Opportunistic rain rate estimation from measurements of satellite downlink attenuation: A survey

Recent years have witnessed a growing interest in techniques and systems for rainfall surveillance on regional scale, with increasingly stringent requirements in terms of the following: (i) accuracy of rainfall rate measurements, (ii) adequate density of sensors over the territory, (iii) space‐time continuity and completeness of data and (iv) capability to elaborate rainfall maps in near real time. The devices deployed to monitor the precipitation fields are traditionally networks of rain gauges distributed throughout the territory, along with weather radars and satellite remote sensors operating in the optical or infrared band, none of which, however, are suitable for full compliance to all of the requirements cited above. More recently, a different approach to rain rate estimation techniques has been proposed and investigated, based on the measurement of the attenuation induced by rain on signals of pre‐existing radio networks either in terrestrial links, e.g., the backhaul connections in cellular networks, or in satellite‐to‐earth links and, among the latter, notably those between geostationary broadcast satellites and domestic subscriber terminals in the Ku and Ka bands. Knowledge of the above rain‐induced attenuation permits the retrieval of the corresponding rain intensity provided that a number of meteorological and geometric parameters are known and ultimately permits estimating the rain rate locally at the receiver site. In this survey paper, we specifically focus on such a type of “opportunistic” systems for rain field monitoring, which appear very promising in view of the wide diffusion over the territory of low‐cost domestic terminals for the reception of satellite signals, prospectively allowing for a considerable geographical capillarity in the distribution of sensors, at least in more densely populated areas. The purpose of the paper is to present a broad albeit synthetic overview of the numerous issues inherent in the above rain monitoring approach, along with a number of solutions and algorithms proposed in the literature in recent years, and ultimately to provide an exhaustive account of the current state of the art. Initially, the main relevant aspects of the satellite link are reviewed, including those related to satellite dynamics, frequency bands, signal formats, propagation channel and radio link geometry, all of which have a role in rainfall rate estimation algorithms. We discuss the impact of all these factors on rain estimation accuracy while also highlighting the substantial differences inherent in this approach in comparison with traditional rain monitoring techniques. We also review the basic formulas relating rain rate intensity to a variation of the received signal level or of the signal‐to-noise ratio. Furthermore, we present a comprehensive literature survey of the main research issues for the aforementioned scenario and provide a brief outline of the algorithms proposed for their solution, highlighting their points of strength and weakness. The paper includes an extensive list of bibliographic references from which the material presented herein was taken

METODO PER LA STIMA DI PRESENZA DI PIOGGIA

La presente invenzione ha per oggetto un metodo per la stima di presenza di pioggia del tipo precisato nel preambolo della prima rivendicazione. In particolare, la presente invenzione ha per oggetto un metodo per la stima di presenza di pioggia basato sulla misura della degradazione del segnale sulla tratta in discesa di collegamenti satellitari con regolazione adattiva dei parametri atmosferici di riferimento

Design of a modular Autonomous Underwater Vehicle for archaeological investigations

MARTA (MARine Tool for Archaeology) is a modular AUV (Autonomous Underwater Vehicle) designed and developed by the University of Florence in the framework of the ARROWS (ARchaeological RObot systems for the World's Seas) FP7 European project. The ARROWS project challenge is to provide the underwater archaeologists with technological tools for cost affordable campaigns: i.e. ARROWS adapts and develops low cost AUV technologies to significantly reduce the cost of archaeological operations, covering the full extent of an archaeological campaign (underwater mapping, diagnosis and cleaning tasks). The tools and methodologies developed within ARROWS comply with the "Annex" of the 2001 UNESCO Convention for the protection of Underwater Cultural Heritage (UCH). The system effectiveness and MARTA performance will be demonstrated in two scenarios, different as regards the environment and the historical context, the Mediterranean Sea (Egadi Islands) and the Baltic Sea

The ARROWS project: Adapting and developing robotics technologies for underwater archaeology

ARchaeological RObot systems for the World's Seas (ARROWS) EU Project proposes to adapt and develop low-cost Autonomous Underwater Vehicle (AUV) technologies to significantly reduce the cost of archaeological operations, covering the full extent of archaeological campaign. ARROWS methodology is to identify the archaeologists requirements in all phases of the campaign and to propose related technological solutions. Starting from the necessities identified by archaeological project partners in collaboration with the Archaeology Advisory Group, a board composed of European archaeologists from outside ARROWS, the aim is the development of a heterogeneous team of cooperating AUVs capable of comply with a complete archaeological autonomous mission. Three new different AUVs have been designed in the framework of the project according to the archaeologists' indications: MARTA, characterized by a strong hardware modularity for ease of payload and propulsion systems configuration change; U-C AT, a turtle inspired bio-mimetic robot devoted to shipwreck penetration and A-Size AUV, a vehicle of small dimensions and weight easily deployable even by a single person. These three vehicles will cooperate within the project with AUVs already owned by ARROWS partners exploiting a distributed high-level control software based on the World Model Service (WMS), a storage system for the environment knowledge, updated in real-time through online payload data process, in the form of an ontology. The project includes also the development of a cleaning tool for well-known artifacts maintenance operations. The paper presents the current stage of the project that will lead to overall system final demonstrations, during Summer 2015, in two different scenarios, Sicily (Italy) and Baltic Sea (Estonia

Impact of pilot pattern on carrier frequency recovery for TETRA-like multitone modulations

A study of maximum-likelihood pilot-aided frequency offset recovery for filtered multitone modulations such as that employed in the TETRA Release 2 Enhanced Data Service is presented. An approach is proposed to improve on previously published algorithms. When pilot symbols are arranged on a rectangular time–frequency grid, as envisaged by the cited standard, the acquisition range of a pilot-based frequency synchroniser may seem to be very narrow as it cannot exceed the inverse of pilot spacing in the time-domain. It is shown that the above drawback can be relieved by resorting to a pilot pattern where the pilot symbols are simply shifted in time along the subcarriers with respect to the rectangular arrangement

Carrier Frequency Recovery in All-Digital Modems for Burst-Mode Transmissions

Reliable data detection in time division multiple access (TDMA) communication systems strictly depends on the availability of accurate estimates of the synchronization parameters of the received signal, i.e., carrier frequency/phase and symbol timing, which must be derived from the burst preamble. The authors focus on the carrier frequency estimation aspect, and present a fast, open-loop, all-digital frequency offset estimation technique, whose performance is assessed in two different communication scenarios: a TDMA satellite link employing standard modulation and burst formats, and a mobile cellular terrestrial radio system with signal and channel characteristics obeying the pan-European Group Special Mobile (GSM) recommendations. The use of the algorithm as a frequency error detector (discriminator) in a recursive ("closed-loop") frequency offset estimator is also discussed, and some results concerning both the transient and the steady-state behavior of such a scheme are presented. Finally, the impact of the algorithm on the receiver BER is briefly analyzed