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SIMULINK

Products < Data acquisition < Software < Real-time analysis <

Highspeed Online Processing under Simulink

The Highspeed Online Processing blockset is available for g.BSamp, g.MOBIlab+ and g.USBamp. The blockset allows to acquire biosignal data like EEG, ECoG, EMG, EOG, ECG into a Simulink model for further real-time processing. Therefore the device driver blocks g.BSamp, g.MOBIlab+ or g.USBamp are copied into the Simulink model and are connected to other blocks which do the signal analysis. Then the model is started and the device driver guarantees that the model is updated in real-time.

This Rapid Prototyping environment speeds up the development cycle dramatically and within a few hours the first real-time experiments can already be made. The Highspeed Online Processing blockset allows to use all standard Simulink blocks in your model and to write your own blocks in MATLAB code or C code.

The device driver block gives access to all amplifier specific settings like sampling frequency, digital I/O lines, bandpass and Notch filtering,... Just double-click onto the g.BSamp, the g.MOBIlab+ or g.USBamp block to perform the settings. Then click on Play in the Simulink model to start the biosignal acquisition.

Data are visualized with Scope blocks and stored to harddisk in MATLAB format. The model works with double precision accuracy. With g.MOBIlab+ it's now possible to store the data during acquisition on a SD card inside the unit.

The g.tec blockset g.RTanalyze supports the Rapid Prototyping of biosignal applications by ready-to-use algorithms. Tutorials are provided for brain-computer interface experiments, for ECG analysis and respiration analysis. The Simulink models contained in the Highspeed Online Processing blockset can be used as templates for own applications.

With the Highspeed Online Processing blockset we offer the g.EYEtrackingInterface. It provides a Simulink block that can be easily copied into every model to capture also the eye-movements of the subject.

Highlights

Acquire EEG, ECoG, ECG, EMG, EOG data directly within SIMULINK
Wireless biosignal data acquisition with g.MOBIlab+
Add graphically your own sophisticated data processing algorithms
Benefit from the Rapid Prototyping environment for developing, testing and releasing your biosignal applications
No compilation of the Simulink model is necessary for real-time analysis
Use standard Simulink blocks for online analysis
Add your own algorithms as MATLAB S-Functions or C S-Functions
Store data to the MATALB workspace or to a MATLAB file

Acquire biosignal data with g.MOBIlab+

The Simulink model contains the device driver block g.MOBIlab+. This block reads the biosignal data with 256 Hz into the model over a serial port of the computer. Thereafter a demultiplexer block is used to split the 2 acquired channels. The standard Simulink Scope block is used to visualize the data online. The To File block is used to store the biosignal data on-line onto the harddisk of the computer. By double-clicking onto the block the filename session1.mat can be entered. Therefore the data is stored in MATLAB format and can easily processed after recording. The Bandpower is used to calculate on-line the power distribution of the EEG signal. The paradigm block is used to show the current EEG bandpower to the subject.

It is important to note that the signal analysis, storage and visualization is done with standard Simulink blocks which can be accessed by drag-and-drop from the Library Browser. The Bandpower blocks are from the g.RTanalyze blockset. This allows the easy and fast setup of custom analysis models. The g.MOBIlab+ block guarantees that the processing is done in real-time.

The Scope block is used to visualize two EEG channels. The EEG signal has an amplitude of ± 15 µV because it is recorded with a bipolar derivation.

Remote control of g.MOBIlab+

The g.tec remote control unit allows to read biosignal data over a network connection (TCP/IP) into Simulink. Simulink is used as front-end and all functions of g.MOBIlab+ can be used. Therefore the acquisition of biosignals under difficult conditions like in a vacuum chamber or cold-chamber is supported.

Bluetooth transmission and SD card logging

g.MOBIlab+ can also transmit the data over a Bluetooth connection. Therefore a Bluetooth dongle is inserted into the PC/notebook computer. Then from multiple g.MOBIlab+ a specific one can be identified with the serial number and a connection can be established. The following Simulink model is configured to read in all analog input and digital input channels.

