Message Extraction for 9th Pulse Standard of eLoran Navigation System

Abstract :

In the Standard of 9^th pulse enhanced Loran (eLoran) system, an additional pulse is incorporated into the navigation pulse group for data transmission. The process of extracting messages from the Loran signal involves two stages: first, determining time delay of the data pulse relative to its original position, and second, decoding the data. This paper proposes a method for message extraction using the 9^th pulse standard. Time delay of the data pulse is calculated in two steps, involving envelope shift and phase shift utilizing matched and fractional filters, respectively. Following this, Reed-Solomon (RS) decoding is applied, leading to final message extraction. Furthermore, to enhance pulse delay estimation, particularly in noisy and interference conditions, the reference pulse is chosen as average of the eight pulses preceding the data pulse, resulting in a unique reference pulse for each symbol extraction. Evaluation results show that the error rate before decoding decreases from 0.08 to 0.003 as the signal-to-noise ratio increases from 7 to 15 dB, with a significant reduction in errors after RS correction.

References:

[1] Z. Zuo, X. Qiao, and Y. Wu, "Concepts of comprehensive PNT and related key technologies," in Proc. of the Int. Conf. on Modeling, Analysis, Simulation Technologies and Applications, pp. 365-370, Hangzhou, China, 26-29 2019.
[2] W. Pelgrum and C. Schue, Navigation with Low‐Frequency Radio Signals, Position, Navigation, and Timing Technologies in the 21st Century, 1st Ed, pp. 1281-1333, 2021.
[3] Y. Yang, X. Ren, X. Jia, and B. Sun, "Development trends of the national secure PNT system based on BDS," Sci. China Earth Sci., vol. 66, no. 5, pp. 929-938, May 2023.
[4] C. Yang, S. Li, and Z. Hu, "Analysis of the development status of eLoran time service system in China," Applied Sciences, vol. 13, no. 23, Article ID: 12703, Nov. 2023.
[5] J. Li and H. Wu, "The Loran-C pseudorange positioning and timing algorithm based on the vincenty formula," Remote Sensing, vol. 16, no. 17, Article ID: 3227, Aug. 2024.
[6] Available online: https://rntfnd.org/wp-content/uploads/eLoran-Definition-Document-0-1-Released.pdf International Loran Association, Enhanced Loran (eLoran) Definition Document, Version 1.0, Jan. 2007.
[7] A. P. Grunin, S. V. Sai, and B. P. Zakirov, "All-in-view time difference solution for eLoran," in Proc. Wave Electronics and its Application in Information and Telecommunication Systems, 4 pp., St. Petersburg, Russia, 13 May-4 Jun. 2021.
[8] P. W. Son, S. G. Park, Y. Han, and K. Seo, "ELoran: resilient positioning, navigation, and timing infrastructure in maritime areas," IEEE Access, vol. 8, pp. 193708-193716, 2020.
[9] S. Lo, B. Peterson, P. Enge, and P. Swaszek, "Loran data modulation: extensions and examples," IEEE Trans. Aerosp. Electron. Syst., vol. 43, no. 2, pp. 628-644, Apr. 2007.
[10] B. B. Peterson, C. A. Schue, J. M. Boyer, and J. R. Betz, "Enhanced Loran-C data channel project," in Proc. of the Int. Symp. on Integration of Loran-C/Eurofix and EGNOS/Galileo, pp. 186-197, Bonn, Germany, 20-21 Feb. 2001.
[11] S. C. Lo and P. Enge, "Analysis of the enhanced loran data channel," in Proc. of the Int. Symp. on Integration of Loran-C/Eurofix and EGNOS/Galileo, pp. 159-168, Bonn, Germany, 20-21 Feb. 2001.
[12] D. Van Willigen, G. W. A. Offermans, and A. W. S. Helwig, "Eurofix: definition and current status," in Proc. of the IEEE 1998 Position Location and Navigation Symp., pp. 101-108, Palm Springs, CA, USA, 20-23 Apr. 1996.
[13] T. H. Jorgensen, "Loran-C/eurofix in europe-status and future plans," in Proc. of the 13th Int. Technical Meeting of the Satellite Division of the Institute of Navigation, pp. 2464-2467, Salt Lake City, UT, USA, 19-22 Sept. 2000.
[14] E. E. Elsayed, "Performance enhancement in FSO relay systems with MISO via multi-hop M-ary PPM integrating and spatial modulation over gamma-gamma channels," J. Opt., vol. 2024, 16 pp., 2024.
[15] L. Hartshorn, P. Swaszek, G. Johnson, M. Wiggins, and R. Hartnett, "Performance of Loran-C 9th pulse modulation techniques," in Proc. of the National Technical Meeting of the Institute of Navigation, pp. 384-395, Monterey, CA, USA, 18-20 Jan. 2006.
[16] P. W. Son and T. Hyun Fang, "Enhancing coastal air navigation: eloran 3-D positioning and cycle slip mitigation," IEEE Access, vol. 12, pp. 100230-100239, 2024.
[17] C. Yang, X. Guo, S. Li, and Z. Hu, "Design and performance evaluation of eloran monitoring system," Applied Sciences, vol. 14, no. 16, Article ID: 7350, Aug. 2024.
[18] W. Ma, J. Gao, Y. Yuan, Z. Shi, and X. Xi, "Suppression of continuous wave interference in Loran-C signal based on sparse optimization using tunable Q-factor wavelet transform and discrete cosine transform," Sensors, vol. 21, no. 21, Article ID: 7153, Oct. 2021.
