tutorials/ita_tutorial_record.m

+% Recording with the ITA Toolbox
+%
+% In this tutorial you will learn how to set-up a simple the ITA Toolbox
+% for a simple recording task. The first step is to create an instance
+% of the itaMSRecord class, the basic recording class of the ITA toolbox.
+%
+%
+% <ITA-Toolbox>
+% This file is part of the ITA-Toolbox. Some rights reserved.
+% You can find the license for this m-file in the license.txt file in
+% the ITA-Toolbox folder.
+% </ITA-Toolbox>
+
+%% Set Hardware
+% Set your recording hardware in 'IO Settings'-tab ('recording' and
+% 'playback device'). For a calibrated measurement it is also recommended
+% to check 'Measurement Chain' on the % same 'IO Settings' tab.
+
+
+ita_preferences;
+
+%% Clear Workspace
+% The 'ccx' command basically resets Matlab to its start-up state.
+ccx;
+
+%% Measurement Setup
+% Create instance of recording class
+MS = itaMSRecord;
+
+% Define recording parameters
+% In this example we'll use the input channel 1 of the selected hardware
+% device. In case you activated the 'Measurement Chain' in the
+% ita_preferences, you will be asked about the elements in you input and
+% output chain, once you define the input and output.
+%
+% We'll also define an FFT-degree of 19, meaning that our recording time
+% will be 2^19 Samples.
+%
+% We'll set a sampling rate of 44100 Hz. Combined with the FFT-degree of
+% 19, this will amount to 11.9 s of recording time. With the itaMSRecord
+% class, it is only possible to define fixed recording times. If you
+% need an unknown or infinite recording time, you're probably better off
+% with normal DAWs, e.g. Reaper http://www.reaper.fm .
+MS.inputChannels = 1;
+MS.fftDegree = 19;
+MS.samplingRate = 44100;
+
+%% Calibration
+% To measure absolute SPL, it is mandatory to calibrate the input.
+% This is possible if you enabled the 'Measurement Chain' in the
+% ita_preferences. If you do not wish to calibrate a certain element
+% (not recommended, why would you have specified it before?) you can
+% just accept the default value ('1') by clicking accept. To calibrate
+% the element, connect you calibrator (pistonphone, voltage source, etc),
+% specify the properties of the calibrator in the GUI and click
+% 'calibrate'. If the calibration does not report an error (like 'No
+% calibration signal detected'), a new calibration value will be shown in
+% the GUI. You can either repeat the calibration to see if that value
+% changes, or accept the value if it seems reasonable by clicking
+% 'Accept'. The calibration GUI will then open for the next element to
+% be calibrated. After the last element the GUI will just close.
+MS.calibrate;
+
+% Have a look at the calibrated elements.
+MS.inputMeasurementChain
+
+
+%% Recording
+% Now the the actual recording can be started (class method 'run'). Make
+% sure you use a unique and meaningful target variable name. In this
+% case we'll use the generic name 'result'. This target variable will be
+% an itaAudio object and can be used with all signal processing tools of
+% the ITA Toolbox.
+result = MS.run;
+
+% Have a look at the result in the time domain (.plot_time or pt)
+result.pt
+
+% Have a look at the result in the time domain with a dB scale
+% (.plot_time_dB or ptd)
+result.ptd
+
+% Have a look at the result in the frequency domain (.plot_freq or pf)
+result.pf
+
+% You can also check your calibration by running a measurement with the
+% pistonphone connected. Just repeat the MS.run command (if you don't
+% specify a target variable, the measurement result will be in the
+% standard variable 'ans') and have a look at the frequency domain
+% (.pf). You should see an amplitude of 94dB (depending on your
+% pistonphone) at 1000 Hz (also a property of your phone).
+%
+% Congrats! Now you are able to do a calibrated measurement.
+% Happy data acquisition!	
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