Low-Cost GNSS Software Receiver Performance Assessment

The Software-Defined Receiver (SDR) is a rapidly evolving technology which is a useful tool for researchers and allows users an extreme level customization. The main aim of this work is the assessment of the performance of the combination consisting of the Global Navigation Satellite Systems Software-Defined Receiver (GNSS-SDR), developed by CTTC (Centre Tecnològic de Telecomunicacions de la Catalunya), and a low-cost front-end. GNSS signals were acquired by a Nuand bladeRF x-40 front-end fed by the TOPCON PG-A1 antenna. Particular attention was paid to the study of the clock-steering mechanism due to the low-cost characteristics of the bladeRF x-40 clock. Two different tests were carried out: In the first test, the clock-steering algorithm was activated, while in the second, it was deactivated. The tests were conducted in a highly degraded scenario where the receiver was surrounded by tall buildings. Single-Point and Code Differential positioning were computed. The achieved results show that the steering function guarantees the availability of more solutions, but the DRMS is quite the same in the two tests

Signal in Space Error and Ephemeris Validity Time Evaluation of Milena and Doresa Galileo Satellites

In August 2016, Milena (E14) and Doresa (E18) satellites started to broadcast ephemeris in navigation message for testing purposes. If these satellites could be used, an improvement in the position accuracy would be achieved. A small error in the ephemeris would impact the accuracy of positioning up to ±2.5 m, thus orbit error must be assessed. The ephemeris quality was evaluated by calculating the SISEorbit (in orbit Signal In Space Error) using six different ephemeris validity time thresholds (14,400 s, 10,800 s, 7200 s, 3600 s, 1800 s, and 900 s). Two different periods of 2018 were analyzed by using IGS products: DOYs 52-71 and DOYs 172-191. For the first period, two different types of ephemeris were used: those received in IGS YEL2 station and the BRDM ones. Milena (E14) and Doresa (E18) satellites show a higher SISEorbit than the others. If validity time is reduced, the SISEorbit RMS of Milena (E14) and Doresa (E18) greatly decreases differently from the other satellites, for which the improvement, although present, is small. Milena (E14) and Doresa (E18) reach a SISEorbit RMS of about 1 m (comparable to that of the other Galileo satellites reach with the nominal validity time) when validity time of 1800 s is used. Therefore, using this threshold, the two satellites could be used to improve single point positioning accuracy

Observation Quality Assessment and Performance of GNSS Standalone Positioning with Code Pseudoranges of Dual-Frequency Android Smartphones

The new generation of Android smartphones is equipped with GNSS chips capable of tracking multi-frequency and multi-constellation data. In this work, we evaluate the positioning performance and analyze the quality of observations collected by three recent smartphones, namely Xiaomi Mi 8, Xiaomi Mi 9, and Huawei P30 pro that take advantage of such chips. The analysis of the GNSS observation quality implies that the commonly employed elevation-dependent function is not optimal for smartphone GNSS observation weighting and suggests an application of the C/N0-dependent one. Regarding smartphone code signals on L5 and E5a frequency bands, we found that they are characterized with noticeably lower noise as compared to E1 and L1 ones. The single point positioning results confirm an improvement in the performance when the weights are a function of the C/N0-rather than those dependent on the satellite elevation and that a smartphone positioning with E5a code observations significantly outperforms that with E1 signals. The latter is expressed by a drop of the horizontal RMS from 8.44 m to 3.17 m for Galileo E1 and E5a solutions of Xiaomi Mi 9 P30, respectively. The best positioning accuracy of multi-GNSS single-frequency (L1/E1/B1/G1) solution was obtained by Huawei P30 with a horizontal RMS of 3.24 m. Xiaomi Mi 8 and Xiaomi Mi 9 show a horizontal RMS error of 4.14 m and 4.90 m, respectively

GNSS-SDR pseudorange quality and single point positioning performance assessment

In recent years, we have witnessed a growing demand for GNSS receiver customization in terms of modification of signal acquisition, tracking, and processing strategies. Such demands may be addressed by software-defined receivers (SDRs) which refers to an ensemble of hardware and software technologies and allows re-configurable radio communication architectures. The crux of the SDRs is the replacement of the hardware components through software modules. In this paper, we assess the quality of GNSS observables acquired by SDR against the selected u-blox low-cost receiver. In the following, we investigate the performance level of single point positioning that may be reached with an ultra-low-cost SDR and compare it to that of the low-cost GNSS receiver. The signal quality assessment revealed a comparable performance in terms of carrier-to-noise density ratio and a significant out-performance of the u-blox over SDR in terms of code pseudorange noise. The experimentation in the positioning domain proved that software-defined receivers may offer a position solution with three-dimensional standard deviation error at the level of 5.2 m in a single point positioning mode that is noticeably poorer accuracy as compared to the low-cost receiver. Such results demonstrate that there is still room for SDR positioning accuracy improvement

