Signal Processing for Communication Systems
Key focus: Let’s learn how to simulate matched filter receiver with square root raised cosine (SRRC) filter, for a pulse amplitude modulation (PAM) system. Simulation Model A basic pulse amplitude modulation (PAM) system as DSP implementation, is shown in Figure 1 by adding an upsampler ($latex \uparrow L$), pulse shaping function ($latex p[n]$) at the … Read more
Consider the generic baseband communication system model and its equivalent representation, shown in Figure 1, where the various blocks in the system are represented as filters. To have no ISI at the symbol sampling instants, the equivalent filter $latex H(f)$ should satisfy Nyquist’s first criterion. If the system is ideal and noiseless, it can be … Read more
In digital communications, an eye diagram (or eye pattern) is one of the most intuitive and powerful diagnostic tools for evaluating signal quality. Formed by overlapping consecutive symbol traces of a modulated signal over a fixed time window, the eye diagram instantly reveals the combined effects of Inter-Symbol Interference (ISI), phase jitter, dynamic range limitations, … Read more
Raised-cosine (RC) pulse shaping filter is generally employed at the transmitter. In time domain, a matched filter at the receiver is the mirrored copy of the impulse response of the transmit pulse shaping filter.
In square-root raised cosine (SRRC) filtering, the task of raised cosine filtering is equally split between the transmit and receive filters. The combined impulse response of two SRRC filters is same as the impulse response of the RC filter
As mentioned earlier, the shortcomings of the sinc pulse can be addressed by making the transition band in the frequency domain less abrupt. The raised-cosine (RC) pulse comes with an adjustable transition band roll-off parameter $latex \alpha$, using which the transition band’s rate of decay can be controlled. The RC pulse shaping function is expressed … Read more
Key focus: Baseband communication system and its equivalent DSP implementation (discrete time model) with a pulse shaping & matched filter is briefly introduced. If a train of pulses representing an information sequence need to be sent across a band-limited dispersive channel, the bandwidth of the channel should be large enough to accommodate the entire spectrum … Read more