Earth Exploration Satellite Service Research Articles

Maze-enclosed quad symmetric kite shaped SRR based metamaterial absorber for doppler navigation aids and earth exploration satellite remote sensing services

This paper represents a wide incident angle-polarization insensitive, stable in results, and compact-sized metamaterial absorber that can be used for Doppler navigation aids and remote sensing applications in Earth Exploration Satellite Services. The unit cell dimension was subwavelength-sized of 0.112λ X 0.112λ, with a good effective medium ratio (8.9), and achieved polarization insensitivity at a maximum incident angle up to 180°, making it more effective for proposed applications. The absorber resonated at 3.855 GHz, 5.13 GHz, 9.855 GHz, 13.335 GHz, and 16.02 GHz with single negative metamaterial properties due to negative permeability and absorptions of 99.7 %, 99.2 %, 98.6 %, 98.1 %, and 97.9 %, respectively. An RLC equivalent circuit on ADS was analyzed to validate the simulated results using the dipoles created by the surface currents. The absorber is cost-effective as no lumped elements or multilayer substrate materials were used, making fabricating less time-consuming and simple. The simulated results were validated by measuring data from a vector network analyzer after fabricating it. The proposed metamaterial absorber is suitable for use in Doppler navigation and Earth Exploration Satellite Services, and this research can further be extended to beamforming and sensing applications in the future.

Cognitive Radio Strategy Combined with MODCOD Technique to Mitigate Interference on Low-Orbit Satellite Downlinks.

The concept of cognitive radio (CR) as a tool to optimize the obstacle of spectral coexistence has promoted the development of shared satellite-terrestrial wireless networks. Nevertheless, in some applications like Earth Exploration Satellite Services, which demand high spectral efficiency (bps/Hz) for downlink transmissions, spectral coexistence amidst interferences from cellular Base Stations is still challenging. Our research aims to mitigate these interferences on low-orbit satellite downlinks carrying imaging data received from a ground station. In order to fulfill this, we present cognitive radio approaches to enhance spectrum exploitation and introduce the adaptive modulation and coding (MODCOD) technique to increase RF power and spectral efficiencies. Therefore, we propose a combined methodology using CR and adaptive MODCOD (ACM) techniques. Afterwards, we applied the solution by monitoring the signal to interference plus noise ratio and the MODCOD strategy. Finally, we provide a real in situ case study at the Cuiabá ground station located in Brazil's central area, which receives images from an Earth observation satellite (EOS). In addition to demonstrating the strategy effectiveness in this scenario, we conducted a bench test emulating the interfering wireless communication system. In this sense, we demonstrated the proposed approach, successfully mitigating the harmful effects on the received EOS images.

Design and analysis of single layer Ku/K band integrated element reflectarray antenna

AbstractA linearly polarized dual band reflectarray (RA) antenna designed, fabricated, and tested to operate in the Ku and K band frequencies is reported in this paper. The 24 × 24 cm2 size RA is developed using 1058 integrated elements etched over a 0.275 mm thick Rogers RT5870 substrate. The integrated elements include concentric circular rings distributed co-centric with the source and the Malta cross elements distributed offset from the source. The distribution of these elements is done based on the 590 and 360° phase change observed at 14.25 (Ku) and 22.5 (K) GHz by varying the size of the circular rings and the Malta cross respectively. The designed RA offers a simulated gain of 28.62 dBi at 14.25 GHz and 26.92 dBi at 22.5 GHz. These results are validated experimentally using the fabricated prototype. A measured peak gain of 28 and 26.4 dBi are observed with sidelobe levels (SLL) of −21 and −11 dB at 14.25 and 22.5 GHz respectively. The cross-polarization levels measured at the resonant frequencies are <−31 and <−28 dB. The proposed dual-band RA covers the entire Ku band uplink frequencies utilized for fixed satellite services and the K band downlink frequencies useful for earth exploration satellite services.

Metasurface Dome for Above-the-Horizon Grating Lobes Reduction in 5G-NR Systems

The use of fifth-generation (5G) new radio (NR) spectrum around 26 GHz is currently raising the quest on its compatibility with the well-established Earth exploration-satellite service, which may be blinded by the spurious radiation emitted above the horizon (AtH) by base station (BS) antennas. Indeed, AtH grating lobes are often present during cell scanning due to the large interelement spacing in BS array antennas for achieving higher gains with a reduced number of RF chains. In this letter, we propose an approach based on an electrically thin metasurface-based dome for the reduction of AtH grating lobes in 5G-NR BS antennas. The proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">scanning range shifting approach</i> exploits the natural lower amplitude of the grating lobes when the antenna array scans in an angular region closer to the broadside direction. The grating lobe reduction is here demonstrated considering a 1×4 phased linear antenna array operating under dual-liner ±45°-slant polarization. A simple design procedure for designing the metasurface dome is reported, together with the antenna performances, evaluated through a proper set of numerical experiments. It is shown that the grating lobe radiation toward the satellite region is significantly reduced, whereas the overall insertion loss is moderate.

