Columns and Editorials

Are Reflected Signals Always Undesirable?

Rightfully, the GNSS community almost universally considers reflected signals to be problematic (the field GNSS reflectometry being an obvious exception). Reflected or non-line-of-sight (NLOS) signals combine with line-of-sight (LOS) signals to produce multipath effects, or if the LOS signal is absent NLOS signals can produce large ranging biases. Both phenomena increase measurement error and decrease positioning accuracy, especially in areas with lots of reflecting surfaces such as deep urban canyons.

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By Mark Petovello
August 29, 2018

Ligado Fight Comes Down to Choice of Interference Standard

There was a flurry of filings July 9 just as the window closed for public comment on Ligado Networks’ proposal to repurpose satellite frequencies for a terrestrial network — a plan with the potential to interfere with GPS receivers.

The comments emerged as speculation swirled around a July 3 bid by EchoStar for Ligado spectrum supplier INMARSAT. The bid was rejected and, as of press time, EchoStar will have to wait six months before trying again.

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By Dee Ann Divis
June 15, 2018

GNSS IoT Positioning: From Conventional Sensors to a Cloud-Based Solution

The advent of the Internet of Things (IoT) has considerably increased the number of services and applications that require positioning information. In this sense, IoT positioning sensors usually obtain and deliver their position to a central node where it is further managed and analyzed by a user or scheduler. Nonetheless, the stringent requirements of low-cost IoT sensors in terms of low power consumption to achieve larger battery lifetime are pushing current technologies to their limits.

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By Inside GNSS
June 12, 2018

The Cospas-Sarsat MEOSAR System: A Solution to Support ICAO GADSS Autonomous Distress Tracking Recommendation

Today, it appears that the Cospas-Sarsat MEOSAR system, relying on payloads deployed on GNSS constellations (Galileo, GPS, GLONASS), offers all the conditions to meet the new recommendation of ICAO for ADT-system for Commercial Aviation, with a new generation of in-flight triggered beacons, identical to the current ELT in terms of aircraft integration, but capable of receiving triggers and cancellation events from the avionics, from the crew or from internal sensors, and of detecting and managing their inhibitions to maintain the capability to raise alerts and be localized in any situation.

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By Inside GNSS