Extracting Learning Performance Indicators from Digital Learning Environments

In the last decades, there has been a steady adoption of digital online platforms as learning environments applied to all levels of education. This increasing adoption forces a transition in educational resources which has further been accelerated by the recent pandemic, leading to an almost complete online-only learning environment in some...

High Data-Rate Inter-Satellite Link (ISL) For Space-Based Interferometry

The inter-satellite link (ISL) in swarm and constellation missions is a key enabler in the autonomy of the mission. OLFAR (Orbiting Low Frequency Array for Radio astronomy) is one such mission where 10 to 50+ nanosatellites are placed in the Lunar orbit and perform astronomical observations from the far-side of the moon. Each of the...

Low-frequency observations using high-altitude balloon experiments (LOBE)

The frequency range below 30 MHz remains one of the last unexplored frequency ranges in radio astronomy However, Earth-based observations at these wavelengths are severely impeded, due to man-made radio frequency interference (RFI) and atmospheric opacity. To overcome this impediment, various space-based radio astronomy studies have been...

Software-defined testbed for next generation navigation transponders

This paper presents a software-defined testbed to perform hardware-in-The-loop test of miniaturized coherent transponders. Such a setup has been designed to minimize the access threshold for future users, heavily relying on available open source applications and commercial hardware, targeting future coherent transponders for interplanetary...

Impact of wind farms on low-frequency radio astronomy observations with LOFAR

The LOw Frequency ARray (LOFAR} – developed by ASTRON, the Netherlands Institute for Radio Astronomy – is the world’s largest and most sensitive low-frequency radio telescope. It is a network of geographically distributed antenna stations, each containing hundreds of 'low-band’ (LBA} and 'high-band’ (HBA) dipole antennas. LOFAR stretches across...

Impact of wind farms on low-frequency radio astronomy observations with LOFAR.

The LOw Frequency ARray (LOFAR} – developed by ASTRON, the Netherlands Institute for Radio Astronomy – is the world’s largest and most sensitive low-frequency radio telescope. It is a network of geographically distributed antenna stations, each containing hundreds of 'low-band’ (LBA} and 'high-band’ (HBA) dipole antennas. LOFAR stretches across...

Beamforming in sparse, random, 3D array antennas with fluctuating element locations

The impact of the fluctuations in the locations of elementary radiators on the radiation properties of three-dimensional (3D) array antennas is studied. The principal radiation features (sidelobes level, beam squint) are examined based on illustrative examples. Some atypical behaviours, that are specific to 3D arrays, are highlighted. The effect...

Match filtering approach for signal acquisition in radio-pulsar navigation

Pulsars with their periodic pulses and known positions are ideal beacons for navigation. The challenge, however, is the detection of the very weak pulsar signals that are submerged in noise. Radio based approaches allow the use of advanced techniques and methods for the detection and acquisition of such weak signals. In this paper, an effective...

An extensive and autonomous deep space navigation system using radio pulsars

Interstellar navigation poses significant challenges in all aspects of a spacecraft. One of them is reliable, low-cost, real-time navigation, especially when there is a considerable distance between Earth and the spacecraft in question. In this paper, a complete system for navigation using pulsar radio emissions is described and analysed. The...

A novel astronomical application for formation flying small satellites

OLFAR, Orbiting Low Frequency Antennas for Radio Astronomy, will be a space mission to observe the universe frequencies below 30 MHz, as it was never done before with an orbiting telescope. Because of the ionospheric scintillations below 30 MHz and the opaqueness of the ionosphere below 15 MHz, a space mission is the only opportunity for this as...