GPS World - January 2008 - (Page 34)

Jayanta Ray | Group Manager | Accord Software and Systems Global SBAS ayanta Ray (JR) received his Ph.D. from the University of Calgary in 2000. He has worked in the GPS field since 1992, and is group manager at Accord Software and Systems in Bangalore, India. Alan Cameron: Tell us about Accord’s new GPS-SBAS (satellite-based augmentation systems) receiver. JR: The development of the aerospace GPS-SBAS receiver called NexNav is complete, and it was approved by the Federal Aviation Administration (FAA) on November 1. This receiver can be used in a civilian aircraft as a primary means of navigation during en-route, terminal, approach, and landing. This is the first and so far only certified aerospace GPS-SBAS receiver of its class conforming to the latest FAA standards. An aerospace GPS receiver is characterized by extreme reliability, high accuracy, and very good availability. Of these, reliability is the most important factor. That is achieved by creating a very reliable hardware and software. The hardware reliability has to be very good to the extent that misleading information is less probable than 10–7 during the approach, where the aircraft is very close to the runway; that is, about 200– 250 feet altitude from the runway. This is done through extensive failure mode and effect analysis, fault tree analysis of the hardware, and real-time hardware failure monitoring. To create very reliable software, the GPS receiver software and programmable logic device (PLD) software should should be developed conforming to FAA design assurance standards DO-178B and DO-254. This requires an enormous amount of effort and a large team of avionics experts. As we know, GPS guarantees a certain level of accuracy with say 95 percent probability. But there is no assurance J of accuracy for the remaining 5 percent of the time. With SBAS, the error is bounded to a great extent. An aerospace GPS receiver takes advantage of SBAS to provide error bounds up to 99.99999 percent confidence level during approach. The receiver should also provide the highest level of integrity when there is no SBAS, through a comprehensive fault detection and fault exclusion algorithm (FD/FDE). An aerospace receiver should be able to detect and exclude any satellite failure either through SBAS integrity monitoring or through autonomous FD/FDE within time-to-alert. These and many more requirements related to accuracy, integrity, and interference are specified in RTCA document DO-229D. The FAA gets involved in the development process life cycle right from the planning stage until completion. Throughout the process, the FAAdesignated engineering representatives monitor the program and ensure conformance to FAA development standards. In the case of Accord, we have two centers of excellence — one is the GPS and the other is the avionics software. Therefore it was synergistically appropriate for us to develop an aerospace GPSSBAS receiver. We took more than three years from planning to the completion of the FAA-certified GPS-SBAS receiver. AC: Does such a rigorous procedure mean the receiver is qualified for use elsewhere beside the United States? JR: All the FAA-approved standards for the aerospace GPS receiver are exactly the same for Europe. A GPS receiver approved by the FAA is generally accepted by the European Aviation Safety Agency (EASA). Currently our NexNav receiver is primarily for the U.S. general aviation market, for more than 200,000 aircraft. We already have an airframe and two avionics OEM manufactures as our customers. But it can also be used elsewhere. NexNav receiver is flying in Europe, Australia, and in New Zealand as well. AC: What about other products? JR: We have built GPS receivers for the last 15 years, primarily for the land transportation segment in Latin America, Southeast Asia, and parts of Europe. In this market we partnered with Analog Devices (ADI) of the United States. We have also developed a GPS L2C receiver prototype and were able to acquire and track the L2C signal within three days of the first IIR-M satellite beaming the L2C signal, December 16, 2005. This was published in the Innovation section of GPS World [May 2006]. We have also developed a 24-channel GPS/GLONASS receiver to support domestic market needs. On the indoor www.gpsworld.com 34 GPS World | January 2008 http://www.gpsworld.com

Table of Contents Feed for the Digital Edition of GPS World - January 2008

GPS - January 2008 Contents Out in Front Expert Advice The Money-Go-Round u-Nav Latest Acquisition Apples to Apples Global SBAS 2008 GPS Receiver Survey Advertisers Index & Company Directory The Manufacturer's Road Year of the Who Working Indoor Up and Down Good, Better, Best Marketplace Classifieds Seen + Heard

GPS World - January 2008

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