A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms
In this paper, we compare the performances of radio frequency interference (RFI) suppression between radio frequency interference mitigation (RFIM) and frequency-domain adaptive clutter suppression (FACS) algorithms that apply to ionograms for foF2 scaling through true height analysis. We find that...
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MDPI AG
2023-04-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/8/2169 |
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| author | Zhao-Yu Chen Kai-Jun Ke Ching-Lun Su Hung-Shi Lin Yu-Lei Lai Yen Lin Yen-Hsyang Chu |
| author_facet | Zhao-Yu Chen Kai-Jun Ke Ching-Lun Su Hung-Shi Lin Yu-Lei Lai Yen Lin Yen-Hsyang Chu |
| author_sort | Zhao-Yu Chen |
| collection | DOAJ |
| description | In this paper, we compare the performances of radio frequency interference (RFI) suppression between radio frequency interference mitigation (RFIM) and frequency-domain adaptive clutter suppression (FACS) algorithms that apply to ionograms for foF2 scaling through true height analysis. We find that the use of RFIM and FACS can both effectively suppress RFIs in ionograms to improve the signal-to-clutter (SCR) of the original ionogram. Overall, the RFI clutter suppressed by FACS is about 5–7 dB better than that by RFIM. In addition, the SCR improvement made by FACS with neighboring range cells in a range of 10–40 is also better than that made by RFIM, which is about 5–10 dB for FACS and 4–8 dB for RFIM, respectively. However, the signal-to-noise ratios (SNRs) of the ionospheric echoes of the ionograms with FACS are about 3–5 dB (2–3 dB) smaller than those of RFIM during daytime (nighttime). Intercomparisons reveal that the correlations of the scaled foF2 values between the original and RFIM ionograms are slightly higher than those between the original and FACS ionograms, while the root-mean-square-error (RMSE) and mean bias of the former are slightly larger than the latter. These results indicate that the use of RFIM and FACS algorithms to suppress RFIs in ionograms can conditionally improve the quality of scaled foF2 using Ke et al.’s autoscaling algorithm. Statistical results reveal that the use of FACS algorithms can result in about a 5–12% improvement in uncertainty and a 9–80% improvement in accuracy, provided that 5–20 neighboring range cells are selected. As for the RFIM algorithm with a threshold of 2–2.5 times standard deviation, the improvements in uncertainty and accuracy are, respectively, about 0.9–10% and 11–90%. |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-11T04:33:42Z |
| publishDate | 2023-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-17d7b5142a7d4b5d991812101138e2ab2023-11-17T21:13:00ZengMDPI AGRemote Sensing2072-42922023-04-01158216910.3390/rs15082169A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for IonogramsZhao-Yu Chen0Kai-Jun Ke1Ching-Lun Su2Hung-Shi Lin3Yu-Lei Lai4Yen Lin5Yen-Hsyang Chu6Department of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanDepartment of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanDepartment of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanDepartment of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanDepartment of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanDepartment of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanDepartment of Space Science and Engineering, National Central University, Zhongli, Taoyuan City 320317, TaiwanIn this paper, we compare the performances of radio frequency interference (RFI) suppression between radio frequency interference mitigation (RFIM) and frequency-domain adaptive clutter suppression (FACS) algorithms that apply to ionograms for foF2 scaling through true height analysis. We find that the use of RFIM and FACS can both effectively suppress RFIs in ionograms to improve the signal-to-clutter (SCR) of the original ionogram. Overall, the RFI clutter suppressed by FACS is about 5–7 dB better than that by RFIM. In addition, the SCR improvement made by FACS with neighboring range cells in a range of 10–40 is also better than that made by RFIM, which is about 5–10 dB for FACS and 4–8 dB for RFIM, respectively. However, the signal-to-noise ratios (SNRs) of the ionospheric echoes of the ionograms with FACS are about 3–5 dB (2–3 dB) smaller than those of RFIM during daytime (nighttime). Intercomparisons reveal that the correlations of the scaled foF2 values between the original and RFIM ionograms are slightly higher than those between the original and FACS ionograms, while the root-mean-square-error (RMSE) and mean bias of the former are slightly larger than the latter. These results indicate that the use of RFIM and FACS algorithms to suppress RFIs in ionograms can conditionally improve the quality of scaled foF2 using Ke et al.’s autoscaling algorithm. Statistical results reveal that the use of FACS algorithms can result in about a 5–12% improvement in uncertainty and a 9–80% improvement in accuracy, provided that 5–20 neighboring range cells are selected. As for the RFIM algorithm with a threshold of 2–2.5 times standard deviation, the improvements in uncertainty and accuracy are, respectively, about 0.9–10% and 11–90%.https://www.mdpi.com/2072-4292/15/8/2169ionosondeionogramradio frequency interference (RFI)radio frequency interference mitigation (RFIM)frequency-domain adaptive clutter suppression (FACS) |
| spellingShingle | Zhao-Yu Chen Kai-Jun Ke Ching-Lun Su Hung-Shi Lin Yu-Lei Lai Yen Lin Yen-Hsyang Chu A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms Remote Sensing ionosonde ionogram radio frequency interference (RFI) radio frequency interference mitigation (RFIM) frequency-domain adaptive clutter suppression (FACS) |
| title | A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms |
| title_full | A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms |
| title_fullStr | A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms |
| title_full_unstemmed | A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms |
| title_short | A Comparative Study on Radio Frequency Interference Suppression and foF2 Scaling for Ionograms |
| title_sort | comparative study on radio frequency interference suppression and fof2 scaling for ionograms |
| topic | ionosonde ionogram radio frequency interference (RFI) radio frequency interference mitigation (RFIM) frequency-domain adaptive clutter suppression (FACS) |
| url | https://www.mdpi.com/2072-4292/15/8/2169 |
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