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The EUREF Permanent Network (EPN) currently consists of more than 300 evenly distributed continuously operating Global Navigation Satellite System (GNSS) reference stations. As a result of the continuous modernization of GNSS systems, the equipment of reference stations is subject to changes and upgrades. Changes relating to GNSS receiver antenna replacement are considered the main reason for discontinuities noticed in station position time series. It is assumed that resulting offsets are primarily caused by changes in carrier phase multipath effects after antenna replacement. However, the observed position shifts may also indicate the deficiency in the antenna phase center corrections (PCC) models. In this paper, we identified and interpreted the coordinate shifts caused by antenna/radome changes at selected EPN stations. The main objective was to investigate the correlation between the offset occurrence and PCC model type (type mean, individual robot-derived, individual chamber-derived) as well as multipath changes after antenna replacement. For the study, GNSS data from 12 EPN stations covering the years 2017–2019 were analyzed. The results proved that the antenna replacement is critical in the context of station coordinates stability and, in most cases, results in visible shifts in the position component time series. For GPS-only solutions, the most stable results were achieved using robot-derived individual PCC models. On the other hand, in the case of GPS + Galileo processing, the most stable results were obtained using chamber-derived individual PCC models. Furthermore, discontinuities due to the antenna change were noticed in the position time series in 75% of GPS + Galileo solutions. On the other hand, multipath changes arising as the result of antenna replacement were responsible, depending on solution type, for 21–42% of variations in the coordinates.

The bottleneck of precise GNSS based applications is caused by the receiver antenna and their precision and accuracy. This work aims to contribute to the design of a model and the development of metrics to estimate and evaluate GPS/GNSS antenna calibration values in several networks. At present, there is neither information on the absolute accuracy of antenna calibration values nor a consistent handling of their uncertainties. Rather, these uncertainties repeatedly introduce inaccuracies into time series, which are used to determine global and regional reference frames as a basis for a broad variety of geophysical approaches such as meteorology, hydrography, etc. Several contributions have addressed the issue of the desired quality of GNSS receiver antenna calibrations and the assessment of their impact on GNSS data processing. All approaches lead to the open question regarding the precision and accuracy as well as stability of receiver antenna phase centre corrections. However, comprehensive and fundamental answers to this scientific question are difficult to achieve as complex interactions prevent simple estimation. In this paper, the authors present results regarding the stability of receiver antenna calibrations in the context of time, calibration facility and strategy to help GNSS operators of regional and global GNSS stations to estimate the impact of calibration values on their sites. The quality of the calibration values also has a direct impact on the derived results, such as the zenith path delay (ZPD). We show that deviations of up to 5 mm for different high-grade antenna types occur. In addition, the normal distribution of pattern differences deviations and systematic effects have been found that lead to drifts and offsets in the parameter domain. The frequency dependence is underlined as well, e.g. L1 versus L2(P) and L2(C). The temporal stability of the calibration values is a fundamental issue, which is discussed in this context. Based on a sample of more than 30 different geodetic grade antennas, we identified variations like drifts and azimuth dependencies with magnitudes of up to 5 mm on each individual frequencies. Furthermore, the stability of the type mean versus individual calibrations shows larger differences on the signals L2 and hence leads to higher variances in the derived ionosphere-free linear combination. The results are examined using PPP time series. The derivation of metrics will be an important step to improve the consistency of regional and global GNSS products.

This paper addresses an approach to assess the impact of phase centre correction errors of selected receiving antennas in the Polish ASG-Eupos network using GNSS processing strategies such as zero differencing and double differencing. The objective is to characterise the nature of the error patterns of GNSS receiver antennas and to understand their impact on GNSS derived integrated water vapour and geodetic estimates. A semi-analytical approach for characterising variants of error patterns is applied. Differences of up to +12 mm between type-mean and individual receiver antenna calibrations of current antenna models on the ionosphere-free linear combination are identified for repeatable pattern deformations. The analyses show that repeatable effects on tropospheric estimates of up to 8 mm – which corresponds to approx. 1.2 kg/m2 – occur even though only 5 mm variations were applied to the pattern. The results of our analysis show a strong correlation with the type of error patterns that affect the estimates differently. Due to the complex relationship between datum settings, processing strategy, baseline orientation and satellite sky distribution, artefacts in GNSS processing models and their effects must to be modelled in order to achieve a better understanding in the context of GNSS networks and GNSS meteorology.

