Optimum Path Based Differential Coherent Integration Algorithm for GPS C/A Code Acquisition under Weak Signal Environment

2010 ◽  
Author(s):  
Meng Weixiao ◽  
Ma Ruofei ◽  
Han Shuai
Keyword(s):  
Weak Signal ◽  
Integration Algorithm ◽  
Code Acquisition ◽  
Coherent Integration ◽  
Optimum Path ◽  
Signal Environment

Improved Semi-Bit Differential Acquisition Method for Navigation Bit Sign Transition and Code Doppler Compensation in Weak Signal Environment

2020 ◽  
Vol 73 (4) ◽  
pp. 892-911 ◽  
Author(s):  
M. Nezhadshahbodaghi ◽  
M. R. Mosavi ◽  
N. Rahemi
Keyword(s):  
Signal To Noise Ratio ◽  
Integration Time ◽  
Data Sets ◽  
Weak Signal ◽  
Differential Acquisition ◽  
Global Positioning ◽  
Signal Environment ◽  
Correlation Techniques ◽  
Transition Issues ◽  
Acquisition Method

The presence of code Doppler and navigation bit sign transitions means that the acquisition of global positioning system (GPS) signals is difficult in weak signal environments where the output signal-to-noise ratio (SNR) is significantly reduced. Post-correlation techniques are typically utilised to solve these problems. Despite the advantages of these techniques, the post-correlation techniques suffer from problems caused by the code Doppler and the navigation bit sign transitions. We present an improved semi-bit differential acquisition method which can improve the code Doppler and the bit sign transition issues in the post-correlation techniques. In order to overcome the phenomenon of navigation bit sign transitions, the proposed method utilises the properties of the navigation bit. Since each navigation bit takes as long as 20 ms, there would be 10 ms correlations duration integration time between the received signal and the local coarse/acquisition (C/A) code in which the navigation bit sign transitions will not occur. Consequently, this problem can be cancelled by performing 10 ms correlations in even and odd units separately. Compensation of the code Doppler is also accomplished by shifting the code phase of the correlation results. To validate the performance of our suggested method, simulations are performed based on three data sets. The results show that the quantity of required input SNR to detect at least four satellites in the proposed method is − 48·3 dB, compared with − 20 dB and − 9 dB, respectively, in traditional differential and non-coherent methods.

Based on Block Averaging Pre-Processing Differential Coherent Integration Weak Signal Acquisition Algorithm

2013 ◽  
Vol 706-708 ◽  
pp. 663-666
Author(s):  
Zhao Dong ◽  
Jing Shuo Niu ◽  
Ming He Feng ◽  
Xuan Ru Tao
Keyword(s):  
Monte Carlo Simulation ◽  
Signal Acquisition ◽  
Weak Signal ◽  
Signal Attenuation ◽  
Simulation Experiments ◽  
Coherent Integration ◽  
Coherent Accumulation ◽  
Interference Signals ◽  
The Stability ◽  
Data Length

Aiming at the problem of signal attenuation seriously, a block averaging pre-processing (BAP) differential coherent acquisition algorithm is proposed. BAP algorithm can be used to suppress interference signals and improve the stability of the receiver, but it is still faced with navigation signal transitions problem. Differential coherent algorithm can compensate for square loss caused by non-coherent accumulation. Monte Carlo simulation experiments show that the algorithm is more effective in the same carrier-to-noise ratio and same data length conditions.

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