Global Positioning System Instruments Research Articles

Development of a GIS based tourism infrastructure in Awka, Onitsha and Nnewi urban areas of Anambra state Nigeria

Tourism is now the greener pastures most developing countries have focused attention to due to its enormous benefits like infrastructural development, job creation, conservation of environment etc. In Nigeria, it is an important sector that has not fully developed, though; it is one of the country’s fastest growing industries. Recently, it is contributing about 3% of Nigeria GDP. Tourism is a strong revenue earner; lack of proper management of same has denied Nigeria the benefits accrued from the sector. This research is therefore aimed at the Development of a GIS-Based Tourism Infrastructure in Awka, Onitsha and Nnewi in Anambra State, with the specific objectives of; developing a comprehensive GIS database map showing tourism locations in these cities, to ascertain the pattern of distribution of the tourism infrastructure in Anambra State. This was achieved through the acquisition of base map of the study area and point picking of geometric data of tourism facilities using a handheld Global Positioning System instrument. A functional user friendly spatial database on tourism facilities was developed. ArcGIS 10.7 was used for Geospatial database creation, querying and displaying of results, while Microsoft word 2010 was used for data processing and preparation of reports. The results of database queries showed the locations of tourist locations like, hotel accommodations, relaxation and eating spots, banks and major landmarks all located within Anambra State. In conclusion this research presented the significant role that GIS can play in tourism development in Anambra State, if a complete database for tourism in the state is designed and developed.

ANALISIS PERBANDINGAN KETELITIAN PENGUKURAN KERANGKA KONTROL HORISONTAL ORDE – 4 DENGAN GPS LOWCOST

A point positioning activity can be referred to as mapping. In mapping activities there is the term control framework point. One of the classification of control points is the horizontal control point. In mapping activities there is a minimum order of control points that can be used, that was horizontal control points order-4. The measurement of horizontal control points order-4 can be done by conventional survey methods using terrestrial method or using global positioning system technology. The development of global positioning system (GPS) technology has progressed very fast. One of the evidence of the development of GPS technology is where introduced of various instruments that exist today. Lowcost GPS is one type of GPS that has advantages in terms of more lower prices. The application of lowcost gps is expected to help in mapping activities. In this reserch, a feasibility analysis of lowcost GPS OEM Board K-708 and GPS Tersus BX-316as instruments in the measurement of horizontal control frame order-4 when compared with Geodetic GPS instruments. The analysis used in this study is standard deviation analysis and hypothesis testing using T-test. From the results of analysis conducted resulted in the accuracy of the instrument shown from the value of standard deviation that reached sub "cm", where the instrument GPS OEM Board K-708 has better standard deviation than GPS Tersus BX-316. From the results of hypothesis testing using T-Test showed no significant difference from each of the data, so it can be concluded that the instruments in this reserch are worthy of the use in the measurement of horizontal control framework order-4. Keywords: GPS Lowcost, Jaring Kontrol Horizontal Orde-4, Standar Deviasi, Uji-T

Cost-Effective, Single-Frequency GPS Network as a Tool for Landslide Monitoring.

The constant monitoring of active landslides, particularly those located in the proximity of populated areas or touristic places, is crucial for early warning and risk-management purposes. The commonly used techniques deploy expensive instrumentation that can be hardly afforded, especially by small mountain communities in which landslide events often occur repeatedly. In recent years, the scientific community, as well as the private sector, have devoted growing effort to reducing the costs of monitoring systems. In this work, we present a monitoring network based on single-frequency Global Positioning System (GPS) sensors that have been activated to monitor an active landslide in the Carnic Alps, North-Eastern Italy. The system, which was composed of 12 single-frequency GPS stations, one seismometric station coupled with a single-frequency GPS instrument for real-time monitoring, and one permanent dual-frequency GPS station located in a stable area, provided daily reports of the landslide motion to the local authorities and administration. We show that this system is a valuable, flexible, and cost-effective tool for quick landslide characterization, and has high potential to be used as a landslide early warning system in case of emergency situations.