Precise Point Positioning (PPP) is still considered a new technique of GNSS measurements intensively developed in recent years. One of the main advantages of this method is the autonomous mode of m...

Results of long-term static GNSS observation processing adjustment prove that the often assumed “averaging multipath effect due to extended observation periods” does not actually apply. It is instead visible a bias that falsifies the coordinate estimation. The comparisons between the height difference measured with a geometrical precise leveling and the height difference provided by GNSS clearly verify the impact of the near-field multipath effect.The aim of this paper is analysis the near-field interference effect with respect to the coordinate domain. We demonstrate that the way of antennas mounting during observation campaign (distance from nearest antennas) can cause visible changes in pseudo-kinematic precise point positioning results. GNSS measured height differences comparison revealed that bias of up to 3 mm can be noticed in Up component when some object (additional GNSS antenna) was placed in radiating near-field region of measuring antenna. Additionally, for both processing scenario (GPS and GPS/GLONASS) the scattering of results clearly increased when additional antenna crosses radiating near-field region of measuring antenna. It is especially true for big choke ring antennas. In short session (15, 30 min.) the standard deviation was about twice bigger in comparison to scenario without additional antenna. When we used typical surveying antennas (short near-field region radius) the effect is almost invisible. In this case it can be observed the standard deviation increase of about 20%. On the other hand we found that surveying antennas are generally characterized by lower accuracy than choke ring antennas. The standard deviation obtained on point with this type of antenna was bigger in all processing scenarios (in comparison to standard deviation obtained on point with choke ring antenna).

In recent years, the Global Navigation Satellite Systems (GNSS) have been intensively modernized, resulting in the introduction of new carrier frequencies for GPS and GLONASS and the development of new satellite systems such as Galileo and BeiDou (BDS). For this reason, the absolute field antenna calibrations performed so far for the two legacy carrier frequencies, the GPS and GLONASS, seem to be insufficient. Hence, all antennas will require a re-calibration of their phase center variations for the new signals to ensure the highest measurement accuracy. Currently, two absolute calibration methods are used to calibrate GNSS antennas: field calibration using a robot and calibration in an anechoic chamber. Unfortunately, differences in these methodologies also result in a disparity in the obtained antenna phase center corrections (PCC). Therefore, we analyze the differences between individual PCC obtained with these two methods, specifically for the Leica AR-25 antenna model (LEIAR25). In addition, the influence of PCC differences on the GNSS-derived position time series for 19 EUREF Permanent GNSS Network (EPN) stations was also assessed. The results show that the calibration method has a noticeable impact on PCC models. PCC differences determined for the ionosphere-free combination may reach up over 20 mm and can be transferred to the position domain. Further tests concerning the positioning accuracy showed that for horizontal coordinates differences between solutions were mostly below 1 mm, exceeding 2 mm only at two stations for the GLONASS solution. However, the height component differences exceeded 5 mm for four, six and six stations out of 19 for the GPS, GLONASS and Galileo solutions, respectively. These differences are strongly dependent on large L2 calibration differences.

This study investigates the differences between position estimates obtained using individual and type-mean (igs08.atx) antenna calibration models in GPS pseudo-kinematic processing. We used 15-min observation windows to study the short-period oscillations. Continuous GPS observations from eight selected Polish EUREF Permanent Network stations with the same TRM55971.00 TZGD antenna were used. The results showed that the differences in the calibration models, directly propagate into the position domain, affecting sub-daily results and influencing periodic variations. The sub-daily variations have periods close to half a sidereal day with amplitudes of up to 10 mm in position components. It could also be demonstrated that the mean position offsets, resulting from the use of individual calibrations instead of type-mean igs08.atx calibrations, can reach up to 5 mm in the up component, while the offsets in the horizontal components generally remain below 1 mm.

In this paper, the authors analysed the Precise Point Positioning (PPP) performance in determination of normal heights using observations from a test network consisting of ten sites. One-week observation interval was processed using standard PPP approach and Multi-Station PPP (MS-PPP) with ambiguity resolution using the NAvigation Package for Earth Observation Satellites v. 3.3.1 software. In post-processing corrections like the Earth rotation parameters, ocean loadings, antenna phase centre offsets and variations etc. needed to obtain the most accurate position were utilised. By processing the various lengths observing sessions (1 hour, 30 minutes, 15 minutes) the authors examined the degradation of the position determination precision with shortening the observation time. In the study both high-end receivers used most often at CORS, as well as commercial two-frequency receivers were utilised. Normal heights were obtained using PL–geoid–2011 model. The results of the research show that PPP is a viable al...

