Search

We use Iridium constellation magnetometer data to characterize the global-scale storm-time Birkeland currents. For 11–12 August 2000 we find a strong storm main phase dawn–dusk asymmetry in the latitudes of the region 1–2 current systems and that the total current is not linearly related to the interplanetary electric field, E y . Examination of 23 storms occurring for 1999–2003 shows clear evidence for a non-linear, saturation behavior in total current with E y , with the total Birkeland current constrained to be below 20 MA.

Wrecks are by and large caused because of carelessness in route. As we probably are aware route includes human move in this way mishappen is consistently an opportunity. To decrease this, it is our answer to make a self-governing route-able boat utilizing 'Global Positioning System' support. Latitude and longitude coordinates will allow the boat to decide its precise area on the water body. The coordinates of the destination will be pre-loaded before the flight of the boat. A fanciful way will be resolved between the boat's area and the last area. A magnetometer sensor will be utilized to clarify the geological area of the boat itself to guide the navigation. If there should arise an occurrence of any capricious snag shows up on the radar the boat will be prepared to make an impermanent way to stay away from the deterrent. In the wake of passing the impediment, it will keep on after the recently decided way by following back to the directions that were fixed during setting the last objective directions. The Rockblock 9603 Satellite Communication Module is a special GPS module that can be utilized to send short burst information to the Iridium satellite and back to earth. We will utilize this module to set up a solid association of the boat to the control room. Besides, this module will help us cause the boat to explore independently, with no human intercession.

Subsurface mooring allows researchers to measure the ocean properties such as water temperature, salinity, and velocity at several depths of the water column for a long period. Traditional subsurface mooring can release data only after recovered, which constrains the usage of the subsurface and deep layer data in the ocean and climate predictions. Recently, we developed a new real-time subsurface mooring (RTSM). Velocity profiles over upper 1 000 m depth and layered data from sensors up to 5 000 m depth can be real-time transmitted to the small surface buoy through underwater acoustic communication and then to the office through Beidou or Iridium satellite. To verify and refine their design and data transmission process, we deployed more than 30 sets of RTSMs in the western Pacific to do a 1-year continuous run during 2016–2018. The continuous running period of RTSM in a 1-year cycle can reach more than 260 days on average, and more than 95% of observed data can be successfully transmitted back to the office. Compared to the widely-used inductive coupling communication, wireless acoustic communication has been shown more applicable to the underwater sensor network with large depth intervals and long transmission distance to the surface.

Low Earth Orbit (LEO) satellite has drawn significant attention in recent years as a viable solution to meet the ever-growing demand of mobile users for ubiquitous access to the Internet. However, the conventional handover and authentication mechanism for satellite networks are designed based on individual users, which incurs larger processing overhead and latency due to the high mobility of LEO satellites. In this paper, we propose a novel proactive group handover scheme for the LEO satellite network. The proposed scheme partitions the users with similar patterns into groups. The correlation between the groups is explored to make proactive handover decisions, and the handover time scheduling problem is further modeled as a noncooperative game to minimize the handover delay subject to the transmission capacity constraint. We evaluate the performance of the proposed scheme based on the Iridium satellite constellation. Simulation results demonstrate that the proposed scheme achieves better performance in terms of prediction accuracy and handover delay, and the congestion probability in the handover process can be effectively reduced.

Reducing the cost of data transmission is actively pursued all over the world. A separate direction in this area is the study of possibilities to reduce the cost of transmission of messages via a satellite communication channel. However, studies of the possibility of reducing the cost of message transmission in heterogeneous networks using satellite communication channels in the context of an undeveloped terrestrial network infrastructure and a remote Internet of things have not yet been carried out. This paper reviews and analyzes protocols and technologies for transferring Internet of Things (IoT) data and presents an architecture for a hybrid IoT-satellite network, which includes a long range (LoRa) low power wide area network (LPWAN) terrestrial network for data collection and an Iridium satellite system for backhaul connectivity. Simulation modelling, together with a specialized experimental stand, allowed us to study the applicability of different methods of information presentation for the case of transmitting IoT data over low-speed satellite communication channels. We proposed a data encoding, compressing, and packaging scheme called GDEPC (Gateway Data Encoding, Packaging and Compressing). It is based on the combination of data format conversion at the connection points of a heterogeneous network, message compressing and packaging. GDEPC enabled the reduction of the number of utilized Short Burst Data (SBD) containers and the overall transmitted data size by almost fifteen times.

Most Internet of Things (IoT) communication technologies rely on terrestrial network infrastructure. When such infrastructure is not available or does not provide sufficient coverage, satellite communication offers an alternative IoT connectivity solution. Satellite-enabled IoT devices are typically powered by a limited energy source. However, as of this writing, and to our best knowledge, the energy performance of satellite IoT technology has not been investigated. In this paper, we model and evaluate the energy performance of Iridium satellite technology for IoT devices. Our work is based on real hardware measurements. We provide average current consumption, device lifetime, and energy cost of data delivery results as a function of different parameters. Results show, among others, that an Iridium-enabled IoT device, running on a 2400 mAh battery and sending a 100-byte message every 100 min, may achieve a lifetime of 0.95 years. However, Iridium device energy performance decreases significantly with message rate. This work was supported in part by the Spanish Government through project PID2019- 106808RA-I00, AEI/FEDER, EU, and by Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya through project 2017 SGR 376.

Knowing the location of military personnel and vehicles plays an essential role in military operations, especially when these operations take place in jungles or places of dense vegetation. In this article, the use of the GPS network for the positioning of military vehicles is proposed, in addition, this location is reported through the Iridium satellite network. After the tests, the location of the device is sent, received and stored, with an approximate error of 2m using geodesic points to verify the accuracy of the equipment.

