GPS performance in navigation

Misra, P.; Burke, B.; Pratt, M.

doi:10.1109/5.736342

Cited by 69 publications

(45 citation statements)

References 20 publications

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“…However, the spatial distribution of the match-patches is also important and should be considered as well in assessing the quality of the coregistration. For this task, we adopt the concept of Dilution of Precision (DOP) from GPS, which can be obtained from the coefficient inversion in (1) [18]:…”

Section: Initial Coregistration and Quality Indexmentioning

confidence: 99%

“…For instance, if all the match-patches are located in a small area (i.e. a large DOP value [18]), then the mapping function coefficient estimation will likely be unreliable. Finally, using the cross-correlation results between images and the DOP, we define a quantitative measure to evaluate the quality of the coregistration, a Coregistration Quality Index (CQI), which we define as:…”

Section: Initial Coregistration and Quality Indexmentioning

confidence: 99%

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Improved SAR Image Coregistration Using Pixel-Offset Series

Wang

Jónsson

Hanssen

2014

IEEE Geosci. Remote Sensing Lett.

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Section: Initial Coregistration and Quality Indexmentioning

confidence: 99%

Section: Initial Coregistration and Quality Indexmentioning

confidence: 99%

Improved SAR Image Coregistration Using Pixel-Offset Series

Wang

Jónsson

Hanssen

2014

IEEE Geosci. Remote Sensing Lett.

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“…6 RGPS can be very similar to DGPS in many ways. The exception is that RGPS does not rely on a base receiver at a known location.…”

Section: Relative Guidancementioning

confidence: 99%

Precision SAR Targeting Using Stereoscopy and RGPS aboard a UAV

et al. 2002

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An emerging need for timely and precise poor weather targeting in support of long range weapons is identified. A conceptual system capable of all-weather imaging, target identification, target location, and precision guidance is described. This system is largely an integration of currently available technologies that can dramatically increase the accuracy of guided munitions that utilize the Global Positioning System (GPS). The central element of the system is a high-performance SAR that can quickly localize a target and take two 4-in. resolution spotlight images, within a large performance envelope. The two images are taken from the same aspect, with the single exception of a measured squint angle variance. This variance produces a distinct layover difference that can be exploited with stereoscopic (stereo) SAR algorithms to solve the range/height ambiguity and generate three-dimensional coordinate maps of a composite, orthorectified image of the target scene. These coordinates are subsequently relayed to a standard GPS-guided munition, modified to incorporate a datalink. A specially designed Relative GPS (RGPS) algorithm accounts for the separate navigation solution spaces of the sensor and the weapon and solves for GPS positions that maximize the commonality of the bias errors between the two platforms. Flight testing of the stereo SAR targeting and mock relative guidance show promising results.

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“…Generally, a minimum of 4 satellites are considered necessary to get a good position estimate (N Smin = 4) (Misra et al 1999). Accuracy is increased a little by having 5 or more satellites.…”

Section: Materials and Proceduresmentioning

confidence: 99%

“…Accuracy is increased a little by having 5 or more satellites. HDOP is a unitless measure of how well the positions of the satellites, used to generate the latitude and longitude solutions, are arranged, with lower values indicating a more favorable geometry (Langley 1999;Misra et al 1999). Good satellite geometry is obtained if the satellites are dispersed across the sky.…”

Section: Materials and Proceduresmentioning

confidence: 99%

Correcting for slow platform movement in deep‐water ADCP measurements

Pálmarsson

Steissberg

Schladow

2005

Limnology & Ocean Methods

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Water current measurements based on the Doppler principle have become a standard approach in aquatic sciences. An acoustic Doppler current profiler (ADCP) estimates the water velocity in a series of depth-integrated bins by measuring the Doppler shift in frequency between a transmitted pulse of high-frequency sound and the echo that is reflected from scatterers in the water. If the measurements are performed on a moving boat, then a measure of the boat velocity is needed so the measured ADCP velocity can be corrected by subtracting the boat movement. In waters that are shallow enough for the instrument to locate the bottom, the ADCP's "bottom-tracking" capability provides a good estimate of the boat velocity for the correction. However, in deeper water, navigational information is needed to correct for the boat movement. Shipmounted ADCPs, combined with accurate navigation systems such as the Global Positioning System (GPS), have been used successfully in the past for recording velocity transects (Joyce et al. 1982). The Differential Global Positioning System (DGPS) has provided accurate positioning for many oceanic expeditions (Pierce et al. 1999;Trump and Marmorino 1997). Oceanographic research vessels typically move at 10 kt (5 m s -1 ), and commercial ships of opportunity that are used for oceanographic measurements move at even greater speeds (20 to 30 kt). GPS accuracy is sufficient for many of these cruises, particularly when velocities are averaged over hundreds or even thousands of meters.When an ADCP is used on a near-stationary platform to measure relatively slow currents, navigation errors can significantly degrade the current data. Even if the platform were completely stationary, the collected GPS data would yield a non-zero "velocity" of the platform. A 24-h dockside test (a motionless platform) of a DGPS system showed that 5-minaveraged position data, clustered about their mean values with a standard deviation of 7.7 m, had apparent eastward and northward velocity standard deviations of 1. 55 AbstractWhen boat-mounted acoustic Doppler current profiler (ADCP) velocity measurements are taken in deep water where bottom-tracking capability no longer exists, navigational data via the Differential Global Positioning System (DGPS) are commonly collected to correct for the boat's contribution to the recorded ADCP velocity. The boat's cruise speed and the desired averaging interval for the water velocity are often great enough for navigational errors to become insignificant contributors to the uncertainty of the resulting water velocity. When the boat or other measurement platform is nearly stationary, navigational errors become significant and lead to an incorrect water velocity when navigational corrections are applied. Furthermore, when the water current is on the same order of magnitude as the slowly moving boat, the boat movement may not be easily distinguished from the fluid velocity. Factors that affect the quality of DGPS navigational estimates include the number of available satellites and thei...

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GPS performance in navigation

Cited by 69 publications

References 20 publications

Improved SAR Image Coregistration Using Pixel-Offset Series

Improved SAR Image Coregistration Using Pixel-Offset Series

Precision SAR Targeting Using Stereoscopy and RGPS aboard a UAV

Correcting for slow platform movement in deep‐water ADCP measurements

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