Appraisal of Land use Survey using Total Station and Handheld GPS

A handheld GPS (Global Positioning System) is a device that uses to conduct a survey with less manpower and less time. Mostly total station is used in land use survey with higher accuracy. Hence this study is going to verify the capability of the handheld GPS to replace instead of the Total Station in land use survey. The aim of the study was to evaluate the land use survey results with handheld GPS and total station. GPS (Leica GS 15) instrument was fixed at a Base station named NSG 01 and data collection was done using handheld GPS (Leica Zeno 20) instrument with different modes such as Satellite-Based Augmentation System (SBAS) off and SBAS on. Further the collected data were processed with the Differential GPS (DGPS) and without DGPS approaches using Leica infinity and QGIS software and four plans were prepared. Then the area was calculated for each land use category. Results were compared using the error percentages each land use. Further it was compared using correlation analysis. Finally, the most accurate results were given by the handheld GPS in SBAS on mode. Its error level was 0.46% and it is very low compare with other modes. SBAS on mode Correlation Coefficient was 0.99995 and it was the closest value to 1. So, the SBAS on mode is the best method to improve the accuracy of land use surveys where there is scarcity of manpower and time instead of total station.

MICRO AND SECONDARY NUTRIENT STATUS OF GEOREFERENCED SOILS OF BHADRAK, ANGUL, SONEPUR AND DHENKANAL DISTRICTS OF ODISHA

Soil fertility maps of Dhenkanal, Sonpur, Bhadrak and Angul district of Odisha were prepared by using Global positioning system (GPS) and Geographical Information system (GIS) .soils of each blocks (total 29 blocks) of above districts were collected by Gramin 76 MAPCS x MAKE GPS instruments. Total number of soil samples were collected was 1024 and 124 plant samples. The soil and plant samples were processed and analysed in the laboratory using standard methods. The data were entered in attributed table and linked with GIS software to develop a rational data base. The analogue soil fertility map was georeferenced and digitized by using ArcGIS software. Thematic layers were developed for block boundaries to prepare base map. Superimposing polygons (spatial coverage) of block unit and base map, soil fertility maps for secondary and micronutrient were prepared. Base on fertility maps, the status of organic carbon, DTPA-extractable Fe, Mn, Zn, Cu and Hot water soluble Boron and secondary nutrient like Sulphur were assessed for suitability of crops. The overall conclusion was that these four districts of Odisha were deficient in Sulphur, Zinc and Boron in soil as well as plants whereas Fe, Mn and Cu in soil were found abundant. However, Cu in soil was an emerging issue now-adays and should take care of. It is advocated that the need for fertilization with Sulphur, Zinc and Boron fertilizer to enhance better crop growth and productivity.

The Use of SMAP-Reflectometry in Science Applications: Calibration and Capabilities

