Merge pull request #77 from PayalLakra/main

Adding EEG Guide

Author: lorforlinux

guides/index.rst

@@ -49,6 +49,11 @@ Welcome to the **Guides** section, where you'll find comprehensive resources tha
          :link: resolve-software-issues
          :link-type: ref
 
+      .. grid-item-card:: Recording Quality EEG
+         :text-align: center
+         :link: recording_quality_eeg
+         :link-type: ref   
+
    **Contribution Guide**
 
    .. grid:: 1 1 1 1
@@ -77,6 +82,7 @@ Welcome to the **Guides** section, where you'll find comprehensive resources tha
    troubleshoot/tips/index
    troubleshoot/fix-hardware-setup/index
    troubleshoot/resolve-software-issues/index
+   troubleshoot/recording_quality_eeg/index
 
 .. toctree::
    :hidden:

guides/troubleshoot/media/alpha_waves.jpg

@@ -0,0 +1,101 @@
+.. _recording_quality_eeg:
+
+Recording Quality EEG
+######################
+
+This guide will help you set up and verify your EEG signals using the BioAmp Hardware and Chords software.
+
+Step 1: Skin Preparation
+========================
+
+Proper skin preparation is crucial before recording any biopotential signal, whether it is Electrocardiography (ECG), Electromyography (EMG), Electroencephalography (EEG), or Electrooculography (EOG). It helps to:
+
+- Clean the skin surface  
+- Reduce electrode-skin impedance
+- Improve overall signal quality  
+
+.. note::
+
+    Need help with skin prep? Check out the full guide here: :ref:`Skin Preparation Guide <skin-preparation>`
+
+Step 2: Connecting BioAmp Cables to the Hardware
+================================================
+
+Connect the BioAmp cables to the appropriate input channels of your EEG device. Make sure the ground and reference electrodes are securely connected to the body.
+
+.. figure:: ../media/connections.*
+    :align: center
+    :alt: BioAmp hardware connection
+
+    BioAmp hardware connection
+
+Step 3: Attaching Gel Electrodes on Targeted Areas
+==================================================
+
+Place the gel-based electrodes firmly on the targeted scalp regions—typically the frontal (e.g., Fp1, Fp2) or occipital (e.g., O1, O2) lobes—depending on your signal of interest. Ensure that the electrodes have good skin contact and are not loose.
+
+.. figure:: ../media/eeg_place.*
+    :align: center
+    :alt: EEG gel electrode placement
+
+    EEG gel electrode placement
+
+Step 4: Open Chords Software to Visualize Signals
+=================================================
+
+1. Open a Chromium-based browser such as **Google Chrome**, **Microsoft Edge**, **Opera**, or **Brave**.
+2. Go to: `https://chords.upsidedownlabs.tech <https://chords.upsidedownlabs.tech>`_
+3. Click on the **Visualize Now** button on the home page and then click on the **Chords-Visualizer** button on the next page.
+4. Connect your device via **Serial** by selecting your device's port.
+5. Begin real-time visualization of your EEG signals.
+
+Step 5: How to Check Whether the Signals Are Correct
+====================================================
+
+To verify correct electrode placement and good signal quality, try the following actions and observe their expected EEG responses.
+
+- **Eye Blinks**  
+Blinking creates sharp spikes in the EEG signal - these are EOG artifacts caused by eye movements.
+
+.. figure:: ../media/eye_blink.*
+    :align: center
+    :alt: Eye blink waveform
+
+    Eye blink waveform
+
+- **Jaw Clench**  
+A strong jaw clench produces EMG artifacts in the EEG signal - these are due to facial muscle activity.
+
+.. figure:: ../media/jaw_clench.*
+    :align: center
+    :alt: Jaw clench waveform
+
+    Jaw clench waveform
+
+- **Alpha Waves (Eyes Closed)**  
+
+.. note:: This may or may not be easily observable for all users.
+
+Close your eyes and relax. We're recording EEG from the frontal cortex to observe alpha waves (8–12 Hz), which appear more clearly when you're calm.
+
+.. figure:: ../media/alpha_waves.*
+    :align: center
+    :alt: Alpha waves EEG
+
+    Alpha waves EEG
+
+- **Beta Candle Test**  
+
+.. note:: This may or may not be observable for all users.
+
+To try this:  
+Open **Chords Software** → **Chords Visualizer** → **FFT Visualizer** → Connect your device (Serial/Bluetooth).  
+Then, activate the **Beta Candle** feature. Focus deeply on the candle. As your focus increases, the candle’s brightness and numerical value should increase. When you defocus, the value drops and the candle dims or blows out.
+
+.. figure:: ../media/beta_candle.*
+    :align: center
+    :alt: Beta candle test
+
+    Beta candle test
+
+If all or most of these responses are clearly visible, your setup is correct, and your EEG signals are stable enough for analysis.

guides/troubleshoot/media/beta_candle.jpg

@@ -430,7 +430,7 @@ We have 2 options to measure the EEG signals, either using the gel electrodes or
 
 - **Using gel electrodes to record from prefrontal cortex part of brain:**
 
-.. figure:: media/eeg.*
+.. figure:: media/eeg_placement.*
     :align: center
 
 1. Connect the BioAmp cable to gel electrodes.
@@ -484,6 +484,10 @@ The signals that you can see on the screen right now are originating from prefro
 
 You have placed the electrodes on the forehead (Fp1 & Fp2), the BioAmp EXG Pill is amplifying those signals so that we can detect it and finally sending it to the ADC (Analog to Digital Convertor) of your Arduino Uno and the signals are being visualized in Chords Web.
 
+.. tip::
+
+   To ensure you're recording a high-quality signal, refer to the detailed guide here: :ref:`Troubleshooting EEG Signal Quality <recording_quality_eeg>`.
+
 We hope everything is clear now and you understand how the signals are propagating from your brain to the screen of the laptop.
 
 Glimpses of previous versions