A current- and pressure-recording inverted echo sounder (CPIES) placed on the sea floor monitors aspects of the physical ocean environment for periods of months to years. Until recently, acoustic telemetry of daily-processed data was the existing method for data acquisition from CPIES without full instrument recovery. However, this approach, which requires positioning a ship at the mooring site and operator time, is expensive and time-consuming. Here, we introduce a new method of obtaining data remotely from CPIES using a popup-data-shuttle (PDS), which enables straightforward data acquisition without a ship. The PDS data subsampled from CPIES has 30–60 min temporal resolution. The PDS has a scheduled pop-up-type release system, so each data pod floats to the sea surface at a user-specified date and relays the recorded data via the Iridium satellite system. We demonstrated the capability of an array of PDS-CPIES via two successful field experiments in the Arctic Ocean. The data acquired through the PDS were in agreement with the fully recovered datasets. An example of the data retrieved from the PDS shows that time-varying signals of tides and high-frequency internal waves were well captured. GPS-tracked trajectories of the PDS floating free at the sea surface can provide insights into ice drift or ocean surface currents. This PDS technology provides an alternative method for remote deep-ocean mooring data acquisition.

Software Defined Satellite Networking (SDSN), derived from Software Defined Networking (SDN), has emerged as a new paradigm that significantly simplifies the management of the satellite networks. Controller placement is an important issue in SDSN to quantify the performance of the control plane. Most existing research on controller placement in SDSN assumes a failure-free network. In this paper, we optimally place controllers while taking network failures into account. We first formulate two problems: Controller Placement under Single Satellite Failure (CPSSF) problem and Controller Placement under Single ISL (inter-satellite link) Failure (CPSIF) problem. Network state latency is introduced to characterize the effect of failures on the SDSN control network. With the aim to minimize the network state latency, we propose a simulated annealing placement algorithm (SAP) to solve the above problems efficiently. Finally, our algorithm is evaluated using the IRIDIUM constellation and empirical data. The results indicate that our controller placement strategy can achieve lower network state latency when failures happen compared with previous works.

An extended pathfinding routing and wavelength assignment (RWA) algorithm based on ant colony optimization (ACO-EP) is proposed in order to enhance the global exploratory capability. The algorithm introduces heuristic function which is based on wavelength availability to solve the problem of unbalanced wavelength usage and introduces volatilization coefficient and random interference mechanism based on traffic intensity to improve the shortcoming of easily falling into local optimum. The communication success rate and transmission delay performance are simulated in the scene of Iridium satellite constellation. The results show that when traffic intensity is 138.6Erl, compared with the original ant colony algorithm, ACO-EP algorithm can improve the communication success rate by 23.56% and reduce the communication delay by 13.89%.

Thereis a constant increase of temperature on global scale from north to south. An increase of 0.9 degrees Celsius is monitored since 1906 onward. In addition, this increase of temperature is even more at some particular polar areas both in north of 60°N and south of 60°S. Both Arctic and Antarctic regions require oceanographic observations more than ever now. It is pertinent to mention here that during the past decade, though the temperatures in Antarctic have remained consistent but the Arctic has experienced an increase of 0.75 °C which appears to be much higher than even the global average. Similarly, the Arctic is going through vanishing ice sheets, a gradual rise of traffic in this particular part of the ocean, and, last but not least, a drastic increase in exploration of natural resources. Furthermore, the ice covering protection of Antarctic requires continuous monitoring & persistent measurement. In this regard, polar Argo buoys have initiated collecting data at poles due to technological improvements in buoys. These improvements include the both way communication with the aid of Iridium satellite network, upgraded software to store winter profiles and algorithm development for avoidance of ice. It is recommended to increase Argo standard sampling (3° × 3°) towards poles by enhancing 285 buoys in the sea of Arctic and 360 in the proximity of Antarctic. It is pertinent to mention here that despite the aforementioned improvements, the Argo buoys still experience varying damages caused to their expensive gear on multiple occasions thus limiting their frequent employments. In addition to that, the survivability of Argo floats is compromised in polar regions as compared to the open global oceans. The accumulative effects of such causes make the cost of even a single Conductivity-Temperature-Depth (from now on CTD) profile to be much costly with regard to the profile obtained from open oceans. Similarly, in order to develop gridded fields of salinity & temperature which optimally preserve the temporal and spatial capacities of the profiling buoys for the Argo array, the In-Situ Analysis System (ISAS) was evolved. In 2009, re-analysis on global scale was conducted for the first time. Since then, this particular system has been upgraded to include all kinds of time series along with the profiles of vertical. These gridded spheres of ISAS are utterly comprising in-situ outcomes. This near real-time temperature- salinity gridded data on the global scale is acquired for the upper 2000 meters. An optimum interpolation is the basis of these gridded Argo data sets. These data sets are considered as a source of observation in the bipolar regions of the globe. Finally, animals are equipped with Autonomous CTD-Satellite Relay Data Loggers (from now on CTD-SRDLs) which are mounted on such animals on land. Then, the data is acquired & stored in the form of hydrographic profiles during their foraging travels. The moment these seals return to surface, the data is transmitted by satellite ARGOS. The ARGOS satellites are responsible to ascertain the position of the seals by employing triangulation. On the Southern fronts of the ocean, data is processed and saved by the Sea Mammal Research Unit (SMRU). This data is then received by the Global Telecommunication System (GTS) in real-time. This particular CTD data undergoes a post-processing proceeding which involve editing, rectification, & subsequent endorsement of hydrographic measurements. These records are then made public via varying portals. In general, such CTD-borne animals are relentlessly recording and offering vertical temperature-salinity profiles up to the depth of 2000 meters. This particular study is aimed at analyzing multifarious ways to obtain better estimation of both thermal & salinity measurements in and around the surroundings of polar regions. To accomplish this, the study discusses viable data in the proximity of bipolar regions from Argo, gridded Argo data sets, and CTD-borne animals in order to highlight the prospect of covering polar oceans. Consequently, the data from the 03 sources is presented both on individual and comparative charts at 02 core locations in the proximity of the polar regions.

