Contents
How are the symbols represented in pulse shaping?
Usually the transmitted symbols are represented as a time sequence of dirac delta pulses multiplied with the symbol. This is the formal transition from the digital to the analog domain. At this point, the bandwidth of the signal is unlimited. This theoretical signal is then filtered with the pulse shaping filter, producing the transmitted signal.
What are the drawbacks of a sinc pulse?
The main drawback of the sinc pulse is that it decays too slowly at the rate of as . This implies that the samples that are far apart can cause intersymbol interference in the event of modest clock synchronization errors.
How is the frequency response of a sinc pulse affected?
Figure 2 shows the one-sided frequency response of the sinc pulse that is truncated to various lengths. It is evident that the truncation of sinc pulse in time domain to leads to sidelobes in the frequency domain and the sidelobes become wider for decreasing values of .
Why does a bandlimited signal have a sinc shape?
A bandlimited signal corresponds to an infinite time signal, that causes neighbouring pulses to overlap. As the modulation rate increases, the signal’s bandwidth increases. As soon as the spectrum of the signal is a sharp rectangular, this leads to a sinc shape in the time domain.
Why do you need to use pulse shaping?
The main reason for using pulse shaping is that the bandwidth of the transmitted signal is the same as that of your pulse shape. To avoid ISI, you want your pulse shape to be orthogonal to time-shifted versions of itself.
How is the spectrum of a pulse shaping filter determined?
The signal’s spectrum is determined by the modulation scheme and data rate used by the transmitter, but can be modified with a pulse shaping filter. Usually the transmitted symbols are represented as a time sequence of dirac delta pulses. This theoretical signal is then filtered with the pulse shaping filter, producing the transmitted signal.
Why is pulse shaping important in RF communication?
By filtering the transmitted pulses this way, the intersymbol interference caused by the channel can be kept in control. In RF communication, pulse shaping is essential for making the signal fit in its frequency band. Typically pulse shaping occurs after line coding and modulation .