Fast signal acquisition technology for new GPS/Galileo receivers

Wilde, Wim De; Sleewaegen, Jean-Marie; Simsky, Andrew; Hees, J. Van; Vandewiele, C.; Peeters, Eric; Grauwen, J.; Boon, F.

doi:10.1109/plans.2006.1650712

Cited by 23 publications

(18 citation statements)

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“…Therefore, in one code period there are at least 20 460 samples, and in two periods there are at least 40 920 samples. The E1 signal has a code period of 4 ms, and when this signal is processed as a BOC(1,1) signal with the PCS, the usual minimum sampling frequency considered is 6.138 MHz (still assuming a complex sampling since the signal bandwidth is 4.092 MHz) [4], which is six times the chipping rate (the ratio between the sampling frequency and the chipping rate is higher for BOC than BPSK modulation because the autocorrelation functions are different [22] frequency is in the lower part of these ranges, this solution is not computationally efficient because it implies a lot of zeropadding and discarded samples. Note that the sampling frequencies given here are those required for the acquisition.…”

Section: Straightforward Solution (3-fft Solution)mentioning

confidence: 99%

FFT Splitting for Improved FPGA-Based Acquisition of GNSS Signals

Leclère

Botteron

Landry

et al. 2015

International Journal of Navigation and Observation

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With modern global navigation satellite system (GNSS) signals, the FFT-based parallel code search acquisition must handle the frequent sign transitions due to the data or the secondary code. There is a straightforward solution to this problem, which consists in doubling the length of the FFTs, leading to a significant increase of the complexity. The authors already proposed a method to reduce the complexity without impairing the probability of detection. In particular, this led to a 50% memory reduction for an FPGA implementation. In this paper, the authors propose another approach, namely, the splitting of a large FFT into three or five smaller FFTs, providing better performances and higher flexibility. For an FPGA implementation, compared to the previously proposed approach, at the expense of a slight increase of the logic and multiplier resources, the splitting into three and five allows, respectively, a reduction of 40% and 64% of the memory, and of 25% and 37.5% of the processing time. Moreover, with the splitting into three FFTs, the algorithm is applicable for sampling frequencies up to 24.576 MHz for L5 band signals, against 21.846 MHz with the previously proposed algorithm. The algorithm is applied here to the GPS L5 and Galileo E5a, E5b, and E1 signals.

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Section: Straightforward Solution (3-fft Solution)mentioning

confidence: 99%

FFT Splitting for Improved FPGA-Based Acquisition of GNSS Signals

Leclère

Botteron

Landry

et al. 2015

International Journal of Navigation and Observation

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“…Regarding the primary codes, the range is their length, e.g. 10 230 chips for the L5, E5a and E5b signals, and the usual step between two phases tested is 1/2 chip for a BPSK modulation and 1/6 chip for a BOC(1,1) modulation, which provides a maximum and average loss of 2.50 dB and 1.16 dB, respectively [16].…”

Section: Acquisitionmentioning

confidence: 99%

Acquisition of modern GNSS signals using a modified parallel code-phase search architecture

2014

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The acquisition of global navigation satellite system signals can be performed using a fast Fourier transform (FFT). The FFT-based acquisition performs a circular correlation, and is thus sensitive to potential transitions between consecutive periods of the code. Such transitions are not occurring often for the GPS L1 C/A signal because of the low data rate, but very likely for the new GNSS signals having a secondary code. The straightforward solution consists in using two periods of the incoming primary code and using zeropadding for the local code to perform the correlation. However, this solution increases the complexity, and is moreover not efficient since half of the points calculated are discarded. This has led us to research for a more efficient algorithm, which discards less points by calculating several sub-correlations.It is applied to the GPS L5, Galileo E5a, E5b and E1 signals. Considering the radix-2 FFT, the proposed algorithm is more efficient for the L5, E5a and E5b signals, and possibly for the E1 signal. The theoretical number of operations can be reduced by 21 %, the processing time measured on a * Corresponding author Email address: jerome.leclere@epfl.ch (Jérôme Leclère)Preprint submitted to Signal Processing July 2, 2013 software implementation is reduced by 39 %, and the memory resources are almost halved for an FPGA implementation.

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“…However, for BOC signal, due to the appearance of side-peaks, △τ is chosen so that the tracking stage can avoid to lock to the side-peaks. For BOC(1,1), in order to achieve the same average correlation loss as for a BPSK signal, △τ BOC(1,1) = 0.16 chip (Wilde et al, 2006). As for Doppler shift dimension, △ f D = 2 3T int as in (Kaplan, 2005) or…”

Section: Conventional Acquisition Processmentioning

confidence: 99%