In this paper, iridium satellite communication based integrated Marine environment observation system is studied. There are some problems in the deep ocean, such as bad environment, difficult release of anchored buoy, single measurement of Marine environmental data and low accuracy of Marine environmental data. The system is designed to carry a variety of sensors that transmit real-time observations to a land-based monitoring center via iridium satellite communications. In this way we can get integrated Marine environmental data. The data of systematic observation is of great significance for improving the accuracy of Marine meteorological forecast, Marine ecological environment protection, further research on global Marine climate change and network observation.

In this paper, an iridium satellite radome for smart float is designed. According to the existing iridium satellite and GPS bare antenna, this paper optimizes the design of pressure resistant radome in aspect of material selection and mechanical design. Hydrostatic test, microwave chamber test and communication ability test have been conducted. The results show that the iridium satellite radome can withstand the pressure above 40Mpa, and the iridium antenna with the radome have a gain greater than 2 dB.

Initial orbit determination (IOD) for space objects is challenging, especially in the case where only optical observations, i.e. angles-only observations, are available and the optical observing arcs are very short (i.e. the too-short arc (TSA) problem). One approach to address the TSA problem is to associate several short-arc tracklets to targets across varying time intervals. In order to achieve better association and run-time performance, this study proposes an improvement to the traditional initial value problem (IVP) solution that determines the association by searching for the global minimum of a new loss function defined in a nonsingular canonical space. The improved IVP method was validated using optical data of space objects at different altitudes collected from the Mount Stromlo Observatory and compared with traditional IVP and another popular tracklet association method: the boundary value problem (BVP) approach. Results illustrate that the improved IVP method is superior to IVP and BVP in terms of association performance, and it also achieves good run-time performance. In addition, traditional methods suffer the drawback of incorrectly associating tracklets from different objects in the same constellation. A new approach dubbed the common ellipse method is presented to address this issue. The common ellipse method is tested with 86 Iridium constellation tracklets, and results show that it significantly improves the true negative rate for the tested scenario.

—The article presents a new modification to a measuring–recording apparatus developed at the Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, to monitor anthropogenic noise levels on the northeastern shelf of Sakhalin Island. The functional possibilities of the original devices, modules, and software are described. The main device of the apparatus is the Shelf-2014 underwater bottom station, which records acoustic pressure variations in the 2–15 000 Hz frequency range. For operation in real time, the station is supplemented with a telemetry buoy. The Iridium satellite network serves as the buoy’s data transmission channel. Software at a shore post makes it possible to view the acoustic conditions in real time. The coordinates and technical status of bottom stations and buoys are controlled automatically. An operator receives on-screen notification when the parameters go beyond the permissible limits. The modified apparatus was tested on the shelf of the Sea of Japan.

As a result of out-of-band emissions and spurious emissions from air-borne or space-borne transmitters simulations and analysis methods have been developed. These methods were developed to determine the amount of interference such a transmitter could cause. The method discussed and applied in this paper is the equivalent power flux density (EPFD) method, which is formally described in international telecommunication union (ITU) recommendations. Up until this point this method has been implemented in MATLAB, which can be used for the determination of the amount of data loss in radio telescopes due to the unwanted emissions of the Iridium satellite constellation. In this paper, it is proposed to use the two line elements (TLEs) instead of the licensed Satellite ToolKit in the EPFD calculation. A theoretical case has been implemented, which is adaptable to the user preferences. The flexibility of the algorithm has been improved, while computational time remains in the same order of magnitude.

This paper studies a circular patch antenna which is fed by using a coaxial pin, which is a suitable antenna design for applications where small size is of importance. Such applications are wearable antenna designs. The main purpose of this paper is to design an antenna with wearable capabilities and adequate radiation characteristics for satellite communications and more specifically for the Iridium satellite constellation. The goals for the radiation characteristics of the antenna are the tuning of the antenna to 1.62GHz which is the Iridium's frequency, maximum boresight gain for this frequency, as well as circular polarization.

This paper presents a data acquisition and telemetry system designed and built to monitor oceanographic and meteorological parameters. A voltage regulator and readout module was designed for the reading of data from a set of dedicated commercial sensors and to continuously monitor the voltage level of the power supply. In order to monitor the measured parameters and the status of the buoy remotely, a data string was transmitted every hour using an Iridium satellite transceiver. The described system was implemented and tested in four coastal oceanographic buoys that were deployed and operated in remote sites in the Gulf of Mexico (GoM) for several months in 2016. The data recorded by the buoys is used to describe the oceanographic and meteorological conditions at each site. The system proved to be reliable for long-term monitoring at offshore sites, requiring only minor corrective maintenance during their operation in the field.

Expendable bathythermographs (XBT) to profile upper-ocean temperatures from vessels in motion have been in use for some 50 years now. Developed originally for navy use, they were soon adapted by oceanographers to map out upper-ocean thermal structure and its space–-time variability from both research vessels and merchant marine vessels in regular traffic. These activities continue today. This paper describes a new technology—the Autonomous Expendable Instrument System (AXIS)—that has been developed to provide the capability to deploy XBT probes on a predefined schedule, or adaptively in response to specific events without the presence of an observer on board. AXIS is a completely self-contained system that can hold up to 12 expendable probes [XBTs, XCTDs, expendable sound velocimeter (XSV)] in any combination. A single-board Linux computer keeps track of what probes are available, takes commands from ashore via Iridium satellite on what deployment schedule to follow, and records and forwards the probe data immediately with a time stamp and the GPS position. This paper provides a brief overview of its operation, capabilities, and some examples of how it is improving coverage along two lines in the Atlantic.