Use of the sensors of a latest generation mobile phone for the three-dimensional reconstruction of an archaeological monument: The survey of the Intihuatana stone in Machu Picchu (Peru')

The survey of archaeological monuments presents particular needs and difficulties. Such surveys must in fact be as complete, geometrically correct and accurately geo-referenced as possible. These needs, however, often face problems of difficult accessibility, the need for rapid timing and complex logistical conditions. The latest generation of mobile phones are equipped with ultra-high resolution cameras up to 100 megapixel. Although they do not have the geometric characteristics of professional cameras, they can be used advantageously for the reconstruction of three-dimensional models using Structure from Motion methodologies . At the same time, the latest mobile phones are equipped with GPS/GNSS chips that allow a postprocessing of their positioning allowing to reach decimetric/centimetric accuracies. The use of sensors integrated in a mobile phone greatly simplify the survey both in terms of transportability but also in terms of authorizations by the competent authorities as the equipment is exactly the same that most tourists who visit the sites themselves bring with them. The approach proposed and made possible by these combined features in a latest generation mobile phone have been tested for a rapid survey of the Intihuatana stone in Machu Picchu (Peru), a site with considerable logistical and organizing complexity

Realizzazione di un sistema di geolocalizzazione web-based in ambiente open source mediante l’impiego dell’infrastruttura tecnologica della rete gsm-sms

Oggetto di questa tesi è stato la realizzazione di un sistema integrato che consente la localizzazione in tempo reale degli utenti ad un pubblico vasto come quello di internet, senza la necessità di utilizzare alcun software se non un semplice browser, ad un costo molto ridotto. Il principio di funzionamento è il seguente: un utente munito di un ricevitore GPS integrato con un modem GSM invia la propria posizione ad un server WEB attraverso la rete GSM mediante l’invio di un messaggio di testo (SMS) nel formato NMEA0183. Questa informazione viene inserita in un geodatabase consentendo al software di rendering cartografico l’interpretazione del dato ed il posizionamento corretto su di una cartografia di sfondo. Tutti coloro che sono abilitati (mediante una procedura di autenicazione) possono localizzare l’utente del sistema che ha inviato l’SMS collegandosi semplicemente ad un sito internet. Da questa breve descrizione si evince come l’architettura con la quale è stato progettato il sistema di geolocalizzazione riduca drasticamente i costi di gestione in quanto è sufficiente inviare un solo SMS per poter localizzare la posizione di un utente. Va sottolineato che tra gli obbiettivi che ci si è posti durante la realizzazione del sistema integrato non è presente sicuramente un elevata accuratezza posizionale. Infatti questo sistema è orientato ad un utilizzazione in real time, da parte di un numero elevato utenti, quindi una accuratezza posizionale 10 m è stata giudicata più che sufficiente

G.I.S. ed elettromagnetismo- integrazione dei dati elettromagnetico e satellitare all’interno di un Sistema Informativo Geografico

Abstract. Figures Domestic Violence (domestic violence) both in quantity and quality tends to increase, this could be caused by several things. First, public awareness of human rights has become part of people's lives. Second, because many institutions are quite concerned with the phenomenon of domestic violence so that they can report the numbers of the violence. During the handling of domestic violence is still limited to the victims of violence. Approach to counseling theories that are considered relevant to the case of domestic violence is feminist therapy Islam (Islamic feminist therapy). The concept is built on feminist theory wear integrated systems perspective with Islamic psychology, counseling intervention process means not only to individuals but individuals join the neighborhood to be treated to ensure the completion of the root of the problem is even a touch of spiritual and religious. Counselor ability to empower individuals / communities in the victim a skill that must be honed by a counselor who wears feminist therapy. This theory is based on the principle, namely; First, the personal is political; Second, egalitarian relationships, and third, the valuing perspective. The third concept of the pillars of feminist therapy and weighed with religion becomes an important indicator in determining the ability of the counselor to help assist victims of domestic violence