The essence of GPS signal acquisition is a two-dimensional search process for the carrier Doppler and code phase, generally including correlator, signal capture device, and logic control module. The disposal efficiency of correlator would affect the capture speed of the whole acquisition process. Because of the corresponding relation between frequencydomain multiplication and time-domain convol...

Galileo will be Europe’s own Global Navigation Satellite System (GNSS), which is aiming to provide highly accurate and guaranteed positioning services. Among several services for separate target groups, Galileo Open Services (OS) are designed for mass-markets, and they will be available worldwide and free of charge for all users. Galileo E1 system has a code period of 4ms which is quadruple tha...

The large-scale seismic acquisition system (LSAS) is a kind of field data acquisition system in super scale. It can cover hundreds of square kilometers. To implement the real time transmission of so much data, speed and reliability are the most important criteria of the system. Based on 8b10b code, this paper discusses frame sync technology, error correction code (ECC), and a co-design method o...

In this paper, an acquisition algorithm is discussed in parallel combinatory spread spectrum (PCSS) system. The algorithm model is first built. Then, an improved algorithm utilizing multiple correlation peak accumulation under low SNR is proposed. The simulation results show that Doppler offset and PN code-phase delay can be obtained by using the proposed acquisition algorithms. The simulation ...

In this paper we consider differentially non-coherent code timing acquisition in Direct-Sequence Code-Division Multiple Access (DS-CDMA) communication system. Recently, an advanced method for differentially non-coherent acquisition, DCMUSIC, was proposed and noticed to combine the benefits of both conventional differentially non-coherent matched filter and traditional MUSIC estimator in a meani...

Acquisition of the code timing in DS/SS systems is addressed for time-varying frequency-selective underwater acoustic channels. Acquisition algorithm based on adaptive channel estimation and fitlering is proposed. The algorithm employs feedback of pre-cursor and post-cursor inter-chip interference to provide a channel estimate from which the code timing is acquired. The channel estimate is also...

Direct GPS P (Y)-code acquisition is necessary when GPS C/A code signal is denied. Since the acquisition process is a two-dimensional search in time domain and frequency domain, a successful correlator design with a local P-code generator as reference is very important. As a new programmable technology, FPGA is a good choice for digital system prototyping and design. Especially Xilinx Virtex ch...

An adaptive serial search pseudonoise (PN) code acquisition scheme is proposed, in which the detection threshold is scaled by the instantaneous received power measured prior to PN code correlation. We observe that the proposed scheme achieves significantly improved mean acquisition times compared to the conventional nonadaptive schemes under Rayleigh fading and pulsed Gaussian noise jamming. Fu...

In this paper, we propose a new algorithm for joint time-delay and direction-of-arrival (DOA) estimation, here called two-dimensional code acquisition, in an asynchronous directsequence code-division multiple-access (DS-CDMA) array system. This algorithm depends on eigenvector-eigenvalue decomposition of sample correlation matrix, and requires to know desired user’s training sequence. The perfo...