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Chirp spread spectrum technique non-coherent demodulation method based on fractional Fourier transform

A fractional-order Fourier and non-coherent demodulation technology, which is applied in the field of non-coherent demodulation of Chirp spread spectrum technology and the demodulation field of Chirp spread spectrum technology, can solve problems such as different accuracy and computational complexity

Inactive Publication Date: 2009-03-18
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

Currently, there are several different types of fast algorithms for the discrete fractional Fourier transform, with different accuracies and computational complexities

Method used

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  • Chirp spread spectrum technique non-coherent demodulation method based on fractional Fourier transform
  • Chirp spread spectrum technique non-coherent demodulation method based on fractional Fourier transform
  • Chirp spread spectrum technique non-coherent demodulation method based on fractional Fourier transform

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Embodiment Construction

[0093] Attached below figure 1 , 2 and the FPGA embodiment to describe the content of the invention in detail.

[0094] The present invention relates to a non-coherent demodulation method based on fractional Fourier transform, the principle of which is shown in the attached figure 1 , the implemented algorithm flow is as follows figure 2 As shown, the whole process is decomposed into the following five steps to complete:

[0095] (1) Band-pass filter the intermediate frequency signal of the Chirp spread spectrum system received by the receiver, and mix it with the local oscillator to obtain the baseband signal;

[0096] (2) The baseband signal of the Chirp spread spectrum system is low-pass filtered to complete the digital down-conversion;

[0097] (3) carry out p to the baseband data of Chirp spread spectrum system 0 order fractional Fourier transform (where p 0 =-2·arc cot(μ 0 ) / π), find the modulus value, at u m0 Position calculation peak sample value (u m0 = f 0...

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Abstract

The invention relates to a non coherent demodulation method, which belongs to the signal processing field, is used in Chirp spread spectrum technology demodulation, can reduce phase shift error, multipath time delay error and Doppler shift effect, and achieves better performance over multipath fading channels and IEEE802.15.4a S-V standard channels. The fundamental principle of the invention is: utilizing a Chirp signal as an impulse function in a proper fractional Fourier domain, i.e. fractional Fourier transformation achieves an excellent focusing ability to the Chirp signal sent by the CCS system. For the advantage of Chirp signal processing in fractional Fourier transformation, the fractional Fourier transformation can be used in CSS spread spectrum technology to demodulate Chirp signals with different modulation frequencies. The demodulation to CCS system is realized by implementing fractional Fourier transformation to the received base band data, and judging the code element by detecting the peak value of the focusing order. The method reduces the demand to frequency synchronization, needs no phase synchronization, and achieves better performance over multipath frequency selectively fading channels.

Description

technical field [0001] The invention relates to a non-coherent demodulation method of Chirp spread spectrum technology, belongs to the field of signal processing, and is used for demodulation of Chirp spread spectrum technology. Background technique [0002] Broadband Chirp Spread Spectrum (CSS) technology is a spread spectrum technology that uses the modulation frequency of Chirp signals to carry information. The CSS system has the advantages of both the DSSS system and the UWB system. CSS physical layer technology has been adopted by IEEE802.15.4a standard in August 2007. This standard is a revised version of IEEE802.15.4, which aims to provide a new physical layer alternative for wireless personal area networks (WPANs) in low-to-medium rate and low-power transmission applications such as industrial control, medical monitoring, and wireless sensor networks. , is one of the core standards of WPANs. The CSS system works in the 2450MHz unlicensed frequency band, supports da...

Claims

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Application Information

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IPC IPC(8): H04L27/26H04L25/03
Inventor 陶然黄克武王自宇
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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