The Soil Moisture Active Passive (SMAP) mission became one of the newest spaceborne Global Navigation Satellite System–Reflectometry (GNSS-R) missions collecting Global Positioning System (GPS) bistatic radar measurements when the band-pass center frequency of its radar receiver was switched to the GPS L2C band. SMAP-Reflectometry (SMAP-R) brings a set of unique capabilities, such as polarimetry and improved spatial resolution, that allow for the exploration of scientific applications that other GNSS-R missions cannot address. In order to leverage SMAP-R for scientific applications, a calibration must be performed to account for the characteristics of the SMAP radar receiver and each GPS transmitter. In this study, we analyze the unique characteristics of SMAP-R, as compared to other GNSS-R missions, and present a calibration method for the SMAP-R signals that enables the standardized use of these signals by the scientific community. There are two key calibration parameters that need to be corrected: The first is the GPS transmitted power and GPS antenna gain at the incidence angle of the measured reflections and the second is the convolution of the SMAP high gain antenna pattern and the glistening zone (Earth surface area from where GPS signals scatter). To account for the GPS transmitter variability, GPS instrument properties—transmitted power and antenna gain—are collocated with information collected from the CYclone Global Navigation Satellite System (CYGNSS) at SMAP’s range of incidence angles (37.3° to 42.7°). To account for the convolutional effect of the SMAP antenna gain, both the scattering area of the reflected GPS signal and the SMAP antenna footprint are mapped on the surface. We account for the size of the scattering area corresponding to each delay and Doppler bin of the SMAP-R measurements based off the SMAP antenna pattern, and normalize according to the size of a measurement representative to one obtained with an omnidirectional antenna. We have validated these calibration methods through an analysis of the coherency of the reflected signal over an extensive area of old sea ice having constant surface characteristics over a period of 3 months. By selecting a vicarious scattering surface with high coherency, we eliminated scene variability and complexity in order to avoid scene dependent aliases in the calibration. The calibration method reduced the dependence on the GPS transmitter power and gain from ~1.08 dB/dB to a residual error of about −0.2 dB/dB. Results also showed that the calibration method eliminates the effect of the high gain antenna filtering effect, thus reducing errors as high as 10 dB on angles furthest from SMAP’s constant 40° incidence angle.

Unanticipated Uses of the Global Positioning System

Global Positioning System (GPS) instruments are routinely used today to measure crustal deformation signals from tectonic plate motions, faulting, and glacial isostatic adjustment. In parallel with the expansion of GPS networks around the world, several new and unexpected applications of GPS have been developed. For example, GPS instruments are now being used routinely to measure ground motions during large earthquakes. Access to real-time GPS data streams has led to the development of better hazard warnings for tsunamis, flash floods, earthquakes, and volcanic eruptions. Terrestrial water storage changes can be derived from GPS vertical coordinate time series. Finally, GPS signals that reflect on the surfaces below a GPS antenna can be used to measure soil moisture, snow accumulation, vegetation water content, and water levels. In the future, combining GPS with the signals from the Russian, European, and Chinese navigation constellations will significantly enhance these applications. ▪ GPS data are now routinely used to study the dynamics of earthquake rupture. ▪ GPS instruments are an integral part of warning systems for earth- quakes, tsunamis, flash floods, and volcanic eruptions. ▪ Reflected GPS signals provide a new source of soil moisture, snow depth, vegetation water content, and tide gauge data. ▪ GPS networks can sense changes in soil moisture, groundwater, and snow depth and thus can contribute to water resource assessments.

Mapping of livestock movement routes in Afambo and Teru districts of Afar National Regional State Ethiopia

The study aimed to produce a map for livestock movement routes in Teru and Afambo district in Afar region, Ethiopia. The specific objectives of the study were identifying the major reasons of livestock movement, investigating challenges faced during the movement and producing livestock movement route maps. The primary data were mainly collected through key informant interviews, focus group discussion and Global Positioning System instrument. Stratified and purposive sampling techniques were used to select the study area and key informants respectively. Narration and ArcGIS software were used to analyze the data. The result showed that finding grazing land, market center and salty water are the three main purposes of livestock movement. The pastoralists face several challenges during their movement that affect their livestock lives and themselves. In order to reduce the effect of these challenges infrastructures should be built on the main routes of the movement based on the produced maps.

Improving Paddy Rice Statistics Using Area Sampling Frame Technique

Traditional sampling strategies for paddy rice statistics rely on outdated list frames, incomplete holding information, or administrative data that are prone to numerous biases. The objective of this study is to test the utility of an area frame developed using remote sensing data in three pilot provinces—Savannakhet (Lao People’s Democratic Republic), Ang Thong (Thailand), and Thai Binh (Viet Nam). Direct estimates of total paddy rice area and production are calculated from area frame using two methods––one involving measurement of plot size using a Global Positioning System instrument and the other utilizing a digitized map of farmer-identified plot boundaries on a high-resolution Google Earth image. A third method involving the calculation of ratio estimates using independent mesh-level measures is compared with the first two methods involving direct estimates, and with the estimates generated from administrative data from the countries. Our study finds that ratio estimation significantly improves the level of precision of paddy rice statistics. Substantial deviations are also observed between official statistics and the statistics generated through direct estimation.

