Characteristics of the Global Radio Frequency Interference in the Protected Portion of L-Band
Abstract
:1. Introduction
- A short review of SMAP, its radiometer data, and the RFI presence in its radiometer measurements are given in Section 2.
- An RFI detection and characterization procedure, similar to the one discussed in [17,18] with some improvements, applied to SMAP Level 1A data measured between May 1 and 7, 2019 to extract RFI properties in the protected portion of L-band is presented in Section 3. The multi-domain procedure contains time and frequency domain pulse blanking, kurtosis, and skewness algorithms implemented simultaneously. Then, similar to the SMAP data processing, detection results from individual algorithms are combined with a logical “OR” operator.
- Based on detection results, geo-located characteristics of the L-band RFI environment such as the maximum and average RFI bandwidth and duration, average RFI-free bandwidth, and the variance in such properties between ascending and descending SMAP observations are discussed in Section 4. This section also mentions specific frequencies in the protected portion of L-band susceptible to RFI in different geographic regions.
- Finally, Section 5 discusses the results and provides insight for future L-band microwave radiometry missions regarding required RFI detection and mitigation capabilities.
2. SMAP Data and RFI Presence in L-Band
3. Approach to Reveal L-Band RFI Characteristics
3.1. Step I: Statistics Calculations
3.2. Step II: Cross-Frequency Algorithm
3.3. Step III: Time Domain Pulse Blanking Algorithm
3.4. Step IV: Kurtosis Algorithm
3.5. Step V: Skewness Algorithm
3.6. Step VI: MPD Flags
3.7. Step VII: Identifying Bandwidth and Duration of RFI
3.8. Step VIII: Geo-Locating RFI Signals
4. Results and Discussion
4.1. Spectral Properties of L-Band RFI
4.2. Temporal Properties of L-Band RFI
4.3. Spectral Distribution of L-Band RFI
4.4. Overall Worldwide Spectro-Temporal RFI Properties
5. Conclusions and Discussion
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
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RFI Properties | Africa | Asia | Europe | Americas | Oceania |
---|---|---|---|---|---|
Amplitude | >50 K RFI over Reunion Island. Strong RFI, >50 K, over Sudan, South Sudan, DRC, Nigeria, and Algeria. | >50 K RFI mostly concentrated over discrete regions over Central Asia, the Middle East, and South-Eastern Asia. Widespread, >20K, RFI contamination over Eastern China. | Widespread, >20 K, RFI contamination over Northern Europe. Several discrete regions with >50 K RFI over Southern Europe. | Discrete >50 K RFI regions over Colombia and Cuba. Discrete locations in the U.S. and Brazil with 20–50 K RFI. | ~15–20 K RFI near Melbourne. |
Average Bandwidth | Discrete regions over Eastern Tanzania and Central African Rep. with >4.5 MHz bandwidth. | Wideband RFI over South Korea, Taipei, and Israel with >4.5 MHz bandwidth. 3–4.5 MHz bandwidth over Eastern China, Central Asia, and the Middle East. | Wideband RFI over UK and continental Europe with >4.5 MHz bandwidth. Widespread RFI over Northern Poland and Germany with 2.5–3.5 MHz bandwidth. | A few discrete locations in South America and Alaska with RFI bandwidth >4.5 MHz RFI. | RFI over Northern Australia with 2.5–3 MHz bandwidth. |
Maximum Bandwidth | Discrete regions in Central Africa with RFI bandwidth up to 24 MHz. | RFI with up to 24 MHz bandwidth over Eastern China, South Korea, Central Asia, and the Middle East. | Several regions all over the continent with RFI bandwidth up to 24 MHz. | Regions in South America, Mexico, and Central U.S. with RFI bandwidth up to 24 MHz. | RFI with 24 MHz bandwidth over two locations in Northern Australia. |
Average RFI-free Bandwidth | >20 MHz except few regions in Sudan, South Sudan, and DRC. <12 MHz over Reunion Island and regions in Eastern Tanzania and DRC. | >20 MHz except Eastern China, Central Asia, and the Middle East. Regions in South Korea, Northern China, and South-Eastern Turkey suffer from limited, <12 MHz, band availability. | Mostly >18 MHz all over the continent. | Mostly >20 MHz with discrete regions having 1–2 MHz-less RFI-free spectrum. | Mostly >20 MHz. |
Difference in Maximum Bandwidth between Ascending and Descending Orbits | Ascending bandwidths are larger up to 10 MHz over discrete regions in Central Africa. | >10 MHz wider bandwidth in ascending then descending over Eastern China and Central Asia. ~10 MHz wider bandwidth in descending orbits over discrete locations in China, Northern India, and the Middle East | Descending bandwidths are usually 5–10 MHz larger in Central and Eastern Europe. Over the Balkans and Italy, discrete regions with ~10 MHz larger ascending bandwidths. | ~10 MHz wider bandwidths in ascending orbits over certain locations Central and Southern U.S as well as Mexico. | No difference observed. |
