508 Chapter 8. Signal Processing
: Sampled Points: Sampled PointsAliasingAnalog PulseAnalog PulseTime
(a)Time
(b)Pulse HeightPulse HeightFigure 8.8.2: (a) Undersamling of data leads to
aliasing. (b) Aliasing can be avoided by sampling
at higher than Nyquist frequency.digital signal processing becomes much superior and powerful than its analog coun-
terpart. The tasks of complicated pulse manipulations, which would otherwise take
extremely complex analog circuitry, can be handled using computer codes. Further-
more the algorithms and the computer codes can be modified and changed according
to the particular requirements without changing any hardware components.
Although digital signal processing has many advantages, its design and imple-
mentation are not very easy. First of all, as we just discussed, aliasing is one of
the biggest problems in DSP design as it requires use of very fast ADCs. But this
is not the whole story, since the resolution and dynamic range of the ADC should
also be good enough to properly sample and digitize the signal. However, as we
saw earlier in the chapter, the resolution and speed have conflicting requirements on
ADC design. Another problem is that the ADCs themselves introduce noise in the
system, thus deteriorating the overall signal to noise ratio.
8.8.A DigitalFilters...........................
Discussion of digital filters is a very broad subject in itself and is out of the scope of
this book. However due to its importance we will introduce here the reader to the
basic concepts and designs of such filters.
The basic building blocks of a digital filter are