The economic impact on the UK of a disruption to GNSS

Like all modern economies, much of everyday life in the UK is reliant on Global Navigation Satellite Systems (GNSS). It is sometimes called the invisible utility.

GNSS provide signals from satellites orbiting in space to give us accurate information on positioning, navigation and timing. These systems have a large range of uses but, until now, the economic benefits haven’t always been well understood. It is not clear what the economic impact of a GNSS outage would be on the UK.

This report looks at what would happen to the UK economy if GNSS were unavailable for 5 days.

The Impact of quantum technologies on the EU’s future policies: Part 1 Quantum Time

Atomic clocks are a quantum technology, used in national metrology laboratories to define UTC and in various networked infrastructure. Developments in the clocks themselves, and in the distribution of precise time, can be expected to affect several application areas of importance to European policy.

Galileo navigation program: FOC

Spacecraft     Launch    Mission Status     Navigation Payload     Ground Segment    References

The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002.

Lexique GNSS

Ce lexique couvre le domaine du positionnement par GNSS, en langue française. Il devrait permettre de se repérer dans le jargon des GNSS et non d’acquérir une  connaissance approfondie des GNSS. Pour cela le Groupe de travail conseille au lecteur de se référer entre autres au site mis en ligne par l’ESA.

Monitoring the ionosphere altitude variation with a sound card

DCF-77 is a German very low frequency (VLF) emitter locked on the Cs clocks of PTB used for synchronizing radiofrequency-disciplined clocks found, for example, in low-cost weather stations. VLF signals propagate through the waveguide whose boundary conditions are defined on the one hand by ground, and on the other hand by the ionosphere (charged) layer altitude. In addition to the amplitude modulation of the Cs-locked DCF-77 frequency standard, a phase modulation is imprinted on the carrier for time of flight measurement, allowing for « precise » time of flight measurements.

Video avalable at:

The power of cross-correlating: from GPS reception to passive RADAR using SDR

CDMA systems rely on encoding data streams radiated by multiple emitters on the same carrier frequency with (ideally) orthogonal codes. Recovering the signal from each emitter requires identifying the code assiociated with each source, which hence also requires recovering the carrier to account for relative emitter/receiver motion (Doppler shift), thermal drift and oscillator bias. We demonstrate this concept with the reception of GPS signal — a constellation of satellites orbiting 20000 km over the surface of the earth — with 20 euro worth of equipment centered on a DVB-T receiver designed for receiving neighbouring television signals. We extend the concept to passive radar, in which a radiofrequency emitter (television, broadcast radio) signal reflected on a mobile target is used for identifying the velocity and position of the target. In this approach, no active source is needed: RADAR measurement is only a matter of correlating the direct and reflected signal, after identifying the Doppler induced frequency shift.

Slides + Video available at

VIM : Vocabulaire international de métrologie

Le VIM donne un ensemble de définitions et des termes associés pour les concepts fondamentaux et généraux utilisés en métrologie, ainsi que des schémas conceptuels illustrant leurs relations. Pour un grand nombre de définitions, des informations complémentaires sont données sous forme d’exemples et de notes.

Le VIM se propose d’être une référence commune pour les scientifiques, les ingénieurs, les enseignants et praticiens impliqués dans des problématiques liées à la métrologie, quels que soient le domaine d’application et le niveau d’incertitude de mesure. Il se propose aussi d’être une référence pour les organismes gouvernementaux et intergouvernementaux, les associations commerciales, les comités d’accréditation, les régulateurs et les associations professionnelles.

⇒ Informations sur le VIM, téléchargement du document, de ses annexes et des mises à jour sur le site du BIPM :