GPS navigation data bit decoding error during strong equatorial scintillation

Dongyang Xu,Y T Jade Morton

doi:10.1007/s10291-018-0775-1

Abstract

Strong equatorial scintillation is often characterized by simultaneous fast phase changes and deep amplitude fading. The combined effect poses a challenge for GNSS receiver carrier tracking performance. One of the consequences of the strong scintillation is increased navigation message data bit decoding error. Understanding the rate of the data bit decoding error under equatorial scintillation is essential for high accuracy and high integrity applications. We present the statistical relationship between the data bit decoding error occurrences and the intensity of amplitude scintillation based on the processing of intermediate frequency GPS scintillation data collected on Ascension Island in March 2013. A third-order phase lock loop (PLL) is implemented to process the data and to access the data bit error typically expected in conventional receivers. A Kalman filter-based PLL is also used to process the same data to demonstrate that the data bit decoding error can be reduced through advanced carrier tracking designs.

Highlights

The ionospheric scintillation phenomenon refers to the random amplitude and phase fluctuations observed on radio signals propagating through plasma irregularities in the ionosphere (Yeh and Liu 1982)
The bit decoding error (BDE) results obtained from the selected scintillation data of March 7, 2013 provide a glimpse of the performance improvement of the AKF-phase lock loop (PLL) over proportion-integration filter-based PLL (PIF-PLL)
The majority of BDE occurred on PRN 6, where adaptive Kalman filter-based PLL (AKF-PLL) showed the best improvement over PIF-PLL in reducing the number of BDE by 20%

Summary

Introduction

The ionospheric scintillation phenomenon refers to the random amplitude and phase fluctuations observed on radio signals propagating through plasma irregularities in the ionosphere (Yeh and Liu 1982). The main objective of this work is to present a quantitative analysis of the BDE during strong equatorial scintillation based on processing results from real equatorial scintillation data Such analysis is necessary because the degraded decoding performance can negatively impact high accuracy applications and differential systems where rover receivers and their corresponding ground correction networks share the same satellite orbital and timing parameters. Based on the tracking results of 5 h of strong scintillation signals, the 2 Hz bandwidth implementation generated the least number of signal loss-of-lock incidences Such a low PIF-PLL bandwidth is a possible option because the receiver front end was driven by a low phase noise ovencontrolled crystal oscillator (OCXO). It is applicable to receivers utilizing FLL as it does not require the lock of carrier phase and is, suitable for applications on platforms

10 Fading 0 Threshold

Findings

Summary