code tracking
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2021 ◽  
Vol 2136 (1) ◽  
pp. 012042
Author(s):  
Minshu Zhang ◽  
Lixin Zhang ◽  
Qibing Xu ◽  
Lang Bian

Abstract Based on the traditional BOC modulation system, a new navigation signal system based on FH-BOC is proposed in this paper. The simulation and verification of FH-BOC signal are carried out, and the modulation characteristics, code tracking performance and anti-interference performance of FH-BOC signal are analyzed, and the advantages and disadvantages of the modified system are verified. The results show that FH-BOC signal has good ranging and anti-interference ability, which is suitable for navigation system and can reduce the ambiguity of BOC signal’s secondary peak to a certain extent. At the same time, the T has important scientific significance and application value to improve the countermeasure capability of other satellite navigation systems.


2021 ◽  
Vol 67 (3) ◽  
pp. 2883-2898
Author(s):  
Dah-Jing Jwo ◽  
Jen-Hsien Lai

2020 ◽  
Vol 14 (12) ◽  
pp. 1984-1990
Author(s):  
Yaoding Wang ◽  
Wenxiang Liu ◽  
Long Huang ◽  
Zhibin Xiao ◽  
Feixue Wang

2020 ◽  
Vol 30 (Supplement_5) ◽  
Author(s):  
N Kofler ◽  
F Baylis

Abstract The two panelists will elaborate on 'four practical problems and six ethical objections', which add up to one very bad idea, i.e., the 'immunity passport'. Such an idea is equal to restricting movement on the basis of biology threatens freedom, fairness and public health. Lessons from previous pandemics will be examined in the context of current measures being deployed, assessing practical and ethical aspects. For example, false negatives in people with few antibodies leading to immune individuals being incorrectly labelled as not immune or not having access to testing to demonstrate immunity. Additionally, the case of healthcare workers will be examined considering feasibility of testing, but also in terms of discrimination and stigma. Another aspect to be explored in detail is monitoring and how it erodes privacy, with the main aim of immunity passport controlling movement. Documentation systems are already presenting a serious risk to privacy, with China announcing the QR-code tracking systems is likely to stay in place after the pandemic ends. Access issues to testing can contribute to further discrimination, whereas labelling people on their basis of their COVID19 status would create a new measure of dividing the society to 'immunoprivileged and immonodeprived' people. A labelling particularly disconcerting in the absence of a free, universally available vaccine. Furthermore, Social and financial inequities would be amplified, whereas divisions between nations could be fueled. Already people with HIV are subjected to restrictions on entering, living and working in certain countries with laws that impinge on the rights of those from sexual and gender minorities. Governments should instead invest on pandemic damage limitation - test, trace and isolate, and apps that empower individuals to make safe choices about their own movements should be prioritized. Also, the development, production and global distribution of a vaccine for SARS-CoV-is key. Universal, timely, free access to a vaccination becomes possible could allow for ethical recording of vaccination status in the context of certain activities. Threats to freedom, fairness and public health are inherent to any platform that is designed to segregate society on the basis of biological data. All policies and practices must be guided by a commitment to social justice.


IRNSS is an indigenous satellite navigation system consisting of 7 satellites that provide accurate positioning in the Indian sub-continent region. Each IRNSS satellite transmits a signal which contains information regarding satellite orbital and clock parameters (known as navigation message). The purpose of the receiver is to demodulate the satellite signal and extract navigation message, the receiver must know certain parameters of the signal like its doppler shift and code offset. However, in real-time, due to relative velocity of the satellite and ionospheric interference, these parameters vary with time. Therefore, the receiver must continuously perform the tracking operation to update the varying parameters. Existing tracking systems are based on SDR and SoC’s, which require high-performance processors and iterative algorithms to perform both carrier and phase tracking. Though they are highly accurate, these designs are complex and expensive. In this paper, 1.5-bit ADPLL is used to track the carrier. This design does not require numerous computational loops to perform tracking of the carrier, thus reducing the complexity of the design. This work includes simulation results for 1.5-bit ADPLL. In this work, 2-bit, 1.5-bit, and modified 1.5-bit correlators are simulated and synthesized. It was found that modified 1.5-bit correlator architecture is less complex compared to 2-bit correlator and offers better SNR compared to 1.5-bit correlator. Therefore, modified 1.5-bit correlator is used for code tracking. The IRNSS signal tracking is performed in ModelSim. The system utilizes 77 standard LUTs and exhibit maximum settling time of 714µs and 31.28ms for carrier tracking and code tracking, respectively.


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