In view of the problem of poor real-time transmission of the traditional information transmission method of marine monitoring buoy, the transmission speed is slow. Based on this, iridium data communication system is applied to the information transmission of ocean monitoring buoy. Through the establishment of the overall framework of Iridium satellite communication system, determine the buoy information transmission network protocol. On the basis of the network protocol, use Iridium satellite data communication system to obtain the location information of the marine monitoring buoy, and then process the obtained information. Finally, upload the processed buoy information to complete the transmission of the marine monitoring buoy information. Compared with the traditional method of information transmission of ocean monitoring buoy, the experimental results show that the method of information transmission of ocean monitoring buoy using iridium data communication system can complete the transmission of buoy information in a shorter transmission time, with better real-time transmission.

Birkeland currents that flow in the auroral zones produce perturbation magnetic fields that may be detected using magnetometers onboard low-Earth orbit satellites. The Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) uses magnetic field data from the attitude control system of each Iridium satellite. These data are processed to obtain the location, intensity and dynamics of the Birkeland currents. The methodology is based on an orthogonal basis function expansion and associated data fitting. The theory of magnetic fields and currents on spherical shells provides the mathematical basis for generating the AMPERE science data products. The application of spherical cap harmonic basis and elementary current system methods to the Iridium data are discussed and the procedures for generating the AMPERE science data products are described.

The WireWalker wave-powered profiler system was designed by the Ocean Physics Group at Scripps Institution of Oceanography (SIO) University of California San Diego over 16 years ago [1]. The WireWalker system uses an ingenious ratcheting system to walk down a wire rope due to the wave action acting on a surface buoy, with a wire attached below the buoy and weights at the end of the wire for tautness. A rubber stopper attached to the wire rope at the desired depth trips the ratcheting mechanism to allow for a free-floating clean profile of data on ascent, while an upper stopper trips the mechanism to allow ratcheting down again. The Office of Naval Research and the National Science Foundation supported further development of these systems over the years. In 2016, the successful technology transition allowed for the formation of Del Mar Oceanographic, LLC to manufacture the WireWalker systems under license from the University of California San Diego. In 2017, the Navy funded the Multiscale Ocean Dynamics Group at SIO to provide two WireWalker systems with inductive modems and Iridium Router-Based Unrestricted Digital Internetworking Connectivity Solutions (RUDICS) communications for near-real-time data collection. The requirements of these two WireWalker systems were for transmission of conductivity, temperature, pressure, optical backscatter, chlorophyll a, irradiance, and radiance (along with system health) and for a Nortek Signature 1000 Acoustic Doppler Current Profiler to collect water current data and record the data internally. Within these WireWalkers, RBR Global in Canada integrated its conductivity-temperature-depth recorders with multiple channels and modem capability to transmit data inductively through the wire rope to the surface buoy. RBR Global also provided electronic integration for the surface buoy to transmit data through Iridium satellites utilizing RUDICS. Training at SIO [2] and onboard the R/V Robert Gordon Sproul in September 2017 will be discussed. Details of field experiences in February, September, and October 2018 and January-February 2019 will also be discussed. Technical problems encountered in the field and troubleshooting allowed Naval Oceanographic Office scientists to quickly learn the system and determine its deficiencies. This work helped to further debug and refine the WireWalker real-time system development and technical information required to ensure successful field operations by novice users of the WireWalker system.

It is proposed to create a group of nanosatellites of CubeSat format, which will consist of clusters. Each cluster will be similar functionally to Iridium satellite. One of the possible uses of nanosatellites is their use to build a satellite communications system. To compare such a promising system with existing low-orbit and geostationary satellite systems, an efficiency indicator is proposed. It is shown that the value of this indicator for a nanosatellite system is several times better than for existing systems.

Several post-detection approaches to the mitigation of radio-frequency interference (RFI) are compared by applying them to the strong RFI from the Iridium satellites. These provide estimates for the desired signal in the presence of RFI, by exploiting distinguishing characteristics of the RFI, such as its polarization, statistics, and periodicity. Our data are dynamic spectra with full Stokes parameters and 1[Formula: see text]ms time resolution. Moreover, since most man-made RFI is strongly polarized, we use the data to compare its unpolarized component with its Stokes I. This approach on its own reduces the RFI intensity by many tens of dBs. A comprehensive approach that also recognizes non-Gaussian statistics, and the time and frequency structure inherent in the RFI, permits exceedingly effective post-detection excision provided full Stokes intensity data are available.

This paper presents an analysis of data from the magnetometers on board the Defense Meteorological Satellite Program (DMSP) F-15, F-16, F-17, and F-18 satellites and the Iridium satellite constellation, using an inverse procedure for high-latitude ionospheric electrodynamics, during the period of 29–30 May 2010. The Iridium magnetometer data are made available through the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) program. The method presented here is built upon the assimilative mapping of ionospheric electrodynamics procedure but with a more complete treatment of the prior model uncertainty to facilitate an optimal inference of complete polar maps of electrodynamic variables from irregularly distributed observational data. The procedure can provide an objective measure of uncertainty associated with the analysis. The cross-validation analysis, in which the DMSP data are used as independent validation data sets, suggests that the procedure yields the spatial prediction of DMSP perturbation magnetic fields from AMPERE data alone with a median discrepancy of 30–50 nT. Discrepancies larger than 100 nT are seen in about 20% of total samples, whose location and magnitude are generally consistent with the previously identified discrepancy between DMSP and AMPERE data sets. Resulting field-aligned current (FAC) patterns exhibit more distinct spatial patterns without spurious high-frequency oscillatory features in comparison to the FAC products provided by AMPERE. Maps of the toroidal magnetic potential and FAC estimated from both AMPERE and DMSP data under four distinctive interplanetary magnetic field (IMF) conditions during a magnetic cloud event demonstrate the IMF control of high-latitude electrodynamics and the opportunity for future scientific investigation.

