Proposed Ligado Wireless Network a Concern for High Precision Positioning Applications
NovAtel raises concerns about testing provided by Ligado to US Federal Communications Commission (FCC)
In its filing, NovAtel identified serious flaws in the testing methodology used to evaluate high precision receivers. Although high-precision receivers were used during the testing, the high-precision position modes that are used to achieve centimetre-level positioning accuracy required by many professional and safety-critical applications were not evaluated. The study shows a lack of understanding of the uses of the Global Positioning System (GPS) by assuming that all applications require the same positioning accuracy.
The filing also raises a number of concerns about the potential harmful interference impact on GPS receiver performance. NovAtel is particularly concerned that Ligado has moved away from what it understood to be an agreed upon standard that interference tolerance should be limited to a received interference signal power level that causes no more than 1-dB degradation in the received C/No level. NovAtel disagrees with the conclusion in the RAA Study that there is no meaningful correlation between a 1-dB change and GPS performance. NovAtel submits any interference must not exceed 1-dB degradation in received C/No if robust, precise positioning is to be maintained. Ligado has not yet proven that its use of the spectrum will not be detrimental to high-precision users of the Global Navigation Satellite System (GNSS), which is what the 1-dB C/No degradation metric ensures.
To date, Ligado has not proven that its use of the proposed spectrum can be made compatible with high-precision GNSS. The interference impact on the other GNSS constellations such as Galileo, GLONASS and Beidou has not been addressed. These constellations are increasingly used in combination with GPS for many high-precision applications. Proposed, unverified mitigation methods such as narrowband antennas are presented in the Ligado filing without explanation of who will be responsible for the cost of such design modifications and retrofit programs.
To view NovAtel’s FCC filing in its entirety, please visit the FCC website at: www.fcc.gov
About NovAtel Inc.
NovAtel designs, manufactures and sells high precision OEM positioning technology. Developed for efficient and rapid integration, our products have set the standard in quality and performance for over 20 years. State-of-the-art, lean manufacturing facilities in our North American headquarters produce the industry’s most extensive line of OEM receivers, antennas and subsystems. All of our products are backed by a team of highly skilled customer support and design engineers.
NovAtel Inc. is part of Hexagon (Nasdaq Stockholm: HEXA B; hexagon.com), a leading global provider of information technologies that drive quality and productivity across geospatial and industrial enterprise applications.
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Posted on 20/05/2016