GNSS derived positioni time-series have many short-and long-periodici variations. These periodicities are commoni to processing of differenti types of GNSS (GPS, GLONASS) measurements. The origini of these oscillations in the positioni time-series may have many reasons. In this paper, satellite constellationi dependent periodicities in phase center correction (PCC) models were analyzed. To provei that the periodic signals in GPS (or GLONASS) derivedi position time-series are relatedi to the imperfectioni in satellite constellation dependenti PCC models, calculationi of Lomb-Scargle spectrumi was performed. In analyses the datai of six selectedi ASG-EUPOS stations were used. Usingi spectral analysis, it was foundi that there is visible periodicity in satellitei constellation dependenti PCC models. The results showi that the periodic signals observedi in the GPS (or GLONASS) derivedi position time-series couldi be the result of imperfectioni in elevation or elevationi and azimuth dependenti error sourcesi modeling.

The phase center corrections (PCC) of an GNSS antenna can be precisely determined using the absolute field calibration procedure with a precise robot. Using the Hannover´s automated absolute antenna field calibration technique developed by the Institute of Geodesy (University of Hannover) and Geo++ we demonstrate that the way of antenna mounting on the robot (distance from mechanical structures mounted underneath the antennas) can cause significant changes in the phase center offset and variations. For both the GPS and the GLONASS carrier signals L1 and L2 these changes are in the order of several millimeters. We also analyzed how these changes transfer to the coordinate domain. We investigated the differences between position estimates obtained using two different, individual and type-mean, elevation dependent PCC. There days of GNSS observations on very short baseline were used for these studies. The position time-series were derived using the RTKLib software package. We found that that the differences in the calibrations models propagate directly into the position domain, affecting sub-daily results and giving visible periodic variations in solutions. The best agreement with the “true position” we obtained using PCC from the individual calibrations. DOI: https://doi.org/10.3846/enviro.2017.183

In developed societies cadastre is fundamental and reference system on land for other land information systems. It protects the legal boundaries of the properties. It is also significant from the point of view of property taxes, urban planning and development of real estate markets. It is important that cadastre reflects the current status on the ground. Any changes in both the physical and legal space relating to real estate should be immediately updated in the system. The article presents the study on the effectiveness of cadastre updating in Poland. The effectiveness of updating cadastral data was examined from the point of view of determined criteria as a case study on the example of two municipalities. The research has shown that the current process of updating cadastre in Poland is far from ideal. The repair solutions were suggested. DOI: https://doi.org/10.3846/enviro.2017.184

The integration of GPS with GLONASS is very important in satellite-based positioning because it can clearly improve reliability and availability. However, unlike GPS, GLONASS satellites transmit signals at different frequencies. This results in significant difficulties in modeling and ambiguity resolution for integrated GNSS positioning. There are also some difficulties related to the antenna Phase Center Variations (PCV) problem because, as is well known, the PCV is dependent on the received signal frequency dependent. Thus, processing simultaneous observations from different positioning systems, e.g. GPS and GLONASS, we can expect complications resulting from the different structure of signals and differences in satellite constellations. The ASG-EUPOS multifunctional system for precise satellite positioning is a part of the EUPOS project involving countries of Central and Eastern Europe. The number of its users is increasing rapidly. Currently 31 of 101 reference stations are equipped with GPS/GLONASS receivers and the number is still increasing. The aim of this paper is to study the height solution differences caused by using different PCV calibration models in integrated GPS/GLONASS observation processing. Studies were conducted based on the datasets from the ASG-EUPOS network. Since the study was intended to evaluate the impact on height determination from the users’ point of view, a so-called “commercial” software was chosen for post-processing. The analysis was done in a baseline mode: 3 days of GNSS data collected with three different receivers and antennas were used. For the purposes of research the daily observations were divided into different sessions with a session length of one hour. The results show that switching between relative and absolute PCV models may cause an obvious effect on height determination. This issue is particularly important when mixed GPS/GLONASS observations are post-processed.