The dog and cat population on Maio Island, Cape Verde: characterisation and prediction based on household survey and remotely sensed imagery.

The objective was to estimate and characterise the dog and cat population on Maio Island, Cape Verde. Remotely sensed imagery was used to document the number of houses across the island and a household survey was carried out in six administrative areas recording the location of each animal using a global positioning system instrument. Linear statistical models were applied to predict the dog and cat populations based on the number of houses found and according to various levels of data aggregation. In the surveyed localities, a total of 457 dogs and 306 cats were found. The majority of animals had owners and only a few had free access to outdoor activities. The estimated population size was 531 dogs [95% confidence interval (CI): 453-609] and 354 cats (95% CI: 275-431). Stray animals were not a concern on the island in contrast to the rest of the country.

Comparison of total water vapor column from GOME-2 on MetOp-A against ground-based GPS measurements at the Iberian Peninsula

Water vapor column (WVC) obtained by GOME-2 instrument (GDP-4.6 version) onboard MetOp-A satellite platform is compared against reference WVC values derived from GPS (Global Positioning System) instruments from 2007 to 2012 at 21 places located at Iberian Peninsula. The accuracy and precision of GOME-2 to estimate the WVC is studied for different Iberian Peninsula zones using the mean (MBE) and the standard deviation (SD) of the GOME-2 and GPS differences. A direct comparison of all available data shows an overestimation of GOME-2 compared to GPS with a MBE of 0.7mm (10%) and a precision quantified by a SD equals to 4.4mm (31%). South-Western zone presents the highest overestimation with a MBE of 1.9mm (17%), while Continental zone shows the lowest SD absolute value (3.3mm) due mainly to the low WVC values reached at this zone. The influence of solar zenith angle (SZA), cloud fraction (CF), and the type of surface and its albedo on the differences between GOME-2 and GPS is analyzed in detail. MBE and SD increase when SZA increases, but MBE decreases (taking negative values) when CF increases and SD shows no significant dependence on CF. Under cloud-free conditions, the differences between WVC from GOME-2 and GPS are within the WVC error given by GOME-2. The changes of MBE and SD on Surface Albedo are not so evident, but MBE slightly decreases when the Surface Albedo increases. WVC from GOME-2 is, in general, more precise for land than for sea pixels.

Short Baseline Calibration using GPS and EDM Observations

We conducted a baseline comparison for instrument calibration using GPS (Global Positioning System) and EDM (Electronic Distance Measurement) observations. The experiment was carried out at campus of the Autonomous University of Sinaloa (UAS) in Culiacan, Mexico. The main objective of this research was to establish a short (∼125 m) baseline for calibration of geodetic-grade GPS and EDM instruments of different commercial brands to validate the precision specifications offered by the manufacturers of such instruments. We compared three types of geodetic-grade GPS receivers: Topcon Hiper Lite +, Ashtech Z-Xtreme and Leica SR500 and three types of EDM: Topcon GTS-236W, Pentax R-326EX and Leica TC-407. For the experiment, the baseline components were computed by using ionosphere-free double-difference (DD) GPS carrier phase observations processed using the PAGES software (Program for the Adjustment of GPS EphemerideS). The GPS data were processed with a 1-second sampling rate, 10-degree cutoff angle, and precise GPS orbits disseminated by IGS (International GNSS Service). The length of the calibration baseline was also obtained by averaging 20 measurements of line length directly recorded by the three different EDM instruments. GPS results agree among different brands with differences of ±2mm in contrast with the resulting EDM values that differ within ±3mm.

