Future Time

Existing GNSS systems use clocks based on microwave radio frequency (RF) standards operating at frequencies of up to 10¹⁰ Hz (10 GHz). This article examines the potential improvements and advantages of using clocks based on optical frequency standards, which have much higher natural frequencies of around 5 × 10¹⁴ Hz.

In general, high-precision clocks used to provide time in GNSS systems are based on three elements: a reference “frequency standard,” an oscillator, and a counter to count the oscillations.

Galileo Down to a Millimeter: Analyzing the GIOVE-A/B Double Difference

In December 2005 the first Galileo prototype satellite, GIOVE-A, was launched. Then, on April 26, 2008, a second satellite — GIOVE-B — was successfully put into orbit and soon began transmitting a variety of signals.

With two operational satellites in place, and having two receivers available, which can track both satellites’ signals at the same time (using omni-directional antennas), one can perform a Galileo-only double-difference calculation and analysis.

MBOC vs. BOC(1,1): Multipath Comparison Based on GIOVE-B Data

The GIOVE-B satellite — formally, the second Galileo In-Orbit Validation Element — was launched on April 27, 2008 and began transmission of ranging signals on May 07, 2008.

Unlike its predecessor GIOVE-A, GIOVE-B is meant to be a real prototype of future Galileo satellites: the signal generation and clocks are very close to what will be used by the fully operational capability (FOC) Galileo system.

GIOVE-B is transmitting all the foreseen Galileo signals in all frequency bands: L1BC, L1A, E5a, E5b, E6A, and E6BC.

The View from Chilbolton: In-Orbit Test Results from the Second Galileo Satellite

The second Galileo In-Orbit Validation Element satellite, GIOVE-B, was launched from the Baikonour cosmodrome in Kazakhstan on April 27, 2008.

Its main mission objectives are to maintain frequency filing, provide in‑orbit validation of the Galileo payload units, specifically the passive hydrogen maser (PHM) and solid‑state power amplifiers (SSPAs) that were not flown on GIOVE‑A, measure the middle earth orbit (MEO) radiation environment, and continue signal-in-space (SIS) experimentation.  

Europe Launches Full Galileo Procurement

The European Commission (EC) — with the support of the European Space Agency (ESA) — has launched the procurement process for Galileo with an invitation to companies to submit requests for participation as prime contractors for six work packages (WPs) valued at €2.145 billion (US$3.39 billion).

The deadline for replying to the invitation is August 7.

GIOVE-B Signal Observations Confirm MBOC's Multipath Advantage

Initial results from observations of the Galileo GIOVE-B satellite conducted by researchers at the European Space Agency (ESA) and Septentrio Satellite Navigation indicate that the multiplex binary offset carrier (MBOC) modulation outperforms the BOC(1,1) modulation on the L1 (data + pilot channels) frequency in mitigating the effects of multipath or reflected signals.

First GIOVE-A/B Double Difference Observed

Researchers at Delft University of Technology (TU Delft), the Netherlands, succeeded this week in simultaneously tracking the GIOVE-A and GIOVE-B L1 Open Service signals in space, producing the first reported computation of a double-difference carrier phase integer ambiguity resolution on the first two experimental Galileo satellites in orbit.

ESA Opens Galileo Procurement: Let the Games Begin!

Today (July 1), the European Commission (EC) — with the support of the European Space Agency (ESA) — launched the procurement process for Galileo with an invitation to companies to submit requests for participation as prime contractors for six work packages (WPs) valued at €2.145 billion (US$3.39 billion).

EC Issues ITT for a GNSS Advisor

The European Commission (EC) Directorate-General for Energy and Transport (DG-TREN) has issued an invitation to tender (ITT) for an advisor on the European GNSS program.

With a one-year term renewable up to three times, the contract will be designed to provide a pool of experts and organizations for review and counsel on administrative, financial, strategic and technical matters. The services are outlined in two “workpackages,” one for a fixed set of activities and the other for variable services performed according to specific work orders.

Air Force Tanker Controversy May Influence Galileo Competition

A U.S. Government Accountability Office (GAO) assessment that the U.S. Air Force made “significant errors” in awarding a $35 billion contract for refueling tankers to a consortium including the European Aeronautic Defense and Space Company (EADS) may affect the prospects of foreign participation in development of the Galileo system.