The Department of Transportation is seeking comments on a draft test plan for developing interference tolerance masks for GPS receivers in the 1559-1610 megahertz band. Comments are due Oct. 9 in docket DOT-OST-2015-0099. “The objective of this test is to collect data to determine Interference Tolerance Masks (ITM) for categories of GPS and GNSS receivers processing signals in the 1559-1610 MHz Radionavigation Satellite Service (RNSS) frequency band, as well as receivers that process Mobile Satellite Service (MSS) signals to receive differential corrections,” said the 14-page draft plan.
“DOT is neither developing standards for GPS receivers, nor is it developing standards for transmitters operating in the adjacent radiofrequency bands. These ITMs will be used to assess the adjacent band interference power levels that can be tolerated by GNSS receivers processing desired signals in the RNSS band. This document outlines the requirements, the overall test plan, and the associated output data needed to successfully perform this component of the GPS Adjacent Band Compatibility assessment. This document is not intended to provide the detailed test procedure currently being developed by the DOT team.”
“The first phase of this study will focus on existing GPS/GNSS receivers that are currently fielded,” according to the document. “Seven categories of receivers will be included in this testing: aviation (non-certified), cellular, general location/navigation, high precision, timing, networks, and space-based receivers. While the primary focus of this phase of the effort is on GPS receivers, it is recognized that there are fielded multi-GNSS receivers and they will also be included in this first phase of testing. “Each receiver should be accompanied by use cases defining its regions of operation (dense urban, urban, suburban, and/or rural),” the draft test plan added. ”
The use cases also will identify applications that are vital to economic, public safety, scientific, and/or national security needs and any other factors supporting why this particular receiver model is important to be tested (e.g., quantity in use, economic impact, etc.). The information required for the development of ITMs for GNSS receivers operating in the 1559 – 1610 MHz band will be requested in conjunction with a Non-Disclosure Agreement (NDA).”
LightSquared today criticized the draft test plan. “As the government faces a shutdown due to limited funds, DOT continues to waste scarce taxpayer dollars by proposing work that will not produce any information of value to the FCC,” said LightSquared spokeswoman Ashley Durmer. “Instead of developing a plan to enable technological advancement and spur spectrum innovation, the DOT is proposing to set limits on spectrum use by promoting the continued use of outdated filter technology in receivers. ”
It has taken DOT almost four years to propose a vague study that is absent procedures or timelines and will not answer the critical question of whether wireless broadband would cause any actual harm to the accuracy of GPS devices. In contrast, Roberson & Associates is investigating that critical data and analysis now,” Ms. Durmer added. LightSquared has hired Roberson & Associates, an engineering consulting firm, to explore compatibility between terrestrial broadband and GPS operations. In response to the release of the DoT draft test plan, the GPS Innovation Alliance said, “We are reviewing the test plan and look forward to working with the DOT and interested parties to drive a consensus around compatible uses of the spectrum adjacent to GPS.”- Paul Kirby, paul.kirby@wolterskluwer.com
Courtesy TR Daily