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@@ -126,101 +126,25 @@ Electrode connection to SensEdu
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### Amplifier Circuit
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As a base of the circuit SensEdu offers Dual-Channel Instrumentation Amplifier [AD8222](https://www.analog.com/media/en/technical-documentation/data-sheets/ad8222.pdf). On the shield we have x2 of them, which allows having **up to x4 EMG channels**. All channels are accessible from female 2.54mm sockets:
A 1-second history allows the filter to capture multiple cycles of low-frequency components, such as 10Hz (1 cycle every 100ms) or even lower frequencies (e.g., motion artifacts below 10Hz). This improves:
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The filter's ability to attenuate noise and artifacts.
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The preservation of desired signal components, especially in the lower frequency band.
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A longer history allows low-pass filters (used in envelope detection) to smooth the rectified signal over a larger time frame, resulting in a more robust and stable envelope.
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For example, a 5Hz low-pass filter requires at least 200ms of data for one full cycle. With a 1-second history, the envelope will be less sensitive to short-term fluctuations or noise.
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Sliding Overlapping Windows
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Use a 1-second buffer for filtering and envelope detection, but process overlapping chunks (e.g., update every 40ms). This ensures that decisions are updated frequently without sacrificing the filtering accuracy of the longer window.
* Implement filtering in hardware, you can extend SensEdu with another custom shield which will make half of current signal processing unnecessary greatly reducing latency and required computations. In addition, use right leg drive to decrease noise and offset.
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