Joint Acquisition Estimator of Modern GNSS Tiered Signals Using Block Pre-Correlation Processing of Secondary Code

Abstract

Objective is a joint primary and secondary code (SC) acquisition estimator of tiered Global Navigation Satellite Systems (GNSS) signals. The estimator is based on the Parallel Code Search algorithm (PCS) combined with the Single-Block-Zero-Padding (SBZP) and the Pre-correlation Coherent Accumulation (PCA). The PCA realizes the extension of the coherent integration time in front of the PCS. However, the PCS with the SBZP and the PCA is affected by a navigation/SC bit transition problem due to its cyclic property of a computed Cross-Ambiguity Function (CAF). This CAF is degraded by diverse parasitic fragments and is not directly applicable for an acquisition. A novel analysis of this mechanism and its impact is presented. Then, the proposed modified SBZP (mSBZP) modified PCA (mPCA) PCS estimator is constructed, which does not degrade the CAF. The mSBZP allows the use of the PCS algorithm in the presence of SC bit transition, while the mPCA decreases the number of PCS algorithm calculations by a factor of SC chip count due to SC pre-correlation processing. The algorithm has the same detection performance in comparison with conventional Double-Block-Zero-Padding (DBZP). However, it allows using the PCS of half-length with longer latency up to a factor of SC chip count.

Coherent Combining and Long Coherent Integration for BOC Signal Acquisition under Strong Interference

“…For GNSS signals with high symbol rate data and secondary codes that can change their sign within each primary code period, advanced methods that are tailored to individual code inner structures can be employed (Borio, 2008;Leclère et al, 2017;Svaton & Vejražka, 2020).…”

“…On the other hand, coherent integration over time needs to face large initial frequency (and associated code chipping rate) errors especially during high dynamics (Wu et al 2015) and sign reversals of data bits and secondary codes (Borio, 2008;Leclère et al, 2017;Svaton & Vejražka, 2020). Moreover, during long integration, clock instability becomes critical (Serna et al, 2010).…”

A novel secondary code acquisition algorithm for the BDS‐3 B1C signal

“…At present, there are two main categories of secondary code acquisition algorithms. Since the secondary code chipsign transition restricts the extension of coherent integration time, the first type of algorithm is to sequentially or simultaneously test all possible symbol combinations based on the consecutive correlated results of a primary code period [1,[6][7][8][9][10][11]. However, since the number of possible symbol combinations increases exponentially with the growth of secondary code chips, these methods are only adopted in the case of short coherent integration time.…”

A flexible system-on-chip FPGA architecture for prototyping experimental GNSS receivers

“…Tiered codes enhance GNSS performance through improved receiver sensitivity, superior cross-correlation properties compared to other GNSS signals, increased resistance to narrow-band jamming, and faster bit synchronization. [31].…”