(DM-D modulalation -HIDM)

Understanding DM (powered by Pedro Sá de Melo, H.M. de Oliveira, UFPE, 2010)

FILES = MatlabTM please download:

modula_delta.m (22k)

modula_delta.fig (16k)

modulacao.wav (328k)

Use MatlabTM, run modula_delta.m and open (interface) file modulacao.wav


1.       Adjust the pitch of the DELTA quantizer (cue 0.01) 

Adjust the sampling rate of DM (hint fs = 80 kHz)

Make initial analysis without noise (type: error probability PE= 0)

Use the zoom tool to examine the tracked signal (modulated output)

Check the effect of slope overload with appropriate zoom in stretch

Visualize the audio frequency (spectra: original and demodulated audio)

Listen to different versions of audio, comparing the audio quality.

Change and examine the effect of changes in i) Step size (D) and ii) sampling rate (fs)

2.       Now repeat analysis in the presence of noise (the fixed error rate)

Check and listen to the output with different probabilities of error (Hint PE= 0.01 0.05 0.1)

Realize how delta modulation is robust in the presence of high noise (hence the preference for space communications and military)

3.       Simulate with adaptive delta, introducing different step sizes (cue 0.01 0.02 0.05)

Compare the approximation and quality with several choices of parameters.

See waveforms and spectra such as done in DELTA analysis.

4.       Study the effects of FILTER!