Inter-satellite laser communication can fulfill the requirements of huge-capacity transmission of satellite communication. The space-wide all-optical network is a key way to solve problems such as low-latency, huge-capacity transmission and low-cost on-orbit real-time route switching processing through technologies of Wavelength Division Multiplexing (WDM) inter-satellite links (ISLs) and wavelength routing. Then routing and wavelength assignment (RWA) become its core and main technology. Aiming at the RWA issue, this paper takes the typical LEO satellite constellations Iridium and NeLS as examples, establishes a regular ISLs topology, and proposes a simulation model based on the minimum cost routing strategy and wavelength demand. The results of simulations demonstrate that, compared with the link arbitrary topology, the NeLS constellation with regular network topology can save nearly half of the wavelength resource requirement under the condition of slightly sacrificing node connectivity, and the Iridium constellation has the better connectivity with the same wavelength resource demand. Both NeLS and Iridium constellations show a more stable trend in the link duration, wavelength volatility, and node connectivity volatility.

With the increasing demand for large-scale data transmission and data security in deep sea observation and detection, Iridium and Beidou dual-mode communication has become the main approach in the field of China’s ocean observation and detection. However, the size and weight of the two antennas are not easy to reduce, which presents a challenge to the buoyancy control system of carriers such as deep sea ARGO buoys. According to the fact that the RDSS L frequency band of Beidou satellite is similar to that of Iridium Satellite system and partly coincides with Iridium frequency band, this paper provides the potential of using Beidou deep sea antenna for Iridium communication. Firstly, the electrical characteristics of existing Iridium and Beidou antennas on the market are measured in microwave anechoic chamber and SATIMO system. Then the outdoor measurements are conducted. The results show that the Beidou deep sea antenna can be used for Iridium communication.

Global Navigation Satellite System (GNSS) has been widely used in many geosciences areas with its Positioning, Navigation and Timing (PNT) service. However, GNSS still has its own bottleneck, such as the long initialization period of Precise Point Positioning (PPP) without dense reference network. Recently, the concept of PNTRC (Positioning, Navigation, Timing, Remote sensing and Communication) has been put forward, where Low Earth Orbit (LEO) satellite constellations are recruited to fulfill diverse missions. In navigation aspect, a number of selected LEO satellites can be equipped with a transmitter to transmit similar navigation signals to ground users, so that they can serve as GNSS satellites but with much faster geometric change to enhance GNSS capability, which is named as LEO constellation enhanced GNSS (LeGNSS). As a result, the initialization time of PPP is expected to be shortened to the level of a few minutes or even seconds depending on the number of the LEO satellites involved. In this article, we simulate all the relevant data from June 8th to 14th, 2014 and investigate the feasibility of LeGNSS with the concentration on the key issues in the whole data processing for providing real-time PPP service based on a system configuration with fourteen satellites of BeiDou Navigation Satellite System (BDS), twenty-four satellites of the Global Positioning System (GPS), and sixty-six satellites of the Iridium satellite constellations. At the server-end, Precise Orbit Determination (POD) and Precise Clock Estimation (PCE) with various operational modes are investigated using simulated observations. It is found out that GNSS POD with partial LEO satellites is the most practical mode of LeGNSS operation. At the user-end, the Geometry Dilution Of Precision (GDOP) and Signal-In-Space Ranging Error (SISRE) are calculated and assessed for different positioning schemes in order to demonstrate the performance of LeGNSS. Centimeter level SISRE can be achieved for LeGNSS.

Traditionally, Unmanned Underwater Vehicles (UUVs) serve as data recorders, collecting and storing data for post-processing after the mission is completed. Computer processing power aboard UUVs, however, has steadily increased to match pace with consumer computational hardware. As this computational capacity continues to grow, new opportunities are becoming available for on-board automated target recognition, image processing, mosaicking, and other data product creation. These data products can now be analyzed, compressed, and transmitted mid-mission via acoustic modems, radio modems at the surface, or even over Iridium satellite communications. This mid-mission intelligence lends to greater dynamic mission control, a reduction in operator reaction time, and much lower latency in the age of useful data. In this paper, we will discuss the new L3 OceanServer Iver3 camera system and its use to generate on-board data products like benthic mosaics and 3D reconstructions.

Inter-satellite optical communications can meet the needs of large-capacity transmission of satellite communications. The space-wide optical networks based on WDM intersatellite links (ISLs) and wavelength routing technology is an important approach to solve low-latency, large-capacity transmission and low-power on-orbit real-time routing process. And routing and wavelength assignment are its key technologies. For RWA problem, this paper takes the typical 2π constellation NeLS and π constellation Iridium constellation as examples, and proposes a method to determine the optimal inter-satellite link topology, and establishes a simulation model of two typical constellation routing strategies and wavelength requirements. The results show that the small-scale Iridium constellation has the characteristics of faster RWA algorithm, better connectivity of network topology nodes and lower demand for wavelength resources. The large-scale NeLS constellation of satellites can reduce the wavelength requirement of the link arbitrary optical networks through increasing the physical connectivity or reducing the maximum allowable hops.

