How the features are extracted from the spectrogram block

Keerthivasan · February 22, 2023, 7:24am

Hi Team,
I am working on a model with the PPG continuous time series dataset based on the client application. I am trying to build a better topology of a model with the classification and spectrogram processing block.

As I try to build the model, I want to know how the spectrogram processing block in the edge impulse studio extracts the features and what are the features extracted from the PPG signal. Please provide more information.

Regards,
Keerthivasan

Eoin · February 22, 2023, 11:29am

Hi @Keerthivasan

For high level you can refer to this doc, and if you want to go into the code we have it published to github.

The Spectrogram processing block extracts time and frequency features from a signal. It performs well on audio data for non-voice recognition use cases, or on any sensor data with continuous frequencies.

GitHub repository containing all DSP block code: edgeimpulse/processing-blocks.

Parameter extraction:

github.com

edgeimpulse/processing-blocks/blob/master/spectrogram/parameters.json

{
    "version": 1,
    "info": {
        "title": "Spectrogram",
        "author": "EdgeImpulse Inc.",
        "description": "Extracts a spectrogram from audio or sensor data, great for non-voice audio or data with continuous frequencies.",
        "name": "Spectrogram",
        "preferConvolution": true,
        "convolutionColumns": "fft_length",
        "convolutionKernelSize": 5,
        "cppType": "spectrogram",
        "visualization": "dimensionalityReduction",
        "experimental": false,
        "latestImplementationVersion": 3
    },
    "parameters": [
        {
            "group": "Spectrogram",
            "items": [
                {

This file has been truncated. show original

Hope this helps, I’m not sure how much more we can give on the topic. If its not shared to github or in the documentation.

Best

Eoin

MMarcial · March 15, 2023, 11:38pm

@Keerthivasan I am not sure how much the JSON file helped you but hopefully you figured out the Spectrogram Processing Block code is here. Download the Processing Block, modify it, and test it using this info.