written this VI a few years ago for online heartrate calculation (was included in some custom versions of ActiView), but you can of course use it in off-line applic...
- Mon Aug 11, 2008 2:38 pm
- Forum: BioSemi Hardware
- Topic: Trigger Port Timing
- Replies: 3
- Views: 11212
ActiView saves data in blocks of 1 second (BDF record length). A buffer of 1 second is continuously filled with data, and when the buffer is full, the data is streamed to disc (indicated by a flash of the "write" lamp in the right sidebar) When the Pause button unlocked, ActiView saves the running 1...