maryam moazedi

The spoofing subject is becoming ever increasingly more severe. In addition to the flow of technology, the availability of software-defined radio platforms has increased. Usually, detecting the spoofing is performed by introducing the features that are difficult for the deceiver to counterfeit. Spoofing and countering can be performed in different parts of a GPS receiver. In recent years, less attention has been paid to defense at cold-start. This research presents that the spoofing attack can be diminished during the initial start-up process with a very short effective time. This low-cost method introduces a new decision rule based on a multiple statistical hypothesis test to identify fake peaks in correlation output of acquisition and extract the authentic peaks utilizing the wavelet transform or peak removal process. The main distinction of this method with previous works is investigating different amplitude ratios of spoofing signal to authentic. Simulation results on 10 data sets show that the probability of correct detection and mitigation is more than 90%.

In this paper, a new circuit is proposed for charge pump for using in delay locked loop, and then simulated in ADS software in 0.18 μm TSMC CMOSRF technology with 1.8V in transistor level. By using DLL a precise synchronization can be performed through internal and external clocks. In this paper, based on introduced charge pump current mismatching can be solved and so the jitter will be decreased. Finally, 3.7psec effective jitter in 920MHz for DLL is accrued. In this loop while UP and DN in each duty cycle are proportional to dead zone, not considerable current is flow on the output of CP. Because the UP and DN signals are in current source and by switching each one, probability of following the current to the output will be provided. However, prevents current transition to other switch if turned on.

The Global Positioning System (GPS) receiver is vulnerable to variety of interferences, inclusive of intentional and unintentional ones. This accordingly decreases the navigation accuracy of receiver, and thus causes the receiver cannot work correctly in presence of interference. Consequently, a research effort has begun to study detection and mitigation of GPS spoofing approaches as a serious interference. For the question of GPS spoofing detection, the guidelines are usually raw-based and hard to mathematically model. This make the use of a fuzzy design for the GPS data ideal. A fuzzy logic system is introduced in this paper to analyze and examine the vulnerability of civil GPS receivers towards different kinds of spoofing attacks. This system improves decision-making capability of the receiver from inexact data. The proposed method utilizes the fuzzy set and then the theory of statistical test to recognize fake signals. The studied parameters as input variables are selected from tracking and navigation stage of the GPS receiver.

Supporting the highest bandwidth data rates among new generation of communication devices requires advanced clock management technology such as DL (Delay Line). By introducing object internet increase of the system clock frequency poses some challenges in generating and distributing of the clock with low uncertainty and power, as clocks determine the overall performance of the chip. The generated signal quality determines by several factors as frequency, phase, period, jitter and clock variations. Both analog and digital circuits have some limitations which make it impossible to achieve high quality clock. One of the proposed solutions for performance improvement of DLs is the utilization of both analog and digital circuits in one system. In this thesis a low jitter and wide operation range Mixed-Mode Delay Line presented. Body feed technique and proper bias circuit are used in the proposed multiphase Mixed Controlled Delay-Line (MMCDL) to widen applicable range of control voltage, allow rail-to-rail operation and overcome the nonlinearity of the conventional current starved delay element. Furthermore, two single ended current starved inverters are utilized in a differential structure to minimize the effect of the power supply and the substrate noise. In this way jitter and static phase error specifications are improved. The designed circuit is simulated in ADS software, using TSMC 0.18 um CMOS process at 1.8V supply voltage. Simulation outcomes indicate that the frequency range of the suggested DL is 80-920 MHz. The rms jitter and power dissipation of the designed circuit at 920 MHz are 3.7psec and 3.9 mW respectively.

Nowadays, the navigation services based on Global Positioning System (GPS) become one of the inseparable parts of marine operations. Accordingly, safety and security of GPS system is important for the marine navigation industry. In other side, since the GPS signals travel long distance through space, received signals on the earth are weak and thus vulnerable to kinds of interferences. Therefore, in recent years, spoofing as one of the serious interferences in GPS system has become an important research topic especially in marine navigation. In this paper, we tried to completely investigate the proposed techniques for detection of spoofing in the single frequency GPS receivers. Then, an abbreviated discussion is provided in the interest of the challenges, advantages and disadvantages of each method. It is tried to introduce the techniques in the same sequence are proposed, until the modification and evolution process of methods be more comprehensible. Finally, we have suggested a new method to detect spoofing attacks in the marine navigation system based on pseudo-range measurements and have reported the simulation results.