GNSS observations carried out in a network of Continuously Operating Reference Station (CORS) are a complex systems which offer post-processing as well as corrections sent in realtime. In Poland, such a system has been in operation since June 2008, known as the Polish Active Geodetic Network (ASG-EUPOS). Usually the measurements performed in real time characterized lower accuracy than static measurements. For users who demand the highest precision results the post-processing services are provided. The paper presents an analysis of the position determination accuracy using ASG-EUPOS POZGEO service. It is well known that the final accuracy is e.g. the measuring conditions, time of observations or number of measured frequencies dependent. We processed 4 consecutive days of GPS data to determine how the accuracy of derived positional coordinates depends on the length of the observing session, the characteristics of horizon visibility on points and the used in post-processing observations (L1 or L1+L2). The POZGEO results show that horizontal accuracies of about 1-2 cm and vertical accuracies of 4 cm are achievable provided 0.5 hours dual frequency GPS data. The accuracy clearly decreases for point measured under conditions of strongly limited satellite availability

Precise Point Positioning (PPP) is a combination of the original absolute positioning concept and differential positioning techniques. In PPP we use observation data from a single receiver and additional information of GNSS biases and errors derived from permanent networks. Since PPP was developed based only on GPS observations, the accuracy, availability and reliability of positioning is quite dependent on the number of visible satellites. One possible way to increase the availability of satellites is to integrate GPS and GLONASS observations. Nowadays such integration in PPP is available. The PPP technique has an essential advantage over differential methods. The user needs only a single receiver to obtain accurate position. Unfortunately, current commercial software does not provide processing of measurements taken using the PPP technique. This requires using scientific software or one of several on-line PPP services. This paper presents an analysis of the position determination accuracy in PPP mode. We processed 6 consecutive days of GPS+GLONASS data using the on-line PPP-CSRS service to determine how the accuracy of derived three-dimensional positional coordinates depends on the length of the observing session, the characteristics of horizon visibility on points and the observations used in post-processing (GPS or GPS+GLONAS, L1 or L1+L2). The PPP-CSRS results show that horizontal accuracies of about 5 cm and vertical accuracies of 10 cm are achievable provided 0.5 hours of open sky, low multipath dual frequency GPS-only data. The accuracies clearly decrease for points measured under conditions of limited availability of satellites. Unexpectedly, adding GLONASS observations generally does not improve the results in this case.

At least two simultaneously operating receivers are required for differential global navigation satellite system (GNSS) positioning. In this mode, the systematic errors between stations can be estimated or reduced in order to achieve much higher accuracy. Precise point positioning (PPP) is a rather new category. PPP is a combination of the original absolute positioning concept and differential positioning techniques. In PPP we use observation data of a single receiver and additional information on individual GNSS errors derived from a GNSS network, usually from ground based augmentation systems (GBAS). GBAS systems can be divided by the area of operation into global, continental, national or regional ground support systems (e.g. ASG-EUPOS, CORS, SAPOS, SWEPOS). GBAS systems allow users with a single receiver to position in differential mode based on observations from the reference stations. This paper presents an analysis of the position determination accuracy using single receiver GNSS measurements condu...

Precise Point Positioning (PPP) is a technique used to determine highprecision position with a single GNSS receiver. Unlike DGPS or RTK, satellite observations conducted by the PPP technique are not differentiated, therefore they require that parameter models should be used in data processing, such as satellite clock and orbit corrections. Apart from explaining the theory of the PPP technique, this paper describes the available web-based online services used in the post-processing of observation results. The results obtained in the post-processing of satellite observations at three points, with different characteristics of environment conditions, using the CSRS-PPP service, will be presented as the results of the experiment. This study examines the effect of the duration of the measurement session on the results and compares the results obtained by working out observations made by the GPS system and the combined observations from GPS and GLONASS. It also presents the analysis of the position determination accuracy using one and two measurement frequencies

Before 6 November 2006, the International global navigation satellite system (GNSS) Service used relative phase centre models for GNSS antenna receivers. When absolute calibration models were introduced, it resulted in significant differences in the scale of GNSS networks compared to the very long baseline interferometry and side-looking radar measurements. The differences were due to the lack of the GNSS satellite antenna calibration models. This problem was sufficiently resolved and the International GNSS Service decided to switch from relative to absolute models for both satellites and receivers. This decision caused some variations in the results of the GNSS network solutions – especially in the vertical component. To date, the problem of switching from relative to absolute antenna phase centre variations has been mainly considered for global or continental networks using relatively long observation sessions. The aim of this paper was to study the height differences caused by using different c...