Intercomparison of total precipitable water measurements made by satellite‐borne microwave radiometers and ground‐based GPS instruments

AbstractHigh‐quality, high temporal resolution measurements of total precipitable water (TPW) can be made by evaluating the vapor‐dependent delay of radio signals reaching land‐based Global Positioning System (GPS) receivers from GPS satellites. These measurements are available since the mid‐1990s when the GPS system became operational. Over the world's oceans, satellite‐borne microwave imaging radiometers have been making measurements of TPW for more than 25 years. In this work, we perform an intercomparison of collocated TPW measurements made by these two disparate systems using measurements from 26 GPS stations located on small islands. The two types of measurements agree well, with typical satellite‐station mean differences of less than 1.0 kg m−2. Analysis revealed several cases of inhomogeneities in the GPS data set, and two deficiencies in the Remote Sensing Systems satellite data, demonstrating the usefulness of intercomparison for improving the accuracy of both types of data. After the individual station, biases were removed, the standard deviation of the overall differences between individual satellites and GPS measurements ranged between 1.60 and 1.94 kg m−2. Twelve GPS stations had overlap time periods long enough to evaluate difference trends, yielding 59 satellite‐station pairs when paired with different satellites. More than half of the pairs (39 of 59) did not show a significant trend. The 20 pairs with significant trends did not show trends of predominantly one sign, suggesting that neither system is plagued by a system‐wide drift in TPW.

Climate‐driven vertical acceleration of Icelandic crust measured by continuous GPS geodesy

AbstractEarth's present‐day response to enhanced glacial melting resulting from climate change can be measured using Global Positioning System (GPS) technology. We present data from 62 continuously operating GPS instruments in Iceland. Statistically significant upward velocity and accelerations are recorded at 27 GPS stations, predominantly located in the Central Highlands region of Iceland, where present‐day thinning of the Iceland ice caps results in velocities of more than 30 mm/yr and uplift accelerations of 1–2 mm/yr2. We use our acceleration estimates to back calculate to a time of zero velocity, which coincides with the initiation of ice loss in Iceland from ice mass balance calculations and Arctic warming trends. We show, through a simple inversion, a direct relationship between ice mass balance measurements and vertical position and show that accelerated unloading is required to reproduce uplift observations for a simple elastic layer over viscoelastic half‐space model.

InSAR observations of post-rifting deformation around the Dabbahu rift segment, Afar, Ethiopia

SUMMARY Increased displacement rates have been observed following manylarge earthquakes and mag- matic events. Although an order of magnitude smaller than the displacements associated with the main event, the post-seismic or post-rifting deformation may continue for years to decades after the initial earthquake or dyke intrusion. Due to the rare occurrence of subaerial rifting events,thereareveryfewobservationstoconstrainmodelsofpost-riftingdeformation.In2005 September, a 60-km-long dyke was intruded along the Dabbahu segment of the Nubia-Arabia Plate boundary (Afar, Ethiopia), marking the beginning of an ongoing rifting episode. Con- tinued activity has been monitored using satellite radar interferometry and data from global positioning system instruments deployed around the rift in response to the initial intrusion. Using multiple satellite passes, we are able to separate the rift perpendicular and vertical displacement fields around the Dabbahu segment. Rift perpendicular and vertical rates of up to 180 and 240 mm yr −1 , respectively. Here, we show that models of viscoelastic relaxation alone are insufficient to reproduce the observed deformation field and that a large portion of the observed signal is related to the movement of magma within the rift segment. Our models suggest upper mantle viscosities of 10 18−19 Pas overlain by an elastic crust of between 15 and 30km. To fit the observations, inflation and deflation of magma chambers in the centre of the rift and to the south east of the rift axis is required at rates of ∼0.13 and −0.08km 3 yr −1 .

Soil Fertility Maps Preparation Using GPS and GIS in Dhenkanal District, Odisha, India

Soil fertility maps of Dhenkanal district, Odisha were prepared by using Global Positioning System (GPS) and Geographical Information System (GIS) tomake awareness among the farmers regarding use of balanced fertilization according to soil test based recommendation and integrated nutrient management for higher and sustainable crop production. Soils of different villages for each block were collected b y GPS instrument.