This paper describes the initial development of a low-cost Lagrangian drifter based on solar panels, ultracapacitor and open hardware-software platform. The drifter is powered by a solar panel and a single Ultracapacitor that stores the energy. The drifter has a sensor suite formed by a GPS, temperature, pH, dissolved oxygen, conductivity sensors and a camera. The energy management and signal processing from sensors is supported by an Arduino Mega development board. The communications between the ground station and a deployed drifter is based on Iridium Satellite Terminal. All mechanical and electronic components are self-contained in a pressure housing. The main purpose of this Lagrangian drifter is: detect a red tide near Ecuadorian coasts, obtain physical-chemical parameters in-situ then send the measurements trough a satellite network to a ground station. Results from sea trials are shown.

Field-aligned currents (FACs) play an important role in the coupling between the ionosphere and magnetosphere. Numerical simulation of these phenomena is of increasing interest, but validation has been hampered by a lack of a formal framework to compare simulations to satellite-derived products. We develop a statistical approach to compare FAC simulations from global magnetohydrodynamical models against satellite products. We introduce a robust algorithm that automatically detects and defines regions 1 and 2 FACs. In an example, currents derived from the Iridium satellites are compared against simulated currents from two resolutions of the Lyon-Fedder-Mobarry model on one solar event. We assess both average and structured discrepancies, the former being a level shift of the physical model away from the satellite product, while structural discrepancy refers to time-varying, continuous differences. For this event, the lower resolution version of the Lyon-Fedder-Mobarry is shown to be a poor representation of the satellite-derived FACs, while the higher resolution version substantially reduces discrepancy.

This paper describes a system for providing power and communications to moored profiling vehicles. A McLane Moored Profiler (MP) was equipped with a rechargeable battery pack and an inductive charging system to allow it to move periodically to a charging dock at the top of a subsurface mooring. Power was provided from a large bank of alkaline batteries housed in two 0.94-m steel spheres. Data were transferred inductively from the profiler to a mooring controller, and from there back to shore via radio and Iridium satellite modems housed in a small surface communications float on an “L” tether. An acoustic modem provided backup communications to a nearby ship in the event of loss or damage to the surface float. The system was tested in a 180-m-deep fjord (Puget Sound, Washington) and at Station ALOHA (A Long-Term Oligotrophic Habitat Assessment), a 4748-m-deep open-ocean location north of Hawaii. Basic functionality of the system was demonstrated, with the profiler repeatedly recharging at about 225 W (with an overall efficiency of about 70%). Data were relayed back to shore via Iridium and to a nearby ship via the radio and acoustic modems. The system profiled flawlessly for the entire 6-week test in Puget Sound, but charging at the deep site stopped after only 9 days in the deep-ocean deployment owing to damage to the charging station, possibly by surface wave action.

We acknowledge the use of NASA/GSFC’s Space Physics Data Facility for OMNI data. Simulation results have been provided by the Community Coordinated Modeling Center at Goddard Space Flight Center through their public Runs on Request system (http://ccmc.gsfc.nasa.gov). The CCMC is a multiagency partnership between NASA, AFMC, AFOSR, AFRL, AFWA, NOAA, NSF, and ONR (Paul-Tenfjord-032514-1). We thank the AMPERE team and the AMPERE Science Center for providing the Iridium-derived data products. This study was supported by the Research Council of Norway/CoE under contract 223252/F50.

The paper presents a description and the technical characteristics of an autonomous hydroacoustic station developed at the Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences (TOI DVO RAN) for stationary measurements of variations in acoustic pressure in the frequency range of 2–15 000 Hz on the shelf at the bottom. To organize real-time monitoring of the parameters of seismic survey impulse signals and industrial acoustic noise, the station is additionally equipped with a digital UHF–FM radio telemetry channel. Acoustic data measured in the frequency band of 2–2000 Hz is transmitted through the channel to a shore post, as well as via an Iridium satellite radio telemetry channel. It controls the operation of the UHF–FM radio transmitter and transmits the results of special analysis of acoustic data obtained in subsequent 1 min time intervals.

The critical need for real-time coastal oceanographic and meteorological measurements to support maritime forecasters, emergency managers, pilots, vessel operators, port authorities, coastal planners, and many other decision makers has rapidly grown, along with the variety of scientific research applications that rely on resulting long-term data records. To support the needs for such observations, the National Ocean Service Center for Operational Oceanographic Products and Services (CO-OPS) continues to maintain and develop the National Water Level Observation Network (NWLON) and Physical Oceanographic Real-Time Systems (PORTS®). Together, these networks consist of over 300 long-term, real-time observatories distributed across the nation's coasts.In situdata measured and disseminated in real time from NWLON and PORTS stations include water levels, ocean currents, waves, water temperature, conductivity, bridge clearance, visibility, and several meteorological parameters. CO-OPS invests heavily in analysis of emerging technologies to identify potential improvements in data quality and operating efficiency and to ensure that the evolving needs of its diverse user community are continuously met. Recent enhancements to the CO-OPS network include the transition to microwave radar water level sensors to increase accuracy and simplify installation and maintenance requirements; development and testing of nearshore wave measurement systems; development of standalone, bottom-mounted water level gauges for applications in remote Arctic areas; and expanding data communication capabilities to improve usage of the National Oceanic and Atmospheric Administration (NOAA) Geostationary Operational Environmental Satellites and to broaden use of the Iridium satellite system. An overview of the latest design features of typical CO-OPS real-time stations is presented, along with highlights of recent system developments and enhancements.