GNSS observations in a network of permanent stations are a complex systems which offer both post-processing and corrections sent in real-time. In Poland such a system, known as the Polish Active Geodetic Network (ASG-EUPOS), has been in operation since June 2008. The GNSS development forces also continuous modernization of ASG-EUPOS (e.g.: GPS/GLONASS receivers mounting, ASG+ project) which aims to improve the accuracy of position determination. One of the factors limiting the accuracy (especially the vertical component) is antenna phase center variations (PCV) problem. PCV problem is resolved using the antenna calibration process. As a result, antenna phase center corrections models (PCC) are created. So far three methods have been developed to determine GNSS antenna PCV. For this reason and because of some problems in introducing of absolute models at present we can speak of three models of receiver antennas PCV (so called: relative, absolute converted and absolute). The aim of this paper was to study the height differences caused by using different calibration models in GNSS observation processing done in the ASG-EUPOS POZGEO-D service. The analysis was done using 3 days of GNSS data, collected with four different receivers and antennas, divided by one hour observation sessions. The results of the calculations show that switching between PCV models may have a visible effect on height determination, particularly in high accuracy applications.

It is well known that magnitude of antenna phase center variations (PCV) can reach several centimeters. Unfortunately part of commercial GPS post-processing software does not include corrections related to antenna PCV. This paper presents a proposal of a subroutine which introduces PCV corrections to code and phase observations basing on ANTEX file and RINEX observations and navigation files. This approach has been tested using GPS data collected at four measurement points. Three different types of antenna were used in observations. Observation processing was done with Ashtech Solutions and TopconTools software. The results of calculations show, that the proposed subroutine can be successfully used in commercial software which does not include such correction algorithms. The subroutine can also serve to verify antenna PCV corrections algorithms in commercial software where there is often no possibility of looking into applied algorithms.

So far, three methods have been developed to determine GNSS antenna phase center variations (PCV). For this reason, and because of some problems in introducing absolute models, there are presently three models of PCV receiver antennas (relative, absolute converted and absolute) and two satellite antennas (standard and absolute). Additionally, when simultaneously processing observations from different positioning systems (e.g. GPS and GLONASS), we can expect a further complication resulting from the different structure of signals and differences in satellite constellations. This paper aims at studying the height differences in short static GPS/GLONASS observation processing when different calibration models are used. The analysis was done using 3 days of GNSS data, collected with three different receivers and antennas, divided by half hour observation sessions. The results show that switching between relative and absolute PCV models may have a visible effect on height determination, particularly in high accuracy applications. The problem is especially important when mixed GPS/GLONASS observations are processed. The update of receiver antenna calibrations model from relative to absolute in our study (using LEIAT504GG, JAV_GRANT-G3T and TPSHIPER_PLUS antennas) induces a jump (depending on the measurement session) in the vertical component within to 1.3 cm (GPS-only solutions) or within 1.9 cm (GPS/GLONASS solutions).

It is generally known that the phase center of a GNSS antenna is not a stable point. For any given GNSS antenna, the phase centers will change with the changing direction of the signal from a satellite. The problem is particularly important when different antennae are used in measurements. Ignoring these phase center variations in measurements can lead to serious vertical errors. The way to avoid these errors is by applying antenna phase center variation models in processing. Three major methods are presently available to determine mean antenna phase center offsets as well as variations of the phase center with elevation and azimuth for GNSS receiver antennas. Because of this and because of some problems in introducing of absolute models at present we can speak of three models of receiver antennas PCV (relative, absolute converted and absolute) and two of satellites antennas (standard and absolute). Additionally, processing simultaneously observations from different positioning systems e.g. GPS and GLONASS, we can expect a further complication resulting from different structure of signals and differences in satellites constellations. The aim of this paper is to study the height differences in short static GPS/GLONASS observations processing when different calibration models are used. The analysis was done using 24 hour GNSS data divided by one hour observation sessions. The results show that switching between different PCV models may have a visible effect on height determination, particularly in high accuracy applications.

