• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.56-56
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• 2000

In this paper, the relationship between GPS code and carrier tracking performance is given. Through the error analysis and experiments, the performance of code tracking loop can be improved using narrow correlation. The performance of code tracking loop can be also improved if the better carrier tracking loop is used. On the other hand, the performance of carrier tracking loop is independent of that of code tracking loop.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.983-990
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• 2003

In this paper, a noncoherent code tracking loop is designed for 3GPP MODEM and its performance is analyzed in terms of steady-state jitter variance and transient response characteristics. An analytical closed-form formula for steady-state jitter variance is Int derived for AWGN environments as a general function of a pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth, together with the analysis on the transient response characteristic of a tracking loop. Based on the analysis, the code tracking loop with variable loop bandwidth that is efficient for full digital H/W implementation is designed and its performance is compared with that of the code tracking loop with fixed loop bandwidth, along with the verification by computer simulations.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.501-504
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• 2000

In this paper, performance of a pseudonoise (PN) code tracking loop is analyzed and simulated for a direct-sequence/code-division multiple access ( DS/CDMA) system with imperfect power control in a multipath fading channel. A noncoherent first-order delay-locked loop (DLL) is considered as a PN code tracking loop. Power control error is modeled as a log-normally distributed random variable. From the simulation results, it is shown that for smaller discriminator offset, tracking jitter performance is improved while MTLL performance is degraded. It is shown that large power control error and heavy shadowing substantially degrade the PN tracking performance. The analysis in this paper can be applicable to design of PN code tracking loop for a DS/CDMA system.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.9
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• pp.939-947
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• 2008

The GPS tracking loop consists of three parts in general: discriminator, loop filter and DCO (Digitally Controlled Oscillator). The loop filter is the main part of the tracking loop designed to ensure a good tracking performance. Generally, the loop filter is designed using classical PI(Proportional Integral) control. Although the carrier Doppler and code Doppler are generated by the same relative movement between the satellite and the user, often, the loop filters for each tracking loop are designed separately and independently. Sometimes, they are used in a combined manner such as carrier aided code tracking, FLL assisted PLL, etc. For better GPS signal tracking, we need to design the FLL/PLL/DLL altogether optimally. The purpose of this paper is to design a GPS receiver tracking loop based on the Kalman filter in a combined manner. Also, the proposed GPS receiver tracking loop is compared with a conventional tracking loop in terms of the transfer function and the DCO input. This paper shows that conventional tracking loop is equal to the Kalman filter based tracking loop.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.209-212
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• 2000

In this paper, effect of imperfect power control on performance of a pseudonoise (PN) code tracking loop is analyzed and simulated for a direct-sequence/code-division multiple access (DS/CDMA) system. The multipath fading channel is modeled as a two-ray Rayleigh fading model. Power control error is modeled as a log-normally distributed random variable. The tracking performance of DLL (delay-locked-loop) is evaluated in terms of tracking jitter and mean-time-to-lose-lock (MTLL). From the simulation results, it is shown that the PN tracking performance is very sensitive to the power control error.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.223-228
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• 2006

The main purpose of this paper is to describe the code tracking performance of a non-coherent digital delay lock loop (DLL) or coherent DLL while tracking GNSS signal in the presence of signal masking. The masking effect is usually caused by buildings that obscure the signal in either a periodic or random manner. In some cases, ideal masking is used to remove random or periodic interference. Three types of the masked signal are considered - no masking, periodic masking, and random masking of the signal input to the receiver. The mean time to lose lock (MTLL) of the code tracking loop are evaluated, and some numerical result and simulation results are reported. Finally, the steadystate tracking errors on the performance of the tracking loop in interference environment are also presented.

• Journal of Advanced Navigation Technology
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• v.7 no.1
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• pp.6-13
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• 2003

In this paper, a non-coherent code tracking loop is designed for 3GPP HSDPA MODEM and its performance is analyzed in terms of steady-state jitter variance and transient response characteristics. Analytical closed-form formula for steady-state jitter variance is first derived for AWGN environments as a function of pulse-shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth. Also obtained is the transient response characteristic of a tracking loop. Finally, the performance of the designed tracking loop is confirmed by computer simulations.

• Journal of Advanced Navigation Technology
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• v.1 no.1
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• pp.70-80
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• 1997

In this paper, the performances of two noncoherent code tracking loops, i. e., traditional code tracking loop(TCTL) and modified code tracking loop(MCTL) are analyzed and compared in a CDMA mobile environment. Closed-form formulas for steady-state jitter variance are derived analytically for the two schemes as a function of the pulse shaping filter, timing offset, signal-to-interference ratio, and loop bandwidth. The design issues of the loop filter are also addressed with emphasis on the second-order tracking loop. Finally, the degradation of BER performance due to timing errors is examined in a CDMA reverse link for IMT-2000 designed by ETRI.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.3
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• pp.107-110
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• 2009

In this paper, a PN code tracking loop with extended Kalman filter (EKF) is proposed for a direct-sequence spread-spectrum. EKF is used to estimate amplitude and delay in a multipath. fading channel. It is shown that tracking error performance is significantly improved by EKF compared with a conventional tracking loop.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.165-171
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• 1996

A noncoherent full-digital PN(pseudo noise) code acquisition/tracking loop has been presetned and implemented in FPGA for the CDMA band-limited direct-sequence spread-spectrum (DS-SS) signals. It employs a simple decimator to control of local PN code phase to lower the hardware cost, and a second order loop to enable the more accurate tracking. The proposed acquisition/tracking loop has been designed in RTL-level VHDL, synthesized into logic gates using the design analyzer of synopsys software, implemented in an ALTERA FPGA chip, and tested. The number of logic gates used in the implemented FPGA chip is around 7000. The functionality has been verified using a PC interface circuitry and a logic analyzer.