Research on Anti-printing & Scanning Watermark Algorithm Based on Spread Spectrum Coding

2009 ◽  
Author(s):  
Zhang Jiuhua ◽  
He Guangpu
Keyword(s):  
Spread Spectrum ◽  
Spectrum Coding ◽  
Watermark Algorithm

scholarly journals A New Multiple-Symbol Differential Detection Strategy for Error-Floor Elimination of IEEE 802.15.4 BPSK Receivers Impaired by Carrier Frequency Offset

2019 ◽  
Vol 2019 ◽  
pp. 1-26 ◽  
Author(s):  
Gaoyuan Zhang ◽  
Congzheng Han ◽  
Baofeng Ji ◽  
Congyu Shi ◽  
Ping Xie ◽  
...  
Keyword(s):  
Spread Spectrum ◽  
Carrier Frequency ◽  
Ieee 802.15.4 ◽  
Carrier Frequency Offset ◽  
Frequency Offset ◽  
Coherent Detection ◽  
Differential Detection ◽  
Error Floor ◽  
Detection Strategy ◽  
Spectrum Coding

In this paper, we pay our attention towards the noncoherent demodulation aspect of binary phase shift keying (BPSK) receivers for IEEE 802.15.4 wireless sensor networks (WSNs), and a carrier frequency offset invariant as well as error-floor free multiple-symbol differential detection (MSDD) strategy is proposed over the flat fading channel. This detector is an alternative to the multiple-symbol detector that has been considered almost exclusively in the past. In this new configuration, the receivers do not perform chip-level precompensation as in conventional scheme but bit-level postcompensation. That is, the bit-level autocorrelation operation is first implemented with the “raw” chip sample, and then the carrier frequency offset effect (CFOE) embedded in the achieved statistic is compensated. Correspondingly, the cumulative error in the detection metric is decreased so much that the pervasive error floor for the conventional MSDD scheme is suppressed. Also, complexity efficient estimators for the MSDD scheme are reinvestigated, analyzed, and summarized. Simulation results demonstrate that this new detection strategy may achieve rather more encouraging gain from differential and spread spectrum coding than the conventional single differential coherent detection (SDCD) scheme. The pervasive error floor is also eliminated as compared with conventional MSDD scheme even if the most simple estimator is configured under large bit observation length. Then, much transmitting energy may be saved for each chip symbol, which is practically desired for transmit-only nodes in WSNs.

SPREAD SPECTRUM ASYMMETRICAL WATERMARK ALGORITHM BASED ON WAVELET TRANSFORM

2005 ◽  
pp. 147-153
Author(s):  
YUNFAN SHAN ◽  
BINGFA LI ◽  
LIANG ZHOU ◽  
KE DENG ◽  
QI TIAN ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Spread Spectrum ◽  
Watermark Algorithm

scholarly journals Indoor Localization Using Barely Perceptible Audio Signals

2018 ◽  
Vol 2 (2) ◽  
pp. 26-38
Author(s):  
João Moutinho ◽  
Diamantino Freitas ◽  
Rui Esteves Araújo
Keyword(s):  
Spread Spectrum ◽  
Indoor Localization ◽  
Global Navigation Satellite Systems ◽  
Audio Signals ◽  
Sound System ◽  
Satellite Systems ◽  
Use Of Data ◽  
Accuracy And Precision ◽  
Spectrum Coding ◽  
Global Navigation Satellite

This paper presents a new approach to an audio-based indoor localization system. By using audio signals emitted by a public address sound system, mobile devices may globally localize themselves in an indoor environment where global navigation satellite systems are not viable or reliable. The use of data hiding techniques such as spread spectrum coding or echo hiding has allowed to convey information to a receiver avoiding people’s perception of the added audio content. Results demonstrate a relatively quite good localization with centimetre accuracy and precision and successful data transmission using barely perceptible audio signals.

Image Copyright Protection Watermark Algorithm Based on Spread Spectrum Technology

2014 ◽  
Vol 602-605 ◽  
pp. 3272-3277
Author(s):  
Chang Bao Wei
Keyword(s):  
Ultimate Strength ◽  
Digital Watermarking ◽  
Communication Technology ◽  
Copyright Protection ◽  
Spread Spectrum ◽  
Spread Spectrum Communication ◽  
Chinese Library Classification ◽  
Load Intensity ◽  
Watermark Algorithm

With the application of digital watermarking based on spread spectrum communication technology and the difficult control characteristics of watermark load intensity and invisibility, this paper considers the best compromise between watermark robustness and invisibility factors, and puts forward a digital watermarking algorithm using spread spectrum communication technology. By ultimate strength loading watermark test, the algorithm is verified to have good robustness. Chinese library classification number: TP391 literature identifier: A

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