Seasonal velocities of eight major marine-terminating outlet glaciers of the Greenland ice sheet from continuous in situ GPS instruments

Abstract. We present 17 velocity records derived from in situ stand-alone single-frequency Global Positioning System (GPS) receivers placed on eight marine-terminating ice sheet outlet glaciers in South, West and North Greenland, covering varying parts of the period summer 2009 to summer 2012. Common to all the observed glacier velocity records is a pronounced seasonal variation, with an early melt season maximum generally followed by a rapid mid-melt season deceleration. The GPS-derived velocities are compared to velocities derived from radar satellite imagery over six of the glaciers to illustrate the potential of the GPS data for validation purposes. Three different velocity map products are evaluated, based on ALOS/PALSAR data, TerraSAR-X/Tandem-X data and an aggregate winter TerraSAR-X data set. The velocity maps derived from TerraSAR-X/Tandem-X data have a mean difference of 1.5% compared to the mean GPS velocity over the corresponding period, while velocity maps derived from ALOS/PALSAR data have a mean difference of 9.7%. The velocity maps derived from the aggregate winter TerraSAR-X data set have a mean difference of 9.5% to the corresponding GPS velocities. The data are available from the GEUS repository at doi:10.5280/GEUS000001.

Experimental Test of an Articulated Lorry Swept Path

The regulatory requirements limiting the physical dimensions of heavy vehicles and driving skills do not guarantee the feasibility of negotiating the tightest curves of compact roundabouts. The specific evaluations needed for the intersection and the assumed design vehicle are often achieved by setting vehicle movement trajectories via computer programs, given the possibility of changing the design parameters both quickly and economically. The basic requirement for using these programs is their reliability, but they do have some weaknesses and flaws because of necessary simplifications, without which running the simulations would not be workable. A field test based on global positioning system instrumentation was conducted to define the area covered by a heavy vehicle turning in a real compact roundabout, successively compared with the simulated swept path. The preparation and the results of the experiment are described in the present study.

Application of pollution indexes, cluster analysis and isocontent chart to the study of soil pollution

Statistical methods were applied to the assessment of the multi-elements pollution degree of the soil with heavy metals and arsenic (microelements) in Baia Mare area, NW Romania. The content of several microelements were analyzed in soil samples from four zones in the studied area. Pollution indices were used to define the pollution degree compared to the Romanian regulation. Cluster analysis was used to classify the analyzed microelements (Cu, Zn, Pb, Cd, As, Co, Ni, Cr, Sn, Sb). Based on iso-contents maps for Pb and As, their contents in soil in whole Baia Mare area are assessed. The sampling point coordinates (latitude and longitude) were registered with a GPS (Global Positioning System) instrument. Considering the coordinates of each sampling point and the corresponding concentration of the considered microelement in the sampling point, a matrix XYZ was obtained where X was the longitude; Y was the latitude and Z the concentration of the microelements. A continuous surface was generated beginning with each sampling point. The spatial distribution charts drawn for the most hazardous microelements Pb and As indicated some area high polluted around the pollution source (a lead smelter).

Volcano monitoring using GPS: Developing data analysis strategies based on the June 2007 Kīlauea Volcano intrusion and eruption

The global positioning system (GPS) is one of the most common techniques, and the current state of the art, used to monitor volcano deformation. In addition to slow (several centimeters per year) displacement rates, GPS can be used to study eruptions and intrusions that result in much larger (tens of centimeters over hours‐days) displacements. It is challenging to resolve precise positions using GPS at subdaily time intervals because of error sources such as multipath and atmospheric refraction. In this paper, the impact of errors due to multipath and atmospheric refraction at subdaily periods is examined using data from the GPS network on Kīlauea Volcano, Hawai'i. Methods for filtering position estimates to enhance precision are both simulated and tested on data collected during the June 2007 intrusion and eruption. Comparisons with tiltmeter records show that GPS instruments can precisely recover the timing of the activity.