GPS-only, GLONASS-only and Combined GPS+GLONASS Absolute Positioning under Different Sky View Conditions

Abstract

In recent years GNSS measurements techniques obtained a majority role in civil engineering and other technical fields. An example of this is the monitoring of both natural phenomena and manmade constructions. The main advantages of satellite positioning, as opposite to classical surveying techniques like levelling or total stations, are continuous long term observations and economic advantage, due to the lack of measurement crew. Currently, apart from GPS, other satellite systems in use like GLONASS or Galileo are becoming more important. Together with development of GNSS measurements for satellite positioning in open areas, also urban and mountainous areas can be measured. This kind of areas was excluded from measurements with single GNSS system, due to the lack of the required minimum number of visible satellites. Multi-GNSS (hybrid, integrated-usage of more than one satellite navigation system in measurements) positioning, currently providing more than 80 active satellites, opens new grounds for satellite measurements. Among measurement methods PPP is the most developing one since the beginning of 21 st century. Main PPP advantages are: independence from reference station, lack of limitation of use to certain areas and global coverage with consistent, homogenous solutions. The paper shows the results of 90-days continuous static observations processed with the usage of PPP technique on simulated different sky view conditions. Measurements were made on points with known coordinates as a construction simulation. The data were processed in three modes: GPS-only, GLONASS-only and hybrid GNSS (GPS+GLONASS) using three different elevation cutoff angles. Accuracy analyses were carried out on the basis of final, daily EPN solutions at the observation time.

Measurement of the Geometric Center of a Turnout for the Safety of Railway Infrastructure Using MMS and Total Station

“…Laser scanning and global navigation satellite system (GNSS) technology were used for the spatial analysis of railway infrastructure condition geometry [69][70][71][72][73][74][75]. In [71], a cost-benefit analysis of Building Information Modeling (BIM) in the railway area was presented, including many railway tracks, stations, telecommunication facilities, infrastructure facilities, railway structures, etc.…”

“…The digital twins of a railway turnout in 3D include the scheduling, costs, and sustainability across the whole turnout lifecycle. Maciuk [73,74] noted that GNSS plays an important role in civil engineering and other technical fields. A certain level of accuracy is necessary for solving certain surveying and engineering issues [72,73].…”

Satellite clock stability analysis depending on the reference clock type

“…Precise clock products are extremely important in GNSS positioning. It is extremely important firstly in absolute positioning method called PPP (Precise Point Positioning) demanding high-quality products (Alcay et al 2012a;Maciuk 2018a). Secondly, in real-time positioning methods (Krzyżek 2015), available ultra-rapid orbit might improve results contrary to the broadcasted orbit (Maciuk 2016b).…”

Role of Multi-Constellation GNSS in the Mitigation of the Observation Errors and the Enhancement of the Positioning Accuracy

“…The second one is by combination of the raw observation files between different GNSS systems will improve the geometry of the observed satellites that's because increasing the numbers of visible satellites [8]. For this reason, adding the other GNSS satellites systems and make constellation of the different systems will enhance the accuracy specially in urban area as the huge numbers of tracked satellites will give a chance to neglect the weak signals or the weak accuracy satellite [9]. To Avoid the blocking satellite, the observations of the GPS and other GNSS systems like (GLONASS), the (BEIDOU) and (GALILEO) can be combined [10].…”