Global Positioning System Compass Research Articles

Soil gas radon concentration measurement in estimating the geogenic radon potential in Abeokuta, Southwest Nigeria

The soil gas in-situ radon-222 concentration was measured at 28 locations in Abeokuta, Nigeria using a RAD7 solid-state detector. The measurement sites were chosen based on the extent of the 6 geological formations chosen in a cell, with a spatial sample of at least 3 km between them. The measuring sites' geographical coordinates were established using the Global Positioning System compass. The hydraulic conductivity measuring technique was also used to determine the soil-air permeability for the soil samples collected at the various locations. The measured soil gas radon concentration and the soil-air permeability were used to estimate the geogenic radon potential. The soil gas radon activity ranged from (1004–19250) Bq/m3. The soil-air permeability ranged from (9.7 × 10−13 to 2.64 × 10−11) m2. The Geogenic Radon Potential ranged from 0.5 to 33 whereby 7.69% of the study area had a medium GRP value (10<GRP<35) while 92.31% had a low GRP value (GRP<10) as based on Classification of GRP according to Neznal. Therefore, the GRPs for Abeokuta are low compared with the level where remedial action is needed.

Assessing Error in Locations of Conspicuous Wildlife Using Handheld GPS Units and Location Offset Methods

ABSTRACTCollecting spatially explicit locations of individual animals often is an important part of the study of habitat use. Obtaining accurate locations without disturbing an individual can be difficult for small species and may be limited for species of conservation concern, such as piping plover (Charadrius melodus), where a close approach is undesirable because of the potential for disturbance. To reduce disturbance while estimating an animal's location, an observer can collect their location using Global Positioning System (GPS) and offset that position using a distance and azimuth. Typically, error is not considered when these locations are determined, despite the potential effects of inaccuracy on habitat association results. Therefore, our objectives were to quantify potential error using the offset method and then evaluate how that error may manifest. During the plover breeding season in 2017 (Apr through Sep), we tested the error of Trimble GPS units compared with benchmark locations to assess the accuracy of locations derived from these units. We then assessed the error associated with offset locations of a small target using Trimble GPS units, laser rangefinders, and 2 compass types. Finally, we determined the potential consequence of unaccounted error in our system by comparing the difference between point locations and land‐cover data using our estimated error as a point buffer. Average error of the GPS units at benchmark locations was 0.95 m. The mean error of the offset locations increased with increasing observer distance from the decoy location (from = 2.9 m to 7.6 m at distances of 20 m and 100 m, respectively). Error also increased with increasing error in the distance and azimuth measurements, and was greater using a digital GPS compass as compared with a handheld magnetic compass corrected for magnetic declination. In addition, potential misclassification of land‐cover type increased with increasing potential location error. When modeling animal locations, the error of point locations using this method, especially for land‐cover at the point location, should be accounted for using appropriately sized position buffers. Using this location collection method, we can increase our knowledge and study of conspicuous species to ensure that we consider habitats used throughout the species' life stages. © 2020 The Wildlife Society.

Development of an unmanned surface vehicle for autonomous navigation in a paddy field

The objective of this research was to develop an unmanned surface vehicle (USV) using global positioning system (GPS) compass for autonomous navigation in a paddy field. The surface vehicle used in the research was a radio-controlled air propeller vessel modified into an unmanned surface vehicle platform. The GPS compass was attached to the top of the USV platform as the navigation sensor to provide the position and heading angle. The USV platform can navigate automatically on predefined pathways. From the trajectory data of line-following navigation measured by a total station, the root mean square (RMS) lateral error from the target path was 0.25 m in a no-wind day. The ultimate goal of the research is to realize autonomous herbicide application and paddy growth monitoring based on the USV platform.

GPS compass: novel navigation equipment

A GPS (Global Positioning System)-based compass is designed, which consists of three parts: the pointer, the sensor, and the controller. Using the carrier phase signals from GPS satellites, the 1 m long pointer equipped with two GPS receivers can aim to the desired direction with accuracy less than one degree. A baseline rotation method is proposed to resolve the problem of integer ambiguities. The classical antenna swap method is simply a special case of the rotation method. The rotating character of the compass provides a convenient environment for applying the turning technique. Such a compass may replace the traditional heading devices in navigation systems, such as the magnetic compasses or gyroscopes.