%0 Journal Article %1 Anghileri2006 %A Anghileri, M. %A Pany, T. %A Won, J. H. %A Hein, G. W. %D 2006 %J Proc. of the 19th ION GNSS Conf. %K GPS, acquisition, satnav tracking %T An Algorithm for Bit Synchronization and Signal Tracking in Software GNSS Receivers %X In the framework of research and development of a GPS/Galileo receiver, an algorithm which performs bit synchronization and signal tracking has been designed, implemented and tested with simulated modernized GNSS signals and real GPS C/A-code signals. Innovative applications and services require new generation receivers to handle signals characterized by carrier-to-noise ratio (C/N0) values below 28 dB-Hz, where standard algorithms, like the histogram method, show problems in bit-synchronization. After the signal acquisition, the data bit timing presents a navigation message bit offset ambiguity; the purpose is to avoid integration across a data bit-edge which might cause errors in the navigation message detection. As in 5 the bit-edge estimation is performed using a dynamic programming technique like the Viterbi algorithm (VA). For the final bit-edge estimation an alternative cost function has been used, it evaluates the estimated signal power over a coherent integration interval and turns out to be more robust when working in weak signal environments. This approach shows better performances than using the Viterbi path weight minimization and can be explained analyzing the characteristic of the cost functions at different noise levels. The proposed algorithm shows great bit-edge estimation capability for C/N0 values even below 20 dB-Hz and working with different GNSS signals. Besides, a recursive prediction/correction algorithm based on the Kalman filtering is set in parallel with the VA in order to track the random phase errors and Doppler frequency shifts of the correlator output samples. The new module has been integrated in the architecture of the software receiver developed at our institute following this approach: when the traditional tracking loop, due to weak signal conditions, is no longer able to perform, the channel switches to an open-loop mode and the prompt I/Q values are fed into the new module. After bit synchronization is complete, the channel closes the loop and is able to exploit the fully coherent integration time corresponding to the single bit duration. The phase error model used to simulate the signals includes typical local oscillator timing fluctuations and takes into account the effects caused by the user dynamics. The algorithm shows improved synchronization performances and offers a valid alternative to the traditional signal tracking loops.

@article{Anghileri2006, abstract = {In the framework of research and development of a GPS/Galileo receiver, an algorithm which performs bit synchronization and signal tracking has been designed, implemented and tested with simulated modernized GNSS signals and real GPS C/A-code signals. Innovative applications and services require new generation receivers to handle signals characterized by carrier-to-noise ratio (C/N0) values below 28 dB-Hz, where standard algorithms, like the histogram method, show problems in bit-synchronization. After the signal acquisition, the data bit timing presents a navigation message bit offset ambiguity; the purpose is to avoid integration across a data bit-edge which might cause errors in the navigation message detection. As in [5] the bit-edge estimation is performed using a dynamic programming technique like the Viterbi algorithm (VA). For the final bit-edge estimation an alternative cost function has been used, it evaluates the estimated signal power over a coherent integration interval and turns out to be more robust when working in weak signal environments. This approach shows better performances than using the Viterbi path weight minimization and can be explained analyzing the characteristic of the cost functions at different noise levels. The proposed algorithm shows great bit-edge estimation capability for C/N0 values even below 20 dB-Hz and working with different GNSS signals. Besides, a recursive prediction/correction algorithm based on the Kalman filtering is set in parallel with the VA in order to track the random phase errors and Doppler frequency shifts of the correlator output samples. The new module has been integrated in the architecture of the software receiver developed at our institute following this approach: when the traditional tracking loop, due to weak signal conditions, is no longer able to perform, the channel switches to an open-loop mode and the prompt I/Q values are fed into the new module. After bit synchronization is complete, the channel closes the loop and is able to exploit the fully coherent integration time corresponding to the single bit duration. The phase error model used to simulate the signals includes typical local oscillator timing fluctuations and takes into account the effects caused by the user dynamics. The algorithm shows improved synchronization performances and offers a valid alternative to the traditional signal tracking loops.}, added-at = {2011-05-30T10:41:10.000+0200}, author = {Anghileri, M. and Pany, T. and Won, J. H. and Hein, G. W.}, biburl = {https://www.bibsonomy.org/bibtex/2ea5e8e18d829a42b71fd6181ec37b43e/bmuth}, groups = {private}, interhash = {2fefb04d990a313e6ba21e604f13592a}, intrahash = {ea5e8e18d829a42b71fd6181ec37b43e}, journal = {Proc. of the 19th ION GNSS Conf.}, keywords = {GPS, acquisition, satnav tracking}, owner = {bmuth}, timestamp = {2014-08-11T22:37:44.000+0200}, title = {{An Algorithm for Bit Synchronization and Signal Tracking in Software GNSS Receivers}}, username = {bmuth}, year = 2006 }