Engineering advances, like precise and accurate personal positioning systems, are helping to enable a wide range of commercially and socially beneficial information services. In this context, location privacy (the right of individuals to control information about their personal location) can seem a peripheral or puzzling issue for many engineers. As one engineering colleague put it to me: “If you have nothing to hide, why should you be concerned about location privacy?” However, location privacy is increasingly becoming a vital function of any location-based service, and a function that presents spatial information engineers with interesting new challenges. Read the rest of this entry »

The May 2008 Innovation column describes carrier-phase sequential changes with the immediate benefit of integer cancellation; no need for ambiguity resolution.

In a nutshell, the column correctly notes usefulness of carrier phase sequential changes — but it describes 11 different “caveats” (a term used by those authors for problems/restrictions/limitations encountered in their operation). All 11 have been solved and are documented, with extensive validation by testing, as described in the material below. Read the rest of this entry »

At present, data from Global Navigation Satellite Systems (GNSS) such as GPS and GLONASS are being streamed over the Internet from receivers at base stations all over the globe. Anyone can receive many of these streams for free. While the quality and availability of the service at any given time is not always guaranteed, many streams have good data available most of the time. Whether their subscription is free or for a fee, the data streams can help a great diversity of users find their precise position in real time. Read the rest of this entry »

The limitations of GPS are well understood; urban canyons, tunnels, underground facilities, and dense foliage are but a few examples of GPS challenged environments in which a navigation solution is still desired. Providing a solution to the positioning problem during loss of satellite signal lock can be accomplished by utilizing additional forms of sensory data, such as Inertial Navigation Systems (INS), tachometers, odometers, or similar devices which monitor the motion characteristics of the mobile unit. Our current research attempts to utilize externally derived information to establish an ongoing navigation solution from an initial known point of reference. Read the rest of this entry »

Problems with existing GNSS systems can be addressed by the inclusion of additional ranging signals transmitted from ground-based “pseudo-satellites” (pseudolites). Pseudolites are an exciting technology that can be used for a wide range of positioning and navigation applications, either as a substantial augmentation tool of space-borne systems, or as an independent system for indoor positioning applications, or as a component to be integrated with inertial/vision sensors. Read the rest of this entry »

The GPS modernization program is now in full swing. The benefits of the program have already been seen with the launch of six Block IIR-M satellites transmitting the L2C signal and there is more to come. The next milestone will be the launch of Block IIR-M (20), also known as SVN49, which will carry with it a demonstration payload of the highly anticipated L5 signal. This addition to the GPS constellation will have a significant impact on the number of linear combinations which can be formed from carrier phase observations. Read the rest of this entry »

Outdoor localization services based on Global Navigation Satellite Systems (GNSS) have tremendously matured over the past decade and are widely available in a variety of applications. Current GNSS user performance is generally sufficient for most navigation and guidance applications in rural and suburban areas. In contrast, urban environments with a high density of tall buildings generally referred to as urban canyons still pose very challenging conditions for most GNSS receivers. Deep integration of the Global Positioning System (GPS) and inertial navigation system (INS) allows for processing of GPS signals at a very low signal-to-noise ratio (carrier-to-noise ratios as low as 12 dB-Hz). As a result, GPS signals can be potentially used for navigation even in dense urban environments where the signal propagation between satellites and the end user is often attenuated by buildings and other structures. Read the rest of this entry »

I cannot exactly remember whether I lost my faith in the navigation systems…in Van Wyck or Brooklyn/Queens Express highway? It was a hot summer day, and my friend just picked me up from the JFK airport; she had to get back to her teaching at City College, so, we were in a hurry. Needless to say, it was her first time at the JFK airport, so, we relied on her GPS navigator to take us to Manhattan. We effortlessly got on the Long Island Expressway, and almost passed the toll booth, but since we did not have enough change, we got booked by a cop. Passing a toll booth to enter Long Island Expressway seemed quite normal for the first time, but when we got back to the same toll booth for the second time, and got fined by the same cop, things became a bit surreal. Read the rest of this entry »

Machine guidance systems have been used for construction, mining and agriculture to improve productivity and safety in operating dozers, motor graders, excavators, scrapers, tractors and harvesters. To guide the machines, robotic total stations, GNSS RTK systems, and other sensors (laser systems, INS) have been used in 3D guidance systems. Among the system components, the RTK system takes a key role in providing positioning and navigation information. Read the rest of this entry »

You don’t get a second chance to make a first impression and when it comes to technology, that first chance is conveyed by the out-of-the-box experience, the industrial design of the device and then the user interface. Saying, “How do I turn this thing on?” and actually making the device spring to life can be independent and separate events interleaved with some fumbling and exploring. Once alive, the next challenge is figuring out how to navigate the on-screen menus and draw some level of correlation between physical buttons and a virtual screen world. Making a device work the way that the user intends is another giant step for mankind since there are potentially many concepts that the user needs to understand. Personal navigation devices have not escaped the first impression stakes. Read the rest of this entry »