Saturation of the auroral electrojet (AE) index during storm times is a phenomenon that has been known but not fully understood. To address this puzzle, here we correlate the (provisional) AE index with net field-aligned current (Net-dB) index, which is a data product derived with magnetic field measurements from the Iridium satellite constellation ( Anderson et al., 2010 ), with an assumption that AE is largely measuring convection driven by the field-aligned currents represented by the Net-dB index. The Net-dB index has a time resolution of ∼45 min and is currently available from February 18, 1999, to May 31, 2008. It is found that, for the entire data period, there is a good linear correlation (r=0.74) between the AE index, when averaging over the Net-dB index time grids, and the Net-dB index, suggesting that statistically ∼55% of the ionospheric Hall currents correlate with large scale convection as reflected in the field-aligned currents. It is also found that the correlation decreases during storm times, with a clear decreasing trend toward a more negative Sym-H. For large storms (Sym-H 30 nT and a secondary peak (r=0.66) at Sym-H∼−50 to −30 nT. A further study shows that the variations of the AE–Net-dB correlation are associated with the location of the field-aligned currents into and out of the ionosphere relative to the ground magnetometer stations, as expected often but not demonstrated in the past.

This paper describes the latest innovations and experimental results for assured time and location based on Low Earth Orbit (LEO) satellites. Interest is growing worldwide to identify additional sources of PNT to augment existing GNSS sources. Industry and government groups are actively seeking independent timing solutions to ensure uninterrupted operation of the critical infrastructure, including data centers, financial markets, cellular networks, and power distribution. Military users are also interested in robust and reliable geolocation capabilities, even in environments where GPS or GNSS is not available. Commercial and academic entities serving these industries are actively exploring a wide range of technologies to support a comprehensive solution for assured PNT. Results from three separate user equipment configurations are presented – each of which is intended to increase the real-time performance of the Satellite Time and Location (STL) system, a non-GNSS solution for assured time and location that is highly resilient and physically secure. STL uses the Iridium constellation of 66 communications satellites in Low Earth Orbit (LEO) to transmit specially structured time and location broadcasts. Due to their high RF power and signal coding gain, the STL broadcasts are able to penetrate into difficult attenuation environments, including deep indoors. Like GNSS signals, these broadcasts are specifically designed to allow a receiver to obtain precise time and frequency measurements to derive its position, navigation, and time (PNT). STL is able to augment or serve as a back-up to existing GNSS PNT solutions by providing secure measurements in the presence of high attenuation (deep indoors), active jamming, and/or malicious spoofing. The first configuration substituted a rubidium clock (a very stable frequency source based on atomic physics rather than quartz crystals) for the Temperature Compensated Crystal Oscillator (TCXO) used as the STL receiver’s timebase during earlier experiments. Using the rubidium clock, the STL receiver demonstrated a Maximum Time Interval Error (MTIE) of 170 nanoseconds over a two-week period at a static location which was precisely known a priori. The second configuration utilized the same hardware setup, with the receiver configured to a static location that was unknown, and with a rubidium clock that was still warming up 6 hours after a cold start. The demonstrated MTIE for this configuration was 420 nanoseconds over a seven-day period. The third configuration utilized a nearby STL reference station to transmit localized error measurements to the STL ground segment. The reference receiver used a GPS-derived timebase that was assumed to be perfect. Timing results from 3 receivers, with different internal OCXO oscillators, are presented.

This work describes system engineering of an internet-of-things (IoT) connectivity and satellite data transfer for a pico-hydroelectric power generation system. The system is developed for deployment in remote villages in the Nepal Himalayas. The IoT devices are sensors attached to various points in the system which monitor critical system performance metrics such as generator vibrations and output voltage and control important functions. The data is transmitted from IoT devices using Zigbee. The data is then transmitted to the Iridium satellite system so it can be available to an international team of researchers who developed and monitor the performance of the system. This allows for optimization and performance improvements with the goal of perfecting the system so it can be implement in other villages. This work describes the system, why it is needed, and the hardware. The result is an IoT enabled monitoring system with real time data transmitted using satellites.

Satellite communication has triumphed as one of the most fascinating stream of telecommunication engineering for last 75 years. While the world has moved on in tremendous pace, Bangladesh mostly stayed out of the procession, up until now. Recently Bangladesh has procured its first communications satellite and is on the brink of launching it to the orbit, which makes it a high time to talk about satellite communication (SATCOM). This presentation attempts to shed some light on SATCOM System Design in general. The topics that will be covered are — brief history of communication satellites, orbital dynamics, geostationary/geosynchronous satellites, channel propagation characteristics, communication system design — link budgeting, antennas, ground stations, example of real SATCOM system such as Iridium Satellite Phone, GPS, DVB standard, and new frontiers in SATCOM known as SmallSat and CubeSat.

"Telekom SRBIJA" a.d.;Ericsson;et al.;ETF - School of Electrical Engineering, University of Belgrade;Ministry of Trade, Turism and Telecommunications;VLATACOM d.o.o, 25th Telecommunications Forum, TELFOR 2017 -- 21 November 2017 through 22 November 2017 -- -- 134133, 2-s2.0-85045762752, The Archimedean spiral antenna is a popular type of selfcomplementary antenna. This study presents a two-arm Archimedean spiral antenna for GPS and Iridium applications. Circular symmetrical artificial magnetic conductor (AMC) is used as a ground plane in low-profile two-arm spiral antenna design. Proposed AMC structure enhanced the gain and axial ratio characteristics of traditional sipral antenna. Simulation results show good axial ratio, impedance match and stable gain for both operation bands. © 2017 IEEE.

The IceCube Neutrino Observatory is a cubic kilometer neutrino telescope located at the geographic South Pole which can observe neutrinos at energies from GeV to above a PeV. Now that IceCube has realized its primary goal, the detection of high-energy astrophysical neutrinos, the task remains to identify the sources of these neutrinos. Observing neutrinos in coincidence with transient astrophysical events would be a smoking gun for hadronic acceleration and provide other valuable insights into the nature of the sources. This contribution discusses a new approach to investigate transient phenomena by performing a rapid follow-up analysis. This is done by searching for neutrinos in coincidence with detections by other observatories so that the results can be distributed rapidly to the rest of the astronomical community. In order to accomplish this with minimum delay, the data must be processed immediately at the South Pole and be transmitted to the Northern Hemisphere via the Iridium satellite network. The data processing pipelines, maximum likelihood analysis, and sensitivity of this analysis will be discussed.

