Publication

Method for sending information signals over a communication channel, and corresponding encoder

2001
Patents

Abstract

Pulse amplitude modulation scheme with the same spectral efficiency as QAM, that is twice the spectral efficiency of conventional PAM schemes, comprising the steps of: (1) forming a train of pulses q(t -kT/2) = p(t - k T/2)cos2 pi fo(t- k T/2), wherein p(t) is a Nyquist pulse for the symbol interval T and wherein f0 = 1/T (l+1/2) for some positive integer l, (2) modulating the amplitude of each of said pulses q(t - k T/2) with the value of the symbol ak in said stream, (3) sending said train of amplitude modulated pulses over said communication channel.

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2001
Patents

Abstract

Official source

Related concepts (32)

Modulation

In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the carrier signal, with a separate signal called the modulation signal that typically contains information to be transmitted. For example, the modulation signal might be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing a sequence of binary digits, a bitstream from a computer.

Amplitude modulation

Amplitude modulation (AM) is a modulation technique used in electronic communication, most commonly for transmitting messages with a radio wave. In amplitude modulation, the amplitude (signal strength) of the wave is varied in proportion to that of the message signal, such as an audio signal. This technique contrasts with angle modulation, in which either the frequency of the carrier wave is varied, as in frequency modulation, or its phase, as in phase modulation.

Pulse shaping

In electronics and telecommunications, pulse shaping is the process of changing a transmitted pulses' waveform to optimize the signal for its intended purpose or the communication channel. This is often done by limiting the bandwidth of the transmission and filtering the pulses to control intersymbol interference. Pulse shaping is particularly important in RF communication for fitting the signal within a certain frequency band and is typically applied after line coding and modulation.

Related publications (1)

Method for sending information signals over a communication channel, and corresponding encoder

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To Code, Or Not To Code: On the Optimality of Symbol-by-Symbol Communication