The signal reconstruction of a D-to-A converter is presentated from a practical point of view as a generalization of interpolation.

By visualizing the spectrogram of a synthesized chirp and listening to the sound,
we experience the fact that a D-to-C converter cannot create output signals
with frequencies higher than one half of the sampling frequency.

The Continuous-Discrete Sampling Demo (con2dis)
is a program that shows the continuous
and discrete spectra (and signals) during sampling.

**Features:**

- Users can change the input frequency and sampling rate.
- Frequency axis can be labeled in hertz or radians/sec.
- Reconstruction through D/A is also shown.

The Continuous-Discrete Sampling Demo is a program that shows the continuous
and discrete spectra (and signals) during sampling.

The objective in this lab is to introduce digital images as a
second useful signal type. We will show how the
A-to-D sampling and the D-to-A reconstruction processes are
carried out for digital images. In particular,
we will show a commonly used method of image zooming
(reconstruction) that gives poor results a later
lab will revisit this issue and do a better job.
[Files]

The objective of this lab is to study further the spectral content of signals analyzed via the *spectrogram*.
There are several specific steps that will be considered in this lab:

- Synthesize a linear-FM chirp with a Matlab M-file, and display its spectrogram. Choose the chirp parameters so that aliasing will happen.
- Synthesize a periodic triangle wave with a Matlab M-file, and display its spectrogram. Relate the harmonic line spectrum to the fundamental period of the triangle wave.
- Compare spectrograms using different scales for amplitude: decibels (dB) for amplitude versus linear amplitude.
- Examine details of the harmonic lines in the dB spectrogram of the triangle wave.
*Spectrogram*: make a spectrogram of your voice signal, and relate the harmonic line spectrum to your previous measurement of pitch period.