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Composite modulation system compatible with medium-wave analogue amplitude modulation (AM) broadcast

A compound modulation and AM broadcasting technology, applied in the fields of modulation and demodulation, information modulation and demodulation, can solve the problems of low transmission bit rate and high peak level, save investment, improve spectrum utilization, and reduce sampling frequency. Effect

Inactive Publication Date: 2014-01-08
苏州东奇信息科技股份有限公司
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Problems solved by technology

[0036] For MPPSK / EBPSK modulated signals, it can be seen from equations (1) and (2) that when the modulation period The number of carrier cycles within At a certain time, the symbol period The number of carrier cycles within The larger the , the lower the main lobe and sideband of the signal power spectrum, but according to formula (3), the lower the transmission code rate at this time; and when certain time, The larger is, although the main lobe of the signal power spectrum is narrower, but its peak level is also higher

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  • Composite modulation system compatible with medium-wave analogue amplitude modulation (AM) broadcast
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  • Composite modulation system compatible with medium-wave analogue amplitude modulation (AM) broadcast

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Embodiment Construction

[0087] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. The descriptions here are used to provide a further understanding of the present invention and constitute a part of the application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention.

[0088] Composite Modulation Transmitter System

[0089] The high-speed data-modulated signal used to replace the pure sine carrier in AM broadcast modulation, the so-called digital carrier, is a key factor in the realization of a composite modulation system. We hope that it meets the following four conditions at the same time:

[0090] ①Amplitude constant envelope.

[0091] This is because the current analog audio frequency performs DSB-AM modulation on the sinusoidal carrier, so any change in the amplitude envelope of...

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Abstract

The invention discloses a composite modulation system compatible with medium-wave analogue amplitude modulation (AM) broadcast. According to the system, a low-sideband m-ary position phase keying (MPPSK) signal with modulated high-speed data is adopted to replace a sinusoidal carrier; carrier-retained double sideband amplitude modulation is performed with an analogue audio signal; after a receiver performs up-conversion and impacting filter on the received composite modulation signal and extracts a coherent carrier to multiply, an analogue audio signal is separated by using spectral distribution difference, and MPPSK modulated data is demodulated by using correlation matching. According to the system, the frequency resource and the 9 kHz bandwidth division of the conventional medium-wave amplitude modulation broadcast band, the infrastructures of an amplitude modulation broadcast transmitter, the broadcast system of DSB-AM (Double Sideband Amplitude Modulation) transmission and a mature product of a medium-wave amplitude modulation radio are directly used to realize that the original analogue sound signal and a new digital code stream are really broadcast at the same bandwidth on the same channel at the same time, so that the spectrum utilization efficiency and the energy utilization rate of the digital AM broadcast system are greatly improved.

Description

technical field [0001] The invention belongs to the field of information modulation and demodulation in communication, relates to a digital broadcast communication system, in particular to a modulation and demodulation technology in a composite modulation system compatible with amplitude modulation (AM) broadcast. Background technique [0002] Digitization has become an inevitable trend in the development of broadcasting and television in the world. How to make full use of new technologies to achieve effective coverage of broadcast programs and realize a smooth transition from analog audio broadcasting to digital audio broadcasting is a major issue that the broadcasting industry needs to solve urgently. Digital audio broadcasting has the advantages of good audio quality, high spectrum utilization rate, and support for new data services. Developed countries such as Europe and the United States have led the development of a number of digital audio broadcasting technologies and...

Claims

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Application Information

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IPC IPC(8): H04L1/00H04L27/20
Inventor 吴乐南逄军王继武李旭森朱超越
Owner 苏州东奇信息科技股份有限公司
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