[19] ا. عفیفی، ا. خرمی و س. عزیزی، "بهبود الگوريتم گيرنده داده لورن برای کانال های نويزی،" صنایع الکترونیک، سال 11، شماره 2، صص. 41-33، تابستان 1399.
[20] S. C. Lo and P. Enge, "Data transmission using Loran-C," in Proc. of the Int. Loran Association 29th Annual Meeting, 11 pp., Washington, DC, USA, Nov. 2000.
[21] S. C. Lo, B. B. Peterson, and P. K. Enge, "Loran data modulation: a primer," IEEE Aerospace and Electronic Systems Magazine, vol. 22, no. 9, pp. 31-51, Sept. 2007.
[22] S. F. Li, Y. L. Wang, Y. Hua, and Y. L. Xu, "Research of Lloran-C data demodulation and decoding technology," Chin. J. Sci. Instrum, vol. 33, no. 6, pp. 1407-1413, Jun. 2012.
[23] J. Yuan, W. Yan, S. Li, and Y. Hua, "Demodulation method for Loran-C at low SNR based on envelope correlation-phase detection," Sensors, vol. 20, no. 16, Article ID: 4535, Aug. 2020.
[24] B. Lyu, Y. Hua, W. Yan, J. Yuan, and S. Li, "Data demodulation algorithm of enhanced Loran system," in Proc. Int. Conf. on Electronic Information Technology, Article ID: 1225434, Chengdu, China, 19-21 May 2022.
[25] K. Zhang, F. Yang, W. Wang, and X. Ye, "Eloran signal message prediction algorithm based on Alexnet‐ECA," IET Radar, Sonar & Navigation, vol. 18, no. 3, pp. 500-513, Mar. 2024.
[26] Z. Zhao, et al., "Measurement and analysis of Loran-C sky waves throughout the day," Electronics, vol. 13, no. 7, Article ID: 1240, Mar. 2024.
[27] SAE International, SAE 9990: Transmitted Enhanced Loran (eLoran) Signal Standard, 2018.
[28] Q. Liang, W. Xiong, and Y. Li, "Research on modulation technique of high-speed Loran-C data channel," in Proc. 8th In. Conf. on Wireless Communications, Networking and Mobile Computing, 3 pp., Shanghai, China, 21-23 Sept. 2012.
[29] C. Yang, Y. Wang, S. Li, and W. Yan, "Experimental study of a signal modulation method to improve eLoran data channel communications," Sensors, vol. 20, no. 22, Article ID: 6504, Nov.- 2 2020.
[30] D. P. F. Swaszek, et al., "Improved signal processing methodologies for the loran data channel," in Proc. of the National Technical Meeting of the Institute of Navigation, pp. 948-959, San Diego, CA, USA, 28-30 Jan. 2008.
[31] K. Dykstra and B. Peterson, "The Loran data channel: progress to date and future plans," in Proc. of 35th Annual Technical Symp., Int. Loran Association, Groton, 8 pp., San Diego, CA, USA, 22-25 Oct. 2006.
[32] P. W. Son, S. Lee, T. H. Fang, and K. Seo, "Analysis of LDC message reception performance of korean eLoran pilot service according to modulation methods," J. of Navigation and Port Research, vol. 46, no. 6, pp. 525-529, Dec. 2022.
[33] B. Peterson, K. Dykstra, D. Lown, and K. Shmihluk, Loran Data Channel Communications Using 9th Pulse Modulation, Peterson Integrated Geopositioning, LLC, and USCG Loran Support Unit, White Paper, Version 1.3, 20 Oct. 2006.
[34] S. Mamidi, D. Iancu, A. Iancu, M. J. Schulte, and J. Glossner, "Instruction set extensions for Reed-Solomon encoding and decoding," in Proc. IEEE Int. Conf. on Application-Specific Systems, Architecture Processors, pp. 364-369, Samos, Greece, 23-25 Jul. 2005.
[35] W. Liu, Z. Jiang, Z. Huang, L. Song, and H. Hou, Reed-Solomon Codes over Cyclic Polynomial Ring with Lower Encoding/Decoding Complexity, arXiv preprint arXiv: 2405.01043, May 2024.
[36] P. Mursanto, "Performance evaluation of Galois field arithmetic operators for optimizing Reed Solomon codec," in Proc. Int. Conf. on Instrumentation, Communication, Information Technology, and Biomedical Engineering, 6 pp., Bandung, Indonesia, 23-25 Nov. 2009.
[37] S. Nabipour, "Arithmetic Operators over Finite Field GF(2m) for Error Correction Codes Application," arXiv e-prints arXiv-2310, Oct. 2023.
[38] K. Carroll, et al., "Differential Loran-C," in Proc. of GNSS, the European Navigation Conf., 15 pp., Rotterdam, Netherland, May 2004.
[39] W. Yan, K. Zhao, S. Li, X. Wang, and Y. Hua, "Precise Loran-C signal acquisition based on envelope delay correlation method," Sensors, vol. 20, no. 8, Article ID: 2329, Apr.-2 2020.
[40] J. Safar, P. Williams, A. Grant, and F. Vejrazka, "Analysis, modeling, and mitigation of cross-rate interference in eLoran: analysis of cross-rate interference in eloran," J. Inst. Navig., vol. 63, no. 3, pp. 295-319, Sep. 2016.
[41] C. Lubeigt, F. Vincent, L. Ortega, J. Vilà-Valls, and E. Chaumette, "Approximate maximum likelihood time-delay estimation for two closely spaced sources," Signal Processing, vol. 210, no. C, Article ID: 109056, Sept. 2023.
[42] Y. Zhang, Y. Jin, Y. Wu, C. Hao, and D. Orlando, "Sparsity-based time delay estimation through the matched filter outputs," IEEE Signal Processing Letters, vol. 29, pp. 1769-1773, 2022.
[43] C. L. Boyce, J. D. Sherman Lo, and P. E. Powell, Analysis of Noise and Cycle Selection in a Loran Receiver, Stanford University, 2001.