Spread-spectrum code acquisition in the presence of Doppler shift and data modulation

Cheng, Unjeng; Hurd, W. J.; Statman, Joseph I.

doi:10.1109/26.47859

Cited by 104 publications

(39 citation statements)

References 9 publications

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“…For example, with the GPS L1 C/A signal, if the carrier frequency is shifted by 5 kHz due to the Doppler effect, the code chipping rate will be shifted by about 3.25 chip/s (i.e., 5000×1.023/1575.42). This means that the code replica and the received code will shift by about 3.25 chips every second, or one quarter of a chip every 77 ms. To reduce this effect, the frequency search space must be cut into several smaller spaces [12]. …”

Section: ) Parallel Frequency Searchmentioning

confidence: 99%

Comparison Framework of FPGA-Based GNSS Signals Acquisition Architectures

Leclère

Botteron

Farine

2013

IEEE Trans. Aerosp. Electron. Syst.

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Abstract-The acquisition of Global Navigation Satellite Systems signals using Code Division Multiple Access can be performed through classical correlation or using a Fourier transform. These methods are well known but what is missing is a comparison of their performance for a given hardware area or target. This paper presents this comparison for FieldProgrammable Gate Arrays, describing the different parameters involved in the acquisition, detailing some optimized implementations where hardware elements are duplicated, and estimating and discussing the performances. The influence of the Doppler effect on the code, is also discussed as it plays an important role, particularly for new signals using a high chipping rate.

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Section: ) Parallel Frequency Searchmentioning

confidence: 99%

Comparison Framework of FPGA-Based GNSS Signals Acquisition Architectures

Leclère

Botteron

Farine

2013

IEEE Trans. Aerosp. Electron. Syst.

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“…For the delay-locked loop, the timing phases of the "early" and "late" local reference PN codes are typically separated from those of the "on-time" code by half of the chip duration. The zeropadding method [24] obtains a similar design for the carrier frequency offset estimation. Figure 8 shows the Doppler compensation loop structure employing the proposed carrier frequency offset estimation algorithm for Doppler compensation after the 2-D search.…”

Section: A Developed Doppler Shift Compensation Algorithmmentioning

confidence: 99%

“…Manuscript received June 18, 2001; revised Oct. 24,2001. This work was supported in part by the Korean Ministry of Information and Communication.…”

mentioning

confidence: 99%

Rain Attenuation and Doppler Shift Compensation for Satellite Communications

Kim¹,

Lim²,

Choi³

et al. 2002

ETRI J

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structure and the ability to effectively compensate for rain attenuation and the Doppler shift.The non-geostationary satellite channel for high speed communications cannot be considered an additive white Gaussian noise (AWGN) channel because of signal fading due to rain and the Doppler shift on the channel. For these reasons, we developed our own rain attenuation model with which we can synthesize the dynamic characteristics of rain attenuation. Carrier offset induced by the Doppler shift is also modeled by the orbit constellation parameters of a non-geostationary orbit satellite system.A simple and efficient estimation and prediction algorithm for channel conditions was required for allocating suitable transmission schemes at each sampling time. We developed various control algorithms and estimated their performance using the rain attenuation model. This paper proposes an efficient transmission system which can be adaptively applied in rain attenuation situations. Our system uses a block turbo code with an M-ary phase shift keying (PSK) strategy and for Doppler shift compensation, a 2-dimensional search algorithm which uses fast Fourier transform (FFT). Because of the successful development of code division multiple access (CDMA) technology for terrestrial mobile communications [3], application of CDMA to satellite communication is now being attempted. We developed a CDMA-based Doppler shift compensation technique to conform to this technological trend.In section II, we briefly present a simulation modeling technique for rain attenuation and the Doppler shift on the satellite communication channel. Section III describes the adaptive transmission scheme and the Doppler shift compensation method, and demonstrates simulation results using our own developed simulation software (S/W) packages. Section IV introduces a hardware (H/W) emulation board with an adaptive rain attenuation compensation algorithm. Finally, conclusions are drawn in section V. II. CHANNEL MODEL 1. Rain Attenuation ModelWe previously developed a rain attenuation model with which we can synthesize time-varying rain attenuation for any given time interval at Ku and Ka frequency bands [4]. This was necessary so that we could estimate the performance of the proposed adaptive compensation algorithm.Several papers have presented techniques on dynamic rain attenuation modeling [5]- [7]. Because Korea experiences heavy rain during a short period, it was difficult to synthesize rain attenuation. Therefore, we believed it necessary to develop a rain attenuation model which could synthesize typical Korean rain attenuation dynamics. The rain attenuation model we developed used measured attenuation data from the 12.25 GHz beacon signal of Koreasat 2 for two years; an example is shown in Fig. 1. Motivated by the fact that rain attenuation is a Markov process, a Markov chain [8] was used to model the rain attenuation process. We assumed that a rain event could be characterized by a 4-state Markov-chain. That is, a rain event consists of a beginning, a fading, ...

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“…The acquisition is thus a two-dimensional problem, for each satellite. There are different methods to perform the acquisition, such as the serial search, which tests the different combinations for the carrier frequency and code delay one by one [16]; the parallel frequency search, which tests one code delay and several or all the carrier frequencies in parallel using an FFT [17], [18], [19]; the parallel code search, which tests one carrier frequency and all the code delays in parallel using an FFT-based correlation [20], [16], [13]; or there are also methods that parallelize the search in the two dimensions [21], [22], [23]. For a high sensitivity hardware receiver, the parallel code search seems the most suitable method because of its high level of parallelization, its moderate memory requirements, and because it can compensate the code Doppler whereas the parallel frequency search and its derivates cannot [13], [24].…”

Section: B Parallel Code Search Acquisitionmentioning

confidence: 99%

High sensitivity acquisition of GNSS signals with secondary code on FPGAs

Leclère¹,

Botteron

Farine

2017

IEEE Aerosp. Electron. Syst. Mag.

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Abstract-The presence of a secondary code in modern global navigation satellite system signals complicates the acquisition of these signals, because there is a potential sign transition between each period of the primary code. Some previous works proposed to use the parallel code search by performing the correlation over the primary code several times and then combining the results according to the secondary code chips. In this article, we will focus on this method and compare different hardware implementations, to determine if it is better to do the combinations before or after the correlations, and to compare serial and parallel architectures. In a second part, we will show a simple method that manipulates the local secondary code to rearrange the equations, which approximately halves the theoretical number of operations related to the secondary code correlation and the processing time for hardware implementations, without any impact on the sensitivity.

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Spread-spectrum code acquisition in the presence of Doppler shift and data modulation

Cited by 104 publications

References 9 publications

Comparison Framework of FPGA-Based GNSS Signals Acquisition Architectures

Comparison Framework of FPGA-Based GNSS Signals Acquisition Architectures

Rain Attenuation and Doppler Shift Compensation for Satellite Communications

High sensitivity acquisition of GNSS signals with secondary code on FPGAs

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