For a better understanding of the air-sea interactions that occur during typhoons and improved accuracy in typhoon forecasting, the Institute of Oceanography at the National Taiwan University has developed a buoy that can measure meteorological and hydrographic conditions, and transmit the high-precision data in near real-time. The buoy captures various types of meteorological data, including air temperature, air pressure, relative humidity, wind speed and direction, rainfall, and solar radiation. Additionally, the buoy measures key hydrographic data, such as the temperature and salinity profiles of the upper 500-m water layer. The newly designed of buoy system is a low-power-consumption system and it can be in sleep mode between successive samplings to save power energy. The buoy is supplied electric power by lithium batteries and it can support buoy operation for more than 18 months. The sampling interval and data transmission rate are adjustable via Iridium satellite or UHF radio communications. When a typhoon approaching buoy, the operator can transmit a command to buoy via Internet/Iridium satellite communications to change data transmission rate from standard mode to intensive mode. In addition, the raw data can be retrieved through UHF radio communication between the buoy and a nearby ship. A prototype and two improved buoys were deployed off southeastern Taiwan for trial in summers of 2015 and 2016, respectively. These buoys survived nine typhoons and successfully collected important data on all nine of them. The detail of buoy system and mooring design are presented in this paper.

In order to get the ice melting rate and the acousto-optic reflection characteristics of sea ice profile, the acoustic ranging system and the auxiliary environment parameter measurement system are developed. The instrument collects the underwater ultrasonic sensor's data via the RS485 bus, store the data to SD card and then send them to computer by iridium satellite. Its main advantages are that lossless, non-contact and high precision so that it is suitable for melting information monitoring of sea ice. In the paper the proposed hardware architecture and software architecture are presented. Due to the result obtained during the experimental tests, the proposed instrument can be considered as a reference of monitor application on sea ice melting.

We present results from two separate experiments intended to increase the accuracy of the real-time timing outputs available from the Satellite Time and Location (STL) system, a non-GNSS solution for assured time and location that is highly resilient and physically secure. STL uses the Iridium constellation of 66 communications satellites in Low Earth Orbit (LEO) to transmit specially structured time and location broadcasts. Due to their high RF power and signal coding gain, the STL broadcasts are able to penetrate into difficult attenuation environments, including deep indoors. Like GNSS signals, these broadcasts are specifically designed to allow an STL receiver to obtain precise time and frequency measurements to derive its position, navigation, and time (PNT). STL is able to augment or serve as a back-up to existing GNSS PNT solutions by providing secure measurements in the presence of high attenuation (deep indoors), active jamming, and/or malicious spoofing. The first experiment substituted a “rubidium clock” (a very stable frequency source based on atomic physics rather than quartz crystals) for the Temperature Compensated Crystal Oscillator (TCXO) used as the STL receiver’s timebase during earlier experiments. Using the rubidium clock, the STL receiver demonstrated a Maximum Time Interval Error (MTIE) of 170 nanoseconds over a two-week period at a static location which was precisely known a priori. The same setup demonstrated an MTIE of 656 nanoseconds over a seven-day period when the receiver’s location was only initialized to within 5 km and the rubidium clock was still warming up from a cold start (or 420 nanoseconds, starting 6 hours after the cold start). The second experiment used a nearby STL reference receiver to transmit differential corrections to the receiver under test. The reference receiver used a GPS-derived timebase that was assumed to be perfect. Using these corrections, the test receiver demonstrated a MTIE of 484 nanoseconds over 24 hours when the receiver’s location was only initialized to within 5 km.

We present the development considerations and design for ground-based instrumentation that is being deployed on the East Antarctic Plateau along a 40° magnetic meridian chain to investigate interhemispheric magnetically conjugate geomagnetic coupling and other space-weather-related phenomena. The stations are magnetically conjugate to geomagnetic stations along the west coast of Greenland. The autonomous adaptive low-power instrument platforms being deployed in the Antarctic are designed to operate unattended in remote locations for at least 5 years. They utilize solar power and AGM storage batteries for power, two-way Iridium satellite communication for data acquisition and program/operation modification, support fluxgate and induction magnetometers as well as a dual-frequency GPS receiver and a high-frequency (HF) radio experiment. Size and weight considerations are considered to enable deployment by a small team using small aircraft. Considerable experience has been gained in the development and deployment of remote polar instrumentation that is reflected in the present generation of instrumentation discussed here. We conclude with the lessons learned from our experience in the design, deployment and operation of remote polar instrumentation.

The Active Magnetosphere and Planetary Electrodynamics Response Experiment uses magnetic field data from the Iridium constellation to derive the global Birkeland current distribution every 10 min. We examine cases in which the interplanetary magnetic field (IMF) rotated from northward to southward resulting in onsets of the Birkeland currents. Dayside Region 1/2 currents, totaling ~25% of the final current, appear within 20 min of the IMF southward turning and remain steady. Onset of nightside currents occurs 40 to 70 min after the dayside currents appear. Thereafter, the currents intensify at dawn, dusk, and on the dayside, yielding a fully formed Region 1/2 system ~30 min after the nightside onset. The results imply that the dayside Birkeland currents are driven by magnetopause reconnection, and the remainder of the system forms as magnetospheric return flows start and progress sunward, ultimately closing the Dungey convection cycle.