Aiden Morrison

Collaborative navigation for defense objectives

This paper describes the design and testing of a system implementing SINTEFs patent pending collaborative navigation technology, as applied to a building entry and search operation.

Design of a Multiband Global Navigation Satellite System Radio Frequency Interference Monitoring Front-End with Synchronized Secondary Sensors

This paper investigates the challenges of developing a multi-frequency radio frequency interference (RFI) monitoring and characterization system that is optimized for ease of deployment and operation as well as low per unit cost. To achieve this, we explore the design and development of a multiband global navigation satellite system (GNSS) front-end which is intrinsically capable of synchronizing side channel information from non-RF sensors, such as inertial measurement units and integrated power meters, to allow the simultaneous production of substantial amounts of sampled spectrum while also allowing low-cost, real-time monitoring and logging of detected RFI events. While the inertial measurement unit and barometer are not used in the RFI investigation discussed, the design features that provide for their precise synchronization with the RF sample stream are presented as design elements worth consideration. The designed system, referred to as Four Independent Tuners with Data-packing (FITWD), was utilized in a data collection campaign over multiple European and Scandinavian countries in support of the determination of the relative occurrence rates of L1/E1 and L5/E5a interference events and intensities where it proved itself a successful alternative to larger and more expensive commercial solutions. The dual conclusions reached were that it was possible to develop a compact low-cost, multi-channel radio frequency (RF) front-end that implicitly supported external data source synchronization, and that such monitoring systems or similar capabilities integrated within receivers are likely to be needed in the future due to the increasing occurrence rates of GNSS RFI events.

Phase scintillation decorrelation impact on multi-frequency users

This paper discusses the phase scintillation decorrelation as observed between dual and triple frequency civil GNSS signals. Comparisons are made between the characteristics of data collected in Norway during events of strong and persistent phase activity versus data collected in Hanoi during periods of vigorous amplitude and phase scintillation. Under both types of scintillation activity a degree of decorrelation is observed between the multiple carriers which is not attributable to nominal ionospheric behavior, and in turn the assumption that the ionosphere-free combination is for all intents and purposes free of the influence of the ionosphere is violated.

Collaborative indoor navigation for emergency services personnel

First responders and other emergency services personnel must often enter buildings which prevent the use of GPS or other satellite navigation signals for positioning. Loss of navigation capability combined with the fact that the buildings are often unknown to the personnel in question makes it more difficult for individual team members to coordinate with one another, and difficult or impossible for the team leader to monitor and direct the actions of each team member. While inertial navigation or pedestrian dead reckoning provide for some degree of navigation in GPS signal denied environments, these solutions degrade with time and may require prohibitively large and expensive inertial solutions to navigate over extended periods, while also allowing each individual user to accumulate independent positioning errors and thereby appearing to ‘drift away’ from one another. This paper presents an implementation of a collaborative navigation system utilizing each of user-to-user radio links, Global Navigation Satellite Systems (GNSS) when available, inertial navigation, pedestrian dead reckoning, as well as camera based Simultaneous Location and Mapping (SLAM) to provide a team of users with absolute and relative situational awareness for themselves and their team. The application of collaborative navigation to such a team provides the triple benefits of providing improved absolute navigation accuracy, improved relative navigation accuracy, and greatly enhanced situational awareness for all cooperating team members.

On the cleansing and inspection of GPS ephemeris data 2000–2016

Archived GPS ephemeris data for years 2000–2016 is investigated by cleansing and precision measures. The goal of this work was twofold: (1) to reveal and remove incorrect ephemeris data so that the cleansed data is as close to the real broadcasted data as possible, and (2) to analyse the quality of the cleansed data by comparing ephemeris based satellite locations to true locations. Our findings show that, besides obvious duplicates, many erroneous data epochs were also detected by monitoring the slowly changing I0 and Ω0 parameters. The cleansed data shows small deviation precision errors steadily decay in the 2000– 2016 period, as expected. Also the number of large errors show a decaying nature. Many large errors occur frequently in first operation period of new satellite vehicles, especially the new Block IIF, but these happened also to show in time epochs close to periods flagged as unhealthy. Further, it is shown that ephemeris data performance is independent on Toe parameter being modulo 100 or not.