Average Duration | >4.5 ms over certain locations in Reunion Island, DRC, Sudan, South Sudan, and Algeria. | >4.5 ms over certain locations in South Korea, Central Asia, and the Middle East. Widespread RFI with ~2.5 ms duration over Northern China. | >4.5 ms over Moscow, Russia, and discrete locations in Southern Europe. | >4.5 ms over a location in Colombia. | RFI near Melbourne with ~2.5–3.5 ms duration. |
Maximum Duration | >80 ms over locations in Reunion Island, Sudan, Nigeria, Algeria, and DRC. | >90 ms over locations in South Korea, Central Asia, and the Middle East. Widespread RFI with durations 30–50 ms. | >90 ms over locations in Central Russia, the Balkans, and Italy. Many more locations with 30–50 ms durations all over the continent. | >90 ms over a few locations in Colombia, Chile, and Argentina. 30–50 ms RFI over regions in Eastern U.S., California, and Brazil. | 30–50 ms over discrete regions in South-Eastern Australia. |
Difference in RFI Duration between Ascending and Descending Orbits | >8 ms difference over locations in Reunion Island, Algeria, Nigeria, Sudan, DRC, Uganda, and Kenya. | >8 ms difference over several regions in Eastern China, South Korea, Central and South-Eastern Asia, and the Middle East. | Widespread difference up to >8 ms all over the continent. | Discrete locations in North and South America with differences up to >8 ms. | No significant differences observed. |
SMAP Channels | Africa | Asia | Europe | Americas | Oceania |
---|---|---|---|---|---|
1400/1424 MHz | >20 over certain regions in Sudan, South Sudan, Ethiopia, and Uganda. | >20 over regions in Central Asia, South-Eastern China, and the Middle East. ~10 over many other locations in Eastern China and the Middle East. | >20 over many regions in Italy, the Balkans, and Northern Spain. Widespread RFI with RFI percentage ~10 over Eastern Europe and Russia. | >20 over discrete regions in Colombia, Chile, and California. | No significant RFI observed. |
1401.5 MHz | >20 over certain regions in South Sudan and Uganda. | >20 over a few regions in Northern India and Eastern China. ~10 over several locations in the Middle East and Central Asia. | >20 over many regions in Italy, Ukraine, Russia, and the tU.K. Several locations with RFI percentage ~10 over Eastern Europe and Russia. | >20 over discrete regions in Mexico, Chile, and California. | No significant RFI observed. |
1403 MHz | >20 over locations in Algeria and Rwanda/Burundi. | >20 over regions in Central Asia, Turkey, and Eastern China. Widespread RFI with RFI percentage ~10 over Central Asia. | >20 over Albania and many locations in Russia. ~10 over several locations across the continent. | >20 over certain locations in Texas and California. ~12 over regions in Mexico and Chile. | No significant RFI observed. |
1404.5 MHz | >20 over locations in Algeria. | >20 over Southern Saudi Arabia and Northern Yemen. 8–15 over several regions in Central Asia, India, and Turkey. | 15–20 over several locations in Russia and Ukraine. | No significant RFI observed. | No significant RFI observed. |
1406 MHz | ~15 over a coastal region near Ghana. | >20 over certain locations in the Philippines and Pakistan. Widespread RFI with RFI percentage 8–16 over China and Korea. | 8–20 over discrete regions in Russia and the Balkans. | >20 over a region in Ecuador. | No significant RFI observed. |
1407.5 MHz | 12–20 over several locations in Ghana, Uganda, Rwanda/Burundi, and Congo. | >20 over many regions in Central Asia. 12–15 over several locations in China and Korea. ~12 over Sinai and Tajikistan. | >20 over regions in Southern Italy and Central Russia. 8–12 over many regions throughout the continent. | No significant RFI observed. | No significant RFI observed. |
1409 MHz | >20 over locations in Nigeria, Uganda and Congo. 10–15 over regions in Rwanda/Burundi and Ghana. | >20 over several locations in Central Asia, Korea, and the United Arab Emirates. 8–12 over several locations in China, Korea, and Sinai. | >20 over a few regions in Northern Italy, Southern France, and Spain. 8–14 over several locations in Russia and continental Europe. | ~20 over some locations in Brazil, Argentina, Cuba, and California. | No significant RFI observed. |
