Technical Article Archives - Page 12 of 12 - Inside GNSS - Global Navigation Satellite Systems Engineering, Policy, and Design

October 25, 2010

Local Oscillator Phase Noise

FIGURE 1: Block-diagram of a GNSS direct-conversion receiver

For the complete story, including figures, graphs, and images, please download the PDF of the article, above.

GNSS systems rely on direct sequence spread spectrum (DSSS) transmissions to achieve high receiver sensitivity. Typically, GNSS user equipment compares the signal received from a satellite with an internally generated replica of its corresponding code until the maximum correlation for a given delay is achieved. This provides an indirect measurement of the satellite-receiver range.

By Inside GNSS

September 15, 2010

GNSS Simulation: A User’s Guide to the Galaxy

FIGURE 1: Screenshot of RF simulation software showing GPS + GLONASS + Galileo constellations

In the first article in this series (Inside GNSS, July/August, 2010) we looked at the range of tasks that require GNSS signal simulation during design, manufacturing, certification, and maintenance of GNSS equipment. The second installment (Inside GNSS, September, 2010) described a range of simulation solutions.

In this final article, we try to find a simulation solution that best suits a particular task.

By Inside GNSS

September 7, 2010

When GNSS Goes Blind

A completely GPS-based navigation solution is generally not feasible in GNSS signal–challenged environments such as urban canyons. However, even in these difficult environments a partial set of GPS signal measurements may still be available. For instance, one or two satellites are generally still visible even in dense urban canyons.

By Inside GNSS

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August 17, 2010

GPS IIF-1 Satellite

FIGURE 1: Geographical overview of the 170 IGS stations tracking SVN62/PRN25 during its current 90-day checkout period. The blue curve illustrates the ground track of the spacecraft on August 9, 2010.

For the complete story, including figures, graphs, and images, please download the PDF of the article, above.

On May 27, 2010, the U.S. Air Force successfully launched the first satellite of the Block II “follow-on” (Block IIF) series, the fourth generation of GPS spacecraft that features more precise and powerful signals, an extended design life, and several other technical advances.

By Inside GNSS

July 27, 2010

GNSS Simulators

FIGURE 1: GNSS multi-channel signal simulator 10 years ago on its own (left) and with its ever-growing family (right)

For the complete story, including figures, graphs, and images, please download the PDF of the article, above.

In this article we describe the design and operation of a generic GNSS RF simulator. We also will look at the main types of GNSS RF simulators, their designs and specifics, their advantages and disadvantages.

By Inside GNSS

Meet GINA

GINA On-Board Unit (OBU)

For at least the past two decades, managing traffic on Europe’s road networks has been a growing concern for European policy makers and citizens alike. While demand for transport has consistently increased over the years, Europe’s road network capacity has failed to keep pace, leading to increasing levels of congestion and pollution.

By Inside GNSS

June 22, 2010

Level Crossing Rate Estimation (LCRE)

For the complete story, including figures, graphs, and images, please download the PDF of the article, above.

Knowledge of carrier-to-noise ratio (CNR) can be of great value in the context of GNSS.

By Inside GNSS

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Testing Multi-GNSS Equipment

FIGURE 1: Single- and multi-channel simulators, GPS/Galileo (on top) and GPS/GLONASS software receiver USB front end with controlled power source

For the complete story, including figures, graphs, and images, please download the PDF of the article, above.

Testing procedures comprise an important element in the development, manufacturing, and integration of GNSS devices. Essentially, everybody involved in GNSS will be involved in or affected by testing at one time or another.

By Inside GNSS

GLONASS CDMA

For the complete story, including figures, graphs, and images, please download the PDF of the article, above.

The decades of successful exploitation of satellite navigation systems GPS and GLONASS have confirmed their unique status as a basic resource for reliable worldwide, all-weather, all-season, round-the-clock positioning and timing. Nevertheless, the permanently widening sphere of their practical applications — as well as challenging requirements emerging from potential new users — give these systems a momentum for further evolution and progress.

By Inside GNSS