Pulse Shaping Archives - GaussianWaves

Constellation diagram – investigate phase transitions

Mathuranathan — Sun, 28 Jun 2020 12:15:57 +0000

The phase transition properties of the different variants of QPSK schemes and MSK, are easily investigated using constellation diagram. Let’s demonstrate how to plot the signal space constellations, for the various modulations used in the transmitter. Typically, in practical applications, the baseband modulated waveforms are passed through a pulse shaping filter for combating the phenomenon ... Read more

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GMSK implementation and simulation – part 1

Mathuranathan — Thu, 10 Oct 2019 07:38:19 +0000

What’s the need for GMSK Minimum shift keying (MSK) is a special case of binary CPFSK with modulation index . It has features such as constant envelope, compact spectrum and good error rate performance. The fundamental problem with MSK is that the spectrum is not compact enough to satisfy the stringent requirements with respect to ... Read more

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Simulate matched filter system with SRRC filtering

Mathuranathan — Fri, 15 Feb 2019 07:09:27 +0000

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 (), pulse shaping function () at the transmitter and a ... Read more

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Precoding for partial response signaling schemes

Mathuranathan — Wed, 23 Jan 2019 07:33:34 +0000

Introduction to precoding Intersymbol interference (ISI) is a common problem in telecommunication systems, such as terrestrial television broadcasting, digital data communication systems, and cellular mobile communication systems. Dispersive effects in high-speed data transmission and multipath fading are the main reasons for ISI. To maximize the capacity, the transmission bandwidth must be extended to the entire ... Read more

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Partial response schemes: impulse & frequency response

Mathuranathan — Tue, 22 Jan 2019 07:40:03 +0000

Impulse response and frequency response of PR signaling schemes Consider a minimum bandwidth system in which the filter is represented as a cascaded combination of a partial response filter and a minimum bandwidth filter . Since is a brick-wall filter, the frequency response of the whole system is equivalent to frequency response of the FIR ... Read more

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Partial response (PR) signaling Model

Mathuranathan — Mon, 21 Jan 2019 06:45:21 +0000

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 should satisfy Nyquist’s first criterion. If the system is ideal and noiseless, it can be characterized by ... Read more

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Construct eye diagram from stored signal samples

Mathuranathan — Thu, 22 Nov 2018 06:15:05 +0000

Eye diagram is a powerful tool to analyze the overall quality of a communication link. It reveals important characteristics of a communication link, that includes timing sensitivity, noise margin, inter-symbol interference (ISI) and zero-crossing jitter. It also shows the optimum sampling time for the receiver, which indicates when to sample the incoming signal for converting ... Read more

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Square-root raised-cosine pulse shaping

Mathuranathan — Mon, 15 Oct 2018 07:41:19 +0000

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

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Raised cosine pulse shaping

Mathuranathan — Tue, 09 Oct 2018 07:12:54 +0000

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 , using which the transition band’s rate of decay can be controlled. The RC pulse shaping function is expressed in ... Read more

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Sinc pulse shaping

Mathuranathan — Fri, 05 Oct 2018 09:02:20 +0000

Key focus: Sinc pulse shaping of transmitted bits, offers minimum bandwidth and avoids intersymbol interference. Discuss its practical considerations & simulation. Sinc pulse shaping As suggested in the earlier post, the pulse shape that avoids ISI with the least amount of bandwidth is a sinc pulse of bandwidth . Here, is the baud rate of ... Read more

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