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Unformatted text preview: is never bandlimited. Therefore, for a bandlimited channel, Ú ´Øµ and, hence, Ú £ Ú ´Øµ are not timelimited and hence ISI is, in general, present. One common way
to observe and measure (qualitatively) the effect of ISI is to look at the eye diagram of the received
signal. The effect of ISI and other noises can be observed on an oscilloscope displaying the output ½ Ì . Such
For illustration, let us consider the basic waveform Ù´Øµ is the of the matched ﬁlter on the vertical input with horizontal sweep rate set at multiples of
a display is called an eye diagram. rectangular pulse ÔÌ ´Øµ and binary signaling is employed. The eye diagrams for the cases where the
channel is all-pass (no ISI) and lowpass (ISI present) are shown in Figures 4.1 and 4.2, respectively.
The effect of ISI is to cause a reduction in the eye opening by reducing the peak as well as causing
ambiguity in the timing information. 4.3 Wong & Lok: Theory of Digital Communications 4. ISI & Equalization 1.5 1 0.5 0 −0.5 −1 −1.5 5 10 15 20 25 30 Figure 4.2: Eye diagram of a BPSK signal with ISI 4.2 Nyquist Pulses
A careful observat...
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This note was uploaded on 12/13/2012 for the course EEL 6535 taught by Professor Shea during the Spring '08 term at University of Florida.
- Spring '08