TY - GEN
T1 - Real-time dual-frequency (L1/L5) GPS/WAAS software receiver
AU - Chen, Yu Hsuan
AU - Juang, Jyh-Chin
AU - De Lorenzo, David S.
AU - Seo, Jiwon
AU - Lo, Sherman
AU - Enge, Per
AU - Akos, Dennis M.
PY - 2011/12/1
Y1 - 2011/12/1
N2 - This paper demonstrates a real-time software receiver supporting GPS/WAAS dual-frequency (L1/L5) processing. The software receiver is implemented on a widely-available recent generation multi-core processor and is capable of post-processing datasets from collection hardware. Key contributions of this software receiver are that 1) it is perhaps the first receiver capable positioning solely on L5 ranging despite there being only one operational GPS L5 signal and 2) it estimates ionosphere delay using L1-L5 measurements The architecture of such a software receiver needs to be carefully developed so that it can process signals from each individual frequency. Multitasking and synchronization mechanisms were developed to support the tracking of multiple channels in real time. To achieve real-time capability, parallel operations are necessary to reduce computation complexity. Bit-wise operations are exploited and implemented by Single Instruction Multiple Data (SIMD) instructions in the software correlator. An assistance mechanism between L1 and L5 is built for shortening the acquisition time and increasing the sensitivity of tracking L5 data-free channel. Currently, positioning using GPS/WAAS L5 signal needs assistance from L1 signal because the ephemeris on GPS L5 is currently not provided. However, using the L1 GPS ephemeris from L1 should consider the time offset or interfrequency bias (IFB) between L1 and L5 which results from the difference of antenna phase center and other hardware on the satellite. Besides, a time offset exists between WAAS and GPS time. These time offsets are solved by adding another unknown into position solution. The solutions of the time offset are used to correct the pseudorange of L5 and then perform positioning by three methods 1) L1 only 2) L5 only 3) iono-free combination. The results of positioning by the dual-frequency software receiver are illustrated and the positioning accuracy is analyzed in this paper.
AB - This paper demonstrates a real-time software receiver supporting GPS/WAAS dual-frequency (L1/L5) processing. The software receiver is implemented on a widely-available recent generation multi-core processor and is capable of post-processing datasets from collection hardware. Key contributions of this software receiver are that 1) it is perhaps the first receiver capable positioning solely on L5 ranging despite there being only one operational GPS L5 signal and 2) it estimates ionosphere delay using L1-L5 measurements The architecture of such a software receiver needs to be carefully developed so that it can process signals from each individual frequency. Multitasking and synchronization mechanisms were developed to support the tracking of multiple channels in real time. To achieve real-time capability, parallel operations are necessary to reduce computation complexity. Bit-wise operations are exploited and implemented by Single Instruction Multiple Data (SIMD) instructions in the software correlator. An assistance mechanism between L1 and L5 is built for shortening the acquisition time and increasing the sensitivity of tracking L5 data-free channel. Currently, positioning using GPS/WAAS L5 signal needs assistance from L1 signal because the ephemeris on GPS L5 is currently not provided. However, using the L1 GPS ephemeris from L1 should consider the time offset or interfrequency bias (IFB) between L1 and L5 which results from the difference of antenna phase center and other hardware on the satellite. Besides, a time offset exists between WAAS and GPS time. These time offsets are solved by adding another unknown into position solution. The solutions of the time offset are used to correct the pseudorange of L5 and then perform positioning by three methods 1) L1 only 2) L5 only 3) iono-free combination. The results of positioning by the dual-frequency software receiver are illustrated and the positioning accuracy is analyzed in this paper.
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M3 - Conference contribution
AN - SCOPUS:84861353616
SN - 9781618394750
T3 - 24th International Technical Meeting of the Satellite Division of the Institute of Navigation 2011, ION GNSS 2011
SP - 767
EP - 774
BT - 24th International Technical Meeting of the Satellite Division of the Institute of Navigation 2011, ION GNSS 2011
T2 - 24th International Technical Meeting of the Satellite Division of the Institute of Navigation 2011, ION GNSS 2011
Y2 - 19 September 2011 through 23 September 2011
ER -