Symmetrical raised cosine keying and amplitude unified modulation method

A technology of joint modulation and raised cosine, applied in multi-carrier systems and other directions, can solve the problems of discontinuous change of carrier signal frequency, reduction of frequency band utilization rate of communication system, influence of audio signal reception quality, etc., to improve frequency band utilization rate and frequency band utilization. The effect of high rate and smooth frequency change

Inactive Publication Date: 2015-04-08
三亚哈尔滨工程大学南海创新发展基地
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Problems solved by technology

[0004] Although the time-domain waveform of the VMCK signal is continuous, there are frequency jump points, which will broaden the spectrum of the VMCK signal and reduce the frequency band utilization of the communication system
And the discontinuous change of the frequency of the carrier signal will affect the receiving quality of the audio signal. At the same time, when the linear frequency modulation signal is used for modulation, the signal confidentiality is not high

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  • Symmetrical raised cosine keying and amplitude unified modulation method
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  • Symmetrical raised cosine keying and amplitude unified modulation method

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Embodiment Construction

[0029] The present invention will be described in more detail below with reference to the accompanying drawings.

[0030] figure 1 It is a block diagram of the modulation structure of the transmitting end of the present invention. The digital signal generates the SRCK signal through the SRCK modulator. The audio signal is sent to the AM (Amplitude Modulation, AM) modulator, and is moved to the corresponding frequency domain by the signal with the SRCK signal as the carrier. Finally, the modulated signal passes through a band-pass filter to form the final modulated waveform and send it out.

[0031] figure 2 It is a structural block diagram of receiving end demodulation of the present invention. The modulated signal received by the receiving end first passes through a band-pass filter to extract the in-band signal, and then sends it to the correlator and the envelope detector for processing. The local sample corresponding to correlator 1 is s 1 (t), the local sample corre...

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Abstract

The invention provides a symmetrical raised cosine keying and amplitude unified modulation method. A modulation parameter D is calculated according to a frequency modulation bandwidth B and a code element period T required by a system; two shifting register clock (SRCK) signal waveform samples s1(t) and s2(t) are generated according to center frequency fc of modulated signals, the code element period T and the modulation parameter D; SRCK modulated signals s(t) are generated according to a mapping standard between binary data to be sent and the SRCK waveform samples; and SRCK signals serve as carrier waves to conduct amplitude treatment on sound signals sm(t) to be sent to generate amplitude-modulated signals sa(t) to send. The symmetrical raised cosine keying and amplitude unified modulation method adopts the SRCK signals to serve as the carrier waves of amplitude modulation, improves use ratio of unoccupied bandwidth, and transmits more digital information. Frequency changes of the SRCK signals are nonlinear, so that the SRCK signals have strong anti-intercepting capability compared with linear frequency modulation signals.

Description

technical field [0001] The invention is a digital communication modulation method, specifically a symmetrical raised cosine keying and amplitude modulation joint modulation method. Background technique [0002] The AM broadcasting communication system uses a higher frequency sine wave to move the analog audio signal to the corresponding high frequency area for transmission. During the transmission process, the sine wave loads the audio signal through the change of the signal amplitude, and the audio bandwidth is 50~5000Hz, and the speech bandwidth is 300~3400Hz, then the range of ±50Hz or ±300Hz near the carrier component of the modulated signal is a blank frequency band, that is There are no frequency domain components. Due to the existence of this blank frequency band, it will affect the frequency band utilization of the communication system. [0003] In order to solve the problem that the vacant frequency band will cause the information capacity and frequency band utili...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/34
Inventor 郭黎利周彬孙志国高飞刘湘蒲曹雪
Owner 三亚哈尔滨工程大学南海创新发展基地
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