Method for detecting empty symbol

A technology of null symbols and signals, which is applied in the field of detecting null symbols in DAB signals by digital audio broadcasting receivers, can solve the problems of false detection and edge detection errors of null symbols, so as to improve the accuracy and overcome the situation of false detection. Effect

Inactive Publication Date: 2009-10-07
SICHUAN PANOVASIC TECH
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Problems solved by technology

[0008] However, in the prior art, the method of detecting null symbols based on the energy of the DAB signal, for DAB signals in a low signal-to-noise ratio environment, false detections caused by edge detection errors of null symbols may occur

Method used

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Embodiment 1

[0027] Step (1) of the present invention, that is, detect the start position and the end position of the empty symbol according to the energy of the DAB signal. The energy signal S_ave(n) of the DAB signal:

[0028] S _ ave ( n ) = Σ i = 1 AVE _ NULL S _ in ( n - i + 1 ) - - - ( 1 )

[0029] In formula (1), n ​​is a sampling point, and the sampling time of the AVE_NULL sampling point is the width of a null symbol in the DAB signal frame structure.

[0030] Compare the two data in the energy signal S_ave(n) with an interval of AVE_NULL sampling...

Embodiment 2

[0038] In this embodiment, a rough null signal Is_null is obtained by detecting the start position and end position of the null symbol according to the energy of the DAB signal in step (1) of the present invention. In this embodiment, the high level 1 of the null symbol signal Is_null represents a null symbol period, and the low level 0 represents a data period.

[0039] image 3 It is a timing diagram of a DAB signal, a detected empty symbol signal and a template signal in a specific embodiment of the present invention.

[0040] Such as image 3 As shown, step (2) of the present invention is to use an empty symbol in the detected empty symbols as the current empty symbol to generate a periodic template signal representing the empty symbol period and the data period, which is used for the receiver time reference to the OFDM symbol Coarse synchronization; the empty symbol period and the data period of the template signal are determined according to the transmission mode of the ...

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Abstract

The invention discloses a method for detecting empty symbol, which detects empty symbol through DAB signal energy, and generates transmission mode through present empty symbol to determine periodical template signals during empty symbol period and data period, for coarse synchronization of receiver time reference to OFDM identifier, if width difference value between present empty symbol and next empty symbol and time difference value between next empty symbol and template signal corresponding empty symbol are less than set threshold value, judging as time domain frame head that captures DAB signal, entering synchronization condition of the time domain frame head to trace. Judgment of the empty symbol is done after obtaining transmission mode, error detection probability is reduced. The invention greatly improves accuracy of DAB signal empty symbol detection under low signal-to-noise ratio environment and effectively prevents production of error detection.

Description

technical field [0001] The invention relates to a method for detecting empty symbols, in particular to a method for detecting empty symbols in DAB signals by a digital audio broadcasting receiver. Background technique [0002] Digital Audio Broadcasting, DAB (Digital Audio Broadcasting) for short, is the third-generation broadcasting system following AM and FM broadcasting. [0003] Over the past few decades, frequency modulation (FM) radio has been popular with listeners for its high-quality transmitted and received sound. But the main problem of this simulated narrowband transmission method is the lack of resistance to multipath propagation. In order to improve the quality of FM broadcasting, although some new methods and technologies have been adopted and a lot of results have been received, they all have certain limitations. [0004] Digital Audio Broadcasting (DAB) uses digital technology as a means to transmit high-quality sound programs and data services from broadc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04L1/00
Inventor 舒勇谢翔杨刚
Owner SICHUAN PANOVASIC TECH
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