Presence Of Sign Transition Research Articles

Low-Computation GNSS Signal Acquisition Method Based on a Complex Signal Phase in the Presence of Sign Transitions

During signal acquisition in a global navigation satellite system acquisition stage, a method of signal parameters estimation with low computational complexity is needed. However, due to the influence of sign transitions, the correct peak corresponding to the signal parameters is difficult to detect. For the estimation of the code phase of the received signal in the presence of sign transitions with low computational complexity, an acquisition method based on a complex signal phase (AMCSP) is proposed. The problem of estimating the sign transition position and the code phase is transformed into a problem of solving for a complex signal phase. Special block matrixes are constructed to obtain the complex signal phase, and integration processing is utilized to improve the detection probability performance. Based on an analysis of undesirable cases, a final code phase estimation process is proposed. Furthermore, expressions for the detection performance and computational complexity of AMCSP are derived. Simulation results demonstrate that the computational cost of AMCSP is much lower than that of a fast Fourier transform-based method.

Weak BeiDou signal acquisition in the presence of sign transition over multiple periods

SummaryTo improve the acquisition sensitivity of weak BeiDou signal, multiple periods accumulation is applied. However, as the Neumann‐Hoffman code is modulated onto the BeiDou MEO/IGSO signal, the sign transition may occur in even 1‐ms interval. This paper proposes a modified multiblock zero padding method to solve the sign transition problem for weak BeiDou signal acquisition. The proposed modified multiblock zero padding method applies differentially coherent accumulation to detect the weak signal. To evaluate the performance of the proposed method, the Monte Carlo simulation experiments are conducted. Simulation experiments have demonstrated the validity and availability of the proposed method, which can achieve weak signal acquisition under the BeiDou‐challenged environment.

Data and pilot optimised combining method for new composite global navigation satellite system signal acquisition

With the increasing adoption of high bit rate navigation signals, the performance of detection is significantly affected by sign transition. To reduce the correlation loss caused by the sign transition, three optimised channel combining methods, which include the optimised non-coherent channel combining, optimised coherent channel combining and optimised differential channel combining, are proposed in this study. Three corresponding analytical expressions of probabilities of detection for the authors methods are derived. To better evaluate the performance of their methods, three corresponding analytical expressions of probabilities of detection for conventional channel combining methods in the presence of sign transition are also derived. Comparing with conventional channel combining and zero padding methods, although increasing the computational cost, their methods can achieve 2–2.5 and 4–6 dB acquisition sensitivity improvements according to the analytic and simulated results. Moreover, experiments on real data from global positioning system L5 further evaluate the detection performance of their methods.

Multi‐correlation strategies fusion acquisition method for high data rate global navigation satellite system signals

With the increasing use of high data rate navigation signals, the detection performance is severely affected by sign transition. An acquisition method based on multiple correlation strategies fusion (MCSF) has been proposed to reduce the correlation loss caused by the sign transition. The detection performances of non-coherent (NCH) method, zero-padding (ZP) method and MCSF in the presence of sign transition have been analysed. The theoretical and simulation results show that the proposed method can provide 1–3 dB acquisition sensitivity improvement compared with the NCH and ZP methods, and reduce the mean acquisition time by 21.3 and 8.5%, respectively. Moreover, the real data from GPS L5 and BeiDou Navigation Satellite System B2I have been used to analyse the performance.

GNSS Signal Acquisition in the Presence of Sign Transition

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper, the problem of acquiring the pilot and data channel of the next-generation systems (as Galileo, and GPS modernization) is addressed and analyzed, focusing the majority of the attention to the problem of managing the higher sign reversal transition rate due to the navigation message in the data channel and to the secondary code in the pilot channel. It must be considered that in the case of the Galileo E1 signals, each period of the spreading sequence may suffer of a sign change which can reduce the correlation gain. Moreover, the sign transition occurred on the block of samples being processed produces a correlation peak splitting along the Doppler axis of the search space matrix constructed during the acquisition phase and this may lead to a wrong Doppler estimate. Here, we propose an acquisition detection methodology in order to cope with the aforementioned impairments. The main idea behind the proposed algorithm derives by the fact that even though a sign transition occurs, the total useful signal energy remains unchanged, so it is possible to process the search space in order to recover in a nonambiguous way not only the presence of a satellite but also the correct spreading code delay phase and its Doppler shift. The effectiveness of the proposed method will be deeply assessed with a simulation campaign in terms of detection and false detection rate, which will be presented by means of the so-called receiver operative characteristic curves and compared with the state-of-the-art acquisition methodologies. </para>