diff --git a/data/df_senzor2_cvetkovic.xlsx b/data/df_senzor2_cvetkovic.xlsx
new file mode 100644
index 0000000..92f9043
Binary files /dev/null and b/data/df_senzor2_cvetkovic.xlsx differ
diff --git a/environment.yml b/environment.yml
index 24d89ec..bef1f4a 100644
--- a/environment.yml
+++ b/environment.yml
@@ -17,3 +17,4 @@ dependencies:
- git+https://github.com/LinkedEarth/Pyleoclim_util.git@master
- git+https://github.com/LinkedEarth/pylipd.git@main
- watermark
+ - openpyxl
diff --git a/notebooks/L1_time_semanics.ipynb b/notebooks/L1_time_semanics.ipynb
new file mode 100644
index 0000000..075da8e
--- /dev/null
+++ b/notebooks/L1_time_semanics.ipynb
@@ -0,0 +1,480 @@
+{
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Time Semantics"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Preamble"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Goals\n",
+ "- load timeseries data using Pandas\n",
+ "- create a Pandas Series with desired time intervals\n",
+ "- create Pyleoclim Series with desired time intervals\n",
+ "- Plot Pyleoclim Series \n",
+ "- Plot spectral analysis with Pyleoclim\n"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Keywords"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Pre-requisites\n",
+ "None. This tutorial assumes basic knowledge of Python. If you are not familiar with this coding language, check out this tutorial: http://linked.earth/LeapFROGS/."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Relevant Packages\n",
+ "Pyleoclim, Pandas"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Data Description\n",
+ "Data provided by @bdamir5. \"The data are my own measurements of CO2 concentration in the urban area of city Zagreb. They are sampled at a two-second frequency with the common low-cost CO2 sensor Senseair K30 and saved in .txt or .log files. Then I did some Python gymnastics to load all those log files to Pandas dataframe and extract whole-hour measurements. I exported the data to Excel to have them in one place when uploading here.\""
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Demonstration\n",
+ "\n",
+ "First import all necessary packages"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 1,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "import numpy as np\n",
+ "import pandas as pd \n",
+ "import matplotlib.pyplot as plt\n",
+ "from matplotlib import dates as mdates\n",
+ "from matplotlib.ticker import FuncFormatter\n",
+ "import os \n",
+ "import pyleoclim as pyleo\n",
+ "import datetime"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Load dataset \n",
+ "Load dataset (excel file) as Pandas dataframe and print contents to see format."
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 2,
+ "metadata": {},
+ "outputs": [
+ {
+ "data": {
+ "text/html": [
+ "\n",
+ "\n",
+ "
\n",
+ " \n",
+ " \n",
+ " | \n",
+ " Time | \n",
+ " CO2 Value [ppm] | \n",
+ "
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+ " \n",
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