From 8b53aa27344f8e497e88de8db478345f56199a38 Mon Sep 17 00:00:00 2001
From: "paul.ewing" <paul.ewing@ecam.fr>
Date: Mon, 18 Mar 2024 09:38:17 +0100
Subject: [PATCH] added spectrogram

---
 spectrogram.m | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 spectrogram.m

diff --git a/spectrogram.m b/spectrogram.m
new file mode 100644
index 0000000..5829c03
--- /dev/null
+++ b/spectrogram.m
@@ -0,0 +1,36 @@
+function spectrogram(signal, samplingFreq, step_size, window_size)
+%%%%%%%%%%%%%%%%%%%%%%%
+%function spectrogram(signal, samplingFreq, step_size, window_size)
+% ex.:  spectrogram(signal, 300, 50, 1000)
+%
+% Task: Plot the spectrogram of a given signal
+%
+% Inputs:
+%    -signal: temporal signal to analyse 
+%    -samplingFreq: sampling frequency of the temporal signal
+%     -step_size: how often the power spectrum will be computed in ms
+%    -window_size: size of the analysing window in ms
+%
+% Ouput: None
+%
+% author: Guillaume Gibert (guillaume.gibert@ecam.fr)
+% date: 14/03/2023
+%%%%%%%%%%%%%%%%%%%%%%%
+
+figure;
+    subplot(2,1,1);
+t=0:1/samplingFreq:length(signal)/samplingFreq-1/samplingFreq;
+plot(t, signal');
+xlim([0 length(signal)/samplingFreq-1/samplingFreq]);
+ylabel('Amplitude (norm. unit)');
+    
+    subplot(2,1,2);
+step = fix(step_size*samplingFreq/1000);     % one spectral slice every step_size ms
+window = fix(window_size*samplingFreq/1000);  % window_size ms data window
+
+
+[S, f, t] = specgram(signal);
+specgram(signal, 2^nextpow2(window), samplingFreq, window, window-step);
+xlabel('Time (s)');
+ylabel('Frequency (Hz)');
+title('hello');
\ No newline at end of file