1410.5 MHz | >20 over locations in Libya, Nigeria, Uganda, and Congo. 10–14 over some locations in Ghana and Rwanda/Burundi. | >20 over regions in Bangladesh, Pakistan, Hong Kong, and Taiwan. 8–14 over several location in Central Asia, China, Korea, and Sinai. | >20 over a few regions in Northern Italy, Southern France, and near Moscow. Widespread RFI with RFI percentage 10–12 over Northern and Central Europe. | ~20 over some locations in Argentina. | No significant RFI observed. |
1412 MHz | >20 over regions near Congo and Libya. ~12 over a location near Ghana. | >20 over several locations in Kuwait, Central Asia, Bangladesh, North-Eastern China, Caucasus, and Siberia. 8–12 over a large region in Pakistan and Afghanistan. | Widespread RFI over almost the entire continent with >8 RFI percentage. >20 over discrete regions in Russia. | 15–20 over a few regions in Argentina and Brazil. | No significant RFI observed. |
1413.5 MHz | Widespread RFI with RFI percentage >20 over Reunion Island. >20 over a location near Congo. | >20 over a few locations in Bangladesh, Central Asia, and Northern China. 8–12 over a few regions in Pakistan, China, and Korea. | Widespread RFI over almost the entire continent with >8 RFI percentage. >20 over discrete regions in Russia, Germany, and Sweden. | >20 over a few locations in Brazil. | No significant RFI observed. |
1415 MHz | >20 over locations near Congo and Reunion Island. | ~14 over certain regions in Saudi Arabia, Pakistan, and Bangladesh. 8–12 over several locations in the Middle East, Pakistan, China, and Korea. | Widespread RFI with RFI percentage 10–12 over Northern Europe. ~15 over several locations in Portugal, Russia, and Central Europe. | 15–20 over several locations in New England, Chicago as well as in Argentina, Mexico, Peru, and Ecuador. | No significant RFI observed. |
1416.5 MHz | 10–12 over a few regions near Congo and Central African Republic. | 8–20 over many regions in China, Korea, Central Asia, Iran, Saudi Arabia, and Siberia. | 8–20 over several regions throughout the continent. | No significant RFI observed. | No significant RFI observed. |
1418 MHz | Large RFI with RFI percentage >20 over Algeria. 10–12 over some regions in Central Africa. | >20 over regions in Pakistan, Taiwan, Central Asia, Turkey, and Northern Japan. 8–14 over several regions in the Middle East, Siberia, China, and Central Asia. | >10 over many regions in Central and Eastern Europe, Greece, Southern Italy, Spain, and Portugal. | >20 over a few regions in New England, Northern U.S., and Canada. | >15 over a few discrete regions in Southern and Eastern Australia. |
1419.5 MHz | 10–14 over a few locations in Central Africa and South Sudan. | >12 over many regions in Turkey, the Middle East, Pakistan, Central Asia, and Siberia. | >8 over several discrete regions scattered over the continent. | No significant RFI observed. | ~15 over a region in Eastern Australia. |
1421 MHz | >20 over a few regions in Sudan, South Sudan, and near Libya. ~10 over a few regions in Central and Eastern Africa. | 10–16 over several regions in China, the Middle East, Central Asia, and Siberia. | >8 over several discrete regions scattered over the continent. | >12 over discrete regions in Cuba as well as Northern and Eastern U.S. | No significant RFI observed. |
1422.5 MHz | >20 over a few locations in Libya, Sudan, and South Sudan. | 12–14 over many locations in the Middle East. ~20 over several regions in Myanmar, Bangladesh, and China. ~8–10 over scattered discrete regions. | >20 over a large area in the Balkans. >20 over discrete regions over Spain and Northern Europe. Widespread RFI over Eastern Europe with RFI percentage 8–10. | >14 over a region near the Great Lakes. | No significant RFI observed. |
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Aksoy, M.; Rajabi, H.; Atrey, P.; Mohamed Nazar, I. Characteristics of the Global Radio Frequency Interference in the Protected Portion of L-Band. Remote Sens. 2021, 13, 253. https://doi.org/10.3390/rs13020253
Aksoy M, Rajabi H, Atrey P, Mohamed Nazar I. Characteristics of the Global Radio Frequency Interference in the Protected Portion of L-Band. Remote Sensing. 2021; 13(2):253. https://doi.org/10.3390/rs13020253
Chicago/Turabian StyleAksoy, Mustafa, Hamid Rajabi, Pranjal Atrey, and Imara Mohamed Nazar. 2021. "Characteristics of the Global Radio Frequency Interference in the Protected Portion of L-Band" Remote Sensing 13, no. 2: 253. https://doi.org/10.3390/rs13020253
APA StyleAksoy, M., Rajabi, H., Atrey, P., & Mohamed Nazar, I. (2021). Characteristics of the Global Radio Frequency Interference in the Protected Portion of L-Band. Remote Sensing, 13(2), 253. https://doi.org/10.3390/rs13020253