Precise Point Positioning is a relatively new technique which can be used to determine high precision 3D position by processing of observations from a single GNSS receiver. For this reason some errors that are mostly eliminated in the differential approach have to be estimated in the PPP. These errors, which are mainly related to physical phenomena, include e.g.: solid earth and ocean tides, carrierphase wind-up, relativistic effects, etc. On the other hand no base stations and no simultaneous observations are necessary to determine receiver position. In recent years, the development of PPP method and GNSS systems allows to effectively deal with the disadvantages of this technique, such as slow convergence times, problematic ambiguity resolution etc. The aim of this paper is to study the position determination accuracy obtained using PPP technique. Because current commercial software packages do not provide the processing of measurements done using PPP, it is necessary to use scientific software or one of several online services. We processed daily GNSS observations that have been made at two points characterized by different environment conditions. The post-processing of observations covered a variety of development strategies, such as different measurement intervals (0.5 h, 1 h, 2 h, 4 h) or utilization combined observations from GPS and GLONASS systems.

Sea level is traditionally observed with tide gauges (TG). These measurements are relative to the Earth’s crust. To improve the understanding of sea level changes it is necessary to perform measure - ments with respect to the Earth’s center of mass. This can be done with satellite techniques. Global Navigation Satellite System (GNSS) is a tool that can solves several hundred kilometers vectors with centimeter level of accuracy and can measure point height changes relative to the reference ellipsoid WGS84 which is centred at the actual center of mass of the Earth. Although in the past two decades GNSS were used in almost every field of geodetic measurements, it is still almost not in use in the field of sea level monitoring. Attempts of using GNSS equipped buoys for the determination of precise sea level (at centimeter level) were successful and suggest that GNSS is capable of replacing the conventional tide gauges. A review of recent efforts made on observing sea level variations using data from a GNSS receivers were presented here. Furthermore, presented review resulted in a conclusion that the use of a GNSS based Tide Gauge (GNSSTG) system for the determination of sea level changes is possible,and that its accuracy level (averaged) is equal to a float based tide gauge. More than that, an absolute change of sea level should be easier to be determined using GNSSTG system., Razina mora se tradicionalno promatra s mareografima (TG). Ova mjerenja se odnose na Zemljinu koru. Kako biste poboljšali razumijevanje promjena razine mora potrebno je izvršiti mjerenja s obzirom na središte Zemlje mase. Takva mjerenja se provode pomoću sateliteskih tehnika (metoda).Globalni navigacijski satelitski sustav (GNSS) je alat koji može izmjeriti nekoliko stotina kilom -etara vektora s razinom točnosti do u centimetar, te može izmjeriti visinu točke promjene u odnosu na referentnog elipsoida WGS84 koji je usmjeren na stvarni centar Zemljine mase.Iako se u posljednja dva desetljeća GNSS upotrebljava u gotovo svakom području geodetskih mjerenja, ipak još uvijek gotovo da nije u uporabi u području praćenja razine mora. Pokušaji primjene plutača opremljenih GNSS-om za određivanje precizne razine mora (na razini centimetara) bili su uspješni, a ukazuju na to da GNSS može zamijeniti konvencionalne mareografe. Pregled posljednjih promatranja promjena razine mora u kojima se koriste podaci iz GNSS prijemnika su prikazane u ovom radu. Nadalje, predstavljeni pregled u ovom radu rezultirao je zaključkom da se korištenje GNSS temelji na mareografskom (GNSSTG) sustavu za određivanje promjena razine mora, a da je njegova točnost razine (u prosjeku) jednaka plutajućem plovku mareografa. Štoviše, apsolutna promjena visine trebala bi se lakše moći odrediti pomoću GNSSTG sustava.

GNSS antenna phase center variations (PCV) are defined as shifts in positions depending on the observed elevation angle and azimuth to the satellite. When identical antennae are used in relative measurement the phase center variations will cancel out, particularly over short baselines. When different antennae are used, even on short baselines, ignoring these phase center variations can lead to serious (up to 10 cm) vertical errors. The only way to avoid these errors, when mixing different antenna types, is by applying antenna phase center variation models in processing. Till the 6th November 2006, the International GNSS Service used relative phase center models for GNSS antenna receivers. Then absolute calibration models, developed by the company "Geo++", started to be used. These models involved significant differences on the scale of GNSS networks compared to the VLBI and SLR measurements. The differences were due to the lack of the GNSS satellite antenna calibration models. When this problem was sufficiently resolved, the IGS decided to switch from relative to absolute models for both satellites and receivers. This decision caused significant variations to the results of the GNSS network solutions. The aim of this paper is to study the height differences in short baseline GNSS observations processing when different calibration models are used. The analysis was done using GNSS data collected at short baselines moved with different receiver antennas. The results of calculations show, that switching from relative to absolute receiver antenna PCV models has a significant effect on GNSS network solutions, particularly in high accuracy applications.