Extended Symmetric FM Keying Modulation Method

Abstract

The invention provides an extended symmetric frequency modulated keying (ESFMK) modulation method, which comprises the following steps of: selecting frequency variation functions g1(t) and g2(t) of each band; correcting the frequency variation functions of each band according to the frequency variation functions of each band, a frequency modulation bandwidth B, an information code element period T and a modulation parameter tau to obtain corrected frequency variation functions of each band, and generating frequency variation functions f1(t) and f2(t) corresponding to two modulated signal waveform samples s1(t) and s2(t) according to the corrected frequency variation functions of each band, the information code element period T, the center frequency fc of a modulated signal and the modulation parameter tau; and selecting a corrected modulated signal waveform sample according to a binary data code element, and generating an ESFMK modulated signal. The phase of the modulated signal is continuous, and the modulated signal waveform samples are slightly different, so that the modulated signal generated by the ESFMK modulation method has a high energy concentration degree, and high-bandwidth utilization rate digital communication is facilitated.

Description

technical field [0001] The invention relates to a band-pass digital modulation method, which belongs to the field of digital communication. Background technique [0002] In digital communication, since the energy of the digital baseband signal is mainly concentrated in the low-frequency part, in order to realize long-distance wired or wireless transmission, it is necessary to use a high-frequency sine (cosine) wave as the carrier at the transmitter, and use the baseband signal to change a certain part of the carrier. These parameters make it change according to the change law of the baseband signal, realize the spectrum shift of the baseband signal, and make it suitable for information transmission. Recover the modulated signal with the corresponding circuit at the receiving end to realize demodulation. [0003] In the patent document whose publication number is CN 101146072A, a very small chirp keying modulation ultra-narrowband communication method (namely "VMCK") is disc...

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Problems solved by technology

[0004] However, the amplitude of the very small LFM keying modulation waveform is not constant, so it is not suitable for use in some applications that require a constant amplitude modulation waveform

Analysis of the VMCK power spectrum shows that the attenuation from the carrier frequency point to both sides is relatively slow, and the sidelobe attenuation is not very large, so it is necessary to perform waveform shaping on the modulation waveform during modulation, and the transmitter includes an amplitude modulation part , which increases the complexity and resource occupation of the system circuit

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