119 lines
3.5 KiB
Plaintext
119 lines
3.5 KiB
Plaintext
{
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"cells": [
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{
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"cell_type": "markdown",
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"id": "d709b880",
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"metadata": {},
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"source": [
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"# Input"
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]
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},
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{
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"cell_type": "markdown",
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"id": "5f40e11b",
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"metadata": {},
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"source": [
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"Here you can download the input files (right click / save as...):\n",
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"* <a href=_static/2024-06-07-16k.in download>2024-06-07</a>\n",
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"* <a href=_static/2024-06-06-16k.in download>2024-06-06</a>\n",
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"* <a href=_static/2024-03-16-16k.in download>2024-03-16</a>\n",
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"* <a href=_static/2023-04-20-16k.in download>2023-04-20</a>\n",
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"* <a href=_static/2023-06-15-16k.in download>2023-06-15</a>\n",
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"* <a href=_static/2024-03-14-16k.in download>2023-03-14</a>"
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]
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},
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{
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"cell_type": "markdown",
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"id": "6ab69020",
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"metadata": {},
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"source": [
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"In this project, we work with audio data.\n",
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"To facilitate reading it into your program, we provide the inputs in a simple format:\n",
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"\n",
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"```{admonition} Format\n",
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"The first line contains $n$, the number of samples ($0 \\leq n < 2^{32}$).\n",
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"\n",
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"Afterwards, $n$ lines follow, each with one sample $x$ as an integer ($-2^{15} \\leq x < 2^{15}$).\n",
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"```\n",
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"\n",
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"The sampling rate $f_s$ is fixed at 16640 Hz.\n",
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"\n",
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"## Example\n",
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"```\n",
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"10\n",
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"623\n",
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"-310\n",
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"-273\n",
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"3404\n",
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"4745\n",
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"655\n",
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"-454\n",
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"3463\n",
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"3375\n",
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"-5350\n",
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"```\n",
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"\n",
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"```{note}\n",
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"Although the samples are given as integer numbers, for the rest of the project it makes sense to convert them into a floating point format at this point already.\n",
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"```"
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]
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},
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{
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"cell_type": "markdown",
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"id": "cfcac6c9",
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"metadata": {},
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"source": [
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"# Visualization\n",
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"\n",
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"It can be helpful during this project to visualize the result after every step.\n",
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"Wen can do this for example like this:\n",
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"- The signal contains 2 lines with 2080 pixels each per second. With $f_S = 16640\\text{Hz}$, we have 4 samples per pixel.\n",
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"- We take every 4th sample. For complex numbers, we calculate the magnitude $(a + ib \\mapsto \\sqrt{a^2+b^2} =\\mathrel{\\vcenter{:}} v)$.\n",
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"- We find $v_{min}$ and $v_{max}$, the smallest and largest values we obtained.\n",
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" Then we scale each $v$ to $255 \\cdot (v - v_{min}) / (v_{max} - v_{min})$.\n",
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" The result is a value between 0 and 255.\n",
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"- We can save these values as pixels in an image file.\n",
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" To do this, we can use the [](pgm-format) for example.\n",
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" \n",
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"```{figure} img/reference/raw_full_scaled.webp\n",
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"---\n",
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"name: fig:raw_full.en\n",
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"---\n",
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"Visualization, directly after reading the input.\n",
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"The image can be discerned already, but it is quite dark.\n",
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"```\n",
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"\n",
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"```{figure} img/reference/raw_detail.webp\n",
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"---\n",
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"name: fig:raw_detail.en\n",
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"---\n",
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"Detail view.\n",
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"We can clearly see vertical lines, stemming from the modulation onto the 2.4 kHz carrier.\n",
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"```"
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]
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}
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],
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"display_name": "Python 3 (ipykernel)",
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"language": "python",
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"name": "python3"
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.11.13"
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"nbformat": 4,
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