Search results
Modulation and Demodulation. Introduction. A communication system that sends information between two locations consists of a transmitter, channel, and receiver as illustrated in Figure 1. The channel refers to the physical medium carrying the information signal (voice, video, data etc.) from one location to another.
Oct 31, 2023 · This paper presents an approach to evaluate communication technologies for industrial control systems during the system engineering phase, considering future application conditions.
Using a highly accessible, lecture style exposition, this rigorous textbook first establishes a firm grounding in classical concepts of modulation and demodulation, and then builds on these to introduce advanced concepts in synchronization, non-coherent communication, channel equalization, information theory, channel coding, and wireless communi...
- 171KB
- 17
The primary purpose of modulation in a communication system is to generate a modulated signal which is well suited to the characteristics of transmission medium. The audio frequency message signal carrying information can‘t be transmitted for distance directly without modulation.
- Binary Bits to Input signals
- Signal decoder �
- 6.2.2 Channel imperfections: a preliminary view
- k uk p(t
- 6.3.3 Relation between PAM and analog source coding
- 6.6.1 Distance and orthogonality
- k vkp(t
- 6.7 Carrier and phase recovery in QAM systems
- 6.7.1 Tracking phase in the presence of noise
Signals to � waveform Baseband to � passband sequence of signals baseband waveform � passband Channel waveform
Waveform to signals � Passband to baseband � Figure 6.1: The layers of a modulator (channel encoder) and demodulator (channel decoder). ARQ has always been an active area of communication and information theoretic research, but it will not be discussed here for the following reasons: It is important to understand communication in a single direction...
Physical waveform channels are always subject to propagation delay, attenuation, and noise. Many wireline channels can be reasonably modeled using only these degradations, whereas wireless channels are subject to other degrations discussed in Chapter 9. This subsection provides a preliminary look at delay, then attenuation, and finally noise. The t...
modulator is determined by the signal constellation , the signal interval A kT ), for a PAM − T and the real L2 modulation pulse p(t). It may be helpful to visualize p(t) as the impulse response of a linear time-invariant filter. Then u(t) is the response of that filter to a sequence of T -spaced impulses ukδ(t kT ) . The problem { − } of choosing ...
The main emphasis in PAM modulation has been that of converting a sequence of T -spaced signals into a waveform. Similarly, the first part of analog source coding is often to convert a waveform into a T -spaced sequence of samples. The major difference is that with PAM modulation, we have control over the PAM pulse p(t) and thus some control over t...
Previous sections have shown how to modulate a complex QAM baseband waveform u(t) up to a real passband waveform x(t) and how to retrieve u(t) from x(t) at the receiver. They have also discussed signal constellations that minimize energy for given minimum distance. Finally, the use of a modulation waveform p(t) with orthonormal shifts, has connecte...
− and the energy difference in the signal points by
Consider a QAM receiver and visualize the passband-to-baseband conversion as multiplying the positive frequency passband by the complex sinusoid e− 2πifct . If the receiver has a phase error φ(t) in its estimate of the phase of the transmitted carrier, then it will instead multiply the incoming waveform by e− 2πifct+iφ(t). We assume in this analysi...
The problem of deciding on or detecting the signals uk} from the received samples r(kT ) { { } in the presence of noise is a major topic of Chapter 8. Here, however, we have the added complication of both detecting the transmitted signals and also tracking and eliminating the phase error. Fortunately, the problem of decision making and that of phas...
analysis, modulation, demodulation, spread spectrum, equalization, channel fading effects, and channel coding, it provides step-by-step mathematical derivations to aid understanding of background material.
People also ask
What is modulation in a communication channel?
Why do we need a comprehensive understanding of modulation techniques?
What is the difference between digital modulation and decoding?
What is QAM modulation?
Why is modulation important in Communication Technology?
What is phase modulation?
Introduction to Communication Systems is an accessible yet rig-orous new text that does for undergraduates what his digital communications book did for graduate students. It provides a superior treatment of not only the fundamentals of analog and digital communication, but also the theoretical underpinnings needed to understand
