Quick Start

Hopefully, a person could start using the MATLAB Continuous-Discrete Sampling tool without any need to read these help files. Features were designed to be intuitive and familiar to those with basic computer experience.

For those who like to read the manual, this section will give you the minimum you need to get started and be comfortable with the use of the GUI.

First, if you have not already done so, follow the information given in the Installation section to install and start the MATLAB Continuous-Discrete Sampling tool.

  1. To begin with, set the input sinusoid's frequency f0 and phase. You can set the frequency f0 in Hz by using the slider at the bottom-left of the GUI. Another way to set the input frequency is, you can use the mouse to click and drag the 'blue' stem plot corresponding to the Input signal in the Continuous time spectrum (Plot axes at the bottom left). The phase of the signal can be entered in the edit box below the text Phase. You should be able to see the corresponding change in Input, sampled signal x[n], Output and the corresponding Spectrums.
  2. You can also set the sampling rate (fs in Hz) at which the input needs to be sampled. This can be done using the slider at bottom-right of the GUI.
  3. Instead of specifying the frequencies in Hz, the input frequency and sampling rate can also be set in rad/s.i.e., w0 and ws, by toggling the radio-button Rad/sec to 'ON'. Equivalently, you can achieve the same, using the menu Plot Options: Show Radian Frequency. This also toggles the frequency axis of input and output spectrum plots between rad/s and Hz.
  4. If the sampling frequency selected is less than the Nyquist rate (2f0), then you will see the text ALIASING! displayed in the output spectrum plot, indicating the outputs have aliased.
  5. You can also toggle the frequency axis in the Discrete Time Spectrum between the normalized cyclic frequency f or normalized radian frequency w, using the Radian radio-button.
  6. In the case of output being aliased, you can toggle the reference plot overlying the Discrete time x[n] plot, to show either the high-frequency or low-frequency aliased component. i.e. between the aliased and un-aliased signals. This can be done using the menu, Plot Options: Show Lower Frequency Signal or double-clicking on the x[n] plot axes.
  7. Another useful feature of the Demo is its color-coded plots.
    • If the frequency of the input signal lies within the range indicated by the 'yellow' strip, then the output signal is not aliased.
    • Un-aliased frequency components are marked in 'blue' and the aliased components are marked in 'red', in the spectrum plots.
    • When Aliasing occurs in the output signal, such that the original signal cannot be reliably reconstructed, then the text ALIASING! is displayed in the output Continuous Time Spectrum plot axes.

That's it!  You now understand the basics of how to use the MATLAB Continuous-Discrete Sampling tool; For a more in depth description of Continuous-Discrete Sampling theory see the Theory section. The Controls and Menus sections provide a description of the various elements in the user interface.