By double-clicking on the g.MOBIlab+ block, the following dialog opens:

HighSpeed On-Line Function Block Parameters in SIMULINK

Check each channel that should be transmitted from the amplifier g.MOBIlab+. Typically channels 1 and 2 are used for EEG recordings, channels 3 and 4 are used for DC recordings (respiration, EEG, pulse), channels 5 and 6 for ECG or EMG and channels 7 and 8 for external sensors (GSR, temperature). The 8 digital channels can be used as input (channel 1 - 8) or output channels (channel 4 - 7) or can be disabled. The COM Port identifies the Bluetooth communication channel from the PC/notebook to the g.MOBIlab+. Check the Testmode box to enable a sawtooth signal generation on the g.MOBIlab+.

Then start the Simulink model by pressing on Start Simulation. The Scope shows the sawtooth signals with different frequencies on the different analog channels. The digital inputs show rectangular signal with different frequencies.

g.MOBIlab+ is also able to stream data onto a mini SD card. The SD card is inserted into the water protected battery compartment first.

Then check the Enable writing to SD card checkbox into the configuration dialog, enter as filename GMOBILAB and start the acquisition. g.MOBIlab+ is now streaming the data onto the SD card and is sending simultaneously the signals to the PC/notebook for visualization. After checking the signal quality of the biosignals press the Stop button. A dialog window appears which asks if you want to stop the data acquisition or if you want to disconnect the Bluetooth connection.

Click on Disconnect to keep on streaming the data onto the SD card but to close the signal transmission over Bluetooth. Now the subject can move freely around for 36 hours for home observation, sports activities or other physiological experiments.

When the subject returns from the experiment startup the Simulink model again and click on Start again. The Bluetooth connection will be established again and the biosignal data can be visualized.

Finally stop the acquisition with Stop Simulation in the Simulink model. Now the SD card can be removed from g.MOBIlab+ and inserted into a card reader on the PC to analyze the physiological data. With a 1 GB SD card about 70 hours of data can be recorded.

High-resolution biosignal acquisition with g.USBamp

The g.USBamp Highspeed Online Processing block provides a graphical interface to the g.USBamp hardware which can be used under Simulink to specify the amplifier properties and to acquire the data.

The g.USBamp block output signal provides the biosignal data. The data format is single (float32) and it is scaled in µV. If all analog input channels (16) and the trigger signal (1) are acquired the line width is 17. Use a Demux block to de-multiplex the channels.

g.USBamp configuration dialog in SIMULINK

Double click on the g.USBamp block to access the configurtion window. The configuration window allows to specify the sampling frequency of the amplifier and to select the channels that should be acquired. Additionally the bandpass and Notch filters can be selected for each channel. Bipolar derivations can also be defined. The amplitude, frequency and the offset of the test-signal can also be adjusted.

After performing the configuration click on the Play button of the Simulink model to start the biosignal acquisition and visualization. The Simulink model is updated in real-time because of the hardware interrupt driven g.USBamp block.

This Simulink Scope shows an acquired ECG signal with a sampling frequency of 1200 Hz.

Impedance measurement and calibration with g.USBamp

The g.USBamp blockset contains also blocks for calibrating the amplifier and to measure the electrode impedance. Therefore copy the blocks into the Simulink model.

Double-click on the Impedance Check window to measure the electrode impedance of each electrode. The window shows the 16 input channels and the 4 reference electrodes. The electrodes are marked in green, yellow, red and blue colors according to their impedance values.

Double-click on the Calibration block to adjust the offset and the gain of each channel of the amplifier.

Tutorials

g.BSamp

Calculate heart rate and respiration rate with g.BSamp and Simulink (PDF 516 kByte)
Brain computer interface with g.BSamp and Simulink (PDF 589 kByte)

g.MOBIlab+

Calculate heart rate and respiration rate with g.MOBIlab+ and Simulink (PDF 136 kByte)
Brain computer interface with g.MOBIlab+ and Simulink (PDF 152 kByte)
Remote control of g.MOBIlab+ with Simulink (PDF 55 kByte)

g.USBamp

Calculate heart rate and respiration rate with g.USBamp and Simulink (PDF 154 kByte)
Brain computer interface with g.USBamp and Simulink (PDF 152 kByte)

Prerequisites

MATLAB and Simulink (Release 2008b)
The Signal Processing Blockset is a useful extension for doing signal analysis in time and frequency domain.

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