Quantitative Measurement of Radio Frequency Interference for SMOS Mission

The Earth Exploration Satellite Service (EESS) for passive sensing has a primary frequency allocation in the 1400–1427 MHz band. All emissions unauthorized in this band are called RFI (Radio Frequency Interference). The SMOS (Soil Moisture and Ocean Salinity) mission is greatly perturbed by RFI impeding ocean salinity retrieval, especially in coastal areas such as the SCS (South China Sea), where the observed data has been discarded massively. At present, there is no way to eliminate the RFI impact on the retrieved salinity, other than by detecting and shutting down the emissions from the sources. However, it may be effective in a scientific sense if RFI can be quantified and applied to the salinity retrieval process. Therefore, this study proposes an RFI measuring method that can investigate contamination in both prominent and moderate respects, aroused either by on-site emissions or nearby continents. Based on the proposed method, two levels of hierarchical RFI maps of the SCS region, including the separated one and the merged one, are presented and discussed, indicating more severe contamination in northern and western SCS. Moreover, to verify the generalization of the method on open oceans far from continents, an area in the middle central Pacific is selected and tested. The result shows few or no RFI in this unattended region, which is consistent with the authors’ knowledge. This study presents the concept of the “RFI map” to describe the contamination, which will hopefully help researchers comprehend the RFI state intuitively and assist in ocean salinity retrieval statistically.

Implementation of hybrid fractal metamaterial inspired frequency band reconfigurable multiband antenna for wireless applications

In the present paper authors propose the design and analysis of a hepta band metamaterial inspired octagonal shape antenna using hybrid fractals for wireless applications. Multiband characteristics in the designed antenna is accomplished by introducing of slotted octagonal shape radiating part with hybrid fractal form of Moore curve and Koch curve and two SRR cells. The frequency band reconfigurability is obtained with aid of PIN diodes placed inside the strips connected between Moore curve (fused with centered Koch curve) and feedline. During ON mode of PIN diode antenna operates at seven microwave frequency S-band WiMAX (3.4~3.69 GHz—IEEE 802.16e)/Lower C-band terrestrial fixed and mobile broadband application (4.25~4.76 GHz)/C-band WLAN (5.15~5.35/5.75~5.825 GHz—IEEE 802.11a] (5.4~5.9 GHz)/Lower X-band Earth exploration-satellite service ITU region 2 (7.9~8.4 GHz)/Upper X-band Amateur satellite operating band (10.45~10.50 GHz)/Lower Ku-band Radar communication application (13.25~13.75 GHz)/Middle Ku-band Geostationary satellite service (14.2~14.5 GHz) covering various wireless applications. Proposed design exhibit hexa/hepta band features during OFF/ON mode of PIN diode. An acceptable gain, stable radiation characteristics, and good impedance matching are observed at all the resonant frequencies of the proposed structure.

Analysis on the New Progress of Spectrum Planning of IMT-2020(5G)

In order to allocate reasonable spectrum resources above 6 GHz for 5th-Generation (5G) in China, this paper analyzes the new progress of upcoming World Radio Conference-2019 (WRC-19) agenda 1.13, the 3rd Generation Partnership Project (3GPP) 5G New Radio (NR), and Chinese 5G spectrum planning. It analyses the possibility of Chinese spectrum planning in several candidate frequency bands with Monte-Carlo simulation, including 24.75-27.5 GHz, 31.8-33.4 GHz, 37-43.5 GHz, 64-71 GHz, 71-76 GHz and 81-86 GHz. The compatibility is viable between mobile service (MS) and earth exploration satellite service (EESS), radio astronomy service (RAS), inter-satellite service (ISS) in 24.75-27.5 GHz. It’s likely to allocate 24.75-27.5 GHz to 5G in China. There is coexisting difficulty and adverse propagation condition in 31.8-33.4 GHz. It is almost impossible to allocate 31.8-33.4 GHz to 5G in China. It is compatible between MS and fixed-satellite service (FSS), EESS (passive) with additional isolation and out-of- band emission limitation in 37-43.5 GHz. It is possible to allocate 37-43.5 GHz to 5G in China.

Coexistence of 5G With Satellite Services in the Millimeter-Wave Band

In this study, a new method is proposed to confirm the possibility of coexistence between the existing satellite services and potential fifth-generation (5G) cellular services in the millimeter-wave band according to the frequency-designation agenda of International Mobile Telecommunications (IMT)-2020 for 5G. To evaluate the accumulated interference power of numerous 5G systems distributed globally at a satellite receiver, we extend the satellite's interference reception area to the entire coverage area, from which only the land area is extracted using the geospatial terrain data of Earth in three dimensions. This enables more accurate interference assessment than conventional methods that only consider the footprint of the satellite's 3-dB beamwidth. We also place the IMT-2020 (5G) systems in the coverage area using the IMT-2020 parameters and modeling documents for the International Telecommunication Union's coexistence study. The propagation loss is modeled considering the clutter loss, building entry loss, and attenuation from atmospheric gases. Subsequently, we analyze the interference power received by a fixed satellite service (FSS) satellite operating in the same band and an Earth exploration satellite service (EESS) passive sensor operating in an adjacent channel. Our simulation shows that the FSS satellite receives up to 7.9dB more interference than that obtained from the existing method. Although this is a substantial difference, we find that the protection criteria is still satisfied. However, all EESS passive sensors do not meet the protection criteria in most scenarios, and additional frequency separation or interference mitigation techniques are required to protect these sensors. The proposed method is also applicable to the analysis of non-terrestrial network interference from airships, balloons, unmanned aerial vehicles, etc.

Channel State based Adaptive Modulation and Coding for High Bit-Rate Telemetry Applications

This paper defines associate efficient and comprehensive cryptography and modulation resolution able to support a good vary of spectral efficiency values and knowledge rates in conjunction with high out turn. The most target is given by high rate measure applications, i.e., Earth Exploration Satellite Service (EESS) measure payload, wherever the rise of the system out turn by means that of advanced adaptive techniques is deemed essential so as to fulfill the necessities obligatory by future missions. This paper discusses the matter of adaptive modulation theme choice through an efficient realization of Orthogonal Frequency Division Multiplexing (OFDM) primarily based system in conjunction with Serial Concatenated Convolutional Code (SCCC) guarantee a really low error chance. Additionally this theme makes use of Digital Video Broadcasting Second Generation (DVB-S2) customary to produce giant form of modulation techniques and different cryptography rates. Overall, this permits the system to form efficient use of the accessible information measure, adapting itself to the variable conditions of the link.

Design of micro‐machined modified Sierpinski gasket fractal antenna for satellite communications

Modified Sierpinski gasket fractal patch antenna for earth exploration satellite services has been proposed in this article. The proposed antenna is designed up to third iterative fractal geometry on the FR4 substrate having dielectric constant of 4.4 with height of 0.8 mm. The proposed design shows multiband characteristics at 2.8, 6.1, 7.96, 16, and 17 GHz frequencies. The maximum gain of the proposed design is 9.6 dBi has been achieved in Ku-band. The resonating performance characteristics and radiation characteristics of the final iteration are investigated using simulator and experimentally to verify the results of the proposed design. The simulated and measured performance parameters show quite resemblance. Further, proposed design has been simulated on the micro-machined high resistive silicon substrate which causes the improvement in gain and efficiency. Micro-machined fractal antenna is compatible with monolithic microwave integrated circuits (MMICs).

Sharing and compatibility studies of IMT systems with Earth Exploration-Satellite Service in 26 GHz frequency band

In this paper, the coexistence interference of 26 GHz-band International Mobile Telecommunications (IMT) and Earth Exploration-Satellite Service is analyzed based on actual satellite orbit and ITU-R system characteristic. Specifically, the aggregate interferences of IMT system base stations (BS) and users (UE) to Earth Exploration-Satellite Service earth station are studied, considering high frequency band radio propagation clutter loss. The results show that the IMT base station and user deployment can coexist with the Earth Exploration-Satellite Service in the band. The provided results are useful for design of future 26 GHz IMT-2020 (5G) wireless communications systems and Earth Exploration-Satellite Service.

SMAP L-Band Microwave Radiometer: RFI Mitigation Prelaunch Analysis and First Year On-Orbit Observations

The National Aeronautics and Space Administration's (NASA) Soil Moisture Active and Passive (SMAP) mission, which was launched on January 31, 2015, is providing global measurements of soil moisture and freeze/thaw state. The SMAP radiometer operates within the protected Earth Exploration Satellite Service passive frequency allocation of 1400-1427 MHz. However, unauthorized in-band transmitters and out-of-band emissions from transmitters operating at frequencies adjacent to this allocated spectrum are known to cause interference to microwave radiometry in this band. Because measurement corruption by these terrestrial transmissions, which is referred to as radio-frequency interference (RFI), threatens mission success, the SMAP radiometer includes special flight hardware to enable the detection and filtering of RFI. Results from the first year of SMAP data show the presence of RFI with frequent occurrence over Asia and Europe. During the calibration/validation stage of the mission, the RFI detection and mitigation algorithms were modified to provide enhanced performance. Analysis of the L1B_TB products indicates good algorithmic performance with respect to RFI detection and removal. However, some regions of the globe (e.g., Japan) continue to experience complete data loss. This paper summarizes updates to the SMAP RFI processing algorithms based on prelaunch tests and on-orbit measurements, as well as RFI information obtained in SMAP's first year on orbit.

Spectrum Access for the Passive Services: The Past and the Future

The radio astronomy service (RAS), Earth exploration satellite service (passive) [EESS (passive)], and space research service (passive) [SRS (passive)], collectively known as the passive services, have unique spectrum requirements. Radio astronomy requires access to the spectrum at approximately octave intervals for continuum observations, and in addition to a large number of spectral lines that provide unique information about specific physical processes. The EESS, known more commonly as satellite remote sensing, has somewhat similar requirements. Due to the similarities, and because the passive services are much more sensitive to interference than active communication services, they have been mostly co-allocated and some bands have been allocated to them on an exclusive, primary basis. When looked at closely, however, the RAS and EESS (passive) requirements differ in terms of geographic location, timing, and other details. As the radio spectrum becomes increasingly congested, sharing on a band-by-band basis between active and passive services becomes increasingly difficult. This paper discusses how sharing between the passive services, particularly radio astronomy, and the active services evolved, and some of the issues the RAS and EESS community must resolve.

SMOS Radiometer in the 1400–1427-MHz Passive Band: Impact of the RFI Environment and Approach to Its Mitigation and Cancellation

The Soil Moisture and Ocean Salinity (SMOS) radiometer operates within the Earth Exploration Satellite Service passive band at 1400-1427 MHz. Since its launch in November 2009, SMOS images are strongly impacted by radio frequency interference (RFI). So far RFI sources distributed worldwide have been detected. Up to 42% of these RFIs could be suppressed thanks to the co-operation of the National Spectrum Management Authorities. Some of the strongest RFI sources might mask other weaker sources underneath, hence it is expected the total number of RFI detected may increase as strong ones are progressively identified and switched off. Most RFIs are located in Asia and Europe, which together hold ~73% of the active sources and of the strongest interference. The areas affected by RFI may experience either an underestimation in the retrieved values of soil moisture and ocean salinity or data loss, with the associated detrimental impact on the scientific return. ESA and the teams participating in SMOS mission have put in place different strategies to alleviate this RFI situation.

Scan Loss Pattern Synthesis for Adaptive Array Ground Stations

We present several techniques for maximizing the contact time between low Earth orbiting satellites (LEOs) and a ground station (GS). The GS comprises an adaptive array of electronically steered space-fed lenses (SFLs). Each SFL is manufactured as a low-cost printed circuit with the result that it exhibits scanning loss. By differently orienting the boresights of the SFLs in the adaptive array, the SFL's scanning losses can be made to optimally complement the path loss of the LEO, thereby reducing the cost of the GS while maximizing the download capacity of the satellite link. The optimization, implemented with a genetic algorithm (GA), can be viewed as a kind of pattern synthesis. Such arrays will benefit Earth exploration satellite service (EESS) and telemetry applications, promising a decreased cost and increased reliability as compared with GSs consisting of a large dish antenna. We show that a network of these GSs comprising a total of fourteen small antennas can achieve an average daily data rate that is comparable with that of a single large dish antenna for the Earth Observing One (EO-1) satellite, without increasing the output power of the satellite. We also analyze the case in which the satellite transmits with a variable bit rate (VBR). Furthermore, we show that by selectively populating the focal surface of the SFL with feeds, simultaneous communications with multiple satellites can be achieved with a single GS.

고해상도 위성 탑재 영상 레이다(SAR)의 지상 레이다에 미치는 간섭 영향 분석

최근 WRC-07에서 지구 탐사 업무용 위성 영상 레이다(SAR)의 해상도를 향상하기 위하여 국제 허용 주파수 대역폭을 500 MHz의 초광대역으로 확장하였다. 따라서 현재 동일한 주파수 대역에서 사용하거나 사용 예정인 지상 레이다에 직접적인 전파 간섭을 야기할 수 있을 것으로 우려하고 있다. 본 본문에서는 위성 영상 레이다로 부터 지상 레이다가 받을 수 있는 간섭 영향을 예측하기 위하여, 레이다 특성 파라미터 분석을 통한 레이다 전파 간섭 모델을 활용하고, 위성 SAR의 운용 특성을 고려한 간섭 모델을 이용하여 시간, 공간, 주파수 영역에서 지상 레이다의 간섭 영향을 분석하였다. 최근 발사되어 운용 중인 위성 영상 레이다인 TerraSAR-X 모델과 ITU-R에서 권고하는 지상의 기상 레이다 모델을 이용하여 시뮬레이션을 수행하여 한반도 내에서 운용하는 지상 레이다가 받을 수 있는 간섭 영향을 분석하고 예측하였다. Recently, World Radio Conference(WRC)-2007 approved the ultrawide bandwidth of 500 MHz for the use of spaceborne synthetic aperture radar in X-band for the EESS(Earth Exploration Satellite Service) in order to improve the SAR imaging resolution. It is concerned about the interference impact from the spaceborne SAR that may cause to most of ground radars due to the extended ultra wideband. In this paper, in order to predict the interference impact of the ground-based radar from the spaceborne radar, radar interference model is presented using radar characteristic parameters by taking into account the operating environments of the spaceborne and ground based radar in the time, space, and spectrum domains. Using the spaceborne SAR model of TerraSAR-X and ground radar model of meteorological radar recommended by ITU-R, the interference impact was assessed through the computer simulation to see the possible interference impact of the ground based radar operating in the Korean peninsula.

Auxiliary Trellis Based Viterbi Decoding Algorithm Research of 4D-8PSK-TCM

由于地球探测卫星(EESS)的不断增加,空间数据传输的频带日趋拥挤.为此,空间频率协调组织(SFCG)建议采用高效率调制技术(调制效率不低于1.75bit/symbol)进行数据传输,以有效地利用空间的频率资源,从而避免由于拥挤导致的临近频带之间的相互干扰.4D-8PSK-TCM是CCSDS(空间数据系统咨询委员会)针对SFCG关于EESS 8025～8400 MHz频带调制效率不低于1.75 bit/symbol的高效率调制要求而提出的高效率编码调制标准,在满足抗噪声性能要求的基础上,有效地提高了频带利用率.本文研究了调制效率为2.5比特/符号的4D-8PSK-TCM系统及其维特比译码算法,并在Matlab Simulink下进行了维特比译码算法的仿真.在算法实现中,针对路径度量的复杂性,采用了一种辅助网格的方法,使计算路径度量时只需要64次比较,相对于直接计算所需的2032次比较,极大降低了路径度量的运算复杂度.

Interference from 24-GHz automotive radars to passive microwave earth remote sensing satellites

The automotive industry is currently considering the introduction of short-range radars (SRR) operating near 24 GHz for improving road traffic safety. SSRs are intended to observe the full azimuthal space cover around a vehicle using up to eight sensors. The sensors would operate in an ultrawideband (UWB) mode, occupying 3-5 GHz of bandwidth. Interference from SRR transmitters with passive microwave remote sensing satellites used for weather and climate monitoring could occur as the result of several coupling mechanisms, including direct coupling via the transmit antenna beam and scattering and diffraction of the transmitted signals from leading vehicles, buildings, and other nearby objects. In this study, we estimate the amount of coupling anticipated to occur from SRRs, including the direct and scattered contributions. The calculations are based on bistatic scattering measurements of a typical automobile and ray optical simulations of reflection and propagation in an urban environment. Using these calculations, the maximum allowable SRR transmitted power for interference levels acceptable for meteorological and climatological remote sensing applications are quantified. The study provides criteria for SRR operation with the Earth Exploration Satellite Service on a noninterference basis.

World Radio Conference WRC-2000

The World Radio Conference 2000 must be considered the most important one for radio astronomy since WARC-79. The conference agenda contains about 30 topics of substance, and more than 10 of these have direct impact on radio astronomy frequency allocations. From the perspective of radio astronomy the most important items are: “Allocation of Frequency Bands above 71 GHz to the Earth-Exploration Satellite Service (passive) and Radio Astronomy Service” and the agenda items dealing with Recommendation 66 (Unwanted Emissions). A review of the status of preparations is given.

Space communications

Six proposals for enhancing or expanding the electromagnetic spectrum allocated for communications supporting research in space, which will be heard by the 1992 World Administrative Radio Conference, are discussed. They will cover extravehicular activities, space operations, data relay links, deep space interplanetary probes, future planetary missions, and Earth exploration satellites. Of primary importance to most space agencies is the need to improve the status of the allocation of the space research, space operations, and Earth exploration satellite services in the bands 2.025-2.110 GHz and 2.20-2.29 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>