Information modulation and demodulation method of constant amplitude high frequency band utilizing rate

Abstract

A method for modulating and demodulating information of equivalent amplitude high frequency band usage utilizes binary information symbols to directly change the waveform of a sine carrier wave to minimize the waveform difference between the modulated signal corresponding to logic 'D' go (t) and g1(t) corresponding to logic '1' and the sine signals and only one parameter is used to control the waveform difference and signal bandwidth. Since in the process of zero-cross detection to the information demodulation, only one sample judgment is needed at the middle of the received signal waveform (t=T / 2) to finish the demodulation and hard limitation is applied to suppress interference of pulse noise.

Description

technical field [0001] The invention relates to an information modulation and demodulation method for digital communication, belonging to the technical field of digital information transmission. Background technique [0002] In a digital communication system, the process of moving the baseband signal representing binary data up to a given transmission frequency band is called modulation, and the opposite process is called demodulation. In order to achieve the highest possible frequency band utilization, that is, to transmit a higher digital rate (measured in bps / Hz) within the unit frequency band, we are applying for a patent application "Information modulation method for high frequency band utilization" (application number: 03152978.X), a high-efficiency modulation method called "minimum waveform difference keying" (abbreviated as VWDK) was proposed. The key to the invention is to make the modulated signal g representing "0" 0 (t) and the modulate...

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Problems solved by technology

[0003] but, figure 1 The amplitudes of the two halves of the VWDK waveform in (a) are different. That is to say, the modulation method invented by this patent application introduces amplitude modulation. In order to avoid clipping distortion, the communication system needs a larger dynamic range. Some occasions with limited amplitude will affect its demodulation performance

And its power spectrum as figure 2 As shown in (a), it is not difficult to see that the amplitude of the higher harmonics (that is, the line spectrum in the figure) is still high, which not only wastes the energy of the signal, but also affects the further narrowing of the bandwidth

In addition, in our "03152978.X" patent application figure 1 (a) The VWDK modulated output signal adopts correlation demodulation. Although the performance is better, it requires a higher sampling rate, which increases the cost of hardware implementation and affects the improvement of the frequency of the modulated signal.

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