An Anti-aliasing Modem for Hybrid AM Broadcasting System

Abstract

The invention discloses an anti-aliasing modulation demodulator for an analog-digital hybrid amplitude modulation broadcasting system. According to the demodulator, aiming at a MPPSK (M-ary Position Phase Shift Keying) digital modulation signal separated from a MPPSK / DSB-AM (M-ary Position Phase Shift Keying / carrier-reserved Double Side Band-Amplitude Modulation) hybrid modulation system received signal, DL (Deep Learning) training is carried out by utilizing an SAE (Sparse Autoencoder) neural network, so that the trained DL-SAE neural network can carry out classification on an MPPSK received signal sample which generates interference between strong codes due to bandwidth limitation of a sending end, and thus, compared with demodulation bit error rates of a conventional amplitude integral judgment demodulator and matched filtering judgment demodulator, a demodulation bit error rate of the anti-aliasing modulation demodulator is reduced by at least one magnitude order, and simultaneous and hybrid transmission of an analog audio and high-speed data in a 9kHz amplitude modulation broadcasting channel is ensured.

Description

technical field [0001] The invention relates to a digital communication system with intersymbol interference, in particular to the problem of decision demodulation of modulated signals of a composite modulation system compatible with AM broadcasting with intersymbol interference, and belongs to the field of digital communication and nonlinear signal processing. Background technique [0002] As an ancient communication system, the traditional analog amplitude modulation (AM) broadcasting has been used for nearly a hundred years, but it is far from meeting people's needs. Digital broadcasting has become an inevitable trend of its development. How to make full use of new technologies to achieve effective coverage of broadcast programs and realize the smooth transition from analog audio broadcasting to digital audio broadcasting needs to be solved urgently; several solutions existing in the prior art are given below. [0003] 1.MPPSK transmission system [0004] In order to mak...

AI Technical Summary

Problems solved by technology

However, in order to make the PSD sidebands of the MPPSK / DSB-AM composite modulated transmission signal meet the regulations of the radio management department, and reduce the damage to the demodulated sound quality of the analog audio signal, it is also necessary to modify the already low PSD sidebands of the MPPSK modulated signal itself. Further spectrum mask restrictions are imposed, which greatly affects the transmission performance of MPPSK digitally modulated signals and introduces serious intersymbol interference (ISI). The demodulation error rate when channel coding is added is only on the order of 1%, and a better demodulation method must be invented to improve the demodulation performance of MPPSK / DSB-AM composite modulation signals

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