NovAtel (Canada)

As the peak of solar cycle 25 approaches, increased ionospheric and scintillation activity is being observed, which is negatively impacting the quality of GNSS measurements and presenting challenges in the positioning domain. Ionospheric refraction and diffraction introduce delays and distortions to GNSS carrier phase measurements, leading to positioning errors that exceed the anticipated accuracies. These position errors can be a significant concern for users across the world who depend on precise GNSS positioning, such as in agriculture, offshore marine positioning and autonomous automotive positioning. To understand the direct impact on NovAtel receivers and its positioning engines, a comprehensive analysis was conducted. A closer look was taken at what happened in 2023–2024 by characterizing scintillation using the amplitude scintillation index (S4) values in an equatorial region. Additionally, the scintillation effect on the receivers was characterized through the analysis of C/N0, lock breaks, double differences and other indicators. With a substantial amount of data collected at 20° latitude, where high solar activity occurs due to the proximity to the equator, the positioning performance of Real-Time Kinematic (RTK) and Precise Point Positioning (PPP) was analyzed.

Given the plethora of advantages attributed to agile methodologies, why are there only infrequent reports of their application in the embedded systems world? We believe this has two principal causes. First, embedded applications go through a life cycle that differs from desktop life cycles, so that desktop application production processes must be significantly altered to meet the demands of this new domain. Second, without providing for full life-cycle tool support, no change to embedded production processes will ever succeed, and again desktop tools must be adapted to meet the new environment's constraints. Here, the authors discuss their thoughts on an XP-inspired embedded life cycle and their successes in developing, extending, and using embedded test-driven development frameworks for customers (Matlab-Fit and Embedded-FitNesse) and developers (MUnit and Embedded-Unit).

ABSTRACT: Precise Point Positioning (PPP) has received increased interest within the GPS community for a number of reasons: simplified field operation, cost-effectiveness, and no base station requirement. PPP with dual-frequency receivers and precise GPS products has demonstrated centimeter to decimeter positioning accuracy. Using real-time precise GPS products, this accuracy is also obtainable in a real-time mode. This paper investigates PPP using single-frequency GPS data which will be of interest to a broad range of applications because the majority of GPS users are using single-frequency GPS receivers. Since the ionospheric effect will be the biggest error source for single-frequency receiver based precise point positioning, different methods for ionospheric effect mitigation will be assessed and compared so that sub-meter positioning accuracy becomes obtainable.

NovAtel Inc. and KVH Industries have jointly developed a commercial grade, single enclosure GPS/INS system. The integrated KVH CG-5100 IMU features fiber-optic gyros and MEMs accelerometers, and provides inertial data at 100 Hz. NovAtelpsilas OEMV3 receiver is the GPS engine. Weighing 5.2 lbs, the combined system will feature the tightly coupled architecture that is a key characteristic of NovAtelpsilas SPAN (Synchronized Position Attitude Navigation) technology. The GPS receiver provides aiding information for the INS, and is reciprocally aided by feedback from the INS to improve signal tracking. The feedback from the INS to the GPS engine is the deeply coupled aspect of the system. It is also tightly coupled. GPS measurements are used to update the INS filter, providing high quality aiding information whenever there are least two satellites available. The combined system has an optional wheel sensor, which is used to further aid the INS during times of reduced GPS availability in land vehicle applications.

Two Wide Area Augmentation System (WAAS) satellites are now transmitting the standard L1 and L5 carriers and codes of the Global Positioning System (GPS), though with a five times higher data-bit rate. Since these are geostationary satellites, it is possible to aim a parabolic dish at one and obtain high-gain, low-multipath interference signals without interruption. Such high-gain dishes, along with appropriate GPS receivers, were set up at three timing laboratories in North America: the National Institute of Standards and Technology (NIST) in Boulder, Colorado, U.S.A., the United States Naval Observatory (USNO) in Washington D.C., U.S.A., and the National Research Council (NRC) in Ottawa, Ontario, Canada. We report the results of this experiment over a 104 d period: January 1 to April 14, 2008, though with several significant outages, and other clock/data problems.

Global Navigation Satellite Systems (GNSS) is a concept that relays accurate information of a position or location anywhere on the globe using a minimum of four satellites, a control station, and a user receiver. GNSS owes its origins to Rabi’s work in the early 1940s with the concept of an atomic clock (Nobel Museum, http://www.nobel.se/physics/laureates/1944/rabi-bio.html). In October 1940, the National Defense Research Council in the U.S. recommended implementing a new navigation system that combined radio signals with this new technology of time interval measurements. From this, MIT developed Long Range Radio Aid to Navigation (LORAN), which was refined by scientists at John Hopkins University and utilized during World War II through the late 1950s.

For pt.I see ibid. (1992). Statistical analyses of indoor radio propagation data are reported. The database includes 12000 impulse response profiles of the channel collected at two office buildings. Statistical properties of the number of multipath components for each profile are described. A Poisson fit to the arrival time data proved to be unsatisfactory. A modified Poisson model showed good fit to the data. Amplitudes were found to be lognormally distributed over both local and global areas, with a log-mean value that decreases almost linearly with increasing the excess-delay. There is a high degree of spatial correlations on path variables which has been quantified for the amplitude sequence.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Residual frequency offsets may often result in poor functioning of a digital receiver. This is particularly true in a frequency selective environment where an adaptive equalizer may be required. In this paper, a frequency offset estimation algorithm is presented which is based on applying a nonlinear operation on the received sampled baseband signal. Tones at multiples of the clock frequency are produced and the phases of these tones provide both the desired frequency offset and clock phase information. This algorithm is intended to operate without knowledge of the pulse shape and therefore may be suitable for frequency selective environments. Additionally, the clock phase may be estimated with very little overhead. Simulations with AWGN, flat and frequency selective fading channels are included. >

A computer simulation tool for evaluating the speech traffic handling capability of digital cordless telecommunications systems has been developed. The focus of the paper lies on the teletraffic engineering problems posed by time division multiple access (TDMA) systems operating with time division duplex (TDD) on one radio transceiver in radio environments. The impacts of fixed station separation, fixed station capacity, spatial traffic variability, dynamic channel assignment, microdiversity, and propagation model on the system capacity are investigated. The simulator serves as an invaluable tool for conducting sensitivity studies and its outputs provide useful insights on traffic performance of digital cordless systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>