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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 ...

You can use any ST-ST cable, with 62.5/125 um or 50/125 um multimode specification.

Best regards, Coen (BioSemi)

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...

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...

Use the "Free Choice" channels selection to display just the EOG channels in the monopolar display, and select "Monopolar Displayed Channels" as save subset in the file save dialog.

Best regards, Coen (BioSemi)

ActiveTwo is a DC system, signals are stored to BDF file without any high-pass filter.

During review, you should normally aplly a high-pass filter to suppress drift in the electrode offset voltages.

Best regards, Coen (BioSemi)

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...

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...

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;...

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 ...

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...

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...

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)

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

You are using a special custom made version of the ActiveTwo, so information about your particular connectors would not be relevant to anyone else on the forum. Please email BioSemi directly for help, thank you !

Best regards, Coen (BioSemi)

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 ...

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...

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...

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...

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)

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...

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 ...

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...

The blue light is probably blinking (Common Mode not in range). Please contatc BioSemi for further service.

This forum is meant as a platform for discussion. Please direct questions about service directly to BioSemi.

Best regards, Coen (BioSemi)

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 ...

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:...

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...

For a single trigger line, you can just sent 0V and 5V to a single pin on the trigger port

Best regards